CN112803740B - Soft start method and system for mixed input series output parallel DC transformer - Google Patents
Soft start method and system for mixed input series output parallel DC transformer Download PDFInfo
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- CN112803740B CN112803740B CN202011627046.8A CN202011627046A CN112803740B CN 112803740 B CN112803740 B CN 112803740B CN 202011627046 A CN202011627046 A CN 202011627046A CN 112803740 B CN112803740 B CN 112803740B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/36—Means for starting or stopping converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/3353—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter
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Abstract
The soft start method comprises the configuration of capacitance value and withstand voltage value of an ISOP input side capacitor and a soft start method of three-section variable modulation strategies of SR-DAB and PS-DAB; the method limits the starting current and the voltage overshoot of the capacitor and the load by using different modulation, current limiting and conversion control strategies at different starting stages, and enables the ISOP output to quickly and stably reach the specified output voltage; the soft start problem of the hybrid ISOP direct current transformer can be solved, the over-current and over-voltage problems are avoided, the implementation is simple, the high efficiency and the low loss are realized, and the practical value is very high.
Description
Technical Field
The disclosure relates to the technical field of starting control of direct current transformers, in particular to a soft starting method and system of a hybrid input-series output-parallel direct current transformer.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
With the rapid development of power electronic technology, direct current loads represented by distributed energy and electric vehicles are increasing. Compared with the traditional alternating current system, the direct current distributed system can better adapt to the demand of modern life on distributed energy and the development of future loads. The direct current transformer is used as a key device for connecting direct current buses and direct current loads with different voltage grades in a direct current distributed system, and the indexes of the direct current transformer such as operation reliability, efficiency and volume need to be improved urgently.
The Input-series-output-parallel (ISOP) type topological structure has the advantages of low device voltage stress, redundancy design, high reliability, high voltage transmission ratio and the like, and is widely applied to direct current transformers or direct current power distribution network engineering in China.
However, the conventional ISOP type DC transformer usually only adopts Series resonance Dual Active Bridge (SR-DAB) or Phase Shift Dual Active Bridge (PS-DAB). The ISOP type transformer based on SR-DAB has the advantage of high transmission efficiency, but the voltage regulating capability is lower than that of PS-DAB, while the ISOP type transformer based on PS-DAB has the advantage of wide voltage regulating range, but the efficiency is lower than that of SR-DAB, so that the existing ISOP type direct current transformer is difficult to obtain good balance between the voltage regulating range and the efficiency, and the hybrid ISOP direct current transformer mixing two topologies of SR-DAB and PS-DAB becomes a hotspot of academic research and engineering practice.
The inventor finds that the hybrid ISOP direct current transformer has two different topologies, namely SR-DAB and PS-DAB, because the input and the output of a plurality of converters in the hybrid ISOP direct current transformer are coupled and mutually influenced, compared with the traditional ISOP based on only SR-DAB or PS-DAB, the hybrid ISOP direct current transformer has more complicated starting control, if the hybrid ISOP direct current transformer is directly started or is improperly controlled, overcurrent and overvoltage are easily generated in the starting process of the hybrid ISOP direct current transformer to cause starting failure, however, at present, few researches on the soft starting method of the hybrid ISOP direct current transformer exist.
Disclosure of Invention
In order to solve the defects of the prior art, the soft start method and the soft start system for the hybrid input-series output-parallel direct current transformer are provided by the disclosure, a three-section type modulation strategy is used, the start process is divided into three stages, and each stage adopts different modulation strategies, so that the ISOP can be quickly and stably transited to a stable working state through the start process, the impulse voltage and the impulse current of a power electronic device during start are effectively inhibited, and the ISOP device is protected; meanwhile, the voltage of the capacitor at the input side can quickly reach a stable state, the voltage of the capacitor at the output side is smoothly established, and the time that the capacitor at the input side and the capacitor at the output side are in an unstable state or bear overvoltage is greatly reduced.
In order to achieve the purpose, the following technical scheme is adopted in the disclosure:
the first aspect of the disclosure provides a soft start method for a hybrid input-series output-parallel direct current transformer.
A soft start method of a hybrid input-series output-parallel direct current transformer comprises the following steps:
the voltage withstanding and capacitance values of input side capacitors of PS-DAB and SR-DAB are configured according to the input side voltages and voltage proportions of PS-DAB and SR-DAB in normal operation;
according to the input voltage and the output reference voltage of the powered SR-DAB, the operation selection of the SR-DAB and the PS-DAB is carried out;
adjusting the capacitor voltage at the input sides of PS-DAB and SR-DAB to reach a steady state value or within a preset range of the steady state value by adopting duty ratio modulation;
the increase speed of the SR-DAB duty ratio is limited, so that the duty ratio is increased under the condition of not causing overcurrent, the PS-DAB duty ratio is controlled, and the input voltage of the SR-DAB is maintained to be a steady state value or within a preset range of the steady state value;
and (3) switching PS-DAB from duty ratio modulation to single phase shift modulation, adjusting the phase shift angle of the PS-DAB to continuously maintain the input voltage of the SR-DAB to be a steady state value or within a preset range of the steady state value until the SR-DAB enters a series resonance state, and finishing ISOP starting.
As possible implementation manners, the withstand voltage of the PS-DAB and SR-DAB input side capacitors is determined according to the input side voltage values shared by the PS-DAB and SR-DAB in rated working states, the PS-DAB and SR-DAB bear small voltage, and the withstand voltage and the capacitance value of the input capacitors are small and large when the input capacitors are selected.
As possible implementation manners, if the input side voltage of the SR-DAB is larger than the voltage value in the steady state, the SR-DAB works and the PS-DAB does not work, and under the condition that the SR-DAB is not in overcurrent, the SR-DAB input voltage is adjusted to the steady state value or the preset range of the steady state value by controlling the duty ratio to increase the speed.
As possible implementation manners, if the input side voltage of the PS-DAB is larger than the voltage value in the steady state, the PS-DAB works, SR-DAB does not work, and the input voltage of the PS-DAB is adjusted to the steady state value or the preset range of the steady state value by controlling the duty ratio to increase the speed under the condition that the PS-DAB is not in overcurrent.
As some possible implementation manners, when the input voltage of the SR-DAB reaches a steady state value or is within a preset range of the steady state value, the duty ratio of the SR-DAB is continuously increased, and meanwhile, the PS-DAB determines the increase and decrease of the PS-DAB duty ratio according to the input voltage of the SR-DAB and the magnitude of the steady state value;
and if the PS-DAB continuously increases the duty ratio and overcurrent occurs, maintaining the current values of the PS-DAB duty ratio and the SR-DAB duty ratio, and continuously increasing until overcurrent does not occur.
As some possible realization modes, PS-DAB is transited from duty ratio modulation to single phase shift modulation by using a 0.25T starting method or an instantaneous current control method.
As a further limitation, the duty ratio of SR-DAB and the phase shift angle of PS-DAB are increased simultaneously, if one of the PS-DAB and SR-DAB is in the process of increasing, the duty ratio or the phase shift angle is not increased in the control period until overcurrent does not occur, the duty ratio or the phase shift angle is continuously increased until SR-DAB enters a series resonance state, and the start is finished.
The second aspect of the present disclosure provides a soft start system of a hybrid input-series output-parallel direct current transformer.
A soft start system of a hybrid input-series output-parallel direct current transformer comprises:
a capacitance configuration module configured to: the voltage withstanding and capacitance values of input side capacitors of PS-DAB and SR-DAB are configured according to the input side voltages and voltage proportions of PS-DAB and SR-DAB in normal operation;
an operation selection module configured to: according to the input voltage and the output reference voltage of the powered SR-DAB, the operation selection of the SR-DAB and the PS-DAB is carried out;
a duty cycle control module configured to: adjusting the capacitor voltage at the input sides of PS-DAB and SR-DAB to reach a steady state value or within a preset range of the steady state value by adopting duty ratio modulation;
a duty cycle increase control module configured to: the increase speed of the SR-DAB duty ratio is limited, so that the duty ratio is increased under the condition of not causing overcurrent, the PS-DAB duty ratio is controlled, and the input voltage of the SR-DAB is maintained to be a steady state value or within a preset range of the steady state value;
a modulation policy switching module configured to: and (3) switching PS-DAB from duty ratio modulation to single phase shift modulation, adjusting the phase shift angle of the PS-DAB to continuously maintain the input voltage of the SR-DAB to be a steady state value or within a preset range of the steady state value until the SR-DAB enters a series resonance state, and finishing ISOP starting.
A third aspect of the present disclosure provides a medium having a program stored thereon, where the program when executed by a processor implements the steps in the soft start method of the hybrid input-series output-parallel dc transformer according to the first aspect of the present disclosure.
A fourth aspect of the present disclosure provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor, where the processor executes the program to implement the steps in the method for soft starting a hybrid input-series output-parallel dc transformer according to the first aspect of the present disclosure.
Compared with the prior art, the beneficial effect of this disclosure is:
1. according to the method, the system, the medium or the electronic equipment, overvoltage of the capacitor at the input side of the ISOP is avoided in the starting process, the voltage of the capacitor at the input side can be ensured to reach a steady-state value as soon as possible, time of uneven or overlarge voltage bearing of the capacitor due to non-ideal factors such as capacitance value errors and the like is avoided, the service life of the capacitor can be prolonged, and the reliability of the ISOP is improved.
2. The method, the system, the medium or the electronic equipment limit the peak current of the PS-DAB and SR-DAB switching devices in the ISOP starting process, further limit the current of the switching devices at the turn-off time, and can effectively prevent the devices from overvoltage, overcurrent, overheating and the like.
3. The method, the system, the medium or the electronic equipment enable the voltage of the ISOP output side to be gradually increased, the increasing speed is high, the voltage overshoot is close to 0, and the load overvoltage in the starting process is effectively avoided.
4. The method, the system, the medium or the electronic equipment can ensure that the ISOP has unsatisfactory capacitance voltage division and output side voltage target value V caused by capacitance value error of the input side when the input voltage of the ISOP is larger than or smaller than a rated valueoutrefFast and smooth start-up under different conditions.
5. The method, the system, the medium or the electronic equipment can conveniently modify the current peak limit value in the soft start process, maximally utilize the performance of the device and adapt to ISOP (inter-Integrated Circuit) of different devices and power levels.
6. The method, the system, the medium or the electronic equipment can adapt to the conditions of different numbers and proportions of PS-DAB and SR-DAB according to the actual voltage and power level requirements of ISOP, can be widely applied to different occasions such as medium and low voltage, and has strong expansibility and practicability.
7. The method, the system, the medium or the electronic equipment can start the ISOP in a mode without an external resistor, has high starting efficiency and low loss, effectively reduces the heating of the direct current transformer, and improves the service life and the reliability of devices.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
Fig. 1 is a schematic topology diagram of a hybrid input-series output-parallel dc transformer provided in embodiment 1 of the present disclosure.
Fig. 2 is a flowchart of a first stage of a start-up process provided in embodiment 1 of the present disclosure.
Fig. 3 is a flowchart of a second stage of the startup process provided in embodiment 1 of the present disclosure.
Fig. 4 is a third stage flowchart of the start-up process provided in embodiment 1 of the present disclosure.
Fig. 5 shows that the capacitor voltage at the input side and the output side of the soft start process provided in embodiment 1 of the present disclosure rapidly reaches and maintains the steady-state voltage VoutrefSchematic diagram of nearby effects。
FIG. 6 is a diagram illustrating PS-DAB phase-shifted inductor current and SR-DAB resonant cavity current in the soft start process provided in embodiment 1 of the present disclosure.
Fig. 7 is a schematic diagram of duty cycle and phase shift angle given to PS-DAB and SR-DAB in the soft start process provided in embodiment 1 of the present disclosure.
Fig. 8 is a schematic waveform diagram of switching duty cycle modulation to SPS modulation when phase two transitions to phase three, which is provided in embodiment 1 of the present disclosure.
Detailed Description
The present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict.
Example 1:
the embodiment 1 of the present disclosure provides a soft start method for a hybrid input-series output-parallel direct current transformer, including:
step 1: before the soft start method is implemented, the input side capacitance withstand voltage and the capacitance value of PS-DAB and SR-DAB need to be configured according to the input side voltage and the voltage proportion of PS-DAB and SR-DAB in normal operation.
Specifically, the withstand voltage of the input side capacitors of PS-DAB and SR-DAB is determined according to the value of the input side voltage shared by the two capacitors in rated working states. The capacitance value ratio of the capacitors at the input sides of the two capacitors can ensure that the capacitors connected in series are charged by rated input voltage under the condition that PS-DAB and SR-DAB do not work, and the capacitor voltage reaches the rated voltage value. That is, PS-DAB and SR-DAB bear small voltage, and the withstand voltage and the capacitance value of the selected input capacitor are small and large.
Step 2: according to input voltage and output reference voltage V of SR-DAB after power-onoutrefAnd the operation selection of SR-DAB and PS-DAB is carried out, duty ratio modulation is adopted during operation, and the input side capacitor voltage of PS-DAB and SR-DAB is rapidly adjusted to be close to a steady state value. Meanwhile, by limiting the size of the duty ratio, the ISOP overcurrent and overvoltage are avoided. And the time for the input side capacitors of PS-DAB and SR-DAB to bear unsteady-state voltage or overvoltage is reduced.
Specifically, if the input side voltage of SR-DAB is larger than the voltage value nSRC V in steady stateoutrefIf the SR-DAB works, the PS-DAB does not work, and further, under the condition of ensuring that the SR-DAB does not overflow, the input voltage of the SR-DAB is adjusted to nSRC V by controlling the duty ratio to increase the speedoutrefNearby.
On the contrary, PS-DAB works, SR-DAB does not work, and the SR-DAB input voltage is adjusted to nSRC V under the condition of ensuring that PS-DAB does not overflowoutrefNearby.
Wherein nSRC is the turn ratio of the SR-DAB transformer, VoutrefIs its output side voltage.
And step 3: after the capacitor voltage at the input sides of PS-DAB and SR-DAB reaches the vicinity of a steady state value, the duty ratio of the SR-DAB is increased under the condition of not causing overcurrent by limiting the increasing speed of the duty ratio of the SR-DAB. Meanwhile, the duty ratio of PS-DAB is controlled, the input voltage of SR-DAB is maintained to be close to a steady-state value, and the voltage of the input side is prevented from exceeding the voltage-withstanding range of the capacitor.
Specifically, when the input voltage of SR-DAB reaches nSRC VoutrefNearby, the duty cycle of SR-DAB continues to increase. Meanwhile, PS-DAB inputs voltage and nSRC V according to SR-DABoutrefDetermining the increase and decrease of the PS-DAB duty ratio, if the PS-DAB continues to increase the duty ratio and overcurrent occurs, maintaining the current values of the PS-DAB duty ratio and the SR-DAB duty ratio, and continuing to increase until overcurrent does not occur, so that the PS-DAB duty ratio and the SR-DAB duty ratio are increased continuouslyThe SR-DAB input voltage is kept stable.
And 4, step 4: because the PS-DAB can only step down during Phase shift modulation, and the ISOP requires the PS-DAB to have a step-up and step-down function, the PS-DAB needs to be transited from duty cycle modulation to Single Phase-shift (SPS) modulation. To avoid the rush current of the converter when switching suddenly to SPS modulation, it is chosen to restart SPS modulation at 1/4 switching period (0.25T).
Specifically, when the voltage of the ISOP output rises to a certain value, the duty ratio modulation method cannot boost the voltage, the PS-DAB continues to use the duty ratio modulation, and the voltage of the ISOP output cannot rise further, so that the PS-DAB needs to be transited from the duty ratio modulation to the SPS modulation, and the transition method can use a 0.25T starting method, an instantaneous current control method and the like to reduce the magnetic bias and the current stress during the switching of the transformer. In the present disclosure, the transition method is selected to be a 0.25T start-up method.
And 5: after PS-DAB enters SPS modulation, the duty ratio of SR-DAB is still slowly increased, so that the phase shift angle of PS-DAB needs to be adjusted to continuously maintain the input voltage of SR-DAB to be close to a steady-state value. Until SR-DAB enters the series resonance state. At this time, the ISOP input and output voltage reaches a steady state, and the ISOP is started.
Specifically, at this time, the duty ratio of the SR-DAB and the PS-DAB phase shift angle are increased simultaneously, and if one of the PS-DAB and the SR-DAB is overcurrent during the increase process, the duty ratio or the phase shift angle is not increased in the control cycle until overcurrent does not occur, and the control cycle can be continuously increased. And finishing starting until SR-DAB enters a series resonance state.
More specifically, the following contents are included:
PS-DAB and SR-DAB input side capacitor CinDABAnd CinSRCCapacity and withstand voltage determination method:
FIG. 1 shows an ISOP topology, according to the rated operating condition CinDABAnd CinSRCRated voltage URatedDABAnd URatedSRCAnd leave a margin to determine CinDABAnd CinSRCThe withstand voltage of (1). Powering up according to rated input voltage when PS-DAB and SR-DAB do not work, CinDABAnd CinSRCIn series connectionVoltage is U when charging is completedRatedDABAnd URatedSRCDetermining the capacitance value ratio, such as formula (1), and determining C according to the ripple requirement of input side voltage and current based on engineering experience or simulationinDABAnd CinSRCAnd (4) capacity value.
The soft start control method of the ISOP direct current transformer comprises the following steps: the starting process of PS-DAB and SR-DAB is controlled in three stages, the starting current is limited, and overcurrent of switching devices of PS-DAB and SR-DAB and overvoltage of passive devices are prevented.
Fig. 2, fig. 3 and fig. 4 are flowcharts of three phases of the soft start process of the present embodiment. In each stage, the flowchart of the present embodiment is executed with a cycle of 25 kHz. The estimation method of the PS-DAB resonant inductor current and the SR-DAB resonant cavity current in the figures 2, 3 and 4 is as follows:
duty cycle modulation, transformer peak current for PS-DAB in Continuous Conduction Mode (CCM):
modulation of duty ratio, peak current of transformer of PS-DAB under discontinuous conduction mode DCM:
wherein, VinDABIs input voltage of PS-DAB, and nDAB is transformer transformation ratio of PS-DAB, VoutIs the output voltage of ISOP, fswSwitching frequency, L, for PS-DABDABIs the phase-shifting inductor of PS-DAB. DDAB is the duty cycle, which is 1 when the H-bridge outputs a square wave.
Duty ratio modulation, under the condition that DSRC is less than or equal to 0.25, the peak current of the SR-DAB transformer is as follows:
duty ratio modulation, under the condition that DSRC is more than 0.25, the peak current of the transformer of SR-DAB is as follows:
wherein, Vcr_absIs the resonant cavity capacitance voltage peak value, VinSRCIs an input voltage of SR-DAB, Lr、CrThe DSRC is the duty ratio under an SR-DAB modulation mode, wherein the SR-DAB is a series resonance mode when the DSRC is 0.5.
FIG. 2 is a working flow chart of a stage-one of the soft starting process of the ISOP, one of the PS-DAB and the SR-DAB adopts a duty ratio control mode to carry out current-limiting starting, so that the voltage of the capacitor at the input side can quickly reach a rated voltage value.
The specific process is as follows: firstly, judging whether the SR-DAB input voltage is U or notRatedSRCNearby if in URatedSRCWithin +/-1V, ending the first stage, otherwise according to the SR-DAB input voltage and URatedSRCThe comparison of the magnitudes determines whether PS-DAB start or SR-DAB start until the SR-DAB input voltage is adjusted to U without overcurrent in the converterRatedSRCWithin + -1V.
FIG. 3 is a flow chart of the second stage of the ISOP soft start process, in which the SR-DAB duty cycle is gradually increased and the PS-DAB duty cycle is adjusted and controlled to maintain the input voltage of SR-DAB at URatedSRCNearby, the whole process needs to ensure that SR-DAB and PS-DAB do not overflow until reaching the specified time Tswitch(in this example T)switch0.04s) and then stage three. The specific process is as follows: if the SR-DAB input voltage is less than URatedSRCThe PS-DAB duty ratio is increased, otherwise, the PS-DAB duty ratio is reduced, when the duty ratio is changed, the PS-DAB and the SR-DAB are not overcurrent, and meanwhile, the SR-DAB duty ratio is increased under the condition of ensuring that the SR-DAB is not overcurrent.
FIG. 4 is a phase three workflow diagram of the ISOP soft start process, PS-DSwitching AB into SPS modulation, starting SPS modulation at 0.25T, wherein the waveform of the switching process is shown in figure 5, and the specific process is as follows: if the SR-DAB input voltage is less than URatedSRCThe PS-DAB phase shift angle is increased, otherwise, the phase shift angle is reduced, and when the phase shift angle changes, the PS-DAB and the SR-DAB are not overcurrent. Meanwhile, the duty ratio of SR-DAB is increased under the condition of ensuring that the SR-DAB is not subjected to overcurrent.
Fig. 6 shows the input and output capacitor voltage waveforms during the start-up process, and it can be seen that in the first phase, the capacitor voltage quickly reaches around the steady state value of 560V, and the second and third phase input capacitor voltages are also successfully maintained around 560V. Meanwhile, no overcurrent occurs in both SR-DAB and PS-DAB.
FIG. 7 shows the PS-DAB phase-shifted inductor current i during the start-up processLAnd SR-DAB cavity current iLrAnd (4) waveform. In the embodiment, according to the mathematical model formulas (2), (3), (4) and (5) of PS-DAB and SR-DAB, i under the condition of the current duty ratio or phase shift angle is predictedLAnd iLr. And according to preset iLrAnd iLThe limit value 60A determines whether the duty cycle and the phase shift angle can be further increased. It can be seen that the first stage PS-DAB current is limited by the second and third stage SR-DAB currents.
Meanwhile, when the duty ratio modulation of PS-DAB is changed into SPS modulation, a 0.25T starting method is used, the phase-shifting inductive current has no obvious direct current bias, the magnetic bias and the inductive saturation of a transformer are avoided, and the overcurrent and overvoltage problems of active and passive devices are also avoided.
When the duty cycle of SR-DAB reaches the maximum value of 0.5, SR-DAB enters the series resonance mode.
FIG. 8 is a schematic diagram showing the change of the duty ratio or phase shift angle between PS-DAB and SR-DAB during the starting process, wherein the PS-DAB works in the duty ratio modulation mode in the first and second stages, the SR-DAB works in the duty ratio modulation mode in the second and third stages, the PS-DAB works in the SPS modulation mode in the third stage, and the SR-DAB successfully transits to the series resonance mode in the third stage.
And starting the ISOP after the completion, wherein the PS-DAB works in an SPS modulation mode, and the SR-DAB works in a series resonance mode.
Therefore, the three-stage soft start method of the embodiment is adopted: firstly, input side capacitor voltage balancing is carried out, then the output side capacitor voltage is raised under the condition that the input side capacitor voltage is kept almost unchanged, and meanwhile PS-DAB and SR-DAB gradually transit to SPS modulation and series resonance modes respectively; the voltage and the current are controlled and limited in the soft start process, overvoltage and overcurrent caused by adopting SPS modulation by PS-DAB and using series resonance mode by SR-DAB for direct start are avoided, damage to a load or a converter is avoided, and the transition process is stable.
Meanwhile, through simple improvement, the embodiment can be suitable for the working conditions of a higher power and a more complex hybrid ISOP system, and has strong practicability; the number of PS-DAB and SR-DAB can be selected according to the actual voltage grade requirement, so that the method can be widely applied to different occasions such as low and medium voltage and has strong expansibility and practicability. The method is simple to implement, strong in expansibility, simple to apply, strong in practicability and wide in prospect in the fields of power systems and renewable energy power generation.
Example 2:
the embodiment 2 of the present disclosure provides a soft start system of a hybrid input-series output-parallel direct current transformer, including:
a capacitance configuration module configured to: the voltage withstanding and capacitance values of input side capacitors of PS-DAB and SR-DAB are configured according to the input side voltages and voltage proportions of PS-DAB and SR-DAB in normal operation;
an operation selection module configured to: according to input voltage and output reference voltage V of SR-DAB after power-onoutrefThe operation selection of SR-DAB and PS-DAB is carried out;
a duty cycle control module configured to: adjusting the capacitor voltage at the input sides of PS-DAB and SR-DAB to reach a steady state value or within a preset range of the steady state value by adopting duty ratio modulation;
a duty cycle increase control module configured to: the increase speed of the SR-DAB duty ratio is limited, so that the duty ratio is increased under the condition of not causing overcurrent, the PS-DAB duty ratio is controlled, and the input voltage of the SR-DAB is maintained to be a steady state value or within a preset range of the steady state value;
a modulation policy switching module configured to: and (3) switching PS-DAB from duty ratio modulation to single phase shift modulation, adjusting the phase shift angle of the PS-DAB to continuously maintain the input voltage of the SR-DAB to be a steady state value or within a preset range of the steady state value until the SR-DAB enters a series resonance state, and finishing ISOP starting.
The working method of the system is the same as the steps in the soft start method of the hybrid input-series output-parallel direct current transformer provided in embodiment 1, and details are not repeated here.
Example 3:
the embodiment 3 of the present disclosure provides a medium, on which a program is stored, where the program, when executed by a processor, implements the steps in the soft start method for the hybrid input-series output-parallel dc transformer according to the embodiment 1 of the present disclosure, where the steps are:
the voltage withstanding and capacitance values of input side capacitors of PS-DAB and SR-DAB are configured according to the input side voltages and voltage proportions of PS-DAB and SR-DAB in normal operation;
according to input voltage and output reference voltage V of SR-DAB after power-onoutrefThe operation selection of SR-DAB and PS-DAB is carried out;
adjusting the capacitor voltage at the input sides of PS-DAB and SR-DAB to reach a steady state value or within a preset range of the steady state value by adopting duty ratio modulation;
the increase speed of the SR-DAB duty ratio is limited, so that the duty ratio is increased under the condition of not causing overcurrent, the PS-DAB duty ratio is controlled, and the input voltage of the SR-DAB is maintained to be a steady state value or within a preset range of the steady state value;
and (3) switching PS-DAB from duty ratio modulation to single phase shift modulation, adjusting the phase shift angle of the PS-DAB to continuously maintain the input voltage of the SR-DAB to be a steady state value or within a preset range of the steady state value until the SR-DAB enters a series resonance state, and finishing ISOP starting.
The detailed steps are the same as the soft start method of the hybrid input-series output-parallel direct current transformer in embodiment 1, and are not described again here.
Example 4:
the embodiment 4 of the present disclosure provides an electronic device, which includes a memory, a processor, and a program stored in the memory and capable of running on the processor, where the processor executes the program to implement the steps in the soft start method for the hybrid input-series output-parallel dc transformer according to the embodiment 1 of the present disclosure, where the steps are as follows:
the voltage withstanding and capacitance values of input side capacitors of PS-DAB and SR-DAB are configured according to the input side voltages and voltage proportions of PS-DAB and SR-DAB in normal operation;
according to input voltage and output reference voltage V of SR-DAB after power-onoutrefThe operation selection of SR-DAB and PS-DAB is carried out;
adjusting the capacitor voltage at the input sides of PS-DAB and SR-DAB to reach a steady state value or within a preset range of the steady state value by adopting duty ratio modulation;
the increase speed of the SR-DAB duty ratio is limited, so that the duty ratio is increased under the condition of not causing overcurrent, the PS-DAB duty ratio is controlled, and the input voltage of the SR-DAB is maintained to be a steady state value or within a preset range of the steady state value;
and (3) switching PS-DAB from duty ratio modulation to single phase shift modulation, adjusting the phase shift angle of the PS-DAB to continuously maintain the input voltage of the SR-DAB to be a steady state value or within a preset range of the steady state value until the SR-DAB enters a series resonance state, and finishing ISOP starting.
As will be appreciated by one skilled in the art, embodiments of the present disclosure may be provided as a method, system, or computer program product. Accordingly, the present disclosure may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present disclosure may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.
The present disclosure is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the disclosure. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.
The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, and various modifications and changes may be made to the present disclosure by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Claims (8)
1. A soft start method of a hybrid input-series output-parallel direct current transformer is characterized by comprising the following steps: the method comprises the following steps:
the voltage withstanding and capacitance values of input side capacitors of PS-DAB and SR-DAB are configured according to the input side voltages and voltage proportions of PS-DAB and SR-DAB in normal operation;
according to the input voltage and the output reference voltage of the powered SR-DAB, the operation selection of the SR-DAB and the PS-DAB is carried out; if the input side voltage of the SR-DAB is greater than the voltage value in the steady state, the SR-DAB works and the PS-DAB does not work, and the SR-DAB input voltage is adjusted to the steady state value or the preset range of the steady state value by controlling the duty ratio to increase the speed under the condition of ensuring that the SR-DAB is not overcurrent; if the input side voltage of the SR-DAB is not greater than the voltage value in the steady state, the PS-DAB works, the SR-DAB does not work, and the PS-DAB input voltage is adjusted to the steady state value or the preset range of the steady state value by controlling the duty ratio to increase the speed under the condition of ensuring that the PS-DAB does not overflow;
adjusting the capacitor voltage at the input sides of PS-DAB and SR-DAB to reach a steady state value or within a preset range of the steady state value by adopting duty ratio modulation;
the increase speed of the SR-DAB duty ratio is limited, so that the duty ratio is increased under the condition of not causing overcurrent, the PS-DAB duty ratio is controlled, and the input voltage of the SR-DAB is maintained to be a steady state value or within a preset range of the steady state value;
and (3) switching PS-DAB from duty ratio modulation to single phase shift modulation, adjusting the phase shift angle of the PS-DAB to continuously maintain the input voltage of the SR-DAB to be a steady state value or within a preset range of the steady state value until the SR-DAB enters a series resonance state, and finishing ISOP starting.
2. The soft start method of a hybrid input-series output-parallel dc transformer as claimed in claim 1, wherein:
the withstand voltage of the PS-DAB and SR-DAB input side capacitors is determined according to the shared input side voltage values in the rated working states of the PS-DAB and SR-DAB, who bears the low voltage of the PS-DAB and SR-DAB, and the withstand voltage and the capacitance value of the PS-DAB and SR-DAB capacitors are small when the input capacitors are selected.
3. The soft start method of a hybrid input-series output-parallel dc transformer as claimed in claim 1, wherein:
when the input voltage of the SR-DAB reaches a steady state value or is within a preset range of the steady state value, the duty ratio of the SR-DAB is continuously increased, and meanwhile, the PS-DAB determines the increase and decrease of the PS-DAB duty ratio according to the input voltage of the SR-DAB and the magnitude of the steady state value;
and if the PS-DAB continuously increases the duty ratio and overcurrent occurs, maintaining the current values of the PS-DAB duty ratio and the SR-DAB duty ratio, and continuously increasing until overcurrent does not occur.
4. The soft start method of a hybrid input-series output-parallel dc transformer as claimed in claim 1, wherein:
and (3) the PS-DAB is transited from duty ratio modulation to single phase shift modulation by using a 0.25T starting method or an instantaneous current control method.
5. The soft-start method of a hybrid input-series output-parallel dc transformer as claimed in claim 4, wherein:
the duty ratio of SR-DAB and the PS-DAB phase shift angle are increased simultaneously, if one of the PS-DAB and SR-DAB is in the increasing process, the duty ratio or the phase shift angle is not increased in the control period until the overcurrent does not occur, the duty ratio or the phase shift angle is continuously increased until the SR-DAB enters a series resonance state, and the starting is finished.
6. A soft start system of a hybrid input-series output-parallel direct current transformer is characterized in that: the method comprises the following steps:
a capacitance configuration module configured to: the voltage withstanding and capacitance values of input side capacitors of PS-DAB and SR-DAB are configured according to the input side voltages and voltage proportions of PS-DAB and SR-DAB in normal operation;
an operation selection module configured to: according to the input voltage and the output reference voltage of the powered SR-DAB, the operation selection of the SR-DAB and the PS-DAB is carried out; if the input side voltage of the SR-DAB is greater than the voltage value in the steady state, the SR-DAB works and the PS-DAB does not work, and the SR-DAB input voltage is adjusted to the steady state value or the preset range of the steady state value by controlling the duty ratio to increase the speed under the condition of ensuring that the SR-DAB is not overcurrent; if the input side voltage of the SR-DAB is not greater than the voltage value in the steady state, the PS-DAB works, the SR-DAB does not work, and the PS-DAB input voltage is adjusted to the steady state value or the preset range of the steady state value by controlling the duty ratio to increase the speed under the condition of ensuring that the PS-DAB does not overflow;
a duty cycle control module configured to: adjusting the capacitor voltage at the input sides of PS-DAB and SR-DAB to reach a steady state value or within a preset range of the steady state value by adopting duty ratio modulation;
a duty cycle increase control module configured to: the increase speed of the SR-DAB duty ratio is limited, so that the duty ratio is increased under the condition of not causing overcurrent, the PS-DAB duty ratio is controlled, and the input voltage of the SR-DAB is maintained to be a steady state value or within a preset range of the steady state value;
a modulation policy switching module configured to: and (3) switching PS-DAB from duty ratio modulation to single phase shift modulation, adjusting the phase shift angle of the PS-DAB to continuously maintain the input voltage of the SR-DAB to be a steady state value or within a preset range of the steady state value until the SR-DAB enters a series resonance state, and finishing ISOP starting.
7. A medium having a program stored thereon, wherein the program, when executed by a processor, implements the steps in the method for soft-starting a hybrid input-series-output-parallel dc transformer according to any one of claims 1 to 5.
8. An electronic device comprising a memory, a processor and a program stored on the memory and executable on the processor, wherein the processor implements the steps of the method for soft-starting the hybrid input-series-output-parallel dc transformer according to any one of claims 1 to 5 when executing the program.
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| CN117013831A (en) * | 2023-08-11 | 2023-11-07 | 太原理工大学 | Hybrid ISOP-based wide input voltage range DC-DC converter and voltage regulating method |
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