CN110620741B

CN110620741B - Carrier modulation method, device and storage medium

Info

Publication number: CN110620741B
Application number: CN201810630925.2A
Authority: CN
Inventors: 万成
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2018-06-19
Filing date: 2018-06-19
Publication date: 2020-12-04
Anticipated expiration: 2038-06-19
Also published as: CN110620741A

Abstract

The application provides a carrier modulation method, a carrier modulation device and a storage medium, which can be applied to the field of electric intelligent automobiles to reduce the capacitance value of a capacitor in a motor controller. In the application, the requirement on the capacitance value of the direct current capacitor is reduced in a carrier phase-staggered mode, and the capacitor with a small capacitance value is arranged in the direct current converter, so that the effect which can be achieved by the capacitor with a large capacitance value originally can be achieved, and the volume occupied by the capacitor is reduced. In addition, the first direct current converter can judge whether the first direct current converter and the second direct current converter are in carrier-phase-dislocation according to the direct current voltage of the capacitor in the first direct current converter, the purpose of carrier-phase-dislocation can be achieved by adjusting the phase of the carrier of the first direct current converter and the second direct current converter, communication with the second direct current converter is not needed, and an additional signal line does not need to be arranged between the first direct current converter and the second direct current converter. In addition, the electronic equipment has universality, and the scheme provided by the application can be operated in any electronic equipment with at least two direct current converters so as to reduce the requirement on the capacitance value of the capacitor.

Description

Carrier modulation method, device and storage medium

Technical Field

The present disclosure relates to the field of electronic technologies, and in particular, to a carrier modulation method, a carrier modulation apparatus, and a storage medium.

Background

The electric Vehicle includes a Vehicle Control Unit (VCU), a Motor Control Unit (MCU), and a Motor. During driving, the VCU generates a control command according to the operation of a driver and sends the control command to the MCU. MCU includes signal generator, modulator, switch and direct current electric capacity, and signal generator can produce the carrier, exports the carrier to the modulator, and the modulator can be according to control command, modulates the carrier, obtains switching signal, through the break-make of switching signal control switch, produces output current, and output current can drive motor and produce torque and rotational speed to control electric automobile's the running state.

The direct current capacitor in the MCU is a key component, can stabilize the direct current voltage input to the MCU, provides instantaneous input current for the MCU, but occupies a large volume. Because of the limited space of the vehicle, how to reduce the volume of the direct current capacitor of the MCU is always the focus of attention of each large vehicle factory. And because the larger the capacitance value of the direct current capacitor is, the larger the volume of the direct current capacitor is, therefore, by reducing the requirement on the capacitance value of the direct current capacitor, the direct current capacitor with smaller volume can be placed in the MCU, thereby reducing the volume of the direct current capacitor in the MCU.

There is an electric vehicle, a circuit diagram of which is shown in fig. 1, and the electric vehicle further includes a Direct current to Direct current (Direct Cu) based on a VCU, an MCU and a motorThe Current to Direct Current is hereinafter referred to as: DCDC) converter, which is cascaded with the MCU. In the electric automobile, the MCU and the DCDC are controlled to keep carrier synchronization through a carrier synchronization technology, namely, the phases of the MCU and the DCDC are controlled to be kept the same. Then, since the phase of the carrier wave determines the phase of the switching signal modulated by the carrier wave, and the phase of the switching signal determines the phase of the output current generated by the switching signal, the phases of the output current of the MCU and the output current of the DCDC are kept in synchronization, and since the output current of the MCU and the phase of the input current of the MCU are kept in synchronization, the input current of the MCU and the phase of the output current of the DCDC are kept in synchronization. Then, icap represents the current flowing through the capacitor, iinv represents the input current of the MCU, iconv represents the output current of the DCDC, and at the node indicated by the arrow in fig. 1, according to kirchhoff's current law (hereinafter, KCL's law), the following can be obtained: icap + iconv, and therefore icap-iinv, and since iinv and iconv are in phase synchronization, at any one time icap is reduced by the subtraction of the two amplitudes, according to the capacitance-current equation

The current flowing through the capacitor is reduced, and the requirement for the capacitance value of the direct current capacitor is reduced.

In the specific process of carrier synchronization, since the DCDC converter and the MCU are two independent systems, the DCDC converter and the MCU need to be connected by a signal line, so as to transmit a carrier synchronization signal between the DCDC converter and the MCU through the signal line. Specifically, the DCDC converter generates a carrier synchronization signal according to the current carrier phase, and transmits the carrier synchronization signal to the MCU through the signal line, where the carrier synchronization signal carries the phase of the DCDC converter carrier. After receiving the carrier synchronization signal, the MCU determines the phase of the carrier of the DCDC converter according to the carrier synchronization signal, calculates the phase difference between the carrier of the MCU and the carrier of the DCDC converter, adjusts the phase of the carrier of the MCU according to the phase difference, and compensates the phase difference, so that the carrier of the MCU and the carrier of the DCDC converter are kept synchronous.

In the course of implementing the present application, the inventors found that the related art has at least the following problems:

the requirement on the capacitance value of the direct current capacitor is reduced in a carrier synchronization mode, on one hand, a controller of the DCDC and a controller of the MCU need to be connected through a signal wire, and the connection of the signal wire requires that the controller of the DCDC and the controller of the MCU need to be close to each other in space, so that great inconvenience is brought to the manufacturing and assembling of the electric automobile. On the other hand, the method has no universality, and can only be applied to the condition that the MCU and the DCDC converter are cascaded, but the method cannot be applied to reduce the requirement on the capacitance value of the direct current capacitor of the MCU without the DCDC converter, so that the volume of the direct current capacitor cannot be reduced.

Disclosure of Invention

The embodiment of the application provides a carrier modulation method, a carrier modulation device and a storage medium, which can solve the technical problem that the requirement on the capacitance value of a capacitor in an MCU can be reduced only by connecting the MCU with a DCDC converter through a signal wire in the related technology. The technical scheme is as follows:

in a first aspect, a method for modulating a carrier is provided, the method comprising:

detecting a direct current voltage of a capacitor in the first direct current converter;

determining that the carrier phase difference of the first direct current converter and the second direct current converter does not reach a preset phase difference according to the direct current voltage of a capacitor in the first direct current converter, wherein the first direct current converter is electrically connected with the second direct current converter;

adjusting a phase of a carrier of the first DC converter.

According to the method provided by the embodiment, the requirement on the capacitance value of the direct current capacitor is reduced in a carrier phase-staggered manner, on one hand, the input current amplitude of the first direct current converter and the second direct current converter is reduced, so that the amplitude of the input current required to be provided by the capacitor is reduced, and the requirement on the capacitance value of the capacitor is reduced.

On the other hand, the first direct current converter can determine whether the first direct current converter and the second direct current converter are in carrier-staggered phase or not according to the direct current voltage of the capacitor in the first direct current converter, and when the first direct current converter and the second direct current converter are not in carrier-staggered phase, the carrier-staggered phase of the first direct current converter and the second direct current converter can be realized by adjusting the phase of the carrier of the first direct current converter and the second direct current converter without communicating with the second direct current converter, so that the harsh limitation that the first direct current converter and the second direct current converter need to communicate with each other is eliminated, an additional signal wire does not need to be arranged between the first direct current converter and the second direct current converter, and the manufacturing and assembling processes of the electronic equipment are facilitated.

On the other hand, the method has universality, can be applied to any electronic equipment with two or more direct current converters, and does not need to require the direct current converter to be connected with a DCDC converter, so that the technical scheme provided by the application can be applied to the situation without the DCDC converter, and the requirement on the capacitance value of the direct current capacitor of the MCU is reduced.

On the other hand, in the carrier synchronization technology, a current sensor needs to be additionally arranged to detect the input current of the capacitor. And through the carrier wave phase-dislocation technique that this application provided, through the voltage sensor who takes certainly in the dc converter, can detect the dc voltage of electric capacity to accomplish the process of carrier wave phase-dislocation, and need not to detect the input current of electric capacity, also need not to set up extra current sensor for the process of measuring current yet, greatly practiced thrift the cost, and made things convenient for dc converter's manufacturing and assembly process.

On the other hand, in the carrier synchronization technology, a carrier synchronization signal needs to be transmitted between the MCU and the DCDC converter to perform carrier synchronization, and the carrier synchronization signal is easily interfered by the environment, which makes it difficult to perform carrier synchronization between the MCU and the DCDC converter accurately, and further makes it impossible to reduce the requirement on the capacitance value of the capacitor. In the application, a synchronous signal does not need to be transmitted between the first direct current converter and the second direct current converter, the first direct current converter can realize the purpose of phase dislocation with the second direct current converter by adjusting the phase of the carrier of the first direct current converter, the interference of the environment is avoided, and the accuracy of the control process is improved.

In a possible implementation manner, the determining that the carrier phase difference between the first dc converter and the second dc converter does not reach a preset phase difference according to the dc voltage of the capacitor in the first dc converter includes:

judging whether the direct-current voltage of a capacitor in the first direct-current converter is greater than a preset direct-current voltage threshold value or not, wherein the preset direct-current voltage threshold value is determined according to the direct-current voltage of a capacitor in a direct-current converter i, when the direct-current voltage of the capacitor in the direct-current converter i is the carrier phase difference of two electrically connected direct-current converters and reaches the preset phase difference, the direct-current voltage of the capacitor in the direct-current converter i is the minimum value of the direct-current voltage of the capacitor in the direct-current converter i, and the direct-current converter i is any one of the two direct-;

and if the direct-current voltage of the capacitor in the first direct-current converter is larger than a preset direct-current voltage threshold value, determining that the carrier phase difference between the first direct-current converter and the second direct-current converter does not reach the preset phase difference.

In a possible implementation manner, the determining the preset dc voltage threshold according to the dc voltage of the capacitor in the dc converter i includes:

and the difference value between the preset direct-current voltage threshold value and the minimum value of the direct-current voltage of the capacitor in the direct-current converter i is within a preset range.

In one possible implementation, the two dc converters are the first dc converter and the second dc converter, and the dc converter i is the first dc converter.

In a possible implementation manner, the determining whether the dc voltage of the capacitor in the first dc converter is greater than a preset dc voltage threshold includes:

judging whether the direct current voltage of a capacitor in the first direct current converter is larger than a preset direct current voltage threshold corresponding to a preset torque, wherein the preset torque is the torque of a motor electrically connected with the first direct current converter, the preset direct current voltage threshold is determined according to the torque of a motor i, the motor i is electrically connected with the direct current converter i, the carrier phase difference of two electrically connected direct current converters of the direct current voltage of the capacitor in the direct current converter i reaches the preset phase difference, and when the torque of the motor i is the preset torque, the minimum value of the direct current voltage of the capacitor in the direct current converter i is obtained.

Through the implementation mode, the corresponding direct current voltage threshold values are respectively set for the preset torques of various sizes, and in operation, the corresponding direct current voltage threshold values are determined by combining the current torque, so that the matching of the used direct current voltage threshold values and the current operation condition can be ensured, the matching of the process for detecting whether the carrier is in a phase error state with the current operation condition is also ensured, the accuracy of the process for detecting the carrier in a phase error state is high, and the method is suitable for complex and variable use environments and operation conditions.

In one possible implementation, the motor i is an electric motor to which the first dc converter is electrically connected.

judging whether the direct current voltage of a capacitor in the first direct current converter is greater than a preset direct current voltage threshold corresponding to a preset rotating speed, wherein the preset rotating speed is the rotating speed of a motor electrically connected with the first direct current converter, the preset direct current voltage threshold is determined according to the rotating speed of a motor i, the carrier phase difference of the two direct current converters electrically connected with the direct current voltage of the capacitor in the direct current converter i reaches the preset phase difference, and when the rotating speed of the motor i is the preset rotating speed, the direct current voltage of the capacitor in the direct current converter i is the minimum value.

Through the implementation mode, the corresponding direct current voltage threshold values are respectively set for the preset rotating speeds of various sizes, and in operation, the corresponding direct current voltage threshold values are determined by combining the current rotating speed, so that the matching of the used direct current voltage threshold values and the current operation condition can be ensured, the matching of the process for detecting whether the carrier is in a phase error state and the current operation condition is also ensured, the accuracy of the process for detecting the carrier in the phase error state is high, and the method is suitable for complex and variable use environments and operation conditions.

judging whether the direct current voltage of a capacitor in the first direct current converter is larger than a preset direct current voltage threshold corresponding to preset output power, wherein the preset output power is the output power of a motor electrically connected with the first direct current converter, the preset direct current voltage threshold is determined according to the output power of a motor i, the carrier phase difference of the two direct current converters electrically connected with the direct current voltage of the capacitor in the direct current converter i reaches the preset phase difference, and when the output power of the motor i is the preset output power, the direct current voltage of the capacitor in the direct current converter i is the minimum value.

Through the implementation mode, the corresponding direct current voltage threshold values are respectively set for the preset output powers with various sizes, and in operation, the corresponding direct current voltage threshold values are determined by combining the current output power, so that the matching of the used direct current voltage threshold values and the current operation condition can be ensured, the matching of the process of detecting whether the carrier is in a phase error state with the current operation condition is also ensured, the accuracy of the process of ensuring the carrier phase error is high, and the method is suitable for complex and variable use environments and operation conditions.

judging whether the direct current voltage of a capacitor in the first direct current converter is larger than a preset direct current voltage threshold corresponding to preset output current, wherein the preset output current is the output current of a motor electrically connected with the first direct current converter, the preset direct current voltage threshold is determined according to the output current of a motor i, the carrier phase difference of the two direct current converters electrically connected with the direct current voltage of the capacitor in the direct current converter i reaches the preset phase difference, and when the output current of the motor i is the preset output current, the direct current voltage of the capacitor in the direct current converter i is the minimum value.

Through the implementation mode, the corresponding direct current voltage threshold values are respectively set for the preset output currents of various sizes, and in operation, the corresponding direct current voltage threshold values are determined by combining the current output currents, so that the matching of the used direct current voltage threshold values and the current operation condition can be ensured, the matching of the process of detecting whether the carrier is in a phase dislocation state and the current operation condition is also ensured, the accuracy of the process of ensuring the carrier is high, and the method is suitable for complex and variable use environments and operation conditions.

judging whether the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is the carrier frequency of the first direct-current converter;

and if the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is the carrier frequency of the first direct-current converter, determining that the carrier phase difference between the first direct-current converter and the second direct-current converter does not reach a preset phase difference.

judging whether the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is smaller than a harmonic frequency threshold value, wherein the harmonic frequency threshold value is determined according to the carrier frequency of the first direct-current converter;

and if the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is smaller than the harmonic frequency threshold value, determining that the carrier phase difference between the first direct-current converter and the second direct-current converter does not reach a preset phase difference.

In one possible implementation, the harmonic frequency threshold is a preset multiple of the carrier frequency of the first dc-to-dc converter, and the preset multiple is greater than 1 and less than 2.

In one possible implementation, the adjusting the phase of the carrier of the first dc converter includes:

selecting a carrier having a phase different from a current phase from a plurality of carriers based on the current phase of the carrier of the first DC converter, the plurality of carriers having different phases.

In one possible implementation, before the adjusting the phase of the carrier of the first dc converter, the method further includes:

and generating the plurality of carriers based on a preset phase, wherein the carrier phase difference of any two adjacent carriers in the plurality of carriers is the preset phase.

Through the implementation mode, the first direct current converter reselects the carrier from the input multiple carriers when the carrier needs to be subjected to phase shifting, on one hand, the reselected carrier has a certain phase difference with the originally selected carrier, and after the carrier is reselected, the phase of the currently modulated carrier changes, so that the purpose of changing the phase of the carrier is achieved. On the other hand, the phase of each carrier can be preset, when the carrier phase shifting is to be performed, how large phase needs to be adjusted is not required to be provisionally calculated according to the current phase of the carrier, the phase step length of the phase shifting is not required to be provisionally calculated, and only the carrier is required to be reselected from a plurality of input carriers, so that the strong stability of the control process is ensured, and the condition of carrier phase disorder is not caused. On the other hand, the phase of the carrier can be adjusted to a preset phase by switching the selected carrier once, the phase shifting speed is high, the phase shifting efficiency is high, and meanwhile, the processing logic is simple.

In one possible implementation, after the adjusting the phase of the carrier of the first dc converter, the method further includes:

maintaining the phase of the carrier of the first DC converter constant for at least one period of the carrier of the first DC converter.

By the implementation mode, the first direct current converter can at least achieve the following technical effects every time the phase of the carrier wave is adjusted, namely, the carrier wave is delayed for a certain time: if the phase of the carrier is adjusted in real time, for example, the carrier is replaced in real time among a plurality of carriers, which may cause the switching voltage to be disturbed, and the control is unstable, after the phase of the carrier is adjusted once, the phase of the carrier is kept unchanged in at least one carrier period, and then the phase of the carrier is adjusted again, which may ensure the switching voltage to be stable, thereby ensuring the control stability of the dc converter and ensuring the carrier state to be rapidly converged.

In a possible implementation manner, the number of the at least one period is N × N, where N is a ratio between the preset phase difference and a preset phase, and the preset phase is a phase step of each adjustment of a carrier of the first dc converter.

In a second aspect, there is provided a carrier modulation apparatus, the apparatus comprising:

the detection module is used for detecting the direct-current voltage of the capacitor in the first direct-current converter;

the determining module is used for determining that the carrier phase difference of the first direct current converter and the second direct current converter does not reach a preset phase difference according to the direct current voltage of the capacitor in the first direct current converter, and the first direct current converter is electrically connected with the second direct current converter;

an adjustment module for adjusting a phase of a carrier of the first DC converter

In one possible implementation manner, the determining module includes:

the judging submodule is used for judging whether the direct-current voltage of the capacitor in the first direct-current converter is greater than a preset direct-current voltage threshold value or not, wherein the preset direct-current voltage threshold value is determined according to the direct-current voltage of the capacitor in the direct-current converter i, when the carrier phase difference of two electrically connected direct-current converters reaches the preset phase difference, the direct-current voltage of the capacitor in the direct-current converter i is the minimum value of the direct-current voltage of the capacitor in the direct-current converter i, and the direct-current converter i is any one of the two direct-current converters;

the determining submodule is used for determining that the carrier phase difference between the first direct current converter and the second direct current converter does not reach the preset phase difference if the direct current voltage of the capacitor in the first direct current converter is larger than a preset direct current voltage threshold value.

In one possible implementation, a difference between the preset dc voltage threshold and a minimum value of the dc voltage of the capacitor in the dc converter i is within a preset range.

In a possible implementation manner, the determining submodule is configured to determine whether a dc voltage of a capacitor in the first dc converter is greater than a preset dc voltage threshold corresponding to a preset torque, where the preset torque is a torque of a motor electrically connected to the first dc converter, the preset dc voltage threshold is further determined according to a torque of a motor i, the motor i is electrically connected to the dc converter i, a carrier phase difference between two dc converters electrically connected to the dc voltage of the capacitor in the dc converter i reaches the preset phase difference, and when the torque of the motor i is the preset torque, a minimum value of the dc voltage of the capacitor in the dc converter i is obtained.

In a possible implementation manner, the determining submodule is configured to determine whether a dc voltage of a capacitor in the first dc converter is greater than a preset dc voltage threshold corresponding to a preset rotation speed, where the preset rotation speed is a rotation speed of a motor electrically connected to the first dc converter, the preset dc voltage threshold is further determined according to a rotation speed of a motor i, a carrier phase difference between two dc converters electrically connected to the dc voltage of the capacitor in the dc converter i reaches the preset phase difference, and when the rotation speed of the motor i is the preset rotation speed, a minimum value of the dc voltage of the capacitor in the dc converter i is obtained.

In a possible implementation manner, the determining submodule is configured to determine whether a dc voltage of a capacitor in the first dc converter is greater than a preset dc voltage threshold corresponding to a preset output power, where the preset output power is an output power of a motor electrically connected to the first dc converter, the preset dc voltage threshold is further determined according to the output power of a motor i, a carrier phase difference between two dc converters electrically connected to the dc voltage of the capacitor in the dc converter i reaches the preset phase difference, and when the output power of the motor i is the preset output power, a minimum value of the dc voltage of the capacitor in the dc converter i is obtained.

In a possible implementation manner, the determining submodule is configured to determine whether a dc voltage of a capacitor in the first dc converter is greater than a preset dc voltage threshold corresponding to a preset output current, where the preset output current is an output current of a motor electrically connected to the first dc converter, the preset dc voltage threshold is further determined according to an output current of a motor i, a carrier phase difference between two dc converters electrically connected to the dc voltage of the capacitor in the dc converter i reaches the preset phase difference, and when the output current of the motor i is the preset output current, a minimum value of the dc voltage of the capacitor in the dc converter i is obtained.

In one possible implementation manner, the determining module includes:

the judging submodule is used for judging whether the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is the carrier frequency of the first direct-current converter;

and the determining submodule is used for determining that the carrier phase difference between the first direct current converter and the second direct current converter does not reach a preset phase difference if the harmonic frequency of the direct current voltage of the capacitor in the first direct current converter is the carrier frequency of the first direct current converter.

In one possible implementation manner, the determining module includes:

the judgment submodule is used for judging whether the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is smaller than a harmonic frequency threshold value, wherein the harmonic frequency threshold value is determined according to the carrier frequency of the first direct-current converter;

and the determining submodule is used for determining that the carrier phase difference between the first direct current converter and the second direct current converter does not reach a preset phase difference if the harmonic frequency of the direct current voltage of the capacitor in the first direct current converter is smaller than the harmonic frequency threshold value.

In a possible implementation manner, the adjusting module is configured to select, based on a current phase of a carrier of the first dc converter, a carrier with a phase different from the current phase from a plurality of carriers, where the plurality of carriers are different in phase.

In one possible implementation, the apparatus further includes:

and the carrier generation module is used for generating the plurality of carriers based on a preset phase, and the carrier phase difference of any two adjacent carriers in the plurality of carriers is the preset phase.

In one possible implementation, the apparatus further includes:

a maintaining module for maintaining a phase of a carrier of the first DC converter unchanged during at least one period of the carrier of the first DC converter.

In a third aspect, a dc converter is provided, where the dc converter includes a processor and a memory, where the memory stores at least one instruction, and the instruction is loaded and executed by the processor to implement the first aspect and the carrier modulation method in any possible implementation of the first aspect.

In one possible implementation, the dc converter further includes a signal selector for selecting a carrier having a phase different from a current phase of a carrier of the first dc converter from a plurality of carriers based on the current phase, the plurality of carriers having different phases.

In one possible implementation, the dc converter further includes a signal generator, and the signal generator is configured to generate the plurality of carriers based on a preset phase, where a phase difference between any two adjacent carriers in the plurality of carriers is the preset phase.

In a fourth aspect, an electronic device is provided, which includes a first dc converter and a second dc converter, the first dc converter being configured to perform the carrier modulation method according to the first aspect and any one of the possible implementations of the first aspect.

In a fifth aspect, there is provided a computer-readable storage medium having at least one instruction stored therein, the instruction being loaded and executed by a processor to implement the first aspect and the carrier modulation method in any possible implementation of the first aspect.

Drawings

Fig. 1 is a schematic diagram of a carrier modulation method provided in the related art;

fig. 2 is a schematic structural diagram of a dc converter system according to an embodiment of the present application;

FIG. 3 is a schematic structural diagram of an electric vehicle according to an embodiment of the present disclosure;

fig. 4 is a waveform diagram of an input current provided by capacitors before and after a carrier phase error according to an embodiment of the present application;

FIG. 5 is a schematic structural diagram of an electric vehicle according to an embodiment of the present application;

fig. 6 is a waveform diagram of an input current provided by capacitors before and after a carrier phase error according to an embodiment of the present application;

FIG. 7 is a schematic structural diagram of an electric vehicle according to an embodiment of the present application;

FIG. 8 is a schematic structural diagram of an electric vehicle according to an embodiment of the present application;

fig. 9 is a waveform diagram of an input current provided by capacitors before and after a carrier phase error according to an embodiment of the present application;

fig. 10 is a schematic structural diagram of an electrodynamic transducer provided in an embodiment of the present application;

fig. 11 is a schematic structural diagram of an electrodynamic transducer provided in an embodiment of the present application;

fig. 12 is a schematic structural diagram of an electrodynamic transducer provided in an embodiment of the present application;

fig. 13 is a schematic structural diagram of an electronic device according to an embodiment of the present application;

FIG. 14 is a schematic structural diagram of an electric vehicle according to an embodiment of the present application;

fig. 15 is a circuit diagram of an electric vehicle according to an embodiment of the present application;

fig. 16 is a system architecture diagram of an electric vehicle according to an embodiment of the present application;

fig. 17 is a circuit diagram of an electric vehicle according to an embodiment of the present application;

fig. 18 is a circuit diagram of an electric vehicle according to an embodiment of the present application;

fig. 19 is a flowchart of a carrier modulation method according to an embodiment of the present application;

fig. 20 is a schematic diagram of a carrier modulation method according to an embodiment of the present application;

fig. 21 is a schematic diagram of a carrier modulation method according to an embodiment of the present application;

fig. 22 is a flowchart of carrier switching according to an embodiment of the present disclosure;

fig. 23 is an experimental effect diagram of a carrier modulation method according to an embodiment of the present application;

fig. 24 is an experimental effect diagram of a carrier modulation method according to an embodiment of the present application;

fig. 25 is an experimental effect diagram of a carrier modulation method according to an embodiment of the present application;

fig. 26 is a schematic structural diagram of a carrier modulation apparatus according to an embodiment of the present application.

Detailed Description

To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

Fig. 2 is a schematic structural diagram of a dc converter system according to an embodiment of the present disclosure, where the dc converter system includes a plurality of dc converters electrically connected to each other, for example, the plurality of dc converters may be connected in parallel to a dc network.

The direct current converter system can be connected with a power supply and a load circuit, and is used for converting electric energy of the power supply and outputting the converted electric energy to the load circuit so as to supply power to the load circuit. Specifically, after the power source outputs a dc voltage, the dc converter system may receive the input dc voltage and convert the dc voltage into an ac voltage, for example, the dc converter system may convert the dc voltage into an ac voltage and/or an ac current, thereby outputting the ac voltage to the load circuit.

In the operation of the dc converter system, for the capacitor of each dc converter in the dc converter system, the capacitor not only needs to provide the input current for the dc converter in which the capacitor is located, but also needs to provide the input current for the other dc converters in the dc converter system because the dc converter in which the capacitor is located is electrically connected with the other dc converters in the dc converter system, that is, the input current actually provided by the capacitor is the sum of the input currents provided for each dc converter in the dc converter system. Therefore, in this embodiment, by reducing the sum of the input currents required by each dc converter in the dc converter system, the amplitude of the input current actually provided by the capacitor can be reduced, thereby reducing the capacitance requirement on the capacitor.

The dc converter system provided by the embodiment can be applied to various scenes, and the physical form of the dc converter can be determined according to actual requirements.

In an exemplary application scenario, in an electric vehicle, the dc converter may be provided as an MCU in the electric vehicle, and accordingly, the dc converter system may be provided as an MCU system in the electric vehicle. The electric automobile comprises but not limited to passenger cars, bus cars, commercial vehicles and fuel cell vehicles, the electric automobile is provided with two or more MCUs, and the specific number of the MCUs and the position of each MCU in the electric automobile can be determined according to actual requirements.

For example, the system architecture of the electric vehicle may include the following (1) to (4), and in the following four electric vehicles, the capacitance requirement on the capacitor in the MCU may be reduced by the carrier-induced phase-shifting technique provided in the present application.

(1) Referring to fig. 3, fig. 3 is a system architecture diagram of an electric vehicle according to an embodiment of the present application, where the electric vehicle has two MCUs, and adopts a front-rear single-drive architecture, two front wheels are driven by one MCU, and two rear wheels are driven by another MCU. In the electric vehicle, any one of the two MCUs may execute the carrier modulation method provided by the embodiment of the present application, so that the carriers of the two MCUs are out of phase.

Taking two MCUs as the MCU1 and the MCU2, and the MCU2 executes the carrier modulation method provided by the embodiments of the present application as an example, in the operation of the electric vehicle, the MCU1 can be regarded as a reference object when the MCU2 carries out the phase shift, and the MCU1 does not need to adjust the phase of the carrier, and can keep the phase of the carrier unchanged. The MCU2 can detect the dc voltage of its own capacitor in real time, and whenever the phase difference between the carriers of the MCU2 and the MCU1 does not reach pi, for example, the MCU2 and the MCU1 are just in carrier synchronization, or the phase difference between the carriers of the MCU2 and the MCU1 is very small, the MCU2 adjusts the phase of the carrier, and controls the carrier of the MCU2 to shift left or right in the time domain, so that the carrier of the MCU2 and the carrier of the MCU1 are staggered with each other until the phase difference between the carrier of the MC1 and the carrier of the MCU1 is pi, thereby achieving the effect of complete staggering between the carrier of the MCU2 and the carrier of the MCU1 in the time domain.

By performing the above process, please refer to FIG. 4, when the MCU1 and the MCU2 carry wavesWhen in synchronization, the input current I of the MCU1_inv1And the input current I of the MCU2_inv2Is shown in the left diagram of FIG. 4, I_inv1And I_inv2Since the phases are the same, then I_inv1And I_inv2Will overlap in the time domain, and will therefore be I_inv1And I_inv2Viewed as a whole, I_inv1And I_inv2Superimposed input current I_invIs approximately twice as high as a single input current peak, i.e. the capacitance needs to provide a high amplitude of the input current and thus a large capacitance value. And MCU2 phase shifts by carrier wave I_inv1And I_inv2Is shown in the right diagram of FIG. 4, I_inv1And I_inv2The phase is different by pi, therefore, I_inv1And I_inv2Viewed as a whole, I_inv1And I_inv2Superimposed input current I_invAfter the phase error, the amplitude of the input current required to be provided by the capacitor is reduced to a half of the input current before the phase error, that is, the amplitude of the input current required to be provided by the capacitor is reduced to a half of the input current before the phase error, so that the amplitude of the input current required to be provided by the capacitor is greatly reduced, and the requirement on the capacitance value of the capacitor is reduced.

(2) Referring to fig. 5, fig. 5 is a system architecture diagram of another electric vehicle according to an embodiment of the present disclosure, the electric vehicle includes three MCUs, and adopts a front single-drive and rear double-drive architecture, two front wheels are driven by one MCU, and two rear wheels are driven by corresponding MCUs in the two MCUs. In the electric vehicle, any two MCUs of the three MCUs can execute the carrier modulation method provided by the embodiment of the application, so that the carriers of the three MCUs are staggered.

Taking three MCUs as the MCU1, the MCU2 and the MCU3, and the MCU2 and the MCU3 execute the carrier modulation method provided by the embodiments of the present application as an example, during the operation of the electric vehicle, the MCU2 may be out of phase with the MCU1 carrier, and the MCU3 may be out of phase with the MCU2 carrier, thereby ensuring that the carriers of the MCU1, the MCU2 and the MCU3 are out of phase with each other.

Specifically, the MCU1 can be regarded as a reference object when the MCU2 phase shifts the carrier, and the MCU1 can keep the phase of the carrier unchanged without adjusting the phase of the carrier. The MCU2 can detect the dc voltage of its own capacitor in real time, and whenever the phase difference between the carriers of the MCU2 and the MCU1 does not reach 2/3 pi, e.g., the MCU2 and the MCU1 are just in carrier synchronization, or the phase difference between the carriers of the MCU2 and the MCU1 is very small, the MCU2 adjusts the phase of the carrier, and controls the carrier of the MCU2 to shift left or right in the time domain, so that the carriers of the MCU2 and the MCU1 are staggered with each other until the phase difference between the carriers of the MCU2 and the MCU1 is 2/3 pi, thereby achieving the effect of complete time domain staggering between the carriers of the MCU2 and the carriers of the MCU 1.

Similarly, the MCU2 may be regarded as a reference object when the carrier of the MCU3 is shifted, the MCU3 may detect a dc voltage of its own capacitor in real time, and when it is determined that the phase difference between the carriers of the MCU3 and the MCU2 does not reach 2/3 pi according to the dc voltage of the capacitor, for example, the MCU3 and the MCU2 are in carrier synchronization, or the phase difference between the carriers of the MCU3 and the MCU2 is very small, the MCU3 may adjust the phase of the carrier, and control the carrier of the MCU3 to shift left or right in the time domain, so that the carrier of the MCU3 and the carrier of the MCU2 are staggered with each other until the phase difference between the carrier of the MCU3 and the carrier of the MCU2 is 2/3 pi, thereby achieving the effect that the carrier of the MCU3 and the carrier of the MCU2 are.

By performing the above process, referring to fig. 6, when the MCU1, the MCU2, and the MCU3 are carrier synchronized, the input current I of the MCU1_inv1Input current I of MCU2_inv2And the input current I of the MCU3_inv3Is shown in the left diagram of FIG. 6, I_inv1、I_inv2And I_inv3Since the phases are the same, then I_inv1、I_inv2And I_inv3Will overlap in the time domain, and will therefore be I_inv1、I_inv2And I_inv3Viewed as a whole, I_inv1、I_inv2And I_inv3Superimposed input current I_invIs approximately three times the single input current, the magnitude of the input current that the capacitor needs to provide is high and thus the capacitance value of the capacitor needs to be large. And MCU2 and MCU3 are used for carrying out carrier phase shift, I_inv1、I_inv2And I_inv3Is shown in the right diagram of FIG. 6, I_inv1And I_inv2The phase difference is 2/3 pi, I_inv2And I_inv3The phase difference is 2/3 pi, therefore, I_inv1、I_inv2And I_inv3Viewed as a whole, I_inv1、I_inv2And I_inv3Superimposed input current I_invAfter the phase error, the amplitude of the input current is reduced to one third before the phase error, that is, the amplitude of the input current required to be provided by the capacitor is reduced to one third before the phase error, so that the amplitude of the input current required to be provided by the capacitor is greatly reduced, and the requirement on the capacitance value of the capacitor is reduced.

(3) Referring to fig. 7, fig. 7 is a system architecture diagram of an electric vehicle according to an embodiment of the present application, the electric vehicle has three MCUs, and adopts a front dual-drive and rear single-drive architecture, two front wheels are driven by corresponding MCUs of the two MCUs, and two rear wheels are driven by one MCU. In the electric vehicle, any two MCUs of the three MCUs can execute the carrier modulation method provided by the embodiment of the application, so that the carriers of the three MCUs are staggered.

The specific process and effect of carrier misphasing of the three MCUs are the same as those in (2), and are not described herein.

(4) Referring to fig. 8, fig. 8 is a system architecture diagram of an electric vehicle according to an embodiment of the present application, where the electric vehicle is a four-wheel drive electric vehicle, and the electric vehicle has four MCUs, and each wheel is driven by one MCU. In the electric vehicle, any three MCUs of the four MCUs can execute the carrier modulation method provided by the embodiment of the application, so that the carriers of the four MCUs are staggered.

Taking four MCUs as the

MCUs

1, 2, 3 and 4, and executing the carrier modulation method provided by the embodiment of the application by the MCUs 2, 3 and 4 as an example, in the operation of the electric vehicle, the

MCUs

2 and 1 may be in carrier phase shift, and the MCUs 3 and the MCU2 may be in carrier phase shift, so as to ensure that the carriers of the

MCUs

1, 2 and 3 are in mutual phase shift.

Specifically, the MCU1 can be regarded as a reference object when the MCU2 phase shifts the carrier, and the MCU1 can keep the phase of the carrier unchanged without adjusting the phase of the carrier. The MCU2 can detect the dc voltage of its own capacitor in real time, and whenever the phase difference between the carriers of the MCU2 and the MCU1 does not reach 2/3 pi, e.g., the MCU2 and the MCU1 are just in carrier synchronization, or the phase difference between the carriers of the MCU2 and the MCU1 is very small, the MCU2 adjusts the phase of the carrier, and controls the carrier of the MCU2 to shift left or right in the time domain, so that the carriers of the MCU2 and the MCU1 are staggered with each other until the phase difference between the carriers of the MCU2 and the MCU1 is 1/4 pi, thereby achieving the effect of complete time domain staggering between the carriers of the MCU2 and the carriers of the MCU 1.

Similarly, the MCU2 may be regarded as a reference object when the carrier of the MCU3 is shifted, the MCU3 may detect a dc voltage of its own capacitor in real time, and when it is determined that the phase difference between the carriers of the MCU3 and the MCU2 does not reach 2/3 pi according to the dc voltage of the capacitor, for example, the MCU3 and the MCU2 are in carrier synchronization, or the phase difference between the carriers of the MCU3 and the MCU2 is very small, the MCU3 may adjust the phase of the carrier, and control the carrier of the MCU3 to shift left or right in the time domain, so that the carrier of the MCU3 and the carrier of the MCU2 are staggered with each other until the phase difference between the carrier of the MCU3 and the carrier of the MCU2 is 1/4 pi, thereby achieving the effect that the carrier of the MCU3 and the carrier of the MCU2 are.

Similarly, the MCU3 may be regarded as a reference object when the carrier of the MCU4 is shifted, the MCU4 may detect a dc voltage of its own capacitor in real time, and when it is determined that the phase difference between the carriers of the MCU3 and the MCU4 does not reach 1/4 pi according to the dc voltage of the capacitor, for example, the MCU3 and the MCU4 are in carrier synchronization, or the phase difference between the carriers of the MCU3 and the MCU4 is very small, the MCU4 may adjust the phase of the carrier, and control the carrier of the MCU4 to shift left or right in the time domain, so that the carrier of the MCU4 and the carrier of the MCU3 are staggered with each other until the phase difference between the carrier of the MCU4 and the carrier of the MCU3 is 1/4 pi, thereby achieving the effect that the carrier of the MCU4 and the carrier of the MCU3 are.

By performing the above process, referring to fig. 9, when the MCU1, the MCU2, the MCU3, and the MCU4 are carrier synchronized, the input current I of the MCU1_inv1Input current I of MCU2_inv2Input current I of MCU3_inv3And the input current I of the MCU4_inv4Is shown in the left diagram of FIG. 9, I_inv1、I_inv2、I_inv3、I_inv4Since the phases are the same, then I_inv1、I_inv2、I_inv3、I_inv4Waveform of (2)Overlap will occur in the time domain, therefore, I will be_inv1、I_inv2And I_inv3Viewed as a whole, I_inv1、I_inv2、I_inv3、I_inv4Superimposed input current I_invIs approximately four times the single input current, the amplitude of the input current that the capacitor needs to provide is high and thus the capacitance value of the capacitor needs to be large. And the MCU2, the MCU3 and the MCU4 carry out carrier phase shift, I_inv1、I_inv2、I_inv3、I_inv4Is shown in the right diagram of FIG. 9, I_inv1And I_inv2The phase difference is 1/4 pi, I_inv2And I_inv3The phase difference is 1/4 pi, therefore, I_inv1、I_inv2、I_inv3And I_inv4Viewed as a whole, I_inv1、I_inv2、I_inv3And I_inv4Superimposed input current I_invAfter the phase error, the amplitude of the input current to be provided by the capacitor is reduced to one fourth of the amplitude before the phase error, that is, the amplitude of the input current to be provided by the capacitor is reduced to one fourth of the amplitude before the phase error, so that the amplitude of the input current to be provided by the capacitor is greatly reduced, and the requirement on the capacitance value of the capacitor is reduced.

In summary, the specific process of performing carrier staggering when two MCUs, three MCUs, and four MCUs are provided in the electric vehicle is described above. In a possible implementation, the electric vehicle may also have more than four MCUs, and when the electric vehicle has more than four MCUs, the carrier-phase-staggering process is the same as that described above, for example, if the electric vehicle has N MCUs, each MCU and the previous MCU may be controlled to carry out carrier-phase staggering, and finally, mutual carrier-phase staggering among the N MCUs is achieved.

The effect achieved by the carrier phase-staggered technology provided by the embodiment of the application is explained by combining the application scene of the electric automobile. In addition, the carrier phase-shifting technology provided by the embodiment of the application can also be applied to other application scenarios, and can reduce the capacitance in other devices.

In another exemplary application scenario, in a power plant, the dc converter may be provided as a grid-connected inverter in the power plant, for example, may be a photovoltaic grid-connected inverter in a photovoltaic power plant, a wind grid-connected inverter in a wind power plant, a power plant grid-connected inverter, or the like. Accordingly, the dc converter system may be provided as a grid-connected inverter system in a power plant. Taking application in a photovoltaic power plant as an example, the grid-connected inverter system comprises a plurality of photovoltaic grid-connected inverters, each photovoltaic grid-connected inverter is connected with a photovoltaic module, a photovoltaic combiner box or other solar power generation equipment, and each photovoltaic grid-connected inverter can be connected with a power grid.

By applying the method provided by the embodiment of the application, for any grid-connected inverter in a grid-connected inverter system, the grid-connected inverter can control the carrier of the grid-connected inverter and the carriers of other grid-connected inverters to be in phase dislocation by adjusting the phase of the carrier of the grid-connected inverter, so that the amplitude of input current required to be provided by a capacitor in the grid-connected inverter is reduced, and the requirement on the capacitance value of the capacitor in the grid-connected inverter is reduced. Specifically, when the grid-connected inverter system includes two grid-connected inverters, the specific process and effect of carrier misphasing of the two grid-connected inverters are the same as those in (1) above, when the grid-connected inverter system includes three grid-connected inverters, the specific process and effect of carrier misphasing of the two grid-connected inverters are the same as those in (2) above, and when the grid-connected inverter system includes four grid-connected inverters, the specific process and effect of carrier misphasing of the two grid-connected inverters are the same as those in (4) above, and so on, and details are not repeated herein.

In another exemplary application scenario, in an Uninterruptible Power Supply (UPS), the dc converter may be provided as an inverter in the UPS, and accordingly, the dc converter System may be provided as a grid-connected inverter System of the UPS in a place such as an enterprise or a campus.

By applying the method provided by the embodiment of the application, for any inverter in the UPS, the inverter can control the carrier of the inverter and the carriers of other inverters to be in phase staggering with each other by adjusting the phase of the carrier of the inverter, so that the amplitude of the input current required to be provided by the capacitor in the inverter is reduced, and the requirement on the capacitance value of the capacitor in the inverter is reduced. Specifically, when the inverter system includes two inverters, the specific process and effect of carrier misphasing of the two inverters are the same as those in (1) above, when the inverter system includes three grid-connected inverters, the specific process and effect of carrier misphasing of the two inverters are the same as those in (2) above, and when the grid-connected inverter system includes four inverters, the specific process and effect of carrier misphasing of the two inverters are the same as those in (4) above, and so on, which is not described herein again.

Fig. 10 is a schematic structural diagram of a dc converter provided in an embodiment of the present application, where the dc converter may be an MCU, an inverter, an uninterruptible power supply, or a rectifier, the MCU may be applied in an electric vehicle, for example, may be used to drive a motor of the electric vehicle, the inverter may be applied in a new energy industry, for example, may be a photovoltaic inverter, a wind power converter, or the like, and the inverter may be a grid-connected inverter, for example, a distributed photovoltaic grid-connected inverter.

Referring to fig. 10, the dc converter includes: processor 1001, signal generator 1002, modulator 1003, switch 1004, and the dc converter further includes a capacitor.

Processor 1001, also referred to as a processor of a dc converter, is configured to execute at least one instruction to enable the dc converter to implement a carrier modulation method in the embodiments described below. Taking the dc converter as an MCU in an electric vehicle as an example, the processor 1001 may be an Electronic Control Unit (ECU) in the MCU, and the ECU may be located on a Control board in the MCU.

The Signal generator 1002 is used for generating a carrier wave, and may be a Digital Signal Processing (DSP), an oscillator, a single chip, or the like. The signal generator may generate a plurality of carriers based on a preset phase so as to adjust the phase of the carriers by switching between different carriers. The phase difference between any two adjacent carriers in the multiple carriers is a preset phase. For example, assuming a predetermined phase of 4/π, the signal generator may generate 4 carriers of 0, 4/π, 2/π, 3/4 π.

The modulator 1003 is configured to modulate a carrier, and may be implemented by a hardware circuit built by a comparator, and the modulator 1003 may receive a modulated wave and the carrier generated by the signal generator 1002, modulate the carrier according to the modulated wave to obtain a switching voltage, and output the switching voltage to the switch 1004.

The switch 1004 is used for being turned on and off under the control of the switch voltage so as to control the magnitude of the output current, for example, when the switch 1004 is turned on when the switch voltage is at a high level, the power supply, the inductor and the load circuit are connected in an external circuit of the switch 1004, the power supply supplies power to the load and the inductor, the current in the inductor rises, and the magnitude of the output current in the circuit also rises. When the first switch voltage is at a low level, the switch 1004 is turned off, the power supply is disconnected from the inductor, the inductor supplies power to the load, the current in the inductor decreases, the magnitude of the output current in the circuit decreases, and the turn-off and turn-on time of the switch 1004 can determine the magnitude of the increase and decrease of the current in the inductor, so that the magnitude of the current is controlled. The switch 1004 may be an Insulated Gate Bipolar Transistor (IGBT).

The capacitor may be a capacitor applied in a DC circuit, i.e., a DC capacitor (also referred to as a DC-link capacitor), also referred to as a DC support capacitor, and may perform smoothing filtering on the output voltage of the rectifier in the inverter circuit. The capacitor is used for stabilizing the direct-current voltage input to the direct-current converter and providing instantaneous input current and instantaneous input power for the direct-current converter. Specifically, the direct current capacitor can absorb high-amplitude pulsating current which is required by the inverter to the direct current network, and high-amplitude pulsating voltage generated on the impedance of the inverter is avoided, so that the fluctuation of the voltage on the direct current bus is kept within an allowable range. In this embodiment, since the different dc converters are electrically connected, the capacitor in any dc converter can provide the input current for each dc converter.

Optionally, referring to fig. 11, the dc converter may further include a memory 1005, where the memory 1005 may be any type of non-volatile memory, the memory 1005 is connected to the processor 1001, the memory 1005 stores at least one instruction, and the processor 1001 is configured to load the at least one instruction from the memory 1005 and execute the at least one instruction, so as to enable the processor 1001 to execute the carrier modulation method in the following embodiments.

Optionally, referring to fig. 12, the dc converter may further include a signal selector 1006, the plurality of carriers generated by the signal generator 1002 may be input into the signal selector 1006, and the signal selector 1006 may select a carrier having a phase different from a current phase from the plurality of carriers based on the current phase of the carrier of the dc converter, and output the selected carrier to the switch 1004. For example, the signal selector 1006 may be a multi-channel data selector, and may include a four-channel data selector, an eight-channel data selector, and the like.

Of course, the dc converter may also have other components for realizing the functions of the device, including but not limited to a housing, a heat sink, and the like, which are not described herein.

Fig. 13 is a schematic structural diagram of an electronic device provided in an embodiment of the present application, where the electronic device may be provided as an electric vehicle, or may be provided as another device according to a requirement. The electronic device includes at least a plurality of dc converters 1301, and may further include a power supply 1302 and at least one motor 1303.

The dc converter 1301 is used to convert the electric energy provided by the power supply 1302, for example, the dc converter 1301 may convert dc power into ac power, or may convert ac power into dc power. The plurality of dc converters 1302 are electrically connected, for example, the plurality of dc converters 1302 may be connected in parallel.

At least one of the plurality of dc converters is used to perform a carrier modulation method in the following embodiments. For example, when two dc converters are provided in the electronic apparatus, the carrier modulation method in the following embodiments may be performed by any one of the two dc converters, and when three dc converters are provided in the electronic apparatus, the carrier modulation method in the following embodiments may be performed by any two of the three dc converters.

The power supply 1302 is used to provide power. The power source 1302 may be a battery or a battery pack of multiple batteries, which may be a battery, a fuel cell, an alternating current, a direct current, a disposable battery, or a rechargeable battery.

The Motor 1303 may be a Permanent Magnet Synchronous Motor 1303(Permanent Magnet Synchronous Motor, hereinafter referred to as PMSM), an asynchronous Motor, a switched reluctance Motor, or the like.

Of course, the electronic device may also have other components for implementing the functions of the device, for example, when the electronic device is an electric vehicle, the electronic device further includes, but is not limited to, a tire, a housing, and the like, and details are not described herein.

Taking an electronic device as an electric vehicle as an example, please refer to fig. 14, where fig. 14 is a schematic structural diagram of an electric vehicle provided in an embodiment of the present application, a power source in the electric vehicle may be a battery, each dc converter may be an MCU, and each motor may be a PMSM that drives the electric vehicle to run. In addition, a circuit diagram in the electric vehicle may be as shown in fig. 15.

In the embodiment of the present application, the principle of reducing the capacitance requirement of the capacitor by phase-shifting the carriers of different dc converters is described as follows:

the application scene of the electric automobile is combined, and the analysis is carried out from the perspective of the whole automobile, and most of the electric automobiles are provided with at least two MCUs; one MCU is used for driving the front wheel, one MCU drives the rear wheel, and even some electric automobiles are provided with three or four MCUs which respectively adopt different driving modes. In the application, for two or more MCUs in the electric automobile, whether the carriers of different MCUs have been out of phase or not can be judged by detecting the direct-current voltage of the capacitor, when the carriers of different MCUs have not been out of phase or the degree of out of phase does not meet the requirement, the carrier out of phase of different MCUs is controlled, and through the carrier out-of-phase technology, the waveform of the input current Iinv of the capacitor can be changed into a plurality of pulses appearing in each switching period from a single pulse appearing in each switching period, which can be understood as: in each switching cycle, Iinv is converted from a sharp, overlapping peak to a plurality of short, staggered peaks, thereby reducing the peak value of Iinv and thus reducing the capacitance requirement of the capacitor, which also reduces the volume of the capacitor. Meanwhile, the different MCUs are not required to be connected through signal lines to carry out carrier synchronization, the flexibility is high, the method is very convenient, and the different MCUs are not required to be close to each other in space. Meanwhile, the method has universality, can be applied to the condition without a DCDC converter, and reduces the requirement on the capacitance value of the direct current capacitor of the MCU so as to reduce the volume of the direct current capacitor.

Specifically, the system architecture of the electric vehicle is analyzed, the electric vehicle at least comprises a battery, two MCUs and two PMSMs, the two MCUs are connected in parallel, each MCU is respectively connected with the anode and the cathode of the battery, and each MCU is used for driving the PMSM. Because the capacitors of the two MCUs are connected in parallel to the same direct current network, the capacitors of the two MCUs can be regarded as a whole, so that the two capacitors are combined into one capacitor for analysis, and a system topological diagram of the electric vehicle is obtained, as shown in fig. 16.

Further analysis of fig. 16 shows that from the perspective of the output current, each MCU will output current to an external circuit, and thus the MCU can be considered as one current source, whereas MCU1 and MCU2 are connected in parallel, and thus MCU1 and MCU2 can be considered as two parallel current sources, converting fig. 16 into a circuit diagram, such as that shown in fig. 17.

For further analysis of fig. 17, since two parallel current sources can be equivalent to one current source through a circuit conversion relationship, the MCU1 and the MCU2 are equivalent to one current source as a whole, and fig. 17 is simplified to fig. 18.

For further analysis of fig. 18, in the circuit diagram of fig. 18, a capacitor is used to provide the input current I for the equivalent current source_invThe first to the second_invIs a pulsed current. Let I_invIs a regular pulse current source with equal frequency and equal pulse width. When t e (t)₀,t₁) Then, the equation of state is set forth for FIG. 18, resulting in the following equation (1):

when t e (t)₁,t₂) Then, the equation of state is set forth for FIG. 18, resulting in the following equation (2):

wherein Ud represents the DC voltage of the battery, idc represents the DC current of the battery, C represents the capacitance value of the capacitor, R represents the internal resistance of the battery, U represents₁Representing the maximum value of the capacitor voltage, U₂Representing the minimum value of the capacitor voltage.

By converting the formula (1), the following formula (3) can be obtained, and t ∈ (t) can be obtained₀,t₁) The voltage and current of the battery conform to the following formula (3):

by converting the formula (2), the following formula (4) can be obtained, and t ∈ (t) can be obtained₁,t₂) The voltage and current of the battery conform to the following formula (4):

the following formula (5) is obtained from the above formulae (3) and (4)

In the formula (5), since the internal resistance R of the battery is very small, U is considered to be₁Udc, inWithin one switching period Ts, the duty ratio d is assumed to be (t1-t0)/Ts, and since Ts is sufficiently small, e^xIt can be developed using the taylor formula:

e is to be^xUsing the first order expansion substitution of taylor's formula, the following equation (6) can be obtained:

from the above formula (6), in d, Ts, I_inv1Invariably, the larger C, the larger U2 and the smaller Idc 2. Due to I_invFrom I_inv1And I_inv2Are superposed to form_inv1And I_inv2Substituting the phase difference Ts/2 into the above formula (6) to obtain the following formula (7):

a comparative analysis between the above formula (6) and the above formula (7) revealed that I_invThe denominator of (a) is changed from C to 4C, which corresponds to an increase of 4 times the original capacitance. Therefore, the inventor finds and proves that the rule is as follows: under the condition of idc2 with the same requirement, if the carriers of the two MCUs have a certain phase difference, namely the carriers of the two MCUs are in wrong phase, the equivalent value of the capacitor is increased, and therefore the requirement on the actual capacitance value of the capacitor can be reduced.

Fig. 19 is a flowchart of a carrier modulation method according to an embodiment of the present application, where an execution subject of the method is a first dc converter, and referring to fig. 19, the method includes:

1901. the first direct current converter generates a plurality of carriers based on a preset phase, and the phase difference between any two adjacent carriers in the plurality of carriers is the preset phase.

The first dc converter may generate a plurality of carriers in advance, the phases of the plurality of carriers are different from each other, any two adjacent carriers have a certain carrier phase difference therebetween, and the carriers are staggered from each other in the time domain, so that the phases of the carriers may be changed by switching between the plurality of carriers by the first dc converter, thereby achieving an effect of adjusting the phases.

The waveform of the carrier wave includes, but is not limited to, an isosceles triangle wave, a sawtooth wave, a sine wave, or other carrier waves, and the waveforms of the plurality of carrier waves generated by the first dc converter may all be the same. The frequency of the carrier wave can be determined according to actual requirements, the carrier wave can be a low-frequency signal or a high-frequency signal, and the frequencies of the plurality of carrier waves generated by the first direct current converter can be the same. The number of carriers may be determined from the total number of dc converters in the electronic device, and in one possible implementation, the number of carriers may be 2 times the total number of dc converters. For example, assuming that the electronic device in which the first dc converter is located has 2 dc converters, the number of carriers generated by the first dc converter may be 2. Assuming that the electronic device in which the first dc converter is located has 3 dc converters, the number of carriers may be 6.

Presetting a phase: the preset phase is the carrier phase difference between the previous carrier and the next carrier in the plurality of carriers and is the phase step length of each adjustment of the carriers of the first direct current converter. Specifically, each time the first dc converter adjusts the carrier, it may be realized by switching from the last carrier to the next carrier, and each time the first dc converter adjusts the carrier, it may be regarded that the carrier of the first dc converter is shifted by one step, that is, shifted by a preset phase in the time domain. In one possible design, the predetermined phase may be equal to a ratio between a predetermined phase difference and the number of the plurality of carriers, where the predetermined phase difference is a phase difference achieved by the carriers that control the first dc converter and the second dc converter.

For example, the preset phase difference may be pi, the number of the plurality of carriers may be 4, and the preset phase may be 4/pi, and the first dc converter may generate four carriers, which have phases of 0, 4/pi, 3/4 pi, and 1/2 pi, in sequence.

For a specific implementation of generating a plurality of carriers, in one possible implementation, a signal generator may be included in the first dc converter, the signal generator being configured to generate a carrier of the first dc converter. The first dc converter may control the signal generator, and the plurality of carriers are generated by the signal generator. Specifically, with respect to the specific process of the signal generator generating the plurality of carriers, the signal generator may be one or more DSPs, and the signal generator may generate the plurality of carriers according to the frequency of the carriers and the phase difference of the carriers. For example, the general timer TX of the DSP may be configured in an up-down counting mode, the TXPR of the period register is set according to the carrier frequency, the initial value of the count register is obtained according to the preset phase and the switching frequency, the initial value of the TXCNT is initialized, the initial value of the TXCNT is set to be the preset phase/period angle × the number of clock cycles, and then the timer of the DSP is started to enable the DSP to generate the carrier.

1902. The first dc converter detects a dc voltage of a capacitor in the first dc converter.

The first direct current converter modulates the carrier in operation, and can detect the direct current voltage of the capacitor of the first direct current converter in real time in the modulation process so as to judge whether the phase of the carrier needs to be adjusted or not according to the direct current voltage.

Aiming at the process of modulating the carrier wave, when a user triggers a control operation, the first direct current converter can receive a control instruction and load the control instruction on the carrier wave of the first direct current converter to obtain modulated switch voltage, the switch voltage can control the on-off of a switch in the first direct current converter to generate output current, and the output current can control the running state of the electronic equipment where the first direct current converter is located, so that the electronic equipment responds to the control instruction, and the final running state of the electronic equipment can meet the control requirement of the user.

Taking the electronic device as an electric vehicle as an example, the modulation process may specifically include the following (1) to (4):

(1) and receiving a control instruction.

The control command may be triggered by a control operation of a user, and the control command may carry a control parameter of the electric vehicle, and the control parameter may include at least one of torque, rotational speed, output current, and output power. The control instruction can be triggered by the action of stepping on the accelerator by a driver by combining with the application scene of the electric automobile, and the specific value of the control parameter carried by the control instruction can be determined according to the strength and the speed of stepping on the accelerator.

(2) Based on the control instruction, a modulation wave is generated.

The control instruction can be analyzed to obtain a control parameter carried by the control instruction, and a modulation wave is output through a preset modulation algorithm and a current control algorithm according to the control parameter. The preset Modulation algorithm may include at least one of Space Vector Pulse Width Modulation (SVPWM) and Sinusoidal Pulse Width Modulation (SPWM), and the current control algorithm may be a Maximum Torque current ratio (MPTA) algorithm. The modulated wave may be a three-phase modulated signal, i.e. three modulated voltage signals, which differ in phase.

Taking the control parameter carried by the control command as the torque as an example, referring to fig. 15 or fig. 20, assuming that the torque is Te — ref, the specific process of generating the modulation wave based on the target torque may be:

(2.1) determination of T_e-refAnd the position of the rotor of the motor, for T by the MPTA algorithm_e-refAnd calculating the position of the motor rotor, and outputting a d-axis current command id _ ref and a q-axis current command iq _ ref.

(2.2) sampling the output current of the three-phase motor to obtain a three-phase sampling current i_a1、i_b1And i_c1I is to_a1、i_b1And i_c1Conversion to d-axis current i_d1And q-axis current i_q1。

(2.3) d-axis Current command i_{d_ref}And d-axis current i_d1The comparison generates a first error signal, and the q-axis current command iq _ ref is compared with the q-axis current iq1 to generate a second error signal. For example, a comparator may be provided to compare i_{d_ref}And i_d1The first error signal is input to a comparator and output.

And (2.4) performing Proportional-Integral (PI) control on the first error signal and the second error signal to generate a first voltage command u alpha and a second voltage command u beta.

(2.5) converting the coordinates of u α and u β by an SVPWM algorithm, and outputting three-phase modulation signals mod _ a, mod _ b, and mod _ c.

(3) A carrier wave of the first DC converter is modulated according to the modulation wave to obtain a switching voltage of the first DC converter.

In one possible implementation, Pulse Width Modulation (PWM) may be used for Modulation, and the modulated first switching voltage is a series of Pulse signals, and the Width of the Pulse signals carries information of the modulated wave.

Specifically, the modulated wave may be compared with the carrier of the first dc converter to obtain a difference signal between the modulated wave and the carrier of the first dc converter, and a series of high and low level signals may be finally output to form the first switching voltage according to whether the difference signal is greater than a voltage threshold or not. For example, a modulated wave and a carrier of the first dc converter may be input to the subtractor circuit, the modulated wave may be subtracted from the carrier of the first dc converter, and when a signal obtained by the subtraction is larger than a voltage threshold, a high level may be output, and when the signal obtained by the subtraction is smaller than the voltage threshold, a low level may be output.

(4) And controlling the on-off of the switch in the first direct current converter through the switching voltage to generate output current.

After the switching voltage is obtained by modulation, the switching voltage is input to the control terminal of the switch to be used as the driving voltage of the switch. The switch voltage can drive the switch to be switched on and off, so that the output current in a circuit where the switch is located is controlled to generate the output current. The output current can be determined according to the time, frequency and other rules of the switch on and off.

For example, when the switching voltage is high, the switch is turned on, the power supply, the inductor and the load in the circuit are connected, and the power supply supplies power to the load and the inductor, so that a certain output current is generated. When the switch voltage is low level, the switch is turned off, the power supply is disconnected with the inductor, the inductor supplies power to the load, and then output current with another magnitude is generated.

With reference to the above (1) to (4), taking the dc converter as an example of the MCU in the electric vehicle, please refer to fig. 20, fig. 20 is a block diagram of a control algorithm of the MCU provided in the embodiment of the present application, the control algorithm of the MCU may include an MPTA algorithm module, a current control module, an SVPWM modulation module, a PWM wave output module, and an IGBT module, when the driver steps on the accelerator, the VCU calculates the target torque Te-ref according to the accelerator stepping condition of the driver, and outputs the target torque Te-ref to the MCU. In the MCU, an MPTA algorithm module outputs a d-axis current command value id _ ref and a q-axis current command value iq _ ref, id _ ref and iq _ ref in a dq coordinate system according to Te-ref and a sampled position of a motor rotor, compares the detected currents and outputs a comparison result to a current control module, the current control module outputs a modulation signal u alpha and a modulation signal u beta according to the comparison result, the SVPWM module receives u alpha and u beta, performs SVPWM on the u alpha and u beta, outputs three-phase modulation signals mod _ a, mod _ b and mod _ c, and the PWM wave output module receives mod _ a, mod _ b and mod _ c, modulates a carrier according to the mod _ a, mod _ b and mod _ c, and outputs six switching signals which control the on and off of the IGBT so as to control the torque and the rotating speed of the whole MCU.

The first dc converter may detect a dc voltage of the capacitor, and determine whether a phase difference between the carriers of the first dc converter and the second dc converter has reached a predetermined phase difference according to the dc voltage of the capacitor, thereby determining whether to adjust the phase of the carrier.

Regarding the specific process of detecting the dc voltage of the capacitor, the first dc converter may include a voltage sensor, the voltage sensor is configured to detect the dc voltage of the capacitor, the voltage sensor may be connected to the capacitor, for example, may be connected in parallel to two ends of the capacitor, and the first dc converter may read the dc voltage currently detected by the voltage sensor, so as to obtain the dc voltage of the capacitor. The process of detecting the dc voltage of the capacitor can be performed in real time, that is, the first dc converter can detect the dc voltage of the capacitor in real time, so that the process of adjusting the phase can be performed in real time whenever the phase difference between the carriers of the first dc converter and the second dc converter does not reach the preset phase difference.

It should be noted that, because the dc converter on the market usually has a voltage sensor for detecting the capacitor voltage, in the present application, the dc voltage of the capacitor can be determined through the voltage sensor of the dc converter itself, so as to implement carrier phase error, without additionally providing a sensor for the carrier phase error process, thereby saving the cost of manufacturing and assembling the sensor, providing a low-cost scheme for reducing the capacitance value of the capacitor, and having strong practicability.

Furthermore, whether the carrier phase difference of the first direct current converter and the second direct current converter reaches the preset phase difference or not can be judged through the direct current voltage of the capacitor detected by the voltage sensor, compared with a carrier synchronization method in the related art, the carrier synchronization method does not need to rely on the transmission of high-frequency signals and does not need to detect the strength of the high-frequency signals, the problem that the detection precision is not high due to the fact that the environment interferes with the transmission of the high-frequency signals is avoided, and the high precision of carrier phase dislocation is guaranteed.

1903. And the first direct current converter determines that the carrier phase difference between the first direct current converter and the second direct current converter does not reach a preset phase difference according to the direct current voltage.

Carrier phase difference: i.e. the absolute value of the difference between the phase of the carrier of the first dc-converter and the phase of the carrier of the second dc-converter. Because the capacitor in the first direct current converter and the capacitor in the second direct current converter are connected in parallel on the same direct current network, the capacitor in the first direct current converter not only supplies power for the first direct current converter, but also supplies power for the second direct current converter, correspondingly, after the first direct current converter and the second direct current converter are modulated, output currents generated by the first direct current converter and the second direct current converter can jointly act on two ends of the capacitor to influence the direct current voltage of the capacitor, and therefore the amplitude and the frequency of the direct current voltage of the capacitor can reflect the phase error degree of carriers of the first direct current converter and the second direct current converter.

Based on the electrical law, the first direct current converter can judge whether the first direct current converter and the second direct current converter complete carrier phase dislocation according to the direct current voltage of the capacitor, namely whether the carrier phase difference between the first direct current converter and the first direct current converter reaches a preset phase difference, when the carrier phase difference between the first direct current converter and the second direct current converter does not reach the preset phase difference, the first direct current converter can adjust the phase of a carrier, and finally the carrier phase difference between the first direct current converter and the second direct current converter reaches the preset phase difference. The specific value of the preset phase difference may be determined according to actual requirements, and may be pi, for example.

In one possible implementation manner, it may be determined that the carrier phase difference between the first dc converter and the second dc converter does not reach the preset phase difference by one of the following implementation manners or the second implementation manner:

the method comprises the steps of judging whether the direct-current voltage of a capacitor in a first direct-current converter is larger than a preset direct-current voltage threshold value or not, and if the direct-current voltage of the capacitor in the first direct-current converter is larger than the preset direct-current voltage threshold value, determining that the carrier phase difference of carriers of the first direct-current converter and a second direct-current converter does not reach the preset phase difference.

If the dc voltage is greater than the preset dc voltage threshold, the first dc converter may determine that the carrier phase difference between the first dc converter and the second dc converter does not reach the preset phase difference, that is, the carriers of the first dc converter and the second dc converter are not completely out of phase, and then subsequently adjust the phase of the carrier, so that the carrier phase difference between the first dc converter and the second dc converter reaches the preset phase difference. And when the direct-current voltage is not greater than the direct-current voltage threshold, determining that the phase difference of the carriers of the first direct-current converter and the second direct-current converter reaches a preset phase difference, namely the carriers of the first direct-current converter and the second direct-current converter are completely out of phase, and then, subsequently, the phase of the carrier is not required to be adjusted, the phase of the carrier of the first direct-current converter can be kept unchanged, and the carrier of the first direct-current converter in the current phase can be modulated.

Wherein, judging whether the dc voltage is greater than a preset dc voltage threshold may specifically refer to: judging whether the amplitude of the dc voltage is greater than the preset dc voltage threshold, and judging whether the amplitude of the dc voltage is greater than the preset dc voltage threshold may specifically refer to: and judging whether the peak-to-peak value of the direct current voltage is larger than a direct current voltage threshold value.

Presetting a direct-current voltage threshold: according to the determination of the direct current voltage of the capacitor in the direct current converter i, when the direct current voltage of the capacitor in the direct current converter i is the carrier phase difference of two electrically connected direct current converters and reaches a preset phase difference, the direct current voltage of the capacitor in the direct current converter i is the minimum value of the direct current voltage of the capacitor in the direct current converter i, and the direct current converter i is any one of the two direct current converters. In this case, i may be a natural number and may represent any number. The dc voltage threshold value may be stored in the first dc converter in advance. The dc voltage threshold may be determined by pre-simulation experiments.

The difference between the preset dc voltage threshold and the minimum value of the dc voltage of the capacitor in the dc converter i is within a preset range, where the preset range may be determined according to the requirement for accuracy, and the preset dc voltage threshold may be equal to the minimum value of the dc voltage of the capacitor in the dc converter i, slightly larger than the minimum value of the dc voltage of the capacitor in the dc converter i, or slightly smaller than the minimum value of the dc voltage of the capacitor in the dc converter i.

In one possible implementation, the two dc converters electrically connected may be a first dc converter and a second dc converter, and the dc converter i is a first dc converter. For example, before the first dc converter and the second dc converter leave the factory, a simulation experiment may be performed, the carrier phase difference between the first dc converter and the second dc converter is controlled to be a preset phase difference, the minimum value of the dc voltage of the capacitor in the first dc converter is collected as a preset dc voltage threshold, and then, in an actual operation of the first dc converter and the second dc converter, the first dc converter may adjust the phase of the carrier through the preset dc voltage threshold which is experimentally performed in advance. In another possible implementation, the two dc converters electrically connected may not be the first and second dc converters, e.g., may be the same type as the first and second dc converters, but other dc converters. In an exemplary scenario, two dc converters may be selected from a large number of dc converters to perform a simulation experiment, a carrier phase difference of the two dc converters is controlled to be a preset phase difference, a minimum value of a dc voltage of a capacitor in one of the dc converters is collected as a preset dc voltage threshold, and the preset dc voltage threshold is applied to the other dc converters.

In an exemplary scenario, taking a dc converter as an MCU as an example, assuming that there are MCU1, MCU2, MCU3 and MCU4, a preset dc voltage threshold may be obtained through experiments on MCU1 and MCU2, and the preset dc voltage threshold is directly applied to MCU3 during operations of MCU3 and MCU 4. Specifically, the MCU1 and the MCU2 can be electrically connected, and the MCU1 and the MCU2 can be subjected to simulation experiments under the following conditions: the carrier phase difference of the MCU1 and the MCU2 is pi, the parameters and the output power of the MCU1 and the MCU2 are consistent, the direct current voltage of the capacitor of the MCU1 is sampled at a fixed point in the running process of the MCU1 and the MCU2, the minimum direct current voltage is selected from all the direct current voltages obtained through sampling, and the minimum direct current voltage is used as a preset direct current voltage threshold value and stored in the MCU 3. In actual operation of the MCU3 and the MCU4, the MCU3 and the MCU4 are electrically connected, and the MCU3 can determine whether the carrier phase difference between the MCU3 and the MCU4 reaches a preset phase difference by detecting the dc voltage of the capacitor and determining whether the dc voltage of the capacitor is greater than a preset dc voltage threshold.

In another exemplary scenario, taking the dc converter as the MCU for example, assuming that there are the MCU1 and the MCU2, the preset dc voltage threshold can be obtained through experiments on the MCU1 and the MCU2, and the preset dc voltage threshold is directly applied to the MCU1 during the operations of the MCU1 and the MCU 2. Specifically, the MCU1 and the MCU2 can be electrically connected, and the MCU1 and the MCU2 can be subjected to simulation experiments under the following conditions: the carrier phase difference of the MCU1 and the MCU2 is pi, the parameters and the output power of the MCU1 and the MCU2 are consistent, the direct current voltage of the capacitor of the MCU1 is sampled at a fixed point in the running process of the MCU1 and the MCU2, the minimum direct current voltage is selected from all the direct current voltages obtained through sampling, and the minimum direct current voltage is used as a preset direct current voltage threshold value and stored in the MCU 1. In actual operation of the MCU1 and the MCU2, the MCU1 may determine whether the carrier phase difference between the MCU1 and the MCU2 reaches a preset phase difference by detecting a dc voltage of the capacitor and determining whether the dc voltage of the capacitor is greater than a preset dc voltage threshold.

In a possible design, the preset dc voltage threshold may be determined according to a current working condition, that is, the corresponding preset dc voltage threshold may be determined in advance under experimental conditions of various torques, rotational speeds, output powers, and output currents in consideration of influences of the torques, the rotational speeds, the output powers, and the output currents, so that the first dc converter may determine the corresponding preset dc voltage threshold according to the current torques, rotational speeds, output powers, and output currents during operation, to determine whether the carrier phase difference reaches the preset phase difference under the current working condition.

Specifically, the process of determining whether the carrier phase difference reaches the preset phase difference may include any one or more of the following (1) to (4) in combination with the current operating condition:

(1) and judging whether the direct current voltage of the capacitor in the first direct current converter is greater than a preset direct current voltage threshold corresponding to the preset torque, and if the direct current voltage of the capacitor in the first direct current converter is greater than the preset direct current voltage threshold corresponding to the preset torque, determining that the carrier phase difference between the first direct current converter and the second direct current converter does not reach the preset phase difference.

The preset torque is the torque of a motor electrically connected with the first dc converter, and the torque may be the torque required to be achieved by the electronic device where the first dc converter is located, and the magnitude of the torque may be determined according to the input operation of the user. For the specific process of determining the torque by the first direct current converter, after a user triggers an input operation, the first direct current converter can receive a control command and analyze the control command to obtain the torque carried by the control command. In an exemplary application scenario, taking the first dc converter as an MCU in an electric vehicle as an example, after a driver steps on an accelerator, the VCU receives an accelerator signal, analyzes the accelerator signal by using a relevant algorithm of the VCU to obtain a torque carried by the accelerator signal, generates a control instruction carrying the torque according to the torque, sends the control instruction to the MCU, and the MCU receives the control instruction of the VCU and analyzes the control instruction to obtain the torque.

In this embodiment, the first dc converter may pre-store the preset dc voltage threshold corresponding to each torque, and in actual operation, may obtain the current torque of the electrically connected motor, and query the preset torque as the torque corresponding to the preset dc voltage threshold, so as to obtain the preset dc voltage threshold. The preset dc voltage threshold may be determined according to a dc voltage of a capacitor in the dc converter i and a torque of the motor i.

A motor i: the motor i is electrically connected with the direct current converter i, the direct current voltage of the capacitor in the direct current converter i is the minimum value of the direct current voltage of the capacitor in the direct current converter i when the carrier phase difference of the two electrically connected direct current converters reaches the preset phase difference and the torque of the motor i is the preset torque.

In one possible implementation, the two dc converters electrically connected may be a first dc converter and a second dc converter, the dc converter i is a first dc converter, and the motor i may be a motor electrically connected to the first dc converter.

In another exemplary scenario, taking a dc converter as an MCU as an example, assuming that there are an MCU1 and an MCU2, the MCU1 is electrically connected to the motor 1, a preset dc voltage threshold can be obtained by performing experiments on the MCU1, the MCU2 and the motor 1, and the preset dc voltage threshold is directly applied to the MCU1 during operation of the MCU1, the MCU2 and the motor 1. Particularly, can be connected MCU1 and MCU2 electricity, MCU1 is connected with motor 1, carries out the simulation experiment to MCU1, MCU2, and the experimental condition is: the carrier phase difference of the MCU1 and the MCU2 is pi, the torque of the motor 1 is a preset torque, the parameters and the output power of the MCU1 and the MCU2 are consistent, in the running process of the MCU1 and the MCU2, the direct current voltage of the capacitor of the MCU1 is sampled at a fixed point, the minimum direct current voltage is selected from all the direct current voltages obtained by sampling, and the minimum direct current voltage is used as a preset direct current voltage threshold value and stored in the MCU 1. In actual operation of the MCU1 and the MCU2, the MCU1 may detect the dc voltage of the capacitor, determine which preset torque the torque of the motor is, determine whether the dc voltage of the capacitor is greater than a preset dc voltage threshold corresponding to the preset torque, and determine whether the carrier phase difference between the MCU1 and the MCU2 reaches a preset phase difference.

In another possible implementation, the two dc converters electrically connected may not be the first dc converter and the second dc converter, and the motor i may not be the motor electrically connected to the first dc converter.

In an exemplary scenario, taking a dc converter as an MCU as an example, assuming that there are an MCU1, an MCU2, an MCU3 and an MCU4, the MCU1 is electrically connected to the motor 1, and the MCU3 is electrically connected to the motor 2, a preset dc voltage threshold may be obtained by performing experiments on the MCU1, the MCU2 and the motor 1, and the preset dc voltage threshold is directly applied to the MCU3 during operations of the MCU3, the MCU4 and the motor 2. Specifically, the MCU1 and the MCU2 can be electrically connected, and the MCU1 and the MCU2 can be subjected to simulation experiments under the following conditions: the carrier phase difference of the MCU1 and the MCU2 is pi, the torque of the motor 1 is a preset torque, the parameters and the output power of the MCU1 and the MCU2 are consistent, in the running process of the MCU1 and the MCU2, the direct current voltage of the capacitor of the MCU1 is sampled at a fixed point, the minimum direct current voltage is selected from all the direct current voltages obtained by sampling, and the minimum direct current voltage is used as a preset direct current voltage threshold value and stored in the MCU 3. In actual operation of the MCU3 and the MCU4, the MCU3 and the MCU4 are electrically connected to enable the MCU3 to determine whether the carrier phase difference between the MCU3 and the MCU4 reaches a preset phase difference by detecting the dc voltage of the capacitor, determining which preset torque the torque of the motor is, and determining whether the dc voltage of the capacitor is greater than a preset dc voltage threshold corresponding to the preset torque.

Similarly, the torque of the motor i may be changed, experiments are respectively performed under the condition that the torque of the motor i is various torques, and the steps of sampling and selecting the minimum preset dc voltage threshold are repeatedly performed, so as to obtain the dc voltage threshold corresponding to the torque, and thus obtain the preset dc voltage thresholds corresponding to the various torques. Further, through an experimental process, a preset corresponding relationship between the torque and the preset dc voltage threshold may be established, and the preset corresponding relationship may be regarded as a table and may be stored in the first dc converter. The preset corresponding relation comprises at least one torque and at least one corresponding direct-current voltage threshold, and the preset corresponding relation can be recorded in a form of a list. Illustratively, the preset correspondence may be as shown in table 1 below:

TABLE 1

Torque moment

50Nm

100Nm

150Nm

200Nm

250Nm

300Nm

Threshold value of DC voltage

Umin1

Umin2

Umin3

Umin4

Umin5

Umin6

Combining the corresponding relation between the torque and the direct-current voltage threshold value, after the first direct-current converter acquires the torque of the motor electrically connected with the first direct-current converter, the torque can be used as an index, the preset corresponding relation is inquired, the direct-current voltage threshold value corresponding to the torque is obtained from the preset corresponding relation, and whether the direct-current voltage threshold value is out of phase with the carrier of the second direct-current converter or not is judged according to the direct-current voltage threshold value. For example, assuming that the torque is 50Nm and the first predetermined correspondence is shown in the above table, the first dc converter may determine that the dc voltage threshold is Umin1 after querying the first predetermined correspondence according to 50 Nm.

(2) And judging whether the direct current voltage of the capacitor in the first direct current converter is greater than a preset direct current voltage threshold corresponding to a preset rotating speed or not, and if the direct current voltage of the capacitor in the first direct current converter is greater than the preset direct current voltage threshold corresponding to the preset rotating speed, determining that the carrier phase difference between the first direct current converter and the second direct current converter does not reach the preset phase difference.

The preset rotating speed is the rotating speed of a motor electrically connected with the first direct current converter, the rotating speed is the rotating speed required to be reached by the electronic equipment, and the rotating speed can be determined according to input operation of a user. Aiming at the specific process of determining the rotating speed of the first direct current converter, after a user triggers an input operation, the first direct current converter can receive a control instruction and analyze the control instruction to obtain the rotating speed carried by the control instruction. In an exemplary application scenario, taking the first dc converter as an MCU in an electric vehicle as an example, after a driver steps on an accelerator, the VCU receives an accelerator signal, applies a relevant algorithm of the VCU to obtain a speed corresponding to the accelerator signal, generates a control instruction carrying the rotation speed according to the rotation speed, sends the control instruction to the MCU, and the MCU receives the control instruction of the VCU and analyzes the control instruction to obtain the rotation speed.

In this embodiment, the first dc converter may pre-store the preset dc voltage threshold corresponding to each rotation speed, and in actual operation, may obtain the current rotation speed of the electrically connected motor, and query the preset dc voltage threshold corresponding to the preset rotation speed when the preset rotation speed is the rotation speed, so as to obtain the preset dc voltage threshold. The preset direct-current voltage threshold value can be determined according to the direct-current voltage of a capacitor in the direct-current converter i and the rotating speed of the motor i.

A motor i: the motor i is electrically connected with the direct current converter i, the direct current voltage of the capacitor in the direct current converter i is the minimum value of the direct current voltage of the capacitor in the direct current converter i when the carrier phase difference of the two electrically connected direct current converters reaches the preset phase difference and the rotating speed of the motor i is the preset rotating speed.

In another exemplary scenario, taking a dc converter as an MCU as an example, assuming that there are an MCU1 and an MCU2, the MCU1 is electrically connected to the motor 1, a preset dc voltage threshold can be obtained by performing experiments on the MCU1, the MCU2 and the motor 1, and the preset dc voltage threshold is directly applied to the MCU1 during operation of the MCU1, the MCU2 and the motor 1. Particularly, can be connected MCU1 and MCU2 electricity, MCU1 is connected with motor 1, carries out the simulation experiment to MCU1, MCU2, and the experimental condition is: the carrier phase difference of the MCU1 and the MCU2 is pi, the rotating speed of the motor 1 is a preset rotating speed, the parameters and the output power of the MCU1 and the MCU2 are consistent, in the running process of the MCU1 and the MCU2, the direct current voltage of the capacitor of the MCU1 is sampled at a fixed point, the minimum direct current voltage is selected from all the direct current voltages obtained by sampling, and the minimum direct current voltage is used as a preset direct current voltage threshold value and stored in the MCU 1. In actual operation of the MCU1 and the MCU2, the MCU1 may detect the dc voltage of the capacitor, determine which preset rotation speed the rotation speed of the motor is, determine whether the dc voltage of the capacitor is greater than a preset dc voltage threshold corresponding to the preset rotation speed, and determine whether the carrier phase difference between the MCU1 and the MCU2 reaches a preset phase difference.

In an exemplary scenario, taking a dc converter as an MCU as an example, assuming that there are an MCU1, an MCU2, an MCU3 and an MCU4, the MCU1 is electrically connected to the motor 1, and the MCU3 is electrically connected to the motor 2, a preset dc voltage threshold may be obtained by performing experiments on the MCU1, the MCU2 and the motor 1, and the preset dc voltage threshold is directly applied to the MCU3 during operations of the MCU3, the MCU4 and the motor 2. Specifically, the MCU1 and the MCU2 can be electrically connected, and the MCU1 and the MCU2 can be subjected to simulation experiments under the following conditions: the carrier phase difference of the MCU1 and the MCU2 is pi, the rotating speed of the motor 1 is a preset rotating speed, the parameters and the output power of the MCU1 and the MCU2 are consistent, in the running process of the MCU1 and the MCU2, the direct current voltage of the capacitor of the MCU1 is sampled at a fixed point, the minimum direct current voltage is selected from all the direct current voltages obtained by sampling, and the minimum direct current voltage is used as a preset direct current voltage threshold value and stored in the MCU 3. In actual operation of the MCU3 and the MCU4, the MCU3 and the MCU4 are electrically connected to enable the MCU3 to determine whether the carrier phase difference between the MCU3 and the MCU4 reaches a preset phase difference by detecting the dc voltage of the capacitor, determining which preset rotation speed the rotation speed of the motor is, and determining whether the dc voltage of the capacitor is greater than a preset dc voltage threshold corresponding to the preset rotation speed.

Similarly, the rotating speed of the motor i can be changed, experiments are respectively carried out under the condition that the rotating speed of the motor i is various, the steps of sampling and selecting the minimum preset direct-current voltage threshold value are repeatedly executed, so that the direct-current voltage threshold value corresponding to the rotating speed is obtained, and the preset direct-current voltage threshold values corresponding to various rotating speeds are obtained. Further, through an experimental process, a preset corresponding relationship between the rotation speed and the preset dc voltage threshold may be established, and the preset corresponding relationship may be regarded as a table and may be stored in the first dc converter. The preset corresponding relation comprises at least one rotating speed and at least one corresponding direct-current voltage threshold, and the preset corresponding relation can be recorded in a list form. Illustratively, the preset correspondence may be as shown in table 1 below:

TABLE 2

Rotational speed

500rpm

1500rpm

2000rpm

2500rpm

3000rpm

3500rpm

Threshold value of DC voltage

Umin1

Umin2

Umin3

Umin4

Umin5

Umin6

By combining the corresponding relationship between the rotating speed and the direct-current voltage threshold, after the first direct-current converter obtains the rotating speed of the motor electrically connected with the first direct-current converter, the target rotating speed can be used as an index, a second preset corresponding relationship is inquired, and the direct-current voltage threshold corresponding to the target rotating speed is obtained from the second preset corresponding relationship, so that whether the direct-current voltage threshold is out of phase with the carrier of the second direct-current converter or not is judged according to the direct-current voltage threshold. For example, assuming that the target rotation speed is 1500rpm and the second predetermined corresponding relationship is shown in the above table, the first dc converter may determine that the dc voltage threshold is Umin2 after querying the second predetermined corresponding relationship according to 1500 rpm.

(3) And judging whether the direct-current voltage of the capacitor in the first direct-current converter is greater than a preset direct-current voltage threshold corresponding to preset output power, and if the direct-current voltage of the capacitor in the first direct-current converter is greater than the preset direct-current voltage threshold corresponding to the preset output power, determining that the carrier phase difference between the first direct-current converter and the second direct-current converter does not reach the preset phase difference.

The process of obtaining the output power is the same as that of (2), and is not described herein.

In this embodiment, the first dc converter may pre-store the preset dc voltage threshold corresponding to each output power, and in actual operation, may obtain the current output power of the electrically connected motor, and query the preset dc voltage threshold corresponding to the preset output power when the preset output power is the output power, so as to obtain the preset dc voltage threshold. The preset dc voltage threshold may be determined according to the dc voltage of the capacitor in the dc converter i and the output power of the motor i.

A motor i: the motor i is electrically connected with the direct current converter i, the direct current voltage of the capacitor in the direct current converter i is the minimum value of the direct current voltage of the capacitor in the direct current converter i when the carrier phase difference of the two electrically connected direct current converters reaches the preset phase difference and the output power of the motor i is the preset output power.

In another exemplary scenario, taking a dc converter as an MCU as an example, assuming that there are an MCU1 and an MCU2, the MCU1 is electrically connected to the motor 1, a preset dc voltage threshold can be obtained by performing experiments on the MCU1, the MCU2 and the motor 1, and the preset dc voltage threshold is directly applied to the MCU1 during operation of the MCU1, the MCU2 and the motor 1. Particularly, can be connected MCU1 and MCU2 electricity, MCU1 is connected with motor 1, carries out the simulation experiment to MCU1, MCU2, and the experimental condition is: the carrier phase difference of the MCU1 and the MCU2 is pi, the output power of the motor 1 is preset output power, the parameters and the output power of the MCU1 and the MCU2 are consistent, in the running process of the MCU1 and the MCU2, the direct current voltage of a capacitor of the MCU1 is sampled at a fixed point, the minimum direct current voltage is selected from all the direct current voltages obtained through sampling, and the minimum direct current voltage is used as a preset direct current voltage threshold value and stored in the MCU 1. In actual operation of the MCU1 and the MCU2, the MCU1 may detect the dc voltage of the capacitor, determine which preset output power the output power of the motor is, determine whether the dc voltage of the capacitor is greater than a preset dc voltage threshold corresponding to the preset output power, and determine whether the carrier phase difference between the MCU1 and the MCU2 reaches a preset phase difference.

In an exemplary scenario, taking a dc converter as an MCU as an example, assuming that there are an MCU1, an MCU2, an MCU3 and an MCU4, the MCU1 is electrically connected to the motor 1, and the MCU3 is electrically connected to the motor 2, a preset dc voltage threshold may be obtained by performing experiments on the MCU1, the MCU2 and the motor 1, and the preset dc voltage threshold is directly applied to the MCU3 during operations of the MCU3, the MCU4 and the motor 2. Specifically, the MCU1 and the MCU2 can be electrically connected, and the MCU1 and the MCU2 can be subjected to simulation experiments under the following conditions: the carrier phase difference of the MCU1 and the MCU2 is pi, the output power of the motor 1 is preset output power, the parameters and the output power of the MCU1 and the MCU2 are consistent, in the running process of the MCU1 and the MCU2, the direct current voltage of a capacitor of the MCU1 is sampled at a fixed point, the minimum direct current voltage is selected from all the direct current voltages obtained through sampling, and the minimum direct current voltage is used as a preset direct current voltage threshold value and stored in the MCU 3. In actual operation of the MCU3 and the MCU4, the MCU3 and the MCU4 are electrically connected to enable the MCU3 to determine whether the carrier phase difference between the MCU3 and the MCU4 reaches a preset phase difference by detecting the dc voltage of the capacitor, determining which preset output power the output power of the motor is, and determining whether the dc voltage of the capacitor is greater than a preset dc voltage threshold corresponding to the preset output power.

Similarly, the output power of the motor i can be changed, experiments are respectively performed under the condition that the output power of the motor i is various output powers, the steps of sampling and selecting the minimum preset direct-current voltage threshold value are repeatedly executed, so that the direct-current voltage threshold value corresponding to the output power is obtained, and the preset direct-current voltage threshold values corresponding to the various output powers are obtained. Further, through an experimental process, a preset corresponding relationship between the output power and the preset dc voltage threshold may be established, and the preset corresponding relationship may be regarded as a table and may be stored in the first dc converter. The preset corresponding relation comprises at least one output power and at least one corresponding direct-current voltage threshold, and the preset corresponding relation can be recorded in a list form. Illustratively, the preset correspondence may be as shown in table 3 below:

TABLE 3

Output power

500W

1500W

2000W

2500W

3000W

3500W

Threshold value of DC voltage

Umin1

Umin2

Umin3

Umin4

Umin5

Umin6

(4) And judging whether the direct current voltage of the capacitor in the first direct current converter is greater than a preset direct current voltage threshold corresponding to the preset output current, and if the direct current voltage of the capacitor in the first direct current converter is greater than the preset direct current voltage threshold corresponding to the preset output current, determining that the carrier phase difference between the first direct current converter and the second direct current converter does not reach the preset phase difference.

The process of obtaining the output current is the same as that of (2), and is not described herein.

In this embodiment, the first dc converter may pre-store the preset dc voltage threshold corresponding to each output current, and in actual operation, may obtain the current output current of the electrically connected motor, and query the preset dc voltage threshold corresponding to the preset output current as the output current, so as to obtain the preset dc voltage threshold. The preset dc voltage threshold may be determined according to the dc voltage of the capacitor in the dc converter i and the output current of the motor i.

A motor i: the motor i is electrically connected with the direct current converter i, the direct current voltage of the capacitor in the direct current converter i is the minimum value of the direct current voltage of the capacitor in the direct current converter i when the carrier phase difference of the two electrically connected direct current converters reaches the preset phase difference and the output current of the motor i is the preset output current.

In another exemplary scenario, taking a dc converter as an MCU as an example, assuming that there are an MCU1 and an MCU2, the MCU1 is electrically connected to the motor 1, a preset dc voltage threshold can be obtained by performing experiments on the MCU1, the MCU2 and the motor 1, and the preset dc voltage threshold is directly applied to the MCU1 during operation of the MCU1, the MCU2 and the motor 1. Particularly, can be connected MCU1 and MCU2 electricity, MCU1 is connected with motor 1, carries out the simulation experiment to MCU1, MCU2, and the experimental condition is: the carrier phase difference of the MCU1 and the MCU2 is pi, the output current of the motor 1 is preset output current, the parameters and the output current of the MCU1 and the MCU2 are consistent, in the running process of the MCU1 and the MCU2, the direct current voltage of a capacitor of the MCU1 is sampled at a fixed point, the minimum direct current voltage is selected from all the direct current voltages obtained by sampling, and the minimum direct current voltage is used as a preset direct current voltage threshold value and stored in the MCU 1. In actual operation of the MCU1 and the MCU2, the MCU1 may detect the dc voltage of the capacitor, determine which preset output current the output current of the motor is, determine whether the dc voltage of the capacitor is greater than a preset dc voltage threshold corresponding to the preset output current, and determine whether the carrier phase difference between the MCU1 and the MCU2 reaches a preset phase difference.

In an exemplary scenario, taking a dc converter as an MCU as an example, assuming that there are an MCU1, an MCU2, an MCU3 and an MCU4, the MCU1 is electrically connected to the motor 1, and the MCU3 is electrically connected to the motor 2, a preset dc voltage threshold may be obtained by performing experiments on the MCU1, the MCU2 and the motor 1, and the preset dc voltage threshold is directly applied to the MCU3 during operations of the MCU3, the MCU4 and the motor 2. Specifically, the MCU1 and the MCU2 can be electrically connected, and the MCU1 and the MCU2 can be subjected to simulation experiments under the following conditions: the carrier phase difference of the MCU1 and the MCU2 is pi, the output current of the motor 1 is preset output current, the parameters and the output current of the MCU1 and the MCU2 are consistent, in the running process of the MCU1 and the MCU2, the direct current voltage of a capacitor of the MCU1 is sampled at a fixed point, the minimum direct current voltage is selected from all the direct current voltages obtained by sampling, and the minimum direct current voltage is used as a preset direct current voltage threshold value and stored in the MCU 3. In actual operation of the MCU3 and the MCU4, the MCU3 and the MCU4 are electrically connected to enable the MCU3 to determine whether the carrier phase difference between the MCU3 and the MCU4 reaches a preset phase difference by detecting the dc voltage of the capacitor, determining which preset output current the output current of the motor is, and determining whether the dc voltage of the capacitor is greater than a preset dc voltage threshold corresponding to the preset output current.

Similarly, the output current of the motor i can be changed, experiments are respectively performed under the condition that the output current of the motor i is various output currents, the steps of sampling and selecting the minimum preset direct-current voltage threshold value are repeatedly executed, so that the direct-current voltage threshold value corresponding to the output current is obtained, and the preset direct-current voltage threshold values corresponding to various output currents are obtained. Further, through an experimental process, a preset corresponding relationship between the output current and the preset dc voltage threshold may be established, and the preset corresponding relationship may be regarded as a table and may be stored in the first dc converter. The preset corresponding relation comprises at least one output current and at least one corresponding direct-current voltage threshold, and the preset corresponding relation can be recorded in a list form. Illustratively, the preset correspondence may be as shown in table 4 below:

TABLE 4

Output current

5A

15A

20A

25A

30A

35A

Threshold value of DC voltage

Umin1

Umin2

Umin3

Umin4

Umin5

Umin6

In the first implementation mode, it is considered that the magnitude of the current output power affects the input current amplitude required to be provided by the capacitor, and the corresponding preset dc voltage thresholds are set for the torques of various magnitudes, the rotating speeds of various magnitudes, the output powers of various magnitudes, and the output currents of various magnitudes, in operation, the corresponding preset dc voltage thresholds are determined by combining the parameters of the current target torque, the target rotating speed, the target output power, the target output current, and the like, so that the matching of the used preset dc voltage thresholds with the current operation condition can be ensured, the matching of the process for detecting whether the carrier is in a phase-dislocation state with the current operation condition is also ensured, the accuracy of the process for ensuring the carrier in a phase-dislocation state is high, and the method is suitable for complex and variable use environments and operation conditions.

The first point to be described is that the above (1) to (4) may be executed alternatively or in combination, and regarding a specific implementation manner of the above (1) to (4) in combination, as shown in the following table 5, with the combination of (1) and (2), a fifth preset corresponding relationship between the torque, the rotation speed, and the preset dc voltage threshold may be pre-established, where the fifth preset corresponding relationship includes at least one torque, at least one rotation speed, and at least one corresponding preset dc voltage threshold, and the fifth preset corresponding relationship may be queried based on the target torque and the target rotation speed to obtain the preset dc voltage threshold corresponding to both the target torque and the target rotation speed.

TABLE 5

For example, assuming that the target torque is 150Nm, the target rotation speed is 1500rpm, and the fifth preset corresponding relationship is shown in table 5 above, after the first dc converter queries the fifth preset corresponding relationship according to 150Nm and 1500rpm, it may determine that the preset dc voltage threshold is Umin 32.

The second point to be described is that, in consideration of an abnormal situation that the dc voltage of the capacitor is always greater than the preset dc voltage threshold, during the operation of the first dc converter, a duration that the dc voltage of the capacitor is greater than the preset dc voltage threshold may be counted, when the duration exceeds the preset duration, a setting error of the preset dc voltage threshold may be determined, the process of carrier phase shifting may be suspended, until the first dc converter is stopped and restarted, and the process of carrier phase shifting may be restarted, where the preset duration may be set according to an actual requirement, and may be a period of carriers of a preset number of first dc converters, for example, 16 × 4 — 64 periods of carriers of the first dc converter.

If the dc voltage is always greater than the preset dc voltage threshold, two reasons are mainly included: one is a necessary factor, that is, parameters of the motor change due to long-time operation, which causes a difference between an actual preset dc voltage threshold and a preset dc voltage threshold, that is, the preset dc voltage threshold is inaccurate, and therefore, according to the preset dc voltage threshold, it is determined whether a carrier phase error occurs. The other is an accidental factor, that is, the dc voltage of the capacitor has dynamic fluctuation, the time scale of the dynamic fluctuation is much longer than the time scale of the carrier period, but it cannot be guaranteed that the dc voltage of the capacitor is not affected at all, and if the dc voltage of the capacitor is sampled at the time point of the dynamic fluctuation, failure may be caused, but normal operation of the dc converter is not affected.

Judging whether the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is the carrier frequency of the first direct-current converter; and if the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is the carrier frequency of the first direct-current converter, determining that the carrier phase difference between the first direct-current converter and the second direct-current converter does not reach a preset phase difference.

If the harmonic frequency of the direct current voltage is the frequency of the carrier wave of the first direct current converter, the first direct current converter and the second direct current converter are in carrier synchronization, and therefore it can be determined that the phase difference between the carrier wave of the first direct current converter and the carrier wave of the second direct current converter does not reach the preset phase difference. The frequency of the carrier of the first dc converter is equal to the frequency of the switching voltage in the first dc converter, and the frequency of the carrier of the first dc converter may also be referred to as the switching frequency of the first dc converter. The harmonic frequency of the dc voltage may be obtained by fourier decomposition of the dc voltage.

And if the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is smaller than the harmonic frequency threshold, determining that the carrier phase difference between the first direct-current converter and the second direct-current converter does not reach a preset phase difference.

And if the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is smaller than the harmonic frequency threshold, indicating that the phase difference between the carrier waves of the first direct-current converter and the second direct-current converter is smaller, determining that the phase difference between the carrier waves of the first direct-current converter and the second direct-current converter does not reach the preset phase difference. And when the harmonic frequency of the direct current voltage is not less than the harmonic frequency threshold value, determining that the carrier phase difference of the first direct current converter and the second direct current converter reaches a preset phase difference.

Wherein the harmonic frequency threshold is determined according to the carrier frequency of the first dc-to-dc converter, in a possible implementation, the harmonic frequency threshold is a preset multiple of the frequency of the carrier of the first dc-to-dc converter, which preset multiple may be greater than 1 and less than 2, for example, may be 1.5, if there are two electrical energy converters in the electronic device. If three power converters are provided in the electronic device, the predetermined multiple may be greater than 1 and less than 3, for example, 2.

1904. The first dc converter adjusts a phase of a carrier of the first dc converter.

The process of adjusting the Phase of the Carrier of the first dc converter is also called Carrier Phase Shifting (Carrier Phase Shifting), and may be understood as Shifting the Carrier of the first dc converter to the left or to the right in the time domain. The phase of the carrier of the first dc converter may be adjusted by increasing the phase of the carrier of the first dc converter, shifting the carrier of the first dc converter to the right in the time domain, and delaying the carrier of the first dc converter by a certain phase from the previous carrier. The phase of the carrier of the first dc converter may be adjusted by decreasing the phase of the carrier of the first dc converter, shifting the carrier of the first dc converter to the left in the time domain, and advancing the carrier of the first dc converter by a predetermined phase from the previous carrier.

With regard to the magnitude of each adjustment of the phase of the carrier of the first dc converter, a preset phase may be set, one preset phase being adjusted on the basis of the current phase of the carrier of the first dc converter each time the phase of the carrier of the first dc converter is to be adjusted. Taking the example of a carrier phase shift by incrementing the phase of the carrier of the first dc-to-dc converter, the phase of the carrier of the first dc-to-dc converter may be increased by a preset phase on the basis of the current phase of the carrier of the first dc-to-dc converter, e.g. the phase of the carrier of the first dc-to-dc converter may be adjusted from 2/pi to 3/4 pi assuming that the preset phase is 4/pi and the current phase of the carrier of the first dc-to-dc converter is 2/pi. Taking the example of shifting the phase of the carrier by decrementing the phase of the carrier of the first dc-to-dc converter, the phase of the carrier of the first dc-to-dc converter may be decreased by a preset phase on the basis of the current phase of the carrier of the first dc-to-dc converter, e.g. the phase of the carrier of the first dc-to-dc converter may be adjusted from 2/pi to 1/4 pi assuming a phase step of 4/pi and a current phase of the carrier of the first dc-to-dc converter of 2/pi.

With respect to a specific implementation manner of adjusting the phase of the carrier of the first dc converter, in one possible implementation, the first dc converter may have a signal selector, the signal generator may generate a plurality of carriers with different phases and input the plurality of carriers to the signal selector, and the signal selector may receive the plurality of carriers, select one carrier from the plurality of carriers, and output the one carrier for modulation based on the carrier output by the signal selector.

In this embodiment, when the phase of the carrier of the first dc converter is to be adjusted, the first dc converter may control the signal selector based on the current phase of the carrier of the first dc converter, select a carrier having a phase different from the current phase from the plurality of input carriers, and output a carrier having a phase different from the current phase.

Regarding the implementation of the control signal selector, the processor of the first dc converter may determine a carrier to be reselected by the signal selector based on the current phase of the carrier of the first dc converter, generate a carrier selection instruction according to the reselected carrier, send the carrier selection instruction to the signal selector, and after receiving the carrier selection instruction, the signal selector may reselect the carrier according to the carrier selection instruction and output the reselected carrier.

The carrier selection instruction is used for instructing the carrier newly selected by the signal selector, and in a possible implementation, the carrier selection instruction may be a level signal or a combination of a plurality of level signals, and the level signal may have a high level and a low level corresponding to the carrier of the corresponding first dc converter, for example, the level signal "00" corresponds to the carrier with the phase 0, and the level signal "01" corresponds to the carrier with the phase 1/4 pi. In this way, the logic function table stored in the signal selector may be configured according to the carriers of the plurality of first dc converters, so that the signal selector may select the corresponding carrier based on the logic function table when receiving the carrier selection instruction.

For example, if the first dc converter is required to switch between carriers of four phases during the modulation process, the signal selector may be configured as a four-way data selector, and if the first dc converter is required to switch between carriers of eight phases, the signal selector may be configured as an eight-way data selector.

Taking the first dc converter switching among carriers of four phases, the phases of the carriers of the four phases being 0, 1/4 pi, 1/2 pi and 3/4 pi in sequence as an example, the signal selector of the first dc converter may be a one-out-of-four data selector, and the one-out-of-four data selector may store a logic function table shown in table 6 below, so that when sending a level signal "01" to the one-out-of-four data selector, the one-out-of-four data selector outputs the carrier of the first dc converter with the phase of 1/4 pi.

TABLE 6

Carrier selection instruction	Carrier wave output by signal selector
		00	Carrier wave with phase 0
01	Carrier wave with phase 1/4 pi
		10	Carrier wave with phase 1/2 pi
11	Carrier wave with phase 3/4 pi

With regard to the carrier selected by the control signal selector, optionally, the control signal selector may select a carrier having a phase adjacent to the current phase from among the plurality of carriers based on the current phase of the carrier of the first dc converter, and output the carrier having the phase adjacent to the current phase. Taking a plurality of carriers arranged in order of their phases from small to large as an example, the signal selector may be controlled to select and output a next carrier of the current carrier, for example, assuming that the current carrier is the 2 nd carrier, the signal selector may be controlled to select and output the 3 rd carrier. Of course, the signal selector may also be controlled to select and output the carrier that is previous to the current carrier, for example, assuming that the carrier of the current first dc converter is the 2 nd carrier, the signal selector may be controlled to select and output the 1 st carrier.

For example, please refer to fig. 21, fig. 21 is a schematic diagram of a signal selector for selecting carriers according to an embodiment of the present application, where carrier 1, carrier 2, carrier 3, and carrier 4 are input to the signal selector, phases of carrier 1, carrier 2, carrier 3, and carrier 4 sequentially differ by 4/pi, and the signal selector selects one carrier from carrier 1, carrier 2, carrier 3, and carrier 4 to output at any time, and each time it is determined that the carriers are not in a phase-shifted state according to a dc voltage, the signal selector switches the currently selected carrier, selects a next carrier of the currently selected carrier, and outputs the next carrier, so as to shift the carrier by 4/pi, so that the carriers modulated by the first dc converter can sequentially move according to an order of carrier 1-carrier 2-carrier 3-carrier 4.

Referring to fig. 22, fig. 22 is a logic flow diagram for adjusting carrier phase according to an embodiment of the present application, which may determine which carrier is currently selected by the signal selector according to the current phase of the carrier of the first dc converter, so as to control the signal selector to select a next carrier for output. Taking the phase difference of carriers with adjacent phases as an example of 1/4 pi, if the signal selector currently selects the carrier with the phase of 1/4 pi, the signal selector is controlled to select the carrier with the phase of 1/2 pi, and if the signal selector currently selects the carrier with the phase of 1/2 pi, the signal selector is controlled to select the first carrier with the phase of 3/4 pi.

In this embodiment, when the carrier of the first dc converter is to be phase-shifted, the signal selector is controlled to reselect the carrier from the input multiple carriers, on one hand, the reselected carrier has a certain phase difference with the originally selected carrier, and after the carrier is reselected, the phase of the currently modulated carrier changes, thereby achieving the purpose of changing the phase of the carrier. On the other hand, the phase of each carrier input to the signal selector can be preset, when carrier phase shifting is required, how large a phase needs to be adjusted is not required to be provisionally calculated according to the current phase of the carrier, the phase step length of the phase shifting is not required to be provisionally calculated, and the signal selector is only required to be controlled to reselect the carrier from a plurality of input carriers, so that the stability of the control process is ensured to be strong, and the condition that the carrier phase is disordered is not caused. On the other hand, the signal selector switches the selected carrier once, so that the phase of the carrier can be adjusted to be a preset phase, the phase shifting speed is high, the phase shifting efficiency is high, and meanwhile, the processing logic is simple.

1905. The first dc converter maintains the phase of the carrier of the first dc converter constant for at least one period of the carrier of the first dc converter.

Optionally, after adjusting the phase of the carrier of the first dc converter once, the first dc converter may perform a delay, suspend the process of shifting the phase of the carrier, keep the current phase of the carrier of the first dc converter unchanged, and readjust the phase of the carrier of the first dc converter after at least one period of the carrier of the first dc converter has elapsed.

By delaying the carrier of the first dc converter every time the phase of the carrier is adjusted, at least the following technical effects can be achieved: if the phase of the carrier of the first dc converter is adjusted in real time, for example, the carrier of the first dc converters is replaced in real time, which may cause the switching voltage to be disturbed, so that the control is unstable, and after the phase of the carrier of the first dc converter is adjusted once, the phase of the carrier is maintained in at least one carrier period, and then the phase of the carrier is adjusted again, so that the switching voltage can be ensured to be stable, thereby ensuring the control stability of the dc converter, and ensuring the carrier state to be rapidly converged.

With respect to the number of at least one period of the delay, in one possible implementation, the number of at least one period is N × N, N is a ratio between a preset phase difference and a preset phase, and the preset phase is a phase step of each adjustment of a carrier of the first dc converter, where N is a positive integer. Assuming that the preset phase difference is pi, the preset phase is pi/N, after each carrier of the first dc converter is shifted by pi/N, N × N carrier periods are maintained in the current phase, and after the time has passed N × N carrier periods, the carrier of the first dc converter is shifted by pi/N. In addition, at least one period of the delay time can be configured to be greater than N × N according to actual requirements.

For example, assuming that the predetermined phase difference is pi and the predetermined phase is 1/4 pi, the at least one period may be 4 × 4 — 16. Referring to fig. 22, each time the signal selector switches the currently selected carrier, at least 16 carrier periods are delayed, for example, when the carrier 1 is selected, the carrier 2 is selected, at least 16 carrier periods are delayed, after at least 16 carrier periods have elapsed, the carrier 2 is selected, the carrier 3 is selected, at least 16 carrier periods are delayed again, and so on, until the dc voltage of the capacitor is not less than the preset dc voltage threshold. In addition, if there are three dc converters in the electronic device, the number of delayed carrier cycles may be determined according to the total number of generated carriers, for example, if the dc converters generate carriers with 6 phases, the delay time 6 × 6 is 36 carrier cycles each time the phase of the carrier is adjusted.

By adjusting the phase of the carrier of the first dc converter once and delaying the period of the carrier of the N × N first dc converters, it can be ensured that one carrier period can be maintained after the carrier of the first dc converter is phase-shifted each time to wait for the measurement of the dc voltage of the new capacitor, and therefore, after N × N carrier periods, the completion of the previous period can be waited for. In addition, the control stability of the direct current converter can be ensured, and the carrier state can be rapidly converged.

1906. After the first dc converter passes through at least one period of the carrier of the first dc converter, steps 1902 to 1905 are executed again until it is determined that the phase difference between the carriers of the first dc converter and the second dc converter reaches the preset phase difference according to the dc voltage of the capacitor in the first dc converter.

When the elapsed time has reached at least one period of the carrier of the first dc converter, the first dc converter may perform step 1902 again, determine a current dc voltage of the capacitor, and if it is determined according to the dc voltage that the phase difference between the carrier of the first dc converter and the carrier of the second dc converter has not reached the preset phase difference, adjust the phase of the carrier of the first dc converter again until it is determined according to the dc voltage of the capacitor in the first dc converter that the phase difference between the carrier of the first dc converter and the carrier of the second dc converter has reached the preset phase difference, complete the task of carrier misphasing, that is, the degree of temporal staggering of the carriers of the first dc converter and the second dc converter has satisfied the requirement, and then it is not necessary to continue to adjust the phase of the carrier of the first dc converter.

If the first implementation manner is adopted in step 1903, the first dc converter will determine whether the dc voltage is greater than the preset dc voltage threshold again until the dc voltage is not greater than the preset dc voltage threshold. If the second implementation is adopted in step 1903, the first dc converter determines again whether the harmonic frequency of the dc voltage is the frequency of the carrier of the first dc converter until the harmonic frequency of the dc voltage is not the frequency of the carrier of the first dc converter. If the third implementation manner is adopted in step 1903, the first dc converter will determine again whether the harmonic frequency of the dc voltage is smaller than the harmonic frequency threshold value until the harmonic frequency of the dc voltage is not smaller than the harmonic frequency threshold value.

Combining the signal selector and the design of pre-generating the carriers of the plurality of first direct current converters, the first direct current converter switches the currently modulated carrier of the first direct current converter, and the carrier of the first direct current converter continuously and circularly moves among the plurality of pre-generated carriers, so that the phase is continuously adjusted until the phase difference between the carriers of the first direct current converter and the second direct current converter reaches the preset phase difference.

For example, referring to fig. 21, the signal selector may be controlled to select a next carrier of the current carrier from the 4 carriers for output, and the carriers may be regarded as moving from the original carrier to another carrier, so that the carriers may move cyclically from carrier 1 to carrier 4, that is, moving from carrier 1 to carrier 2, then moving from carrier 2 to carrier 3, moving from carrier 3 to carrier 4, then moving from carrier 4 to carrier 1, and so on.

The method for controlling the signal selector to select another carrier may include setting a determining module in a processor of the first dc converter, where the determining module includes at least one instruction for determining whether a dc voltage of the capacitor is greater than a preset dc voltage threshold, that is, Udc > Udc _ min, or determining whether a harmonic frequency of the dc voltage is greater than a carrier frequency, that is, fudc > fsw, and when the determining module is running, whenever the determining module determines that the dc voltage is greater than the preset dc voltage threshold, or determines that the harmonic frequency of the dc voltage is greater than the carrier frequency, the determining module may generate a carrier selecting instruction, and send the carrier selecting instruction to the signal selector, so that the signal selector reselects and outputs the carrier.

The first direct current converter adjusts the phase of the carrier wave, the phase of the carrier wave is equal to the phase of the first switching voltage, the phase of the first switching voltage is adjusted after the phase of the carrier wave is adjusted, and the phase of the switching voltage is equal to the phase of the output current generated by the switching control, so that the phase of the first output current is adjusted, the phase of the first output current is staggered with the phase of the second output current, the two MCUs are used as an equivalent current source, and the amplitude of the equivalent current source is reduced due to the fact that the waveforms of the first output current and the second output current are staggered.

In this groupOn the basis, because the input and output currents of the same node are identical, the equivalent current source is also equal to the superposition of the first input current and the second input current, and from one perspective, because the capacitor is used for providing instantaneous current for the equivalent current source, the current flowing through the capacitor is equal to the current of the equivalent current source, the amplitude of the equivalent current source is reduced, and then the amplitude of the current flowing through the capacitor is reduced according to a capacitor current formula:

i_capand therefore C, i.e. the capacitance requirement for the capacitor is reduced. Viewed from another perspective, according to formula (7) above:

when the amplitude of the equivalent current source is reduced, the instantaneous voltage at two ends of the capacitor is increased, and the capacitance value required to be reached by the capacitor is inversely related to the instantaneous voltage, so that the requirement on the capacitance value of the capacitor is reduced.

The first point to be described is that, because the capacitor of the first dc converter and the capacitor of the second dc converter are connected in parallel in a dc network, the two capacitors as a whole can be converted into an equivalent capacitor through an electrical conversion relationship, and the first dc converter actually reduces the amplitude of the current required to be provided by the equivalent capacitor by performing carrier phase shift, thereby reducing the requirement on the capacitance value of the equivalent capacitor. That is, after the first dc converter and the second dc converter are in phase-staggered relationship, the capacitance requirement of the capacitor of the first dc converter is reduced, and the capacitance requirement of the capacitor of the second dc converter is also reduced, and the capacitance requirement of each dc converter is reduced by a certain amount, which can be determined according to the actual circuit structure.

The second point to be described is that the present embodiment is described only by taking the example that the first dc converter adjusts the phase of the carrier, the second dc converter does not need to adjust the phase of the carrier, and finally the carrier-induced phase error between the first dc converter and the second dc converter is realized.

Further, it can be applied in the scenario of three dc converters, two dc converters adjust the phase of the carrier, and the remaining one dc converter does not need to adjust the phase of the carrier, and finally, the carrier phase-shifting between the three dc converters is achieved, that is, when two dc converters of the three dc converters execute the above-mentioned method procedure of the first dc converter, the two dc converters will continuously perform the carrier phase-shifting until the dc voltages of the capacitors in the two dc converters are not greater than the preset dc voltage threshold, or until the harmonic frequencies of the dc voltages of the capacitors in the two dc converters are not the frequencies of the corresponding carriers, then, the three dc converters will achieve the carrier phase-shifting, for example, the carrier of the second dc converter lags by a certain phase with respect to the carrier of the first dc converter, and the carrier wave of the third DC converter lags behind the carrier wave of the second DC converter by a certain phase, so that the carrier waves of the three DC converters are staggered from each other in the time domain, thereby reducing the capacitance requirement on the capacitor in each DC converter.

In this way, for the case that the dc converter system includes N dc converters, the (N-1) dc converters of the N dc converters may execute the above-mentioned method procedure of the first dc converter, and then the (N-1) dc converters may continuously perform carrier phase shifting until the dc voltage of the capacitor in the (N-1) dc converters is not greater than the preset dc voltage threshold, or until the harmonic frequency of the dc voltage of the capacitor in the (N-1) dc converters is not the frequency of the corresponding carrier, then the (N-1) dc converters may implement carrier phase shifting, so as to reduce the requirement on the capacitance value of the capacitor in each of the N dc converters.

The inventor respectively adopts the carrier phase-staggered technology provided by the embodiment of the application and the related technology to carry out simulation experiments on various working conditions of the electric automobile, and collects the input current i provided by the capacitor_invDC voltage U of power supply_dcFig. 23 to 25 show experimental results obtained from waveform diagrams of the dc current idc of the power supply. Through comparison of experimental results, it can be seen that the effect that can be achieved only when the capacitance is 380uF in the related art can be achieved when the capacitance is 180uF through the carrier phase-staggered technology provided by the embodiment of the present application, so that the requirement on the capacitance value of the capacitance can be reduced by more than half, and the volume and the cost of the capacitance can be significantly reduced.

In addition, various experiments are carried out under the condition that no additional current sensor is arranged for the capacitor, no signal wire or other communication equipment is arranged between the MCU and the MCU, and the following tests are successfully verified: need not to set up extra current sensor and communications facilities, need not to connect the current sensor and the communications facilities who set up extra with MCU, can reduce the appearance value requirement to the electric capacity by a wide margin, and efficiency is very high, has all brought very big facility to MCU's equipment and manufacturing process.

FIG. 23 is a graph showing the effect of an experiment performed on an electric vehicle at a vehicle speed of 60km/h and a motor torque of 110Nm, which simulates the operation of the electric vehicle in a constant-speed cruising scene. Fig. 23(a) and 23(b) show the same MCU output power, and fig. 23(a) shows a capacitor C of 380uF and does not use the present phasing technique, and fig. 23(b) shows a capacitor C of 180uF and uses the present phasing technique, which indicates that the capacitor C of 180uF during cruise at a fixed speed of the electric vehicle, i.e., the result of the capacitor C of 380uF in the related art is achieved.

Fig. 24 is a graph showing experimental effects of the electric vehicle when the torque of one wheel of the MCU is 1500Nm and the torque of the other wheel of the MCU is 400Nm, and simulates the operation of the electric vehicle in the instability control scenario. Fig. 24(a) and fig. 24(b) show the same MCU output power, and fig. 24(a) shows a capacitor C of 380uF without the phase-shifting technique, and fig. 24(b) shows a capacitor C of 180uF with the phase-shifting technique, which indicates that the electric vehicle achieves the result of the capacitor C of 380uF in the related art when the capacitor C of 180uF is used in the instability control process.

FIG. 25 is a diagram of the experimental effect of the electric vehicle when the torque of one MCU is-1500 Nm and the torque of the other MCU is +1500Nm, and simulates the operation of the electric vehicle in a sharp turning scene. In fig. 25(a) and fig. 25(b), the output power of the MCU is the same, and the capacitor C in fig. 25(a) is 380uF, and the present phase-shifting technique is not used, and the capacitor C in fig. 25(b) is 180uF, and the present phase-shifting technique is used, so that the result obtained when the electric vehicle makes a sharp turn, the capacitor C is 180uF, that is, the capacitor C is 380uF in the related art is achieved.

Combine above-mentioned experimental result, can prove, the technical scheme that this application provided all can reach fine efficiency under electric automobile's different work condition, and the electric capacity can reduce at least half, and because the electric capacity is the essential element who occupies volume in the MCU, also can reduce MCU about 15% volume, simultaneously, also can reduce MCU's cost.

Fig. 26 is a schematic structural diagram of a carrier modulation apparatus according to an embodiment of the present application, applied to a first dc converter, the apparatus including: a detection module 2601, a determination module 2602, and an adjustment module 2603.

A detection module 2601 configured to perform step 1902;

a determining module 2602 for performing step 1903;

an adjusting module 2603 is configured to perform step 1904.

In one possible implementation, the determining module 2602 includes:

the judgment submodule is used for judging whether the direct-current voltage of the capacitor in the first direct-current converter is greater than a preset direct-current voltage threshold value or not;

and the determining submodule is used for determining that the carrier phase difference between the first direct current converter and the second direct current converter does not reach the preset phase difference if the direct current voltage of the capacitor in the first direct current converter is greater than a preset direct current voltage threshold value.

In one possible implementation, the difference between the preset dc voltage threshold and the minimum value of the dc voltage of the capacitor in the dc converter i is within a preset range.

In a possible implementation manner, the determining submodule is configured to perform one or more of (1) in step 1903, (2) in step 1903, (3) in step 1903, and (4) in step 1903.

In one possible implementation, the electric machine i is an electric machine to which the first dc converter is electrically connected.

In one possible implementation, the determining module 2602 includes:

and the determining submodule is used for determining that the carrier phase difference of the first direct current converter and the second direct current converter does not reach a preset phase difference if the harmonic frequency of the direct current voltage of the capacitor in the first direct current converter is the carrier frequency of the first direct current converter.

In one possible implementation, the determining module 2602 includes:

the judgment submodule is used for judging whether the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is smaller than a harmonic frequency threshold value;

and the determining submodule is used for determining that the carrier phase difference of the first direct current converter and the second direct current converter does not reach a preset phase difference if the harmonic frequency of the direct current voltage of the capacitor in the first direct current converter is smaller than the harmonic frequency threshold.

In one possible implementation, the harmonic frequency threshold is a preset multiple of the carrier frequency of the first dc-to-dc converter, the preset multiple being greater than 1 and less than 2.

In one possible implementation, the adjusting module 2603 is configured to select a carrier with a phase different from the current phase from a plurality of carriers.

In one possible implementation, the apparatus further includes:

and the carrier generation module is used for generating the plurality of carriers based on a preset phase.

In one possible implementation, the apparatus further includes:

a holding module for holding a phase of a carrier of the first DC converter constant during at least one period of the carrier of the first DC converter.

In a possible implementation manner, the number of the at least one period is N × N, where N is a ratio between the preset phase difference and a preset phase, and the preset phase is a phase step of each adjustment of the carrier of the first dc converter.

All the above optional technical solutions may be combined arbitrarily to form optional embodiments of the present application, and are not described herein again.

It should be noted that: in the carrier modulation apparatus provided in the above embodiment, when the carrier is modulated, only the division of the above functional modules is illustrated, and in practical applications, the above functions may be distributed by different functional modules according to needs, that is, the internal structure of the dc converter is divided into different functional modules to complete all or part of the above described functions. In addition, the carrier modulation apparatus and the carrier modulation method provided by the above embodiments belong to the same concept, and specific implementation processes thereof are described in the method embodiments for details, which are not described herein again.

In an exemplary embodiment, a computer-readable storage medium, such as a memory, including instructions executable by a processor, which may be a processor in a dc converter, to perform the carrier modulation method in the above embodiments is also provided. For example, the computer-readable storage medium may be a Read-Only Memory (ROM), a Random Access Memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer program instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the application to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer program instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer program instructions may be transmitted from one website site, computer, server, or data center to another website site, computer, server, or data center by wire or wirelessly. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., Digital Video Disk (DVD)), or a semiconductor medium (e.g., solid state disk), among others.

The term "and/or" in this application is only one kind of association relationship describing the associated object, and means that there may be three kinds of relationships, for example, a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" in the present application generally indicates that the former and latter related objects are in an "or" relationship. The above description is only an alternative embodiment of the present application, and is not intended to limit the present application, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present application, and all the changes or substitutions should be covered by the protection scope of the present application.

Claims

1. A method for modulating a carrier, the method comprising:

judging whether the direct-current voltage of a capacitor in the first direct-current converter is greater than a preset direct-current voltage threshold value or not, wherein the preset direct-current voltage threshold value is determined according to the direct-current voltage of a capacitor in a direct-current converter i, when the direct-current voltage of the capacitor in the direct-current converter i is the carrier phase difference of two electrically connected direct-current converters and reaches a preset phase difference, the direct-current voltage of the capacitor in the direct-current converter i is the minimum value of the direct-current voltage of the capacitor in the direct-current converter i, and the direct-current converter i is any one of the two;

if the direct-current voltage of the capacitor in the first direct-current converter is larger than the preset direct-current voltage threshold value, determining that the carrier phase difference between the first direct-current converter and the second direct-current converter does not reach the preset phase difference, and electrically connecting the first direct-current converter and the second direct-current converter;

adjusting a phase of a carrier of the first DC converter.

2. The method of claim 1, wherein the predetermined dc voltage threshold is determined according to a dc voltage of a capacitor in a dc converter i, and comprises:

3. The method according to claim 1 or 2, characterized in that the two dc converters are the first and second dc converters, and the dc converter i is the first dc converter.

4. The method of claim 1, wherein the determining whether the dc voltage of the capacitor in the first dc converter is greater than a predetermined dc voltage threshold comprises:

5. The method of claim 4, wherein the motor i is an electric motor to which the first DC converter is electrically connected.

6. The method of claim 1, wherein the determining whether the dc voltage of the capacitor in the first dc converter is greater than a predetermined dc voltage threshold comprises:

7. The method of claim 1, wherein the determining whether the dc voltage of the capacitor in the first dc converter is greater than a predetermined dc voltage threshold comprises:

8. The method of claim 1, wherein the determining whether the dc voltage of the capacitor in the first dc converter is greater than a predetermined dc voltage threshold comprises:

9. The method of claim 1, further comprising:

10. The method of claim 1, further comprising:

11. The method of claim 10, wherein the harmonic frequency threshold is a preset multiple of a carrier frequency of the first dc converter, the preset multiple being greater than 1 and less than 2.

12. The method of claim 1, wherein the adjusting the phase of the carrier of the first dc converter comprises:

13. The method of claim 12, wherein prior to adjusting the phase of the carrier of the first dc converter, the method further comprises:

14. The method of claim 1, wherein after the adjusting the phase of the carrier of the first dc converter, the method further comprises:

15. The method of claim 14, wherein the number of the at least one period is N x N, where N is a ratio between the preset phase difference and a preset phase, and the preset phase is a phase step per adjustment of a carrier of the first dc converter.

16. A carrier modulation apparatus, characterized in that the apparatus comprises:

a determining module, configured to determine whether a dc voltage of a capacitor in the first dc converter is greater than a preset dc voltage threshold, where the preset dc voltage threshold is determined according to a dc voltage of a capacitor in a dc converter i, and when a carrier phase difference between two electrically connected dc converters of the dc voltage of the capacitor in the dc converter i reaches a preset phase difference, the dc voltage of the capacitor in the dc converter i is a minimum value of the dc voltage of the capacitor in the dc converter i, and the dc converter i is any one of the two dc converters; if the direct-current voltage of the capacitor in the first direct-current converter is larger than the preset direct-current voltage threshold value, determining that the carrier phase difference between the first direct-current converter and the second direct-current converter does not reach the preset phase difference, and electrically connecting the first direct-current converter and the second direct-current converter;

and the adjusting module is used for adjusting the phase of the carrier wave of the first DC converter.

17. The apparatus of claim 16, wherein the difference between the preset dc voltage threshold and the minimum value of the dc voltage of the capacitor in the dc converter i is within a preset range.

18. The apparatus according to claim 16 or 17, wherein the two dc converters are the first dc converter and the second dc converter, and the dc converter i is the first dc converter.

19. The apparatus according to claim 16, wherein the determining module is configured to determine whether a dc voltage of a capacitor in the first dc converter is greater than a preset dc voltage threshold corresponding to a preset torque, where the preset torque is a torque of a motor electrically connected to the first dc converter, the preset dc voltage threshold is further determined according to a torque of a motor i, the motor i is electrically connected to the dc converter i, the dc voltage of the capacitor in the dc converter i is a minimum value of dc voltages of two electrically connected dc converters when a carrier phase difference of the two electrically connected dc converters reaches the preset phase difference, and the torque of the motor i is the preset torque.

20. The apparatus of claim 19, wherein the motor i is an electric motor to which the first dc converter is electrically connected.

21. The apparatus according to claim 16, wherein the determining module is configured to determine whether a dc voltage of a capacitor in the first dc converter is greater than a preset dc voltage threshold corresponding to a preset rotation speed, where the preset rotation speed is a rotation speed of a motor electrically connected to the first dc converter, the preset dc voltage threshold is further determined according to a rotation speed of a motor i, the dc voltage of the capacitor in the dc converter i is a minimum value of a carrier phase difference between two electrically connected dc converters reaching the preset phase difference, and the rotation speed of the motor i is the preset rotation speed.

22. The apparatus according to claim 16, wherein the determining module is configured to determine whether a dc voltage of a capacitor in the first dc converter is greater than a preset dc voltage threshold corresponding to a preset output power, where the preset output power is an output power of a motor to which the first dc converter is electrically connected, the preset dc voltage threshold is further determined according to an output power of a motor i, a carrier phase difference of two dc converters electrically connected to the dc voltage of the capacitor in the dc converter i reaches the preset phase difference, and when the output power of the motor i is the preset output power, a minimum value of the dc voltage of the capacitor in the dc converter i is obtained.

23. The apparatus according to claim 16, wherein the determining module is configured to determine whether a dc voltage of a capacitor in the first dc converter is greater than a preset dc voltage threshold corresponding to a preset output current, where the preset output current is an output current of a motor electrically connected to the first dc converter, the preset dc voltage threshold is further determined according to an output current of a motor i, a carrier phase difference of the two dc converters electrically connected to the dc converter i reaches the preset phase difference, and when the output current of the motor i is the preset output current, a minimum value of the dc voltage of the capacitor in the dc converter i is obtained.

24. The apparatus of claim 16, wherein the determining module is further configured to determine whether a harmonic frequency of a dc voltage of a capacitor in the first dc converter is a carrier frequency of the first dc converter; and if the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is the carrier frequency of the first direct-current converter, determining that the carrier phase difference between the first direct-current converter and the second direct-current converter does not reach a preset phase difference.

25. The apparatus of claim 16, wherein the determining module is further configured to determine whether a harmonic frequency of the dc voltage of the capacitor in the first dc converter is less than a harmonic frequency threshold, wherein the harmonic frequency threshold is determined according to a carrier frequency of the first dc converter; and if the harmonic frequency of the direct-current voltage of the capacitor in the first direct-current converter is smaller than the harmonic frequency threshold value, determining that the carrier phase difference between the first direct-current converter and the second direct-current converter does not reach a preset phase difference.

26. The apparatus of claim 25, wherein the harmonic frequency threshold is a preset multiple of a carrier frequency of the first dc converter, the preset multiple being greater than 1 and less than 2.

27. The apparatus of claim 16, wherein the adjustment module is configured to select a carrier with a phase different from a current phase of a carrier of the first dc converter from a plurality of carriers, the plurality of carriers being different in phase.

28. The apparatus of claim 27, further comprising:

29. The apparatus of claim 16, further comprising:

30. The apparatus of claim 29, wherein the at least one period is N x N, where N is a ratio between the preset phase difference and a preset phase, and the preset phase is a phase step per adjustment of a carrier of the first dc converter.

31. A computer-readable storage medium having stored therein at least one instruction, which is loaded and executed by a processor, to implement a carrier modulation method according to any one of claims 1 to 15.