Control method of multiphase interleaved inverter circuit, power conversion device, energy storage device

Abstract

The application belongs to the technical field of converter control, and provides a control method of a multi-phase interleaved inverter circuit, a power conversion device and an energy storage device. When it is detected that an output waveform of a voltage output signal of the multi-phase interleaved inverter circuit enters a positive half cycle, a lower switch tube of a current conversion bridge arm is controlled to be kept conductive in the positive half cycle. When it is detected that the output waveform enters a negative half cycle, an upper switch tube of the current conversion bridge arm is controlled to be kept conductive in the negative half cycle. When it is detected that the output waveform enters a rising stage of the positive half cycle, the upper switch tube of the power conversion bridge arm is controlled to be conductive or non-conductive, and the lower switch tube of the power conversion bridge arm is controlled to be non-conductive. When it is detected that the output waveform enters a falling stage of the negative half cycle, the lower switch tube of the power conversion bridge arm is controlled to be conductive or non-conductive, and the upper switch tube of the power conversion bridge arm is controlled to be non-conductive. The application reduces the loss of the multi-phase interleaved inverter circuit under no load by improving the switching control logic of the alternating current bridge arm and the power conversion bridge arm.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of converter control, and particularly relates to a control method of a multi-phase interleaved inverter circuit, a power conversion device, and an energy storage device. BACKGROUND

[0002] A bidirectional inverter is a converter that converts direct current into alternating current. In the working process of a traditional multi-phase interleaved inverter, in order to improve efficiency, there are usually two switching tubes working at a fundamental frequency (i.e., a fundamental frequency switching tube) and four switching tubes working at a high switching frequency (i.e., a high frequency switching tube). Within one fundamental frequency period, one fundamental frequency switching tube and the corresponding high frequency switching tube need to be maintained to work simultaneously.

[0003] However, when the inverter is lightly loaded or unloaded, maintaining multiple switching tubes to work simultaneously within one fundamental frequency period will cause the switching tubes to have increased losses and low conversion efficiency. SUMMARY

[0004] The present application aims to provide a control method of a multi-phase interleaved inverter circuit, a power conversion device, and an energy storage device, and aims to solve the problem of increased losses and low conversion efficiency caused by maintaining multiple switching tubes to work simultaneously when the inverter is lightly loaded or unloaded.

[0005] The first aspect of the present application provides a control method of a multi-phase interleaved inverter circuit, the multi-phase interleaved inverter circuit comprising a current conversion bridge arm and a plurality of parallel power conversion bridge arms, the current conversion bridge arm being configured to control the direction of an output signal of the multi-phase interleaved inverter circuit, the power conversion bridge arm being configured to control the power of the output signal of the multi-phase interleaved inverter circuit, the current conversion bridge arm and the power conversion bridge arm each comprising an upper switching tube and a lower switching tube, the control method comprising:

[0006] controlling the lower switching tube of the current conversion bridge arm to remain conductive during a positive half cycle of the output waveform of the multi-phase interleaved inverter circuit, and controlling the upper switching tube of the current conversion bridge arm to remain conductive during a negative half cycle of the output waveform;

[0007] controlling the upper switching tube of the power conversion bridge arm to be conductive or non-conductive and controlling the lower switching tube of the power conversion bridge arm to be non-conductive when the output waveform enters a rising phase of the positive half cycle;

[0008] controlling the lower switching tube of the power conversion bridge arm to be conductive or non-conductive and controlling the upper switching tube of the power conversion bridge arm to be non-conductive when the output waveform enters a falling phase of the negative half cycle.

[0009] In one embodiment, the control method further comprises:

[0010] When detecting that the output waveform enters the falling phase of the positive half cycle or the rising phase of the negative half cycle, outputting a high-frequency PWM signal to control the upper switch tube and the lower switch tube of each power conversion bridge arm to be complementary on.

[0011] In one embodiment, the output PWM signal controlling the upper switch tube of the power conversion bridge arm to be on or off comprises:

[0012] When the output sampling voltage of the multi-phase interleaved inverter circuit is less than the target reference voltage, controlling the upper switch tube of the power conversion bridge arm to be on;

[0013] When the output sampling voltage is greater than the target reference voltage, controlling the upper switch tube of the power conversion bridge arm to be off.

[0014] In one embodiment, the output PWM signal controlling the lower switch tube of the power conversion bridge arm to be on or off comprises:

[0015] When the output sampling voltage of the multi-phase interleaved inverter circuit is greater than the target reference voltage, controlling the lower switch tube of the power conversion bridge arm to be on;

[0016] When the output sampling voltage is less than the target reference voltage, controlling the lower switch tube of the power conversion bridge arm to be off.

[0017] In one embodiment, the control method further comprises:

[0018] Controlling each power conversion bridge arm to work in turn in a staggered phase, and the staggered phase difference is 360° / N, where N is the number of the power conversion bridge arms.

[0019] In one embodiment, the period of the output waveform is 0.02 seconds.

[0020] In one embodiment, the control method further comprises:

[0021] Monitoring the load power, and comparing the load power with a preset power threshold;

[0022] If the load power is greater than the preset power threshold, outputting a PWM signal to control the upper switch tube and the lower switch tube of each power conversion bridge arm to be complementary on when any switch tube of the conversion bridge arm is on.

[0023] The second aspect of the embodiments of the application further provides a power conversion device comprising a multi-phase interleaved inverter circuit and a controller, and the controller is used to execute the control method according to any one of the above.

[0024] In one embodiment, the number of the power conversion bridge arms is 2.

[0025] The third aspect of the embodiments of the present application further provides a power storage device, which comprises the power conversion device according to any one of the above.

[0026] The embodiments of the present application provide a control method of a multi-phase interleaved inverter circuit, a power conversion device and a power storage device. When it is detected that an output waveform of a voltage output signal of the multi-phase interleaved inverter circuit enters a positive half cycle, a lower switch tube of a current conversion bridge arm is controlled to be kept on in the positive half cycle. When it is detected that the output waveform enters a negative half cycle, an upper switch tube of the current conversion bridge arm is controlled to be kept on in the negative half cycle. When it is detected that the output waveform enters a rising stage of the positive half cycle, an output PWM signal controls the upper switch tube of the power conversion bridge arm to be on or off, and controls the lower switch tube of the power conversion bridge arm to be off. When it is detected that the output waveform enters a falling stage of the negative half cycle, the output PWM signal controls the lower switch tube of the power conversion bridge arm to be on or off, and controls the upper switch tube of the power conversion bridge arm to be off. By improving the switching control logic of the AC bridge arm and the power conversion bridge arm, the loss of the inverter at light load or no load is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A structural schematic diagram of a multi-phase interleaved inverter circuit is provided for one embodiment of the present application;

[0028] Figure 2 A flowchart of a control method is provided for one embodiment of the present application;

[0029] Figure 3 An output waveform diagram of a voltage output signal is provided for one embodiment of the present application;

[0030] Figure 4a A current flow direction diagram when the control method is applied to interval A is provided for one embodiment of the present application Figure 1 ;

[0031] Figure 4b A current flow direction diagram when the control method is applied to interval A is provided for one embodiment of the present application Figure 2 ;

[0032] Figure 5a A current flow direction diagram when the control method is applied to interval C is provided for one embodiment of the present application Figure 1 ;

[0033] Figure 5b A current flow direction diagram when the control method is applied to interval C is provided for one embodiment of the present application Figure 2 ;

[0034] Figure 6 Another flowchart of the control method provided for an embodiment of the present application;

[0035] Figure 7a Current flow direction when the control method provided for an embodiment of the present application is applied to interval B Figure 1 ;

[0036] Figure 7b Current flow direction when the control method provided for an embodiment of the present application is applied to interval B Figure 2 ;

[0037] Figure 8a Current flow direction when the control method provided for an embodiment of the present application is applied to interval D Figure 1 ;

[0038] Figure 8b Current flow direction when the control method provided for an embodiment of the present application is applied to interval D Figure 2 ;

[0039] Figure 9 Another flowchart of the control method provided for an embodiment of the present application;

[0040] Figure 10 Another flowchart of the control method provided for an embodiment of the present application. DETAILED DESCRIPTION

[0041] In order to enable persons skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by persons skilled in the art without creative work should fall within the scope of protection of the present application.

[0042] The terms “comprise”, “comprising”, “include”, “including” and “contains”, “containing” in the specification and claims of the present application and the above-mentioned drawings are intended to cover the non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product or device. In addition, the terms “first”, “second” and “third” and the like are used to distinguish different objects, rather than to describe a specific order.

[0043] The SPWM (sinusoidal PWM, sinusoidal pulse width modulation) control mode of the traditional full-bridge inverter greatly reduces the switching loss in the standby state of the inverter due to the considerable switching loss of high-frequency fast tube semiconductors in the no-load and light-load states, and thus the conversion efficiency is not ideal. Especially for mobile energy storage products, the excessive loss in the light-load or no-load state greatly reduces the user experience and the actual use rate of product energy. Therefore, it is urgent to reduce the switching loss, and even a part of the switching loss can bring objective benefits in the light-load or no-load state with small total loss.

[0044] To solve the above technical problems, the embodiment of the present application provides a control method of a multi-phase interleaved inverter circuit, as shown in Figure 1 The multi-phase interleaved inverter circuit includes a current conversion bridge arm 21 and a plurality of parallel power conversion bridge arms (power conversion bridge arm 11, …, power conversion bridge arm 1n, n≥2, and n is the number of power conversion bridge arms), the current conversion bridge arm 21 is used to realize the direction control of the output signal of the multi-phase interleaved inverter circuit, the power conversion bridge arm is used to realize the power control of the output signal of the multi-phase interleaved inverter circuit, and the current conversion bridge arm 21 and all the power conversion bridge arms include upper and lower switch tubes.

[0045] Specifically, as shown in Figure 1 The current conversion bridge arm 21 includes an upper switch tube Z1 and a lower switch tube Z2, the power conversion bridge arm 11 includes an upper switch tube Q11 and a lower switch tube Q12, the power conversion bridge arm 1n includes an upper switch tube Qn1 and a lower switch tube Qn2, and all the power conversion bridge arms are connected to a direct current power supply DC.

[0046] Further, in the multi-phase interleaved inverter circuit, each power conversion bridge arm is connected to an output inductor. For example, the common connection point of the upper switch tube Q11 and the lower switch tube Q12 of the power conversion bridge arm 11 is connected to an output inductor L1, the other end of the output inductor L1 is a first output end, the common connection point of the upper switch tube Z1 and the lower switch tube Z2 of the current conversion bridge arm 21 is a second output end, and the first output end and the second output end are used to connect an external load, such as a load R0.

[0047] Further, as shown in Figure 1 In the multi-phase interleaved inverter circuit, a capacitor is arranged between each output inductor and the load, and the capacitor is connected in parallel with the load, which can filter the voltage output signal of the multi-phase interleaved inverter circuit and also can store energy.

[0048] As shown in Figure 2 The control method in the embodiment includes steps S100 to S300.

[0049] In step S100, when detecting that the output waveform of the voltage output signal of the multiphase interleaved inverter circuit enters the positive half cycle, the lower switch of the current conversion bridge arm is controlled to keep conducting in the positive half cycle, and when detecting that the output waveform enters the negative half cycle, the upper switch of the current conversion bridge arm is controlled to keep conducting in the negative half cycle.

[0050] The working principle of the multiphase interleaved inverter circuit is described in combination with the waveform diagram of the voltage output signal of the multiphase interleaved inverter circuit (as shown in Figure 3

[0051] As shown in Figure 3 , for example, the output waveform of the voltage output signal of the multiphase interleaved inverter circuit is divided into four continuous intervals, interval A, interval B, interval C and interval D, according to the period T, interval A and interval B are the positive half cycle waveform of the voltage output signal, and interval C and interval D are the negative half cycle waveform of the voltage output signal. When detecting that the output waveform of the voltage output signal enters the positive half cycle, the lower switch Z2 of the alternating current bridge arm 21 keeps conducting, in order to control the direction of the output signal of the multiphase interleaved inverter circuit to keep positive, at this time, the upper switch Z1 of the alternating current bridge arm 21 keeps off.

[0052] When detecting that the output waveform of the voltage output signal enters the negative half cycle, the upper switch Z1 of the alternating current bridge arm 21 keeps conducting, in order to control the direction of the output signal of the multiphase interleaved inverter circuit to keep reverse, at this time, the lower switch Z2 of the alternating current bridge arm 21 keeps off.

[0053] In step S200, when detecting that the output waveform enters the rising stage of the positive half cycle, the output PWM signal controls the upper switch of the power conversion bridge arm to conduct or off, and controls the lower switch of the power conversion bridge arm not to conduct.

[0054] In specific applications, the voltage output signal of the multiphase interleaved inverter circuit is a sine wave, which includes a positive half cycle waveform and a negative half cycle waveform, wherein the positive half cycle waveform includes a rising stage (interval A) and a falling stage (interval B), and the negative half cycle waveform includes a falling stage (interval C) and a rising stage (interval D).

[0055] ​If the output waveform of the voltage output signal enters the rising stage of the positive half cycle, at this time, the lower switch tube Z2 of the AC bridge arm 21 remains conducting, in order to reduce the switching loss of the lower switch tube of the power conversion bridge arm, the lower switch tube of the power conversion bridge arm can be kept off (for example, the lower switch tubes Qn1, …, Qn2 are kept off), and the upper switch tube of the power conversion bridge arm can be turned on or off as needed (for example, the upper switch tubes Q11, …, Qn1 can be turned on or off). Specifically, the switching frequency and the switching duty cycle of the upper switch tube of the power conversion bridge arm can be adjusted by sending a corresponding PWM signal to the upper switch tube, adjusting the power of the voltage output signal in the positive half cycle, so that the power of the output voltage meets the preset target.

[0056] Taking two power conversion bridge arms as an example, the following is described in combination with Figure 4a 、 Figure 4b When the output waveform of the voltage output signal enters the rising stage of the positive half cycle (interval A), the upper switch tube Z1 of the AC bridge arm 21 remains off, the lower switch tube Z2 remains conducting, the lower switch tube Q12 and the lower switch tube Qn2 of the power conversion bridge arm remain off, and the upper switch tube Q11 and the upper switch tube Qn1 are turned on or off. When the upper switch tube Q11 and the upper switch tube Qn1 are turned on, the current flows as shown in Figure 4a , at this time, the current flows through the DC power supply DC, the upper switch tube Q11 (the upper switch tube Qn1), the inductor L1 (the inductor Ln), the load R0, and the lower switch tube Z2 to form a loop, the current flowing through the output inductor L1 gradually increases, and the voltage across the load R0 gradually rises. When the upper switch tube Q11 and the upper switch tube Qn1 are turned off, the current flows through the body diode of the lower switch tube Q12 (the lower switch tube Qn2) to form a loop, as shown in Figure 4b , at this time, the current flowing through the output inductor L1 (Ln) decreases, and the voltage across the load R0 gradually decreases.

[0057] In step S300, when it is detected that the output waveform enters the falling stage of the negative half cycle, the PWM signal controls the lower switch tube of the power conversion bridge arm to be turned on or off, and controls the upper switch tube of the power conversion bridge arm to be not conducting.

[0058] If the output waveform of the voltage output signal enters the falling stage of the negative half cycle, at this time, the upper switch tube Z1 of the AC bridge arm 21 remains conducting, the direction of the voltage output signal remains reversed, in order to reduce the switching loss of the upper switch tube of the power conversion bridge arm, the upper switch tube of the power conversion bridge arm can be kept off (for example, the upper switch tubes Q11, …, Qn1 are kept off), and the lower switch tube of the power conversion bridge arm is turned on or off as needed (for example, the lower switch tubes Q12, …, Qn2 can be turned on or off). Specifically, the switching frequency and the switching duty cycle of the lower switch tube of the power conversion bridge arm can be adjusted by sending a corresponding PWM signal to the lower switch tube, the power of the voltage output signal in the negative half cycle is adjusted, and the power of the output voltage meets the preset target.

[0059] Taking two power conversion bridge arms as an example, the control method is described in combination with Figure 5a 、 Figure 5b When the output waveform of the voltage output signal enters the falling stage of the negative half cycle (interval C), the upper switch tube Z1 of the AC bridge arm 21 remains conducting, the lower switch tube Z2 remains off, the upper switch tubes Q11 and Qn1 of the power conversion bridge arm remain off, and the lower switch tubes Q12 and Qn2 are turned on or off. Specifically, when the lower switch tubes Q12 and Qn2 are turned on, the current flows as shown in Figure 5a In a single branch, at this time, the current flows through the DC power supply DC, the upper switch tube Z1, the load R0, the inductor L1 (inductor Ln), and the lower switch tube Q12 (lower switch tube Qn2) to form a loop, the current flowing through the output inductor L1 (inductor Ln) gradually increases, the voltage across the load R0 reverses in direction, and the voltage amplitude gradually increases. When the lower switch tube Q12 is off, the current flows through the body diode of the upper switch tubes Q11 and Qn1 to form a loop, as shown in Figure 5b At this time, the current flowing through the output inductor L1 (inductor Ln) decreases, and the voltage amplitude across the load R0 decreases.

[0060] In a specific application, by sending a PWM modulated wave with a frequency of the power frequency to the upper switch tube and the lower switch tube of the AC bridge arm, the direction of the voltage output signal can be controlled, and the output power of the multi-phase interleaved inverter circuit can be adjusted by the switching duty cycle of the power conversion bridge arm, the switching loss of the power conversion bridge arm is reduced, and the power of the output voltage meets the preset target. Here, the power frequency is the frequency of the AC output signal (for example, the AC voltage signal) of the inverter circuit.

[0061] In one embodiment, referring to Figure 6 The control method in this embodiment further includes a step S400.

[0062] In step S400, when the output waveform is detected to enter the falling phase of the positive half-cycle or the rising phase of the negative half-cycle, a high-frequency PWM signal is output to control the upper and lower switching transistors of each power conversion bridge arm to conduct complementaryly.

[0063] In this embodiment, combined with Figure 1 To explain, when the output waveform of the voltage output signal enters the falling phase of the positive half-cycle (i.e., interval B), by sending corresponding high-frequency PWM signals to the upper and lower switching transistors of the power conversion bridge arm to make them conduct complementaryly, the amplitude of the output voltage can be adjusted so that the output waveform of the voltage output signal meets the target waveform.

[0064] Taking two power conversion bridge arms as an example, combined with Figure 7a and Figure 7b To explain, when the output waveform of the voltage output signal enters the falling phase (interval B) of the positive half-cycle, the upper switch Z1 of the AC bridge arm 21 remains off, and the lower switch Z2 remains on. The upper switches Q11 and Q12 of the power conversion bridge arm are complementaryly on, and the upper switches Qn1 and Qn2 are complementaryly on. Specifically, when the upper switches Q11 and Qn1 are on, and the lower switches Q12 and Qn2 are off, the current is as follows... Figure 7a As shown, at this time, the current flows through the DC power supply DC, the upper switch Q11 (or Qn1), the inductor L1 (or Ln), the load R0, and the lower switch Z2 to form a circuit. The current output inductor L1 (or Ln) gradually increases, and the voltage across the load R0 gradually rises. When the upper switches Q11 and Qn1 are turned off, and the lower switches Q12 and Qn2 are turned on, the current flows through the lower switches Q12 and Qn2 to form a circuit, as shown. Figure 7b As shown, the current flowing through the output inductor L1 (inductor Ln) decreases at this time, and the voltage across the load R0 gradually decreases. When the output waveform of the voltage output signal enters the rising phase of the negative half-cycle (i.e., interval D), by sending corresponding high-frequency PWM signals to the upper and lower switching transistors of the power conversion bridge arm to make them complementary in conduction, the amplitude of the output voltage can be adjusted so that the output waveform of the voltage output signal meets the target waveform.

[0065] Taking two power conversion bridge arms as an example, combined with Figure 8a and Figure 8b To explain, when the output waveform of the voltage output signal enters the rising phase (interval D) of the negative half-cycle, the upper switch Z1 of AC bridge arm 21 remains on, and the lower switch Z2 remains off. The upper switches Q11 and Q12 of the power conversion bridge arm are complementaryly on, and the upper switches Qn1 and Qn2 are complementaryly on. Specifically, when the upper switches Q11 and Qn1 are off, and the lower switches Q12 and Qn2 are on, the current is as follows...Figure 8a As shown in FIG. 6, at this time, the current flows through the DC power supply DC, the upper switch Q11, the load R0, the inductor L1 (the inductor Ln), and the lower switch Q12 (the lower switch Qn2) to form a loop. When the upper switch Q11 and the upper switch Qn1 are turned on and the lower switch Q12 and the lower switch Qn2 are turned off, the current flows through the upper switch Q11 and the upper switch Qn1 to form a loop, as shown in FIG. 7. Figure 8b As shown in FIG. 8, at this time, the current flowing through the output inductor L1 decreases, and the voltage amplitude across the load R0 gradually decreases.

[0066] In one embodiment, in step S200, the output PWM signal controls the upper switch of the power conversion bridge arm to be turned on or turned off, including:

[0067] When the output sampling voltage of the multi-phase interleaved inverter circuit is less than the target reference voltage, the upper switch of the power conversion bridge arm is controlled to be turned on.

[0068] When the output sampling voltage is greater than the target reference voltage, the upper switch of the power conversion bridge arm is controlled to be turned off.

[0069] When the output waveform of the voltage output signal enters the rising phase of the positive half cycle, the lower switch of the power conversion bridge arm is kept turned off, i.e., not turned on. At this time, the power conversion bridge arm is controlled to be turned on or turned off by sending a PWM signal to the upper switch of the power conversion bridge arm, so as to control the power of the voltage output signal.

[0070] Further, the voltage output signal is sampled to obtain an output sampling voltage. If the output sampling voltage is less than the target reference voltage, the upper switch of the power conversion bridge arm is controlled to be turned on. For example, the upper switches Q11, …, Qn1 are kept turned on to increase the voltage of the voltage output signal. At this time, the current direction is as shown in FIG. 9. Figure 4a If the output sampling voltage is greater than the target reference voltage, the upper switch of the power conversion bridge arm is turned off, so that the current flows through the body diode of the lower switch of the power conversion bridge arm. For example, the upper switches Q11, …, Qn1 are kept turned off, and the lower switches Q12, …, Qn2 are kept turned off. At this time, the current flows through the body diode of the lower switch Q12, …, Qn2 to form a loop, as shown in FIG. 10. Figure 4b The body diode of the lower switch of the power conversion bridge arm is used for freewheeling. In the case where the lower switch of the power conversion bridge arm is turned off, the circuit can still work normally, thereby reducing the loss generated by the lower switch of the power conversion bridge arm when it is switched.

[0071] In a specific application, the target reference voltage in the above embodiment can be determined by a voltage function relationship. For example, the target reference voltage can be a sine wave, and the function relationship can be Vref=A*sinα, where A is the amplitude of the target reference voltage, and α is a variable related to the period T.

[0072] In one embodiment, in step S300, the output PWM signal controls the lower switch of the power conversion bridge arm to turn on or off, including:

[0073] When the output sampling voltage of the multi-phase interleaved inverter circuit is greater than the target reference voltage, the lower switch of the power conversion bridge arm is controlled to turn on;

[0074] When the output sampling voltage is less than the target reference voltage, the lower switch of the power conversion bridge arm is controlled to turn off.

[0075] Specifically, when the output waveform of the voltage output signal enters the falling phase of the negative half cycle, the upper switch Z1 remains on, the direction of the voltage output signal is reversed, the upper switch of the power conversion bridge arm is turned off, for example, the upper switches Q11, …, Qn1 are turned off. When the output sampling voltage is greater than the target reference voltage, the lower switch of the power conversion bridge arm is controlled to turn on, for example, the lower switches Q12, …, Qn2 are turned on, at this time the current flow direction is as shown in Figure 5a The voltage amplitude across the load R0 increases.

[0076] If the output sampling voltage is less than the target reference voltage, the lower switch of the power conversion bridge arm is controlled to turn off, for example, the lower switches Q12, …, Qn2 are turned off, at this time the current flow direction is as shown in Figure 5b The voltage amplitude across the load R0 decreases. The body diode of the upper switch Q11, …, Qn1 forms a loop, and the body diode of the upper switch of the power conversion bridge arm is used to continue the current flow. In the case of turning off the lower switch of the power conversion bridge arm, the circuit can still work normally, thereby reducing the loss generated by the lower switch of the power conversion bridge arm when switching.

[0077] In one embodiment, referring to Figure 9 The control method further includes step S500.

[0078] In step S500, each of the power conversion bridge arms is controlled to work in sequence with a phase difference of 360° / N, where N is the number of the power conversion bridge arms.

[0079] In this embodiment, by setting each of the power conversion bridge arms to work in sequence with a phase difference, the multi-phase interleaved inverter circuit outputs an alternating current signal to drive the load R0 to work. For example, the phase difference between adjacent power conversion bridge arms is 360° / N. If N is 3, the multi-phase interleaved inverter circuit is a three-phase interleaved power conversion circuit, and the phase difference between each power conversion bridge arm is 120°.

[0080] In some embodiments, the upper switch and the lower switch in the power conversion bridge arm are configured to receive a high-frequency PWM signal, and the output power of the multi-phase interleaved inverter circuit is adjusted by adjusting the switching duty cycle of the high-frequency PWM signal.

[0081] In some embodiments, the upper switch and the lower switch in the AC bridge arm are configured to receive a power-frequency PWM signal, and the current direction of the voltage output signal is controlled by sending the power-frequency PWM signal to the upper switch and the lower switch in the AC bridge arm, where the frequency of the power-frequency PWM signal is 50 Hz.

[0082] In one embodiment, the period of the output waveform is 0.02 seconds.

[0083] In a specific application, the switching frequency of the AC bridge arm can be selected based on the frequency of the voltage output signal. For example, if the voltage output signal is an alternating current signal with a frequency of 50 Hz, the frequency of the power-frequency PWM signal sent to the AC bridge arm is 50 Hz.

[0084] In one embodiment, referring to FIG. 6, the control method further includes step S600. Figure 10

[0085] In step S600, the load power is monitored, and the load power is compared with a preset power threshold.

[0086] If the load power is less than the preset power threshold, the control method in steps S100-S500 is performed to control the switches in the current conversion bridge arm and the power conversion bridge arm.

[0087] If the load power is greater than the preset power threshold, when any switch in the current conversion bridge arm is turned on, the upper switch and the lower switch of each power conversion bridge arm are controlled to be turned on complementarily by the output PWM signal.

[0088] In this embodiment, the load power of the multi-phase interleaved inverter circuit is monitored, and if the load power is greater than the preset power threshold, when any switch in the current conversion bridge arm is turned on, the upper switch and the lower switch of each power conversion bridge arm are controlled to be turned on complementarily. At this time, the upper switch of the current conversion bridge arm is used to control the forward output of the voltage output signal, and the lower switch of the current conversion bridge arm is used to control the reverse output of the voltage output signal. By setting the upper switch and the lower switch of each power conversion bridge arm to be turned on complementarily when the upper switch or the lower switch is turned on, the current is large when the load power is large, and if the freewheeling is still performed by the body diode, the conduction loss will also increase, which cannot achieve the purpose of reducing the loss. Therefore, at this time, the upper switch and the lower switch of each power conversion bridge arm are controlled to be turned on complementarily, and the freewheeling is no longer performed by the body diode.

[0089] ​The embodiment of the present application further provides a power conversion device, comprising a multiphase interleaved inverter circuit and a controller, wherein the controller is used to execute the multiphase interleaved inverter circuit control method as described in the above embodiments.

[0090] It can be understood that the controller and each switch tube in the multiphase interleaved inverter circuit can be electrically connected in a direct or indirect manner to send a control signal to each switch tube to control the turn-on or turn-off of each switch tube.

[0091] In one embodiment, the number of power conversion bridge arms is 2.

[0092] In a specific application, the number of power conversion bridge arms is 2, and the multiphase interleaved inverter circuit is a two-phase interleaved inverter circuit.

[0093] The embodiment of the present application further provides an energy storage device, which comprises the power conversion device described in any of the above embodiments.

[0094] In some specific application embodiments, the energy storage power supply in the energy storage device can be the direct current power supply in the above embodiments, the energy storage power supply is connected through the power conversion device in the above embodiments, the control method described in any of the above embodiments is executed by the controller to drive the multiphase interleaved inverter circuit to convert the direct current signal into an alternating current signal, and the switching loss of the switch tube is reduced under light load or no load, the switching frequency of the switch tube in the power conversion bridge arm can be reduced without changing the output waveform characteristics, the full cycle switching is shortened to 3 / 4 cycle switching, and a part of the switching loss under light load or no load can be saved.

[0095] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional units and modules is exemplified, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above.

[0096] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in detail in a certain embodiment can be referred to the related description of other embodiments.

[0097] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place or distributed on multiple network units. According to actual needs, part or all of the units can be selected to achieve the purpose of the embodiment.

[0098] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0099] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A control method for a multiphase interleaved inverter circuit, characterized in that, The multiphase interleaved inverter circuit includes a converter bridge arm and multiple parallel power conversion bridge arms. The converter bridge arm is used to control the direction of the output signal of the multiphase interleaved inverter circuit, and the power conversion bridge arms are used to control the power of the output signal of the multiphase interleaved inverter circuit. Both the converter bridge arm and the power conversion bridge arm include an upper switch and a lower switch. The control method includes: When the output waveform of the voltage output signal of the multiphase interleaved inverter circuit is detected to enter the positive half-cycle, the lower switch of the converter bridge arm is controlled to remain on during the positive half-cycle. When the output waveform is detected to enter the negative half-cycle, the upper switch of the converter bridge arm is controlled to remain on during the negative half-cycle. When the output waveform is detected to enter the rising phase of the positive half-cycle, a PWM signal is output during the entire rising phase of the positive half-cycle to control the upper switch of the power conversion bridge arm to turn on or off, and to control the lower switch of the power conversion bridge arm to turn off. When the output waveform is detected to enter the falling phase of the negative half-cycle, a PWM signal is output during the falling phase of the negative half-cycle to control the lower switch of the power conversion bridge arm to turn on or off, and to control the upper switch of the power conversion bridge arm to turn off. When the output waveform is detected to enter the falling phase of the positive half-cycle or the rising phase of the negative half-cycle, a high-frequency PWM signal is output during the entire falling phase of the positive half-cycle or the entire rising phase of the negative half-cycle to control the upper and lower switching transistors of each power conversion bridge arm to conduct complementaryly.

2. The control method as described in claim 1, characterized in that, The output PWM signal controls the upper switch of the power conversion bridge arm to turn on or off, including: When the output sampling voltage of the multiphase interleaved inverter circuit is less than the target reference voltage, the upper switch of the power conversion bridge arm is turned on. When the output sampling voltage is greater than the target reference voltage, the upper switch of the power conversion bridge arm is turned off.

3. The control method as described in claim 1, characterized in that, The output PWM signal controls the lower switch of the power conversion bridge arm to turn on or off, including: When the output sampling voltage of the multiphase interleaved inverter circuit is greater than the target reference voltage, the lower switch of the power conversion bridge arm is turned on. When the output sampling voltage is less than the target reference voltage, the lower switch of the power conversion bridge arm is turned off.

4. The control method as described in claim 1, characterized in that, The control method further includes: Each of the power conversion bridge arms is controlled to operate in a staggered phase, with a phase difference of 360° / N, where N is the number of the power conversion bridge arms.

5. The control method as described in claim 1, characterized in that, The period of the output waveform is 0.02 seconds.

6. The control method according to any one of claims 1-5, characterized in that, The control method further includes: Monitor the load power and compare the load power with a preset power threshold; If the load power is greater than a preset power threshold, when any switch of the converter bridge arm is turned on, a PWM signal is output to control the upper and lower switches of each power conversion bridge arm to conduct in a complementary manner.

7. A power conversion device, comprising a multiphase interleaved inverter circuit and a controller, characterized in that, The controller is used to perform the control method as described in any one of claims 1-6.

8. The power conversion device as described in claim 7, characterized in that, The number of power conversion bridge arms is 2.

9. An energy storage device, characterized in that, The energy storage device includes the power conversion device as described in claim 7 or 8.

Images