JP7409141B2 - power transmission equipment - Google Patents

Description

The present disclosure relates to a power transmission device.

BACKGROUND ART A contactless power supply system that transmits power in a non-contact (wireless) manner is known. A contactless power transfer system includes a power transmitting device including a power transmitting coil and a power receiving device including a power receiving coil, and realizes contactless power transmission by utilizing electromagnetic induction or magnetic field resonance between the coils. If the frequency used for power transmission (switching frequency of an inverter) interferes with the frequency used by other devices, there is a risk that the power transmission will affect other devices, such as noise.

In the contactless power supply device described in Patent Document 1, when the inverter frequency according to the output command value (power command value) overlaps with the frequency band used by other devices, the inverter frequency is adjusted so as not to overlap with the frequency band used by other devices. The frequency is corrected and the PFC (Power Factor Correction) output is adjusted so that an output power value corresponding to the power command value is obtained.

International Publication No. 2014/118972

In the contactless power supply device described in Patent Document 1, after the inverter frequency is adjusted to the frequency according to the power command value, if the inverter frequency overlaps with the used frequency band, the inverter frequency does not overlap with the used frequency band. It will be corrected as follows. Then, the PFC output is increased by the amount of decrease in output power due to the change in the inverter frequency, and the output power value is adjusted to the power command value. According to this configuration, since the inverter frequency is temporarily included in the frequency band used, there is a possibility that noise may be mixed into other devices while the inverter frequency is included in the frequency band used.

The present disclosure describes a power transmission device that can further suppress interference with other devices.

A power transmission device according to one aspect of the present disclosure is a device for supplying power to a power receiving device connected to a load. This power transmission device includes a first coil for contactlessly transmitting power to a second coil of a power receiving device, and a DC-AC converter that converts DC power to AC power and supplies AC power to the first coil. It includes a converter and a controller that brings the power value of the target power close to the power command value by frequency control that changes the frequency of the AC power. The target power is DC power or AC power. When bringing the power value closer to the power command value, the controller performs frequency change processing to change the frequency so that it is not included in the used frequency band if the frequency passes through the used frequency band used by other equipment. .

According to the present disclosure, interference with other devices can be further suppressed.

FIG. 1 is a diagram illustrating an application example of a contactless power supply system including a power transmission device according to an embodiment. FIG. 2 is a circuit block diagram of the contactless power supply system of FIG. 1. FIG. 3 is a diagram showing the frequency characteristics of load power. FIG. 4 is a diagram showing an example of a circuit configuration of a DC/AC converter. FIG. 5 is a flowchart showing a series of power control processes performed by the first controller in FIG. FIG. 6 is a flowchart showing in detail an example of the frequency change process of FIG. FIG. 7 is a diagram for explaining an example of the power control in FIG. 5. FIG. 8 is a diagram for explaining another example of the power control in FIG. 5. FIG. 9 is a diagram for explaining still another example of the power control in FIG. 5. FIG. 10 is a circuit block diagram of a contactless power supply system including a power transmission device according to a modification.

[1] Overview of Embodiments A power transmission device according to one aspect of the present disclosure is a device for supplying power to a power receiving device connected to a load. This power transmission device includes a first coil for contactlessly transmitting power to a second coil of a power receiving device, and a DC-AC converter that converts DC power to AC power and supplies AC power to the first coil. It includes a converter and a controller that brings the power value of the target power close to the power command value by frequency control that changes the frequency of the AC power. The target power is DC power or AC power. When bringing the power value closer to the power command value, the controller performs frequency change processing to change the frequency so that it is not included in the used frequency band if the frequency passes through the used frequency band used by other equipment. .

In this power transmission device, when the power value of the target power is brought close to the power command value, if the frequency of the AC power supplied to the first coil passes through the frequency band used by other equipment, the frequency band used The frequency is changed so that it is not included in the Therefore, the power value of the target power is brought closer to the power command value without the frequency of the AC power being included in the frequency band used. As a result, it becomes possible to further suppress interference with other devices.

The frequency band used may be located between the first frequency and the second frequency. In the frequency change process, the controller may change the frequency characteristic of the target power from the first characteristic to the second characteristic, and the power value when the frequency is the first frequency and the power value when the frequency is the second frequency. The frequency may be changed from the first frequency to the second frequency so that the difference with the power value is smaller than the difference in the first characteristic. In this case, the frequency of the AC power is changed from the first frequency to the second frequency while reducing the amount of variation in the power value of the target power. This makes it possible to reduce the possibility that the power transmission device will malfunction due to the frequency change process.

The controller may change the frequency from the first frequency to the second frequency so that the power value follows the second characteristic. The difference between the power value when the frequency in the second characteristic is the first frequency and the power value when the frequency is the second frequency is smaller than the difference in the power value in the first characteristic. Therefore, according to the above configuration, even if the frequency of AC power is changed from the first frequency to the second frequency, the amount of fluctuation in the power value of the target power can be suppressed. As a result, it is possible to reduce the possibility that the power transmission device will malfunction due to the frequency change process.

The controller may change the frequency from the first frequency to the second frequency so that the power value maintains the power value at the first frequency when the frequency characteristic is the first characteristic. In this case, the frequency of the AC power is changed from the first frequency to the second frequency while the power value of the target power is maintained. Thereby, even if the frequency of AC power is changed from the first frequency to the second frequency, the power value of the target power does not change. As a result, it is possible to further reduce the possibility that the power transmission device will malfunction due to the frequency change process.

If the frequency at which the power value reaches the power command value in the first characteristic is not included in the frequency band used, the controller changes the frequency from the first frequency to the second frequency, and then changes the frequency to the second frequency. In the matched state, the frequency characteristics may be returned to the first characteristics. For example, when frequency characteristics are changed by phase shift control, if the amount of phase shift is large, the impedance tends to become a capacitive load, and the influence of noise such as EMC (Electromagnetic Compatibility) and malfunction tends to occur. On the other hand, after the frequency is changed to the second frequency, the frequency characteristics are returned to the first characteristics. Therefore, since the amount of phase shift can be reduced, the possibility that the impedance becomes a capacitive load can be reduced, and the possibility that the influence of noise will occur can be reduced.

If the frequency at which the power value reaches the power command value in the first characteristic is included in the frequency band used, the controller changes the frequency from the first frequency to the second frequency, and then adjusts the frequency to the second frequency. The power value may be adjusted to the power command value by changing the frequency characteristics in the state in which the power value is adjusted. In this case, the power value of the target power is adjusted to the power command value at a frequency different from the frequency band used. Therefore, it becomes possible to suppress interference with other devices.

The controller may change the frequency characteristics by controlling the phase shift of the DC/AC converter. When the phase shift amount of the DC/AC converter or the voltage of the DC power is changed, the frequency characteristics of the target power change. Phase shift control has better responsiveness than DC power voltage control. Therefore, it is possible to improve the processing speed of frequency change processing by changing the frequency characteristics by phase shift control rather than by changing the frequency characteristics by voltage control.

The controller may change the frequency characteristics by impedance control that controls impedance between the DC-AC converter and the first coil. When the impedance between the DC-AC converter and the first coil or the voltage of the DC power is changed, the frequency characteristics of the target power change. Impedance control has better responsiveness than DC power voltage control. Therefore, it is possible to improve the processing speed of the frequency change process by changing the frequency characteristics by impedance control rather than by changing the frequency characteristics by voltage control.

[2] Illustration of Embodiments Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In addition, in the description of the drawings, the same elements are given the same reference numerals, and redundant description will be omitted.

FIG. 1 is a diagram illustrating an application example of a contactless power supply system including a power transmission device according to an embodiment. As shown in FIG. 1, the contactless power supply system 1 includes a power transmitting device 2 and a power receiving device 3, and is a system for supplying power from the power transmitting device 2 to the power receiving device 3. The power transmitting device 2 and the power receiving device 3 are separated from each other in the vertical direction, for example. The power transmission device 2 is installed, for example, in a parking lot. The power receiving device 3 is mounted on, for example, an electric vehicle EV. The non-contact power supply system 1 is configured to supply electric power to an electric vehicle EV that has arrived at a parking lot or the like using magnetic coupling between coils using a magnetic resonance method, an electromagnetic induction method, or the like. Note that the non-contact power feeding method is not limited to a method using magnetic coupling, and may be, for example, an electric field resonance method.

The power transmission device 2 is a device that supplies power for contactless power supply. The power transmitting device 2 generates desired AC power from the power supplied by the power source PS (see FIG. 2) and sends it to the power receiving device 3. The power transmission device 2 is installed, for example, on a road surface R such as a parking lot. The power transmission device 2 includes a first coil device 4 (power transmission coil device) provided so as to protrude upward from a road surface R of, for example, a parking lot. The first coil device 4 includes a first coil 21 (see FIG. 2), and has, for example, a flat frustum shape or a rectangular parallelepiped shape. Power transmission device 2 generates desired AC power from power supply PS. By sending the generated AC power to the first coil device 4, the first coil device 4 generates magnetic flux.

The power receiving device 3 is a device that receives power from the power transmitting device 2 and supplies power to the load L (see FIG. 2). The power receiving device 3 is mounted on, for example, an electric vehicle EV. The power receiving device 3 includes, for example, a second coil device 5 (power receiving coil device) attached to the bottom surface of a vehicle body (chassis, etc.) of an electric vehicle EV. The second coil device 5 includes a second coil 31 (see FIG. 2), and faces the first coil device 4 while being separated from the first coil device 4 in the vertical direction when power is supplied. The second coil device 5 has, for example, a flat frustum shape or a rectangular parallelepiped shape. When the magnetic flux generated in the first coil device 4 interlinks with the second coil device 5, the second coil device 5 generates an induced current. Thereby, the second coil device 5 receives power from the first coil device 4 in a non-contact (wireless) manner. The power received by the second coil device 5 is supplied to the load L.

With reference to FIG. 2, the circuit configuration of the contactless power supply system 1 will be described in detail. FIG. 2 is a circuit block diagram of the contactless power supply system of FIG. 1. As shown in FIG. 2, the contactless power supply system 1 is a system that receives AC power Pac1 from a power source PS and supplies load power Pout to a load L. The power source PS is an AC power source such as a commercial power source, and supplies AC power Pac<b>1 to the power transmission device 2 . The frequency of AC power Pac1 is, for example, 50 Hz or 60 Hz. The load L may be a direct current load such as a battery, or may be an alternating current load such as a motor.

The power transmission device 2 is supplied with AC power Pac1 from the power source PS. The power transmission device 2 includes a first coil 21, a first converter 22 (converter), a first detector 23, a first communication device 24, a first controller 25 (controller), and a frequency detector for use. A container 28 is provided.

The first converter 22 is a circuit that converts the AC power Pac1 supplied from the power source PS into desired AC power Pac2, and supplies the AC power Pac2 to the first coil 21. The first converter 22 can change the magnitude (power value) of the DC power Pdc and the AC power Pac2 by, for example, frequency control, phase shift control, and voltage control of the DC power Pdc, which will be described later. The first converter 22 includes a power converter 26 and a DC/AC converter 27.

The power converter 26 is an AC/DC converter that converts AC power Pac1 supplied from the power source PS into DC power Pdc. Power converter 26 is, for example, a rectifier circuit. The rectifier circuit may be composed of a rectifying element such as a diode, or may be composed of a switching element such as a transistor. The power converter 26 may further have a PFC (Power Factor Correction) function and a voltage step-up/down function. The first converter 22 may further include a DC/DC converter provided at the output of the power converter 26. The power converter 26 is controlled by the first controller 25 to change the magnitude of the voltage Vdc of the DC power Pdc. The power converter 26 changes the magnitude of the voltage Vdc of the DC power Pdc by, for example, pulse width modulation. Power converter 26 supplies DC power Pdc to DC-AC converter 27 .

The DC/AC converter 27 converts the DC power Pdc supplied from the power converter 26 into AC power Pac2. The frequency of AC power Pac2 is, for example, 81.38 kHz to 90 kHz. The DC/AC converter 27 includes, for example, an inverter circuit. The first converter 22 may further include a transformer provided at the output of the DC/AC converter 27. The DC/AC converter 27 is controlled by the first controller 25 to change the magnitude of the DC power Pdc and the AC power Pac2. The DC/AC converter 27 supplies AC power Pac2 to the first coil 21.

The first coil 21 is a coil for transmitting power to (the second coil 31 of) the power receiving device 3 in a non-contact manner. The first coil 21 generates magnetic flux when AC power Pac2 is supplied from the first converter 22. A capacitor and an inductor (for example, a reactor) may be connected between the first coil 21 and the first converter 22.

The first detector 23 includes a circuit for obtaining a measurement value regarding DC power Pdc. The circuit for obtaining measurements regarding the DC power Pdc is, for example, a voltage sensor, a current sensor, or a combination thereof. The first detector 23 measures the DC power Pdc, the voltage Vdc of the DC power Pdc, or the current Idc of the DC power Pdc. The first detector 23 measures AC power Pac2, voltage Vac2 of AC power Pac2, and current Iac2 of AC power Pac2. The first detector 23 outputs the acquired measurement value to the first controller 25.

The first communicator 24 is a circuit for wirelessly communicating with a second communicator 34 of the power receiving device 3, which will be described later. The first communication device 24 includes, for example, an antenna for a communication method using radio waves, and a light emitting element and a light receiving element for a communication method using optical signals. The first communication device 24 outputs the information received from the power receiving device 3 to the first controller 25.

The first controller 25 is a processing device such as a CPU (Central Processing Unit) and a DSP (Digital Signal Processor). The first controller 25 may include a ROM (Read Only Memory), a RAM (Random Access Memory), an interface circuit connected to each part of the power transmission device 2, and the like.

The first controller 25 performs power constant control to bring the power value of the target power close to a first power command value (power command value). As the target power, DC power Pdc or AC power Pac2 may be used. The first controller 25 calculates a first power measurement based on the measurement of the current Idc detected by the first detector 23 . When the target power is DC power Pdc, the first power measurement value includes the loss of the DC/AC converter 27, the loss of the first coil 21, etc., and the AC power supplied from the DC/AC converter 27 to the first coil 21. This is a measured value including power Pac2. The first controller 25 calculates the first power command value, which is the target value of the DC power Pdc, based on the second power command value received from the power receiving device 3 via the first communication device 24 . As constant power control, the first controller 25 performs a first conversion based on the first power measurement value and the first power command value so that the first power measurement value (DC power Pdc) approaches the first power command value. performs power control to control the device 22.

Note that when the target power is AC power Pac2, the first power command value is a target value of AC power Pac2, and is set according to AC power Pac2. That is, the first controller 25 controls the first converter 22 as constant power control so that the AC power Pac2 approaches the first power command value which is the target value of the AC power Pac2. Hereinafter, a case where the target power is DC power Pdc will be explained.

Note that the first controller 25 may perform command value correction control for correcting the first power command value. The first controller 25 performs command value correction control based on a second power measurement value (described later) and a second power command value (described later) received from the power receiving device 3 via the first communication device 24. Power control is performed to control the first converter 22 so that the power measurement value (load power Pout) approaches the second power command value. Specifically, the first controller 25 corrects the first power command value so that the second power measurement value approaches the second power command value.

As power control, the first controller 25 controls the magnitude (power value) of the DC power Pdc and the AC power Pac2 by controlling the first converter 22, and controls the load power Pout supplied to the load L. Control size. Power control is performed using at least one of frequency control, phase shift control, and voltage control of DC power Pdc. In each control, power control parameters for controlling the magnitudes of DC power Pdc and AC power Pac2 are changed.

Here, frequency control will be explained using FIG. 3. FIG. 3 is a diagram showing the frequency characteristics of load power. The horizontal axis of the graph in FIG. 3 indicates the driving frequency f, and the vertical axis indicates (the magnitude of) the load power Pout. The drive frequency f is the frequency of the AC power Pac2. The frequency of AC power Pac2 is the frequency of AC current or AC voltage output from the first converter 22. Hereinafter, the frequency of AC power Pac2 may be referred to as "drive frequency f". As shown in FIG. 3, the magnitudes of DC power Pdc, AC power Pac2, and load power Pout are changed depending on the drive frequency f. As the driving frequency f, for example, 81.38 kHz to 90 kHz can be used. By changing the drive frequency f, the impedance of reactance elements such as coils and capacitors changes, and the magnitudes of DC power Pdc, AC power Pac2, and load power Pout change. Hereinafter, in this embodiment, it is assumed that as the drive frequency f increases, the magnitudes of the DC power Pdc, the AC power Pac2, and the load power Pout decrease. The first controller 25 performs frequency control to change the magnitude (power value) of the DC power Pdc, the AC power Pac2, and the load power Pout by changing the drive frequency f. The above-mentioned power control parameter in frequency control is the drive frequency f of the DC/AC converter 27 (inverter circuit).

For example, assume that the drive frequency f is initially the frequency fb. The load power Pout at this time is the power Pb. Here, for example, the driving frequency f is decreased from the frequency fb to the frequency fa. Then, the load power Pout becomes the power Pa corresponding to the driving frequency f=fa. Therefore, the load power Pout increases from the power Pb to the power Pa. On the other hand, the driving frequency f is increased from frequency fb to frequency fc. Then, the load power Pout becomes the power Pc corresponding to the driving frequency f=fc. Therefore, the load power Pout decreases from the power Pb to the power Pc.

The first controller 25 brings the load power Pout closer to the desired power by changing the drive frequency f as described above. In control for actually changing (increasing and decreasing) the driving frequency f, the driving frequency f may be changed in steps. The size of one step for changing the driving frequency f is not particularly limited, and may be, for example, several Hz to several tens of Hz, or several tens of Hz to several hundred Hz. The steps are determined by, for example, the resolution of the clock of the CPU, which is the first controller 25.

The specific method of frequency control is not limited. For example, when the DC/AC converter 27 is an inverter circuit, the first controller 25 adjusts the switching frequency of each switching element using a drive signal supplied to each switching element included in the inverter circuit. , change the drive frequency f. As the switching element, for example, a FET (Field Effect Transistor) and an IGBT (Insulated Gate Bipolar Transistor) are used, and in this case, a drive signal is applied to the gate of the switching element.

Next, phase shift control will be explained. The first controller 25 is a phase shifter that changes the magnitude (power value) of the DC power Pdc, the AC power Pac2, and the load power Pout by changing the amount of phase shift of the DC/AC converter 27 (inverter circuit). Implement controls. For example, when the DC/AC converter 27 is an inverter circuit as shown in FIG. 4, the first controller 25 controls the supply time of the drive signals Sa to Sd to the switching elements SWa to SWd included in the inverter circuit By adjusting , the time during which each switching element SWa to SWd is turned on is adjusted.

When the driving time of the switching element SWa and the driving time of the switching element SWd are the same, and the driving time of the switching element SWb and the driving time of the switching element SWc are the same, the energization period (on period) of the inverter circuit is It will be the longest. The more the driving time of switching element SWa and the driving time of switching element SWd deviate (the more the driving time of switching element SWb and the driving time of switching element SWc differ), the shorter the on period of the inverter circuit becomes. The shorter the on period of the inverter circuit is, the smaller the DC power Pdc and the AC power Pac2 become. The above-mentioned power control parameter in phase shift control is the amount of phase shift. The amount of phase shift is the amount of deviation between the driving time of switching element SWa and the driving time of switching element SWd (or the amount of deviation between the driving time of switching element SWb and the driving time of switching element SWc). In other words, the above-mentioned power control parameter in phase shift control is the on-period of the inverter circuit.

Note that in order to realize soft switching of the inverter circuit, the phase of the output voltage from the inverter circuit (voltage Vac2 of AC power Pac2) is the same as or leads the phase of the output current (current Iac2 of AC power Pac2) (impedance is inductive). If the phase difference between voltage and current is kept the same, the impedance will become capacitive due to noise and control errors. Therefore, in order to ensure safety, the phase of the voltage is advanced from the phase of the current so that the phase difference does not become smaller than a predetermined value. This predetermined value is called a phase margin.

The phase shift amount may be expressed as a percentage, for example, with the length of one cycle (that is, 360 degrees) of AC power Pac2 as 100%. In this case, in a state where no phase shift is performed, the amount of phase shift is 0%. In the phase shift control, when the phase shift amount is 0%, the DC power Pdc and the AC power Pac2 are maximized, and the load power Pout is also maximized. The maximum value of the phase shift amount varies depending on the circuit characteristics of the first coil 21 (for example, the characteristics of the resonant circuit including the first coil 21 and a capacitor (not shown)), but is, for example, about 50%. That is, in one aspect, the lower limit value of the phase shift amount may be set to 0%. The upper limit value of the phase shift amount may be set to 50%.

Next, voltage control of DC power Pdc will be explained. The first controller 25 performs voltage control to change the magnitude (power value) of the DC power Pdc, the AC power Pac2, and the load power Pout by changing the magnitude of the voltage Vdc of the DC power Pdc. The voltage Vdc of the DC power Pdc is changed using, for example, the step-up/down function of the power converter 26 described above. For example, as voltage Vdc of DC power Pdc increases, DC power Pdc and AC power Pac2 also increase, and as voltage Vdc of DC power Pdc decreases, DC power Pdc and AC power Pac2 also decrease. Therefore, the above-mentioned power control parameter in voltage control of DC power Pdc is the magnitude of voltage Vdc of DC power Pdc. The buck-boost function can be realized with a chopper circuit, for example.

The used frequency detector 28 is a circuit that detects a used frequency band that is a frequency band used by other devices different from the non-contact power supply system 1. The used frequency detector 28 detects the used frequency band by auto-scanning, for example, similar to automatic tuning of a radio. The used frequency detector 28 acquires the position information of the power transmission device 2 using GPS (Global Positioning System) etc., and detects the allocation allocated to other devices in the area including the position indicated by the position information. A frequency band may be detected as a used frequency band. The assigned frequency bands for each region are set in advance in a memory (not shown). The used frequency detector 28 may use harmonic components of the detected frequency band as the used frequency band. The used frequency detector 28 outputs used frequency information indicating the used frequency band to the first controller 25. Note that the user may set the frequency band to be used in the first controller 25. In this case, the power transmission device 2 does not need to include the used frequency detector 28.

The power receiving device 3 includes a second coil 31 , a second converter 32 , a second detector 33 , a second communicator 34 , and a second controller 35 .

The second coil 31 is a coil for receiving power contactlessly supplied from the power transmission device 2. When the magnetic flux generated by the first coil 21 interlinks with the second coil 31, AC power Pac3 is generated in the second coil 31. The second coil 31 supplies AC power Pac3 to the second converter 32. Note that a capacitor and an inductor (for example, a reactor) may be connected between the second coil 31 and the second converter 32.

The second converter 32 is a circuit that converts the AC power Pac3 supplied from the second coil 31 into a desired load power Pout for the load L. When the load L is a DC load, the second converter 32 is an AC/DC converter (rectifier circuit) that converts AC power Pac3 into DC load power Pout. In this case, the second converter 32 may include a step-up/down function to output a desired load power Pout for the load L. This buck-boost function can be realized, for example, with a chopper circuit or a transformer. The second converter 32 may further include a transformer provided at the input of the AC/DC converter.

When the load L is an AC load, the second converter 32 includes a DC-AC converter (inverter circuit) in addition to an AC-DC converter that converts AC power Pac3 into DC power. The DC/AC converter converts the DC power generated by the AC/DC converter into AC load power Pout. The second converter 32 may further include a transformer provided at the input of the AC/DC converter. Note that if the AC power Pac3 supplied from the second coil 31 is desired AC power for the load L, the second converter 32 may be omitted.

The second detector 33 is a circuit for acquiring a measured value regarding the load power Pout supplied to the load L. The second detector 33 measures the load voltage Vout, load current Iout, or load power Pout supplied to the load L. The second detector 33 is, for example, a voltage sensor, a current sensor, or a combination thereof. The second detector 33 outputs the acquired measurement value to the second controller 35. The load L outputs the second power command value to the second controller 35. The second power command value indicates the desired amount of power to be supplied to the load L. For example, when the load L is a storage battery, the second power command value may be a current, voltage, or power command value determined according to the SOC (State of Charge) of the load L.

The second communicator 34 is a circuit for wirelessly communicating with the first communicator 24 of the power transmission device 2 . The second communication device 34 allows the power receiving device 3 to communicate with the power transmitting device 2 . The second communication device 34 includes, for example, an antenna for a communication method using radio waves, and a light emitting element and a light receiving element for a communication method using optical signals. The second communication device 34 transmits the information received from the second controller 35 to the power transmission device 2.

The second controller 35 is a processing device such as a CPU and a DSP. The second controller 35 may include a ROM, a RAM, an interface circuit connected to each part of the power receiving device 3, and the like. The second controller 35 calculates a second power measurement based on the measurements received from the second detector 33 . The second controller 35 transmits the second power measurement value and the second power command value received from the load L to the power transmission device 2 via the second communication device 34 .

Note that, for example, a storage battery of an electric vehicle is connected to the power transmitting device 2 instead of the power source PS, and a power source PS is connected to the power receiving device 3 instead of the load L, thereby transmitting power from the power receiving device 3 to the power transmitting device 2. It is also possible to do so.

Next, power control will be explained in detail with reference to FIGS. 5 to 8. FIG. 5 is a flowchart showing a series of power control processes performed by the first controller in FIG. FIG. 6 is a flowchart showing in detail an example of the frequency change process of FIG. FIG. 7 is a diagram for explaining an example of the power control in FIG. 5. FIG. 8 is a diagram for explaining another example of the power control in FIG. 5. The series of processes shown in FIG. 5 is started when the first controller 25 receives the second power command value from the power receiving device 3. Note that the initial value of the phase shift amount of the DC/AC converter 27 is set to 0.

The first controller 25 first calculates a first power command value based on the second power command value received from the power receiving device 3 (step S1). Note that when the power receiving device 3 transmits the second power measurement value together with the second power command value to the power transmission device 2, the first controller 25 transmits the second power measurement value to the second power command value so that the second power measurement value approaches the second power command value. 1 power command value may be corrected. Note that if the first power measurement value is equal to the first power command value, the power control ends without performing subsequent processing.

Subsequently, the first controller 25 sets the voltage Vdc (step S2). For example, when the power transmission device 2 is started, the first controller 25 controls the power converter 26 so that the voltage Vdc becomes the minimum voltage in the voltage range of the voltage Vdc that the power converter 26 can output. control. The first controller 25 may control the power converter 26 so that the voltage Vdc becomes a predetermined voltage (for example, 420V). When the power transmission device 2 is operating, the first controller 25 may fix the voltage Vdc output by the power converter 26. Here, an example will be described in which the voltage Vdc is set to the minimum voltage within the voltage range that the power converter 26 can output. At this time, the frequency characteristic of the DC power Pdc becomes, for example, the characteristic C1 (initial characteristic C1) shown in FIG.

Subsequently, the first controller 25 performs frequency control (step S3), and uses the frequency control to bring the first power measurement value closer to the first power command value. Here, along the characteristic C1 (first characteristic), as the drive frequency f is changed, the first power measurement value (the power value of the DC power Pdc) changes. Note that when the power transmission device 2 is started, the drive frequency f before frequency control is set to a frequency (for example, 90 kHz) at which the DC power Pdc is the smallest. When the power transmission device 2 is in operation, the drive frequency f used just before may be used as is. The first controller 25 gradually approaches the first power measurement value to the first power command value, for example, by changing the drive frequency f in steps. Note that in a frequency band where the amount of change in DC power Pdc relative to the amount of change in drive frequency f is small, the first controller 25 may increase the amount of change in drive frequency f per step.

Subsequently, the first controller 25 determines whether the drive frequency f has reached one boundary frequency (first frequency) of the frequency band used (step S4). The frequency band used is located between one boundary frequency and the other boundary frequency, and neither of these boundary frequencies is included in the frequency band used. The boundary frequency is the upper limit frequency or lower limit frequency of the frequency band used. When one boundary frequency is the upper limit frequency, the other boundary frequency (second frequency) is the lower limit frequency. When one boundary frequency is the lower limit frequency, the other boundary frequency is the upper limit frequency.

If it is determined that the drive frequency f has not reached one of the boundary frequencies (step S4; NO), the first controller 25 determines that the first power measurement value has reached the first power command value (matches the first power command value). ) (step S5). If it is determined that the first power measurement value has not reached (does not match) the first power command value (step S5; NO), the first controller 25 continues to perform the frequency control in step S3. On the other hand, if it is determined that the first power measurement value has reached (matches) the first power command value (step S5; YES), the series of processes for power control ends.

If it is determined in step S4 that the drive frequency f has reached one of the boundary frequencies of the frequency band used (step S4; YES), the first controller 25 performs a frequency change process (step S6). In the frequency change process, when the first power measurement value (power value of DC power Pdc) is brought closer to the first power command value, if the drive frequency f passes through the usage frequency band, the drive frequency f is included in the usage frequency band. This process changes the drive frequency f so that the

In the frequency change process of step S6, as shown in FIG. Determination is made (step S11). The target frequency f0 is the driving frequency f when the first power measurement value (the power value of the DC power Pdc) reaches the first power command value in the initial characteristic C1. If it is determined that the target frequency f0 is not included in the used frequency band (step S11; NO), the first controller 25 changes the frequency characteristics of the DC power Pdc (step S12). In this embodiment, the first controller 25 changes the frequency characteristics by controlling the phase shift of the DC/AC converter 27.

Specifically, the first controller 25 changes the phase shift amount by adjusting the supply time of the drive signals Sa to Sd (see FIG. 4). Here, the first controller 25 increases the amount of phase shift. As the phase shift amount increases, the power value of the DC power Pdc at the same drive frequency f decreases. Then, by increasing the phase shift amount, the frequency characteristic of the DC power Pdc changes from the initial characteristic C1 to the characteristic C2 (second characteristic).

At this time, since the drive frequency f is matched (fixed) to one boundary frequency, the power value of the DC power Pdc at one boundary frequency decreases. Note that the difference (absolute value of the difference) between the power value of DC power Pdc at one boundary frequency in characteristic C2 and the power value of DC power Pdc at the other boundary frequency is the DC power at one boundary frequency in initial characteristic C1. It is smaller than the difference (absolute value of the difference) between the power value of Pdc and the power value of DC power Pdc at the other boundary frequency.

Subsequently, the first controller 25 changes the drive frequency f from one boundary frequency to the other boundary frequency (step S13). In other words, the drive frequency f is switched from one boundary frequency to the other boundary frequency. In this embodiment, the first controller 25 changes the driving frequency f from one boundary frequency to the other boundary frequency so that the power value of the DC power Pdc follows the characteristic C2. As a result, the drive frequency f passes through the usable frequency band without being included in the usable frequency band. In other words, the drive frequency f jumps over the usage frequency band.

Then, the first controller 25 restores the frequency characteristics of the DC power Pdc to the original state (step S14). Specifically, the first controller 25 returns the phase shift amount to 0 by adjusting the supply time of the drive signals Sa to Sd (see FIG. 4). As described above, the first controller 25 completes the frequency changing process in step S6, and subsequently performs the frequency control in step S3.

On the other hand, in step S11, if it is determined that the target frequency f0 is included in the operating frequency band through which the drive frequency f is about to pass (enter) (step S11; YES), the first controller 25 controls the direct current power Pdc. It is determined whether control to increase the power value is being performed (step S15). If it is determined that control is being performed to increase the power value of the DC power Pdc (step S15; YES), the first controller 25 changes the frequency characteristics of the DC power Pdc (step S16), and increases the drive frequency f. is changed (jumped) from one boundary frequency to the other boundary frequency (step S17). The processes in steps S16 and S17 are the same as the processes in steps S12 and S13, so their description will be omitted.

Subsequently, the first controller 25 reduces the phase shift amount in the phase shift control (step S18). Specifically, the first controller 25 reduces the amount of phase shift by adjusting the supply time of the drive signals Sa to Sd (see FIG. 4). Thereby, the frequency characteristic of the DC power Pdc changes from the characteristic C2 toward the initial characteristic C1. At this time, since the drive frequency f is matched (fixed) to the other boundary frequency, the power value of the DC power Pdc increases.

The first controller 25 then determines whether the first power measurement value has reached (matches) the first power command value (step S19). If it is determined that the first power measurement value has not reached (does not match) the first power command value (step S19; NO), the first controller 25 continues to perform phase shift control in step S18. On the other hand, if it is determined that the first power measurement value has reached (matches) the first power command value (step S19; YES), the series of processes for power control ends.

If it is determined in step S15 that control is being performed to lower the power value of DC power Pdc (step S15; NO), the first controller 25 increases the phase shift amount in the phase shift control (step S20). ). Specifically, the first controller 25 increases the phase shift amount by adjusting the supply time of the drive signals Sa to Sd (see FIG. 4). As a result, the frequency characteristic of the DC power Pdc changes from the initial characteristic C1 toward the characteristic C2. At this time, since the drive frequency f is matched (fixed) to one boundary frequency, the power value of the DC power Pdc decreases.

Then, the first controller 25 determines whether the first power measurement value has reached (matches) the first power command value (step S21). If it is determined that the first power measurement value has not reached (does not match) the first power command value (step S21; NO), the first controller 25 continues to perform phase shift control in step S20. On the other hand, if it is determined that the first power measurement value has reached (matches) the first power command value (step S21; YES), the series of processes for power control ends.

Note that once the power value (first power measurement value) of the DC power Pdc is adjusted to the first power command value, the first controller 25 adjusts the power value of the DC power Pdc to the first power command value by frequency control. Performs constant power control to maintain a state adjusted to the current condition. If the DC power Pdc cannot be adjusted to the first power command value at the driving frequency f outside the operating frequency band within the range in which the amount of phase shift can be changed by the power control, the first controller 25 adjusts the amount of phase shift. The first power command value may be lowered so that the driving frequency f is set to a frequency outside the frequency band used within the range in which the first power command value can be changed.

An example of the power control in FIG. 5 will be specifically explained using FIG. 7. In the example shown in FIG. 7, frequency bands FB1 and FB2 are set. The frequency band FB1 used is located between the lower limit frequency fl1 and the upper limit frequency fh1. The upper limit frequency fh1 is greater than the lower limit frequency fl1. The used frequency band FB2 is located between the lower limit frequency fl2 and the upper limit frequency fh2. The lower limit frequency fl2 is larger than the upper limit frequency fh1 and smaller than the upper limit frequency fh2. In this example, the initial power of the DC power Pdc is smaller than the first power command value, and the initial frequency of the drive frequency f is larger than the upper limit frequency fh2.

First, the first controller 25 gradually increases the DC power Pdc by gradually decreasing the driving frequency f by frequency control (step S3). Then, when the drive frequency f reaches the upper limit frequency fh2 of the frequency band FB2 used (step S4; YES), the first controller 25 performs a frequency change process (step S6). Since the target frequency f0 is not included in the used frequency band FB2 (step S11; NO), the first controller 25 changes the frequency characteristic of the DC power Pdc to the initial characteristic by increasing the phase shift amount by phase shift control. The characteristic is changed from C1 to characteristic C2 (step S12).

Then, the first controller 25 changes the drive frequency f from the upper limit frequency fh2 to the lower limit frequency fl2 so that the power value of the DC power Pdc follows the characteristic C2 (step S13). As a result, the driving frequency f passes through (jumps over) the frequency band FB2 without being included in the frequency band FB2. Then, the first controller 25 returns the frequency characteristic of the DC power Pdc to the initial characteristic C1 by returning the phase shift amount to the initial value (step S14).

Subsequently, the first controller 25 gradually increases the DC power Pdc by gradually decreasing the drive frequency f from the lower limit frequency fl2 by frequency control (step S3). Then, when the drive frequency f reaches the upper limit frequency fh1 of the frequency band FB1 used (step S4; YES), the first controller 25 performs a frequency change process (step S6). Since the target frequency f0 is included in the used frequency band FB1 (step S11; YES) and control is being performed to increase the power value of the DC power Pdc (step S15; YES), the first controller 25 performs phase shift control. By increasing the phase shift amount, the frequency characteristic of the DC power Pdc is changed from the initial characteristic C1 to the characteristic C2 (step S16).

Then, the first controller 25 changes the drive frequency f from the upper limit frequency fh1 to the lower limit frequency fl1 (step S17). As a result, the driving frequency f passes through (jumps over) the frequency band FB1 without being included in the frequency band FB1. Then, the first controller 25 gradually decreases the phase shift amount (step S18), and when the power value (first power measurement value) of the DC power Pdc reaches the first power command value (step S19; YES). , the series of power control processes ends.

For example, when the load L is a battery, the battery voltage (load voltage Vout) increases as the battery is charged. In this case, the frequency characteristics of the DC power Pdc change, but since constant power control is performed by frequency control, the drive frequency f changes. At this time, whether the drive frequency f increases or decreases depends on the configuration of the resonant circuit, etc. When the drive frequency f decreases, the drive frequency f moves away from the usage frequency band FB1. In this case, the first controller 25 may reduce the phase shift amount in steps. On the other hand, when the drive frequency f increases, the drive frequency f approaches the usable frequency band FB1, so the first controller 25 further increases the phase shift amount so that the drive frequency f falls within the usable frequency band FB1. You may choose not to.

Another example of the power control in FIG. 5 will be specifically explained using FIG. 8. In the example shown in FIG. 8, frequency bands FB1 and FB2 are set as in FIG. 7. In this example, the initial power of the DC power Pdc is greater than the first power command value, and the initial frequency of the drive frequency f matches the lower limit frequency fl1. First, since the initial frequency of the drive frequency f matches the lower limit frequency fl1 (step S4; YES), the first controller 25 performs a frequency change process (step S6).

Since the target frequency f0 is not included in the used frequency band FB1 (step S11; NO), the first controller 25 changes the frequency characteristic of the DC power Pdc to the initial characteristic by increasing the phase shift amount by phase shift control. The characteristic is changed from C1 to characteristic C2 (step S12). Then, the first controller 25 changes the drive frequency f from the lower limit frequency fl1 to the upper limit frequency fh1 so that the power value of the DC power Pdc follows the characteristic C2 (step S13). As a result, the driving frequency f passes through (jumps over) the frequency band FB1 without being included in the frequency band FB1. Then, the first controller 25 returns the frequency characteristic of the DC power Pdc to the initial characteristic C1 by returning the phase shift amount to the initial value (step S14).

Subsequently, the first controller 25 gradually decreases the DC power Pdc by gradually increasing the driving frequency f from the upper limit frequency fh1 by frequency control (step S3). When the drive frequency f reaches the target frequency f0 before reaching the lower limit frequency fl2 of the frequency band FB2 (step S4; NO), the power value (first power measurement value) of the DC power Pdc changes to the first power command value. is reached (step S5; YES), and the series of power control processes ends.

Note that at the upper limit frequency fh1, the power value of the DC power Pdc reaches the first power command value in the process of returning the phase shift amount to the initial value. However, in a state where a phase shift is performed (when the amount of phase shift is greater than 0), noise may occur. For this reason, the first controller 25 returns the phase shift amount to the initial value, and then adjusts the power value (first power measurement value) of the DC power Pdc to the first power command value by frequency control. When the influence of noise is small, the first controller 25 adjusts the phase shift amount at the upper limit frequency fh1 to adjust the power value (first power measurement value) of the DC power Pdc to the first power command value. May be combined.

As explained above, in the power transmission device 2, when the power value (first power measurement value) of the DC power Pdc approaches the first power command value, the drive frequency of the AC power Pac2 supplied to the first coil 21 When f attempts to pass through a frequency band used by another device, the drive frequency f is changed so that it is not included in the frequency band used. Therefore, the power value of the DC power Pdc is brought close to the first power command value without the drive frequency f being included in the frequency band used. As a result, it becomes possible to further suppress interference with other devices.

In the frequency change process, the first controller 25 changes the drive frequency f from one boundary frequency to the other boundary frequency so that the power value of the DC power Pdc follows the characteristic C2. The difference (absolute value of the difference) between the power value when the driving frequency f is one boundary frequency in the characteristic C2 and the power value when the driving frequency f is the other boundary frequency is the above-mentioned power value in the initial characteristic C1. smaller than the difference (absolute value of difference). Therefore, according to the above configuration, even if the drive frequency f is changed from one boundary frequency to the other boundary frequency, the amount of fluctuation in the power value of the DC power Pdc can be suppressed. As a result, when the drive frequency f is changed from one boundary frequency to the other boundary frequency, it is possible to reduce the possibility that the power value of the DC power Pdc exceeds the first power command value, and the protection circuit operates. You can avoid that. As a result, it is possible to reduce the possibility that the power transmission device 2 will malfunction due to the frequency change process.

If the target frequency f0 is not included in the usage frequency band through which the drive frequency f is going to pass, the first controller 25 changes the drive frequency f from one boundary frequency to the other boundary frequency, and then changes the drive frequency f to the other boundary frequency. The frequency characteristic is returned to the initial characteristic C1 while being adjusted to the other boundary frequency. When the amount of phase shift is large, the impedance seen from the DC/AC converter 27 tends to become a capacitive load (C load), and there is a possibility that noise effects (EMC, malfunction, etc.) may occur. On the other hand, according to the above configuration, after the drive frequency f passes through the usage frequency band, the frequency characteristic of the DC power Pdc is returned to the characteristic C1. Therefore, since the phase shift amount becomes 0, it is possible to reduce the possibility that the impedance seen from the DC-AC converter 27 becomes a capacitive load, and also to reduce the possibility that the influence of noise will occur.

If the target frequency f0 is included in the used frequency band through which the drive frequency f is going to pass, the first controller 25 changes the drive frequency f from one boundary frequency to the other boundary frequency, and then changes the drive frequency f to the other boundary frequency. By changing the frequency characteristics while matching the boundary frequency of , the power value (first power measurement value) of the DC power Pdc is adjusted to the first power command value. According to this configuration, the power value of the DC power Pdc is adjusted to the first power command value at a frequency different from the frequency band used. Therefore, it becomes possible to suppress interference with other devices.

The first controller 25 changes the frequency characteristics by controlling the phase shift of the DC/AC converter 27. When the phase shift amount of the DC/AC converter 27 is changed, the frequency characteristics of the DC power Pdc are changed. Phase shift control has better responsiveness than voltage control of DC power Pdc. Therefore, the processing speed of the frequency change process can be improved by changing the frequency characteristics by phase shift control rather than by changing the frequency characteristics by voltage control of the DC power Pdc.

The first controller 25 controls the power converter 26 so that the voltage Vdc is constant. Specifically, the voltage Vdc is set to a low voltage such as the minimum voltage within the voltage range that the power converter 26 can output. According to this configuration, the frequency change process can be performed without increasing the withstand voltage of the DC/AC converter 27. As a result, it becomes possible to suppress interference with other devices without increasing the size of the DC/AC converter 27. Since parts with low withstand voltage can be used for the DC/AC converter 27, the cost of the power transmission device 2 can be reduced.

Furthermore, if a switching element with a high withstand voltage is used as the switching element of the DC/AC converter 27, the on-resistance of the switching element will increase, so the loss in the DC/AC converter 27 will increase. Therefore, by using a switching element with a low withstand voltage, it is possible to reduce the decrease in power efficiency of the power transmission device 2.

Furthermore, in the above embodiment, since the voltage Vdc is not changed, it is possible to follow transient responses such as gap fluctuations.

The lower the voltage Vdc, the higher the power transmission efficiency between the first coil 21 and the second coil 31. Therefore, by lowering the voltage Vdc, it is possible to improve the power transmission efficiency between the first coil 21 and the second coil 31. By lowering the voltage Vdc, the possibility that the power transmission device 2 will be destroyed can be reduced.

By lowering the voltage Vac1 of the AC power Pac1, the voltage Vdc can be further lowered, but the voltage range of the voltage Vac1 becomes narrower. On the other hand, the power converter 26 can further lower the voltage Vdc without narrowing the voltage range of the voltage Vac1 by further including a step-down DC/DC converter at the subsequent stage of the PFC circuit. On the other hand, when the voltage Vdc is set within the voltage range that can be output by the PFC circuit, the step-down DC-DC converter can be omitted, so the cost of the power transmission device 2 can be reduced. Note that in the above embodiment, the voltage Vdc may be changed by about several volts.

Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. For example, the non-contact power supply system 1 is not limited to electric vehicles EV, and may be applied to moving objects such as plug-in hybrid vehicles and underwater vehicles, or may be applied to objects other than moving objects.

In the frequency change process, the first controller 25 changes the drive frequency f from one boundary frequency of the used frequency band to the other boundary frequency, but the frequency change process is not limited to this. For example, arbitrary first and second frequencies sandwiching the used frequency band may be used. In this case, the frequency band used is located between the first frequency and the second frequency, and the first frequency and the second frequency are not included in the frequency band used. When the first controller 25 determines that the drive frequency f has reached the first frequency, it performs a frequency change process. The first controller 25 changes the drive frequency f from the first frequency to the second frequency in the frequency change process.

In the above embodiment, the voltage Vdc is set to the minimum voltage in the voltage range of the voltage Vdc that the power converter 26 can output, but it may be set to a larger voltage. For example, the voltage Vdc may be set to the maximum voltage within the voltage range of the voltage Vdc that the power converter 26 can output. In this case, the first controller 25 may change the frequency characteristics of the DC power Pdc by controlling the voltage of the DC power Pdc. For example, the first controller 25 may change the frequency characteristic of the DC power Pdc from the initial characteristic C1 to the characteristic C2 by controlling the power converter 26 to decrease the voltage Vdc.

As shown in FIG. 9, in the frequency change process, the first controller 25 sets the power value of the DC power Pdc at one boundary frequency when the frequency characteristic of the DC power Pdc is the initial characteristic C1. The driving frequency f may be changed from one boundary frequency to the other boundary frequency so as to maintain the same. That is, the first controller 25 may change the drive frequency f from one boundary frequency to the other boundary frequency while changing the frequency characteristic of the DC power Pdc from the initial characteristic C1 to the characteristic C2.

Specifically, the first controller 25 increases the phase shift amount and decreases the drive frequency f, thereby changing the drive frequency f from one boundary frequency while keeping the power value of the DC power Pdc constant. Change to the other boundary frequency. That is, step S12 and step S13 are performed in parallel, and step S16 and step S17 are performed in parallel. Note that by changing the drive frequency f from one boundary frequency to the other boundary frequency, the power value of the DC power Pdc increases, but the amount of phase shift sufficient to cancel out this increase is calculated in advance, and the first control 25. This phase shift amount may be set for each used frequency band, or may be set commonly for all used frequency bands.

In the above modification, the driving frequency f is changed from one boundary frequency to the other boundary frequency while maintaining the power value of the DC power Pdc. Thereby, even if the drive frequency f is changed from one boundary frequency to the other boundary frequency, the power value of the DC power Pdc hardly changes. As a result, it is possible to further reduce the possibility that the power transmission device 2 will malfunction due to the frequency change process.

The first controller 25 may change the frequency characteristics by impedance control. With reference to FIG. 10, a contactless power supply system 1 including a power transmission device 2 according to a modification will be described. FIG. 10 is a circuit block diagram of a contactless power supply system including a power transmission device according to a modification. As shown in FIG. 10, the contactless power supply system 1 according to the modification is different from the contactless power supply system 1 of the above embodiment in that the first converter 22 of the power transmission device 2 further includes an impedance converter 29. There is a difference.

Impedance converter 29 is provided between DC/AC converter 27 and first coil 21 . The impedance converter 29 is a device for changing the impedance between the DC-AC converter 27 and the first coil 21 (the impedance seen from the DC-AC converter 27). The impedance converter 29 may be, for example, a TMN (Tunable Matching Network). Since TMN is well known, its explanation will be omitted (see US Patent Application Publication No. 2019/0006836, US Patent Application Publication No. 2019/0006885, etc.).

The first converter 22 can change the magnitude (power value) of the DC power Pdc and the AC power Pac2 by impedance control in addition to frequency control, phase shift control, and voltage control of the DC power Pdc. That is, the power control performed by the first controller 25 is performed using at least one of frequency control, phase shift control, voltage control of DC power Pdc, and impedance control.

Next, impedance control will be explained. The first controller 25 changes the magnitude (power value) of the DC power Pdc, the AC power Pac2, and the load power Pout by changing the magnitude of the impedance between the DC AC converter 27 and the first coil 21. Implement impedance control to change the As the impedance between the DC-AC converter 27 and the first coil 21 increases, the DC power Pdc and AC power Pac2 decrease, and as the impedance between the DC-AC converter 27 and the first coil 21 decreases, the DC power Pdc and AC power Pac2 decrease. Power Pdc and AC power Pac2 increase. Therefore, the above-mentioned power control parameter in impedance control is the magnitude of the impedance between the DC-AC converter 27 and the first coil 21.

The power control of the modified example differs from the power control of the above embodiment in that the frequency characteristics are changed by impedance control instead of phase shift control. That is, in steps S12 and S16, the first controller 25 changes the frequency characteristics by impedance control. Specifically, the first controller 25 changes the frequency characteristic of the DC power Pdc from the initial characteristic C1 to the characteristic C2 by controlling the impedance converter 29 to increase the impedance. In step S14, the first controller 25 restores the frequency characteristics of the DC power Pdc by controlling the impedance converter 29 to restore the impedance to the initial value. In step S18, the first controller 25 changes the frequency characteristic of the DC power Pdc from the characteristic C2 toward the initial characteristic C1 by controlling the impedance converter 29 to reduce the impedance. In step S20, the first controller 25 changes the frequency characteristic of the DC power Pdc from the initial characteristic C1 toward the characteristic C2 by controlling the impedance converter 29 to increase the impedance. Other processing is the same as the power control in the above embodiment, so the explanation will be omitted.

In the above modification, when the impedance between the DC-AC converter 27 and the first coil 21 is changed, the frequency characteristics of the DC power Pdc are changed. Impedance control has better responsiveness than voltage control of DC power Pdc. Therefore, the processing speed of the frequency change process can be improved by changing the frequency characteristics by impedance control rather than by changing the frequency characteristics by voltage control of the DC power Pdc. Note that the impedance converter 29 may be provided between the second coil 31 and the second converter 32.

The first controller 25 performs at least one of voltage control of the DC power Pdc, phase shift control of the DC AC converter 27, and impedance control between the DC AC converter 27 and the first coil 21. The frequency characteristics of DC power Pdc may be changed.

As explained above, in the frequency change process, the first controller 25 changes the frequency characteristic of the DC power Pdc from the initial characteristic C1 to the characteristic C2, and changes the frequency characteristic of the DC power Pdc when the drive frequency f is the first frequency. The difference (absolute value of the difference) between the power value and the power value of the DC power Pdc when the driving frequency f is the second frequency is smaller than the difference (absolute value of the difference) between the power values in the initial characteristic C1. , the drive frequency f is changed from the first frequency to the second frequency. In this way, the drive frequency f is changed from the first frequency to the second frequency while reducing the amount of fluctuation in the power value of the DC power Pdc. This makes it possible to reduce the possibility that the power transmission device 2 will malfunction due to the frequency change process.

Note that, as described above, the first controller 25 may control the first converter 22 as constant power control so that the AC power Pac2 approaches the first power command value that is the target value of the AC power Pac2. good. The frequency characteristics of AC power Pac2 are similar to the frequency characteristics of DC power Pdc described above. Power control using AC power Pac2 is similar to power control using DC power Pdc.

1 Contactless power supply system 2 Power transmission device 3 Power receiving device 4 First coil device 5 Second coil device 21 First coil 22 First converter (converter)
23 First detector 24 First communication device 25 First controller (controller)
26 Power converter 27 DC/AC converter 28 Frequency detector 29 Impedance converter 31 Second coil 32 Second converter 33 Second detector 34 Second communication device 35 Second controller C1 Initial characteristics (first characteristics)
C2 characteristic (second characteristic)
EV Electric vehicle FB1 Frequency band used FB2 Frequency band used Idc Current Iout Load current L Load Pac1 AC power Pac2 AC power Pac3 AC power Pdc DC power Pout Load power PS Power supply R Road surface Sa Drive signal Sb Drive signal Sc Drive signal Sd Drive signal SWa Switching element SWb Switching element SWc Switching element SWd Switching element Vdc Voltage Vout Load voltage

Claims (7)

A power transmission device for supplying power to a power receiving device connected to a load,
The first coil is a first coil and is configured to contactlessly transmit the power to a second coil of the power receiving device;
a converter including a DC-AC converter that converts DC power to AC power and supplies the AC power to the first coil;
A controller that brings the power value of the target power closer to the power command value by frequency control that changes the frequency of the alternating current power;
Equipped with
The target power is the DC power or the AC power,
When the controller brings the power value close to the power command value, if the frequency passes through a frequency band used by another device, the controller changes the frequency so that it is not included in the frequency band used. Perform frequency change processing to
The frequency band used is located between a first frequency and a second frequency,
In the frequency changing process, the controller changes the frequency characteristic of the target power from a first characteristic to a second characteristic, and the power value and the frequency when the frequency is the first frequency are the second characteristic. A power transmission device that changes the frequency from the first frequency to the second frequency such that a difference with the power value when the frequency is smaller than the difference in the first characteristic. The power transmission device according to claim 1 , wherein the controller changes the frequency from the first frequency to the second frequency so that the power value conforms to the second characteristic. The controller changes the frequency from the first frequency to the second frequency so that the power value maintains the power value at the first frequency when the frequency characteristic is the first characteristic. The power transmission device according to claim 1 . The controller changes the frequency from the first frequency to the second frequency if the frequency at which the power value reaches the power command value in the first characteristic is not included in the frequency band used. 4. The power transmission device according to claim 1 , wherein the frequency characteristic is returned to the first characteristic while the frequency is adjusted to the second frequency. The controller changes the frequency from the first frequency to the second frequency when the frequency at which the power value reaches the power command value in the first characteristic is included in the frequency band used. The power transmission according to any one of claims 1 to 4 , wherein the power value is adjusted to the power command value by changing the frequency characteristic with the frequency adjusted to the second frequency. Device. The power transmission device according to any one of claims 1 to 5 , wherein the controller changes the frequency characteristics by controlling the phase shift of the DC/AC converter. The power transmission according to any one of claims 1 to 5 , wherein the controller changes the frequency characteristics by impedance control that controls impedance between the DC-AC converter and the first coil. Device.

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