CN116418245A

CN116418245A - Power conversion circuit, control method, power conversion device and photovoltaic power supply system

Info

Publication number: CN116418245A
Application number: CN202310313499.0A
Authority: CN
Inventors: 胡雄; 赵密; 陈熙; 王雷
Original assignee: Ecoflow Technology Ltd
Current assignee: Ecoflow Technology Ltd
Priority date: 2023-03-27
Filing date: 2023-03-27
Publication date: 2023-07-11

Abstract

The application relates to the technical field of circuits, in particular to a power conversion circuit, a control method, a power conversion device and a photovoltaic power supply system, wherein the power conversion circuit comprises an inverter circuit, a switching circuit, an alternating current interface and a direct current interface, and the inverter circuit comprises a first bridge arm, a second bridge arm and a third bridge arm; the second end of the switching circuit is connected with the live wire end of the alternating current interface, the third end of the switching circuit is connected with the zero line end of the alternating current interface, and the switching circuit is used for conducting the first end of the switching circuit and the second end of the switching circuit when the alternating current interface is charged or discharged, so that the first bridge arm and the second bridge arm work in an inversion mode, and the first bridge arm and the third bridge arm work in an inversion mode. According to the power conversion circuit, the switching circuit is used for conducting the connection between the neutral point of the second bridge arm and the alternating current interface, so that the first bridge arm and the second bridge arm work in an inversion mode, and the first bridge arm and the third bridge arm work in an inversion mode, and the charging and discharging power can be effectively improved.

Description

Power conversion circuit, control method, power conversion device and photovoltaic power supply system

Technical Field

The application relates to the technical field of circuits, in particular to a power conversion circuit, a control method, a power conversion device and a photovoltaic power supply system.

Background

In the photovoltaic power supply system, grid-connected charging or grid-connected feeding may be performed by an inverter circuit, for example, the photovoltaic panel may grid-connected feed to the grid or discharge to the load by the inverter circuit. The performance of the inverter circuit determines the power of grid-connected charging and discharging. Along with the increase of the photovoltaic power generation amount and the power consumption amount, the original inverter circuit cannot meet the power requirements of charging and discharging, so how to increase the charging and discharging power of the photovoltaic power supply system is particularly important.

Disclosure of Invention

The application provides a power conversion circuit, a control method, a power conversion device and a photovoltaic power supply system, wherein the power conversion circuit can solve the problem that an original inverter circuit in the related art cannot meet the power requirements of charge and discharge.

In a first aspect, the present application provides a power conversion circuit, where the power conversion circuit includes an inverter circuit, a switching circuit, an ac interface, and a dc interface, and the inverter circuit includes a first bridge arm, a second bridge arm, and a third bridge arm; the first end of the first bridge arm, the first end of the second bridge arm and the first end of the third bridge arm are all connected with a positive direct current bus, the second end of the first bridge arm, the second end of the second bridge arm and the second end of the third bridge arm are all connected with a negative direct current bus, a first neutral point of the first bridge arm is connected with a zero line end of the alternating current interface, a second neutral point of the second bridge arm is connected with the first end of the switching circuit through a first inductor, and a third neutral point of the third bridge arm is connected with a live line end of the alternating current interface through a second inductor; the alternating current interface is used for being connected with a power grid or a load, and the direct current interface is used for being connected with energy storage equipment; the second end of the switching circuit is connected with the live wire end of the alternating current interface, the third end of the switching circuit is connected with the zero line end of the alternating current interface, and the switching circuit is used for conducting the first end of the switching circuit and the second end of the switching circuit when the alternating current interface is charged or discharged, so that the first bridge arm and the second bridge arm form a first inversion module, and the first bridge arm and the third bridge arm form a second inversion module.

In the embodiment, the first bridge arm is added on the basis of the original inverter circuit, and when the charging or discharging is performed, the switching circuit conducts the connection between the neutral point of the second bridge arm and the alternating current interface, so that the first bridge arm and the second bridge arm form the inverter module to work in an inversion mode, and the first bridge arm and the third bridge arm form the inverter module to work in an inversion mode.

In some embodiments, the first bridge arm includes a first diode and a second diode, a cathode of the first diode is connected to the positive dc bus, an anode of the first diode is connected to the first neutral point, a cathode of the second diode is connected to the first neutral point, and an anode of the second diode is connected to the negative dc bus.

In some embodiments, the switching circuit includes a first switch connected between a first end of the switching circuit and a second end of the switching circuit, and a second switch connected between the first end of the switching circuit and a third end of the switching circuit.

In a second aspect, the present application further provides a control method of a power conversion circuit, for controlling the power conversion circuit, where the method includes: in a grid-connected mode, a first end of the switching circuit is controlled to be conducted with a second end of the switching circuit, so that the first bridge arm and the second bridge arm form a first inversion module, and the first bridge arm and the third bridge arm form a second inversion module; the first high-frequency PWM signal is used for controlling the second bridge arm to work and the second high-frequency PWM signal is used for controlling the third bridge arm to work; the frequencies of the first high frequency PWM signal and the second high frequency PWM signal are determined by the frequency of the power grid to which the ac interface is connected.

In the above embodiment, by controlling the first end of the switching circuit to be conducted with the second end of the switching circuit in the grid-connected mode, the first bridge arm and the second bridge arm form the inversion module to work in the inversion mode, and the first bridge arm and the third bridge arm form the inversion module to work in the inversion mode.

In some embodiments, the method further comprises: when grid-connected charging and reactive power output instructions are received, a first end of the switching circuit is controlled to be conducted with a third end of the switching circuit, so that the second bridge arm and the third bridge arm form an inversion module; and controlling the inverter module formed by the second bridge arm and the third bridge arm to work based on a unipolar PWM modulation mode.

In some embodiments, the method further comprises: when grid-connected feeding and a reactive power output request is received, a first end of the switching circuit is controlled to be conducted with a third end of the switching circuit, so that the second bridge arm and the third bridge arm form an inversion module; and controlling the inverter module formed by the second bridge arm and the third bridge arm to work based on a bipolar PWM modulation mode.

In some embodiments, the method further comprises: detecting leakage current of the power conversion circuit during grid-connected feeding; when the leakage current is larger than a preset current threshold value, a first end of the switching circuit is controlled to be conducted with a third end of the switching circuit, so that the second bridge arm and the third bridge arm form an inversion module; and controlling the inverter module formed by the second bridge arm and the third bridge arm to work based on a bipolar PWM modulation mode.

In some embodiments, the method further comprises: determining a temperature value of the inverter circuit, wherein the inverter circuit comprises the second bridge arm and the third bridge arm; and if the temperature value of the inverter circuit is larger than a preset temperature threshold value, controlling the first inverter module and the second inverter module to work in turn, wherein the working states of the first inverter module and the second inverter module are switched at voltage zero crossing points every preset time.

In a third aspect, the present application also provides a power conversion apparatus comprising a memory, a processor, and a power conversion circuit; the memory is used for storing a computer program; the processor is configured to implement the control method of the power conversion circuit as described above when executing the computer program.

In a fourth aspect, the present application further provides a photovoltaic power supply system, which includes a photovoltaic panel, a power grid, a load, and a power conversion device as described above.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic diagram of a photovoltaic power supply system according to an embodiment of the present disclosure;

fig. 2 is a schematic structural diagram of a power conversion device according to an embodiment of the present application;

fig. 3 is a schematic structural diagram of a power conversion circuit according to an embodiment of the present disclosure;

fig. 4 is a schematic structural diagram of another power conversion circuit according to an embodiment of the present disclosure;

fig. 5 is a schematic flowchart of a control method of a power conversion circuit according to an embodiment of the present application;

FIG. 6 is a schematic diagram of an equivalent circuit when the power conversion circuit is connected to a power grid during grid-connected charging according to the embodiments of the present application;

FIG. 7 is a schematic diagram of an equivalent circuit when the power conversion circuit is connected to a power grid during grid-tie feeding according to the embodiments of the present application;

FIG. 8 is a schematic flow chart of another control method of a power conversion circuit provided in an embodiment of the present application;

fig. 9 is a schematic diagram of another equivalent circuit when the power conversion circuit is connected to a power grid during grid-connected charging according to the embodiment of the present application;

FIG. 10 is a schematic flow chart of another control method of a power conversion circuit provided in an embodiment of the present application;

FIG. 11 is a schematic diagram of another equivalent circuit of the power conversion circuit when connected to a grid during grid-tie feeding according to an embodiment of the present application;

FIG. 12 is a schematic flow chart diagram of another control method for a power conversion circuit provided in an embodiment of the present application;

fig. 13 is a schematic structural diagram of another power conversion circuit according to an embodiment of the present disclosure;

FIG. 14 is a schematic flow chart diagram of another control method for a power conversion circuit provided by an embodiment of the present application;

fig. 15 is a schematic diagram of a driving signal waveform of a switching tube according to an embodiment of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

The flow diagrams depicted in the figures are merely illustrative and not necessarily all of the elements and operations/steps are included or performed in the order described. For example, some operations/steps may be further divided, combined, or partially combined, so that the order of actual execution may be changed according to actual situations.

It is to be understood that the terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

It should also be understood that the term "and/or" as used in this specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.

The embodiment of the application provides a power conversion circuit, a control method, a power conversion device and a photovoltaic power supply system. The power conversion circuit can be applied to a power conversion device, and by adding the first bridge arm on the basis of the original inverter circuit, the switching circuit can conduct connection between the neutral point of the second bridge arm and an alternating current interface during charging or discharging, so that the first bridge arm and the second bridge arm form an inverter module to work in an inversion mode, and the first bridge arm and the third bridge arm form the inverter module to work in the inversion mode.

Referring to fig. 1, fig. 1 is a schematic diagram of a photovoltaic power supply system 10 according to an embodiment of the disclosure. As shown in fig. 1, the photovoltaic power supply system 10 may include a photovoltaic panel 11, a power conversion apparatus 12, an energy storage device 13, a power grid 14, and a load 15.

For example, as shown in fig. 1, the photovoltaic panel 11 may feed the grid 14 or power the load 15 via the power conversion device 12. The power conversion device 12 is configured to perform power conversion on the power supplied from the photovoltaic panel 11, and output the power-converted power to the power grid 14 or the load 15 through an ac interface (not shown). In addition, the photovoltaic panel 11 may also charge the energy storage device 13 via the power conversion means 12.

When the power conversion device 12 is connected to the grid 14, it is referred to as grid connection. When the power conversion device 12 is not connected to the power grid 14, it is referred to as off-grid.

For example, as shown in fig. 1, when the power conversion device 12 is connected to the grid, the power grid 14 may also charge the energy storage device 13 through the power conversion device 12, or the energy storage device 13 may feed the power grid 14 through the power conversion device 12. The power conversion device 12 is further configured to perform power conversion on the power supply input to the photovoltaic panel 11, and output the power-converted power supply to the energy storage device 13 through a dc interface (not shown in the figure). The energy storage device 13 may be a mobile energy storage device, a household energy storage device, or an energy storage device mounted on a vehicle.

The power conversion device 12 may be a stand-alone device, or may be a device built into the energy storage device 13. For example, when the power conversion device 12 is built into the energy storage device 13, the power conversion device 12 may be connected to an energy storage module (not shown) in the energy storage device 13 through a dc interface. The energy storage module may include a battery module.

Referring to fig. 2, fig. 2 is a schematic diagram of a power conversion device 12 according to an embodiment of the present application, and as shown in fig. 2, the power conversion device 12 may include a memory 121, a processor 122 and a power conversion circuit 123.

Wherein the processor 122 is connected to the memory 121 and the power conversion circuit 123 via a bus such as I ₂ C (Inter-integrated Circuit, integrated circuit) bus, etc. Processor 122 is operative to provide computing and control capabilities supporting the operation of the entire power conversion device 12.

For example, when power conversion apparatus 12 is a stand-alone device, processor 122 may be a processor in power conversion apparatus 12; when the power conversion apparatus 12 is a component in the energy storage device 13, the processor 122 may be a main processor in the energy storage device 13.

The memory 121 may include a storage medium and an internal memory. The storage medium may store an operating system and a computer program. The computer program comprises program instructions which, when executed, cause a processor to perform a method of controlling a power conversion circuit.

The power conversion circuit 123 is configured to perform power conversion according to a control instruction of the processor 122.

The processor 122 may be a central processing unit (Central Processing Unit, CPU), which may also be other general purpose processors, digital signal processors (Digital Signal Processor, DSP), application specific integrated circuits (application specific integrated circuit, ASIC), field-programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

In the embodiment of the present application, the processor 122, when executing the relevant computer program, may implement the following steps:

in the grid-connected mode, the first end of the switching circuit is controlled to be conducted with the second end of the switching circuit, so that the first bridge arm and the second bridge arm form a first inversion module, and the first bridge arm and the third bridge arm form a second inversion module; the first high-frequency PWM signal is used for controlling the second bridge arm to work and the second high-frequency PWM signal is used for controlling the third bridge arm to work; the frequencies of the first high frequency PWM signal and the second high frequency PWM signal are determined by the frequency of the power grid to which the ac interface is connected.

In one embodiment, the processor 122 is further configured to implement:

when grid-connected charging and reactive power output instructions are received, the first end of the switching circuit is controlled to be conducted with the third end of the switching circuit, so that the second bridge arm and the third bridge arm form an inversion module; and controlling the inverter module formed by the second bridge arm and the third bridge arm to work based on a unipolar PWM modulation mode.

In one embodiment, the processor 122 is further configured to implement:

when grid-connected feeding and reactive power output requests are received, a first end of the switching circuit is controlled to be conducted with a third end of the switching circuit, so that the second bridge arm and the third bridge arm form an inversion module; and controlling the inverter module formed by the second bridge arm and the third bridge arm to work based on a bipolar PWM modulation mode.

In one embodiment, the processor 122 is further configured to implement:

detecting leakage current of the power conversion circuit during grid-connected feeding; when the leakage current is larger than a preset current threshold value, the first end of the switching circuit is controlled to be conducted with the third end of the switching circuit so that the second bridge arm and the third bridge arm form an inversion module; and controlling the inverter module formed by the second bridge arm and the third bridge arm to work based on a bipolar PWM modulation mode.

In one embodiment, the processor 122 is further configured to implement:

determining a temperature value of an inverter circuit, wherein the inverter circuit comprises a second bridge arm and a third bridge arm; and if the temperature value of the inverter circuit is greater than a preset temperature threshold value, controlling the first inverter module and the second inverter module to work in turn, wherein the working states of the first inverter module and the second inverter module are switched at the voltage zero crossing point every preset time.

Some embodiments of the present application are described in detail below with reference to the accompanying drawings. The following embodiments and features of the embodiments may be combined with each other without conflict.

Referring to fig. 3, fig. 3 is a schematic diagram of a power conversion circuit 123 according to an embodiment of the present disclosure. As shown in fig. 3, the power conversion circuit 123 may include an inverter circuit 1230, a switching circuit 1231, an ac interface 1232, and a dc interface 1233, where the inverter circuit 1230 includes a first leg H1, a second leg H2, and a third leg H3.

The first end of the first bridge arm H1, the first end of the second bridge arm H2, and the first end of the third bridge arm H3 are all connected to the positive dc BUS bus+, the second end of the first bridge arm H1, the second end of the second bridge arm H2, and the second end of the third bridge arm H3 are all connected to the negative dc BUS-, the first neutral point of the first bridge arm H1 is connected to the neutral line end N of the ac interface 1232, the second neutral point of the second bridge arm H2 is connected to the first end of the switching circuit 1231 through the first inductor L1, and the third neutral point of the third bridge arm H3 is connected to the live line end L of the ac interface 1232 through the second inductor L2.

The second end of the switching circuit 1231 is connected to the live wire end L of the ac interface 1232, the third end of the switching circuit 1231 is connected to the neutral wire end N of the ac interface 1232, and the switching circuit 1231 is configured to switch on the first end of the switching circuit 1231 and the second end of the switching circuit 1231 when the ac interface 1232 is charged or discharged, so that the first bridge arm H1 and the second bridge arm H2 form a first inverter module, and the first bridge arm H1 and the third bridge arm H3 form a second inverter module.

Referring to fig. 1, ac interface 1232 is used to connect to grid 14 and/or load 15. It should be noted that, in some embodiments, the grid-connected switch and the load switch may be further disposed between the live end L of the ac interface 1232 and the power grid 14 and the load 15, which control the grid-disconnected of the power conversion circuit 123. As shown in fig. 3, ac interface 1232 may further include a third switch S3 and a fourth switch S4. The third switch S3 is used for controlling the on-off between the ac interface 1232 and the power grid 14, i.e. a grid-connected switch; the fourth switch S4 is used for controlling the on-off between the ac interface 1232 and the load 15, i.e. the load switch.

Illustratively, the third switch S3 and the fourth switch S4 may include, but are not limited to, controllable switches such as triodes, field-effect transistors (MOS), insulated gate bipolar transistors (Insulated Gate Bipolar Transistor, IGBTs), optocouplers, or relays.

Referring to fig. 3, as shown in fig. 3, the power conversion circuit 123 further includes a first capacitor C1, where the first capacitor C1 is connected between the live end L and the neutral end N of the ac interface 1232, and is configured to filter the ac power output at the ac interface 1232. In some embodiments, as shown in fig. 3, the first bridge arm H1 may include a first diode D1 and a second diode D2, where a cathode of the first diode D1 is connected to the positive dc BUS bus+, an anode of the first diode D1 is connected to the first neutral point, a cathode of the second diode D2 is connected to the first neutral point, and an anode of the second diode D2 is connected to the negative dc BUS-.

In the above embodiment, by setting the first bridge arm H1 including the first diode D1 and the second diode D2, the first bridge arm H1 and the second bridge arm H2 may form a first inversion module, and the first bridge arm H1 and the third bridge arm H3 may form a second inversion module, so that two paths of inversion modules may be simultaneously used for charging and discharging, and charging and discharging power may be effectively improved.

For example, as shown in fig. 3, the switching circuit 1231 may include a first switch S1 and a second switch S2, the first switch S1 being connected between a first terminal of the switching circuit 1231 and a second terminal of the switching circuit 1231, and the second switch S2 being connected between the first terminal of the switching circuit 1231 and a third terminal of the switching circuit 1231.

The first switch S1 and the second switch S2 may include, but are not limited to, a MOS transistor, an IGBT transistor, an optocoupler, a relay, or the like.

By providing the switching circuit 1231 including the first switch S1 and the second switch S2, the number of inverter modules in the power conversion circuit 123 can be controlled by controlling the on/off of the first switch S1 and the second switch S2. For example, the first end of the switching circuit 1231 and the second end of the switching circuit 1231 may be turned on by controlling the conduction of the first switch S1, so that the first bridge arm H1 and the second bridge arm H2 form a first inverter module, and the first bridge arm H1 and the third bridge arm H3 form a second inverter module. For another example, the first end of the switching circuit 1231 and the third end of the switching circuit 1231 are turned on by controlling the conduction of the second switch S2, so that the second bridge arm H2 and the third bridge arm H3 form the inverter module.

As shown in fig. 3, the second bridge arm H2 may include a first switching tube Q1 and a second switching tube Q2. The first end of the first switching tube Q1 is connected with the positive direct current BUS BUS+, and the second end of the first switching tube Q1 is connected with the second neutral point; the first end of the second switching tube Q2 is connected with a second neutral point, and the second end of the second switching tube Q2 is connected with a negative direct current BUS. The third leg H3 may include a third switching tube Q3 and a fourth switching tube Q4. The first end of the third switching tube Q3 is connected with the positive direct current BUS BUS+, and the second end of the third switching tube Q3 is connected with a third neutral point; the first end of the fourth switching tube Q4 is connected with the third neutral point, and the second end of the fourth switching tube Q4 is connected with the negative direct current BUS.

The first switching tube Q1, the second switching tube Q2, the third switching tube Q3 and the fourth switching tube Q4 may include, but are not limited to, MOS tubes, thyristors, IGBT tubes, and the like.

As shown in fig. 3, ac interface 1232 is used to connect to grid 14 (not shown) or load 15 (not shown), and dc interface 1233 is used to connect to energy storage device 13 (not shown).

Referring to fig. 4, fig. 4 is a schematic diagram illustrating a structure of another power conversion circuit 123 according to an embodiment of the present application. As shown in fig. 4, power conversion circuit 123 may also include an MPPT (Maximum Power Point Tracking ) circuit 1234 and a photovoltaic interface 1235. The photovoltaic interface 1235 is used to connect to the photovoltaic panel 11, and the mppt circuit 1234 is used to regulate the voltage output by the photovoltaic panel 11 to achieve maximum power tracking.

For example, as shown in fig. 4, MPPT circuit 1234 may be a boost circuit. The boost circuit may include a third inductor L3, a fifth switching tube Q5, a third diode D3, and a second capacitor C2. The first end of the third inductor L3 is connected to the pv+ end of the photovoltaic interface 1235, the second end of the third inductor L3 is connected to the anode of the third diode D3, the cathode of the third diode D3 is connected to the first end of the second capacitor C2, the second end of the second capacitor C2 is connected to the PV-end of the photovoltaic interface 1235, the first end of the fifth switching tube Q5 is connected to the second end of the third inductor L3, and the second end of the fifth switching tube Q5 is connected to the PV-end of the photovoltaic interface 1235. The photovoltaic interface 1235 further includes a third capacitor C3, the third capacitor C3 being connected between the pv+ terminal and the PV-terminal.

It should be noted that, in some embodiments, the boost circuit and the photovoltaic interface 1235 may also be used as independent devices, such as an optimizer, and the optimizer is connected between the photovoltaic panel 11 and the power conversion circuit 123, and then the positive dc bus and the negative dc bus of the power conversion circuit 123 form an interface connected with the optimizer.

It should be noted that, in some embodiments, the energy storage device 13 connected at the dc interface 1233 may include an LLC (Series-parallel resonance) circuit 130 and an energy storage module 131. Wherein a first end of LLC circuit 130 is coupled to DC interface 1233 and a second end of LCC circuit 130 is coupled to energy storage module 131. LLC circuit 130 is configured to dc-convert the voltage output by dc interface 1233 to charge energy storage module 131.

In some embodiments, the LLC circuit 130 may also be part of the power conversion circuit 123, where a first terminal of the LLC circuit 130 is connected to the dc bus, and a second terminal of the LCC circuit 130 is connected to the dc interface 1233.

Referring to fig. 5 in conjunction with fig. 1 to 3, fig. 5 is a schematic flowchart of a control method of a power conversion circuit according to an embodiment of the present application. As shown in fig. 5, the control method of the power conversion circuit includes step S101 and step S102.

Step S101, in a grid-connected mode, a first end of a switching circuit is controlled to be conducted with a second end of the switching circuit, so that a first bridge arm and a second bridge arm form a first inversion module, and the first bridge arm and a third bridge arm form a second inversion module.

Note that the grid-connected mode may include a grid-connected charging mode and a grid-connected feeding mode. The grid-connected charging mode refers to charging the energy storage device 13 by the power grid 14 through the power conversion circuit 123, and the grid-connected feeding mode refers to feeding the power grid 14 by the photovoltaic panel 11 or the energy storage device 13 through the power conversion circuit 123.

In the implementation of the present application, the control method of the power conversion circuit may also be applied in the off-grid charging mode. The off-grid charging mode refers to that the power conversion device 12 is disconnected from the power grid 14, the photovoltaic panel 11 or the energy storage device 13 supplies power to the load 15 through the power conversion circuit 123, or the photovoltaic panel 11 charges the energy storage device 13 through the power conversion circuit 123.

In the grid-connected power feeding mode, if the ac interface 1232 is connected to the load 15 at the same time, the power conversion circuit 123 may also supply power to the load 15, which is not limited in this application.

For example, during the grid-connected charging mode, the first end of the switching circuit 1231 may be controlled to be connected to the second end of the switching circuit 1231, so that the first bridge arm H1 and the second bridge arm H2 form a first inversion module, and the first bridge arm H1 and the third bridge arm H3 form a second inversion module. At this time, two inverter circuits can be simultaneously used for charging the energy storage device 13 or two inverter circuits can be simultaneously used for feeding the power grid 14, so that the charging and discharging power is greatly improved.

Step S102, controlling the second bridge arm to work by using a first high-frequency PWM signal and controlling the third bridge arm to work by using a second high-frequency PWM signal; the frequencies of the first high frequency PWM signal and the second high frequency PWM signal are determined by the frequency of the power grid to which the ac interface is connected.

For example, after the first terminal of the control switch circuit 1231 is turned on with the second terminal of the switch circuit 1231, the second bridge arm may be controlled to operate with the first high-frequency PWM signal and the third bridge arm may be controlled to operate with the second high-frequency PWM signal. The frequencies of the first high-frequency PWM signal and the second high-frequency PWM signal are determined by the frequency of the power grid 14 connected to the ac interface, and specific values are not limited herein.

Referring to fig. 3, as shown in fig. 3, at this time, the first bridge arm H1 may be used as a rectifying bridge arm to control the directions (positive current or negative current) of the output currents of the first inverter module and the second inverter module, so that the waveform change of the output currents is consistent with the voltage of the power grid. The second bridge arm H2 and the second bridge arm H3 are respectively used as power bridge arms of the first inversion module and the second inversion module, and the switching tube of the power bridge arm is controlled to be conducted or disconnected with a certain duty ratio through a high-frequency PWM signal, so that the amplitude of the output current (during grid-connected feeding) or the input current (during grid-connected charging) of the first inversion module and the second inversion module can be controlled.

It will be appreciated that the frequencies of the first and second high frequency PWM signals are determined by the frequency of the grid to which ac interface 1232 is connected, meaning that the frequencies of the first and second high frequency PWM signals must be greater than the grid frequency.

It will be appreciated that the duty cycles of the first high frequency PWM signal and the second high frequency PWM signal may be set according to actual needs, where the setting of the duty cycle depends on the power that the power conversion circuit 123 can currently output, and the larger the duty cycle, the larger the output power.

In the above embodiment, by controlling the first end of the switching circuit 1231 to be conducted with the second end of the switching circuit 1231 in the grid-connected mode, the first bridge arm H1 and the second bridge arm H2 form the inversion module to work in the inversion mode, and the first bridge arm H1 and the third bridge arm H3 form the inversion module to work in the inversion mode.

In some embodiments, in both grid-tied charging mode and grid-tied feeding mode, it is also desirable to consider whether the power conversion circuit 123 needs to output reactive power to the grid 14. How to perform grid-tied charging and grid-tied feeding will be described below in connection with the scenarios of grid-tied mode, whether reactive power output to the grid 14 is required or not, and the like.

In some embodiments, when the grid-connected charging is performed and the reactive power output instruction is not received, the first end of the switching circuit 1231 is controlled to be conducted with the second end of the switching circuit 1231, so that the first bridge arm H1 and the second bridge arm H2 form a first inversion module, and the first bridge arm H1 and the third bridge arm H3 form a second inversion module; the first high-frequency PWM signal is used for controlling the second bridge arm to work, and the second high-frequency PWM signal is used for controlling the third bridge arm H3 to work. Wherein the frequencies of the first high frequency PWM signal and the second high frequency PWM signal are determined by the frequency of the power grid 14 to which the ac interface 1232 is connected.

Referring to fig. 6, fig. 6 is a schematic diagram of an equivalent circuit when the power conversion circuit 123 is connected to the power grid 14 during grid-connected charging according to the embodiment of the present application. As shown in fig. 6, when the grid-connected charging is performed and the reactive power output command is not received, a turn-on signal may be sent to the first switch S1 (not shown in the figure) and the third switch S3 (not shown in the figure), so that the first switch S1 turns on the first end and the second end of the switching circuit 1231 (not shown in the figure), and the third switch S3 turns on the ac interface 1232 (not shown in the figure) and the grid 14. At this time, the first bridge arm H1 and the second bridge arm H2 form a first inverter module, and the first bridge arm H1 and the third bridge arm H3 form a second inverter module.

For example, the second bridge arm may be controlled to operate with the first high frequency PWM signal and the third bridge arm may be controlled to operate with the second high frequency PWM signal based on a unipolar PWM modulation scheme. As shown in fig. 6, the first bridge arm H1 is a rectifying bridge arm, the second bridge arm H2 and the third bridge arm H3 are power bridge arms, the second bridge arm H2 and the third bridge arm H3 are driven by high-frequency PWM signals to be complementarily turned on, and further, the magnitude of the output power of the power conversion circuit 123 can be controlled by adjusting the duty ratio of the high-frequency PWM signals of each switching tube in the second bridge arm H2 and the third bridge arm H3.

For example, when the power grid 14 charges the energy storage device 13, during the positive half period of the alternating current, the first high-frequency PWM signal may control the second bridge arm H2 to work, and the first switching tube Q1 and the second switching tube Q2 are complementarily turned on; the third bridge arm H3 can be controlled to work through the second high-frequency PWM signal, and the third switching tube Q3 and the fourth switching tube Q4 are conducted in a complementary mode. At this time, the first diode D1 is turned off, and the second diode D2 is turned on. In the negative half period of the alternating current, the second bridge arm H2 can be controlled to work through the first high-frequency PWM signal, and the first switching tube Q1 and the second switching tube Q2 are complementarily conducted; the third bridge arm H3 can be controlled to work through the second high-frequency PWM signal, and the third switching tube Q3 and the fourth switching tube Q4 are conducted in a complementary mode. At this time, the first diode D1 is turned on, and the second diode D2 is turned off.

For example, during grid-connected charging, the fourth switch S4 may be turned on or turned off according to actual requirements. For example, when a load 15 (not shown) is connected and power to the load 15 is required, the fourth switch S4 may be controlled to close, and the power to the load 15 is directly bypassed by the power grid 14.

In fig. 6, a schematic diagram of the energy storage device 13 receiving charging through the two-way inverter circuit in the power conversion circuit 123 when charging is performed in a grid-connected manner is shown only schematically. In some embodiments, if photovoltaic panel 11 is accessed through photovoltaic interface 1235 at this time, energy storage device 13 may also simultaneously receive charging of photovoltaic panel 11 through a direct current BUS (bus+/BUS as shown in the figures), as this application is not limiting.

In the above embodiment, when the grid-connected charging is performed and the reactive power output instruction is not received, the first end of the switching circuit 1231 is controlled to be conducted with the second end of the switching circuit 1231, so that the first bridge arm H1 and the second bridge arm H2 form a first inversion module, and the first bridge arm H1 and the third bridge arm H3 form a second inversion module.

In other embodiments, when the grid-connected feed is performed and the reactive power output instruction is not received, the first end of the switching circuit 1231 may be controlled to be conducted with the second end of the switching circuit 1231, so that the first bridge arm H1 and the second bridge arm H2 form a first inversion module, and the first bridge arm H1 and the third bridge arm H3 form a second inversion module; the first high-frequency PWM signal is used for controlling the second bridge arm H2 to work, and the second high-frequency PWM signal is used for controlling the third bridge arm H3 to work. Wherein the frequencies of the first high frequency PWM signal and the second high frequency PWM signal are determined by the frequency of the power grid 14 to which the ac interface is connected.

Referring to fig. 7, fig. 7 is a schematic diagram of an equivalent circuit when the power conversion circuit 123 is connected to the power grid 14 during grid-connected feeding according to the embodiment of the present application. As shown in fig. 7, when the grid-connected power is fed and the reactive power output command is not received, a turn-on signal may be sent to the first switch S1 (not shown in the figure) and the third switch S3 (not shown in the figure), so that the first switch S1 turns on the first end and the second end of the switching circuit 1231 (not shown in the figure), and the third switch S3 turns on the ac interface 1232 and the grid 14. At this time, the first bridge arm H1 and the second bridge arm H2 form a first inverter module, and the first bridge arm H1 and the third bridge arm H3 form a second inverter module.

For example, the second bridge arm H2 may be controlled to operate with a first high frequency PWM signal and the third bridge arm H3 may be controlled to operate with a second high frequency PWM signal based on a unipolar PWM modulation scheme. As shown in fig. 7, the second arm H2 and the third arm H3 are driven by high-frequency PWM signals to be complementarily turned on, so that the output power of the power conversion circuit 123 can be controlled by adjusting the duty ratio of the high-frequency PWM signals of each switching tube in the second arm H2 and the third arm H3. The control principles of the first bridge arm H1, the second bridge arm H2, and the third bridge arm H3 in the case of grid-connected feeding and no reactive power output instruction are similar to the control principles of the first bridge arm H1, the second bridge arm H2, and the third bridge arm H3 in the case of grid-connected charging and no reactive power output instruction, and specific control principles are not repeated herein.

In the above embodiment, when the reactive power output instruction is not received and fed in a grid-connected mode, the first end of the switching circuit 1231 is controlled to be conducted with the second end of the switching circuit 1231, so that the first bridge arm H1 and the second bridge arm H2 form a first inversion module, and the first bridge arm H1 and the third bridge arm H3 form a second inversion module.

In other embodiments, when the grid-connected feeding and the leakage current of the power conversion circuit 123 is less than or equal to the preset current threshold, the first end of the switching circuit 1231 and the second end of the switching circuit 1231 may be controlled to be conducted, so that the first bridge arm H1 and the second bridge arm H2 form a first inversion module, and the first bridge arm H1 and the third bridge arm H2 form a second inversion module; the first high-frequency PWM signal is used for controlling the second bridge arm H2 to work, and the second high-frequency PWM signal is used for controlling the third bridge arm H3 to work. Wherein the frequencies of the first high-frequency PWM signal and the second high-frequency PWM signal are determined by the frequency of the power grid 14 connected with the AC interface

For example, the preset current threshold may be set according to practical situations, and specific values are not limited herein. It should be noted that the leakage current means that the power conversion circuit 123 has a small current to the ground after being connected to the power grid 14. In the embodiment of the present application, the leakage current of the power conversion circuit 123 may be collected by a leakage current sensor.

The control principles of the first bridge arm H1, the second bridge arm H2, and the third bridge arm H3 in the case where the grid-connected power feeding and the leakage current of the power conversion circuit 123 are less than or equal to the preset current threshold are similar to the control principles of the first bridge arm H1, the second bridge arm H2, and the third bridge arm H3 in the case where the grid-connected charging and the reactive power output instruction is not received, and the specific control principles are not described herein.

It should be noted that, in the grid-connected mode, including the grid-connected feeding and grid-connected charging scenarios, the power factor of the power conversion circuit 123 is usually defaulted to 1, that is, reactive power is not output to the grid 15 by default. When the grid 15 requires grid-connected equipment for reactive power compensation, then the power conversion circuit 123 receives reactive power output instructions, as will be described below for such scenarios.

Referring to fig. 8, fig. 8 is a schematic flowchart of another control method of a power conversion circuit according to an embodiment of the present application. As shown in fig. 8, the control method of the power conversion circuit includes step S201 and step S202.

And step 201, when grid-connected charging is performed and a reactive power output instruction is received, the first end of the switching circuit is controlled to be conducted with the third end of the switching circuit, so that the second bridge arm and the third bridge arm form an inversion module.

Referring to fig. 9, fig. 9 is a schematic diagram of another equivalent circuit of the power conversion circuit 123 in connection with the grid 14 during grid-connected charging according to the present application. As shown in fig. 9, when the grid-connected charging is performed and the reactive power output command is received, a turn-on signal may be sent to the second switch S2 (not shown in the figure) and the third switch S3 (not shown in the figure), so that the second switch S2 turns on the first terminal and the third terminal of the switching circuit 1231 (not shown in the figure), and the third switch S3 turns on the ac interface 1232 and the grid 14. At this time, the second arm H2 and the third arm H3 form an inverter module, and the first arm H1 and the second arm H2 are connected in parallel.

Step S202, controlling an inversion module formed by the second bridge arm and the third bridge arm to work based on a unipolar PWM modulation mode.

For example, after the first end of the switching circuit 1231 is controlled to be conducted with the third end of the switching circuit 1231, the inverter module formed by the second bridge arm H2 and the third bridge arm H3 may be controlled to operate based on the unipolar PWM modulation mode.

The inverter module formed by the second bridge arm H2 and the third bridge arm H3 is a dual-inductance H-bridge inverter circuit, and the single-polarity PWM modulation mode of the inverter module is slightly different from that of the single-inductance H-bridge inverter circuit of the first inverter module or the second inverter module. Specifically, in the positive and negative half periods of the alternating voltage, the first switching tube Q1 and the third switching tube Q3 are driven by the third high-frequency PWM signal, wherein the phase difference between the first switching tube Q1 and the third switching tube Q3 is 180 °, the second switching tube Q2 and the fourth switching tube Q4 are driven by the fourth high-frequency PWM signal, the second switching tube Q2 is complementarily conducted with the first switching tube Q1, and the fourth switching tube Q4 is complementarily conducted with the third switching tube Q3. At this time, the first diode D1 and the second diode D2 are connected in parallel with the first switch tube Q1 and the second switch tube Q2, so as to reduce the body diode loss of the first switch tube Q1 and the second switch tube Q2, and further improve the efficiency of the power conversion circuit 123.

It can be understood that, since the first diode D1 and the second diode D2 are connected in parallel with the first switch tube Q1 and the second switch tube Q2, the body diode in the first switch tube Q1 and the body diode in the second switch tube Q2 are connected in parallel with the diodes, so that the total impedance can be reduced, and the loss can be further reduced.

In the above embodiment, when the grid-connected charging is performed and the reactive power output instruction is received, the first end of the switching circuit 1231 is controlled to be conducted with the third end of the switching circuit 1231, and since the first bridge arm H1 is connected in parallel with the second bridge arm H2, the loss can be reduced, the conversion efficiency of charging the power conversion circuit 123 can be improved, and the reactive power can be ensured to be output to the grid 14.

Referring to fig. 10, fig. 10 is a schematic flowchart of another control method of a power conversion circuit according to an embodiment of the present application. As shown in fig. 10, the control method of the power conversion circuit includes step S301 and step S302.

And step 301, when grid-connected feeding and a reactive power output request is received, controlling the first end of the switching circuit to be conducted with the third end of the switching circuit so that the second bridge arm and the third bridge arm form an inversion module.

Referring to fig. 11, fig. 11 is a schematic diagram of another equivalent circuit when the power conversion circuit 123 is connected to the power grid 14 during grid-connected feeding according to the embodiment of the present application. As shown in fig. 11, when the grid-connected power is fed and the reactive power output request is received, a turn-on signal may be sent to the second switch S2 (not shown in the figure) and the third switch S3 (not shown in the figure), so that the second switch S2 turns on the first terminal and the third terminal of the switching circuit 1231 (not shown in the figure), and the third switch S3 turns on the ac interface 1232 and the grid 14. At this time, the second arm H2 and the third arm H3 form an inverter module, and the first arm H1 and the second arm H2 are connected in parallel.

Step S302, based on a bipolar PWM modulation mode, an inversion module formed by the second bridge arm and the third bridge arm is controlled to work.

For example, after the first end of the switching circuit is controlled to be conducted with the third end of the switching circuit, the inverter module formed by the second bridge arm and the third bridge arm can be controlled to work based on a bipolar PWM modulation mode.

The inverter module formed by the second bridge arm H2 and the third bridge arm H3 is a dual-inductance H-bridge inverter circuit, and the single-polarity PWM modulation mode of the inverter module is slightly different from that of the single-inductance H-bridge inverter circuit of the first inverter module or the second inverter module. Specifically, in the positive and negative half periods of the alternating voltage, the first switching tube Q1 and the fourth switching tube Q4 are driven to be synchronously turned on or synchronously turned off through a fifth high-frequency PWM signal; the second switching tube Q2 and the third switching tube Q3 are driven to be synchronously turned on or synchronously turned off through a sixth high-frequency PWM signal. The first diode D1 and the second diode D2 are connected in parallel with the second switching tube Q2 and the third switching tube Q3, so as to reduce the body diode loss of the second switching tube Q2 and the third switching tube Q3, and further improve the conversion efficiency of the discharge of the power conversion circuit 123.

By driving the first switching tube Q1 and the fourth switching tube Q4 to be synchronously turned on or synchronously turned off by using the fifth high-frequency PWM signal and driving the second switching tube Q2 and the third switching tube Q3 to be synchronously turned on or synchronously turned off by using the sixth high-frequency PWM signal based on the bipolar PWM modulation scheme, it is possible to ensure that the driving signals and the switching frequencies of the first switching tube Q1 and the fourth switching tube Q4 are the same, and the driving signals and the switching frequencies of the second switching tube Q2 and the third switching tube Q3 are the same, so that reactive power can be output to the power grid 14.

In the above embodiment, when the grid-connected feed is performed and the reactive power output instruction is received, the first end of the switching circuit 1231 is controlled to be conducted with the third end of the switching circuit 1231, and the diode in the first bridge arm H1 is connected in parallel with the switching tube in the second bridge arm H2 and the switching tube in the third bridge arm H3, so that the loss can be reduced, the conversion efficiency of the discharge of the power conversion circuit 123 can be improved, and the reactive power can be ensured to be output to the grid 14.

Referring to fig. 12, fig. 12 is a schematic flowchart of another control method of a power conversion circuit according to an embodiment of the present application. As shown in fig. 12, the control method of the power conversion circuit includes steps S401 to S403.

Step S401, detecting leakage current of the power conversion circuit during grid-connected feeding.

For example, the leakage current of the power conversion circuit may be detected by the leakage current sensor at the time of grid-connected feeding.

And step S402, when the leakage current is larger than a preset current threshold value, controlling the first end of the switching circuit to be conducted with the third end of the switching circuit so that the second bridge arm and the third bridge arm form an inversion module.

For example, when the leakage current is greater than the preset current threshold, the first end of the switching circuit 1231 may be controlled to be conducted with the third end of the switching circuit 1231 so that the second bridge arm H2 and the third bridge arm H3 form the inverter module.

As shown in fig. 11, a turn-on signal may be sent to the second switch S2 (not shown) and the third switch S3 (not shown) to enable the second switch S2 to turn on the first terminal and the third terminal of the switching circuit 1231 (not shown), and the third switch S3 turns on the ac interface 1232 and the power grid 14. At this time, the second arm H2 and the third arm H3 form an inverter module, and the first arm H1 and the second arm H2 are connected in parallel.

Step S403, based on the bipolar PWM modulation mode, controlling the inverter module formed by the second bridge arm and the third bridge arm to work.

For example, after the first end of the switching circuit 1231 is controlled to be conducted with the third end of the switching circuit 1232, the inverter module formed by the second bridge arm H2 and the third bridge arm H3 may be controlled to operate based on the bipolar PWM modulation mode. The control manner of the second leg H2 and the third leg H3 in the case where the grid-connected feeding and the leakage current of the power conversion circuit 123 is greater than the current threshold may be referred to the control manner of the second leg H2 and the third leg H3 in the case where the grid-connected feeding and the reactive power output request is received, which is not described herein again.

The bipolar PWM modulation scheme can effectively reduce leakage current compared with the unipolar PWM modulation scheme. It can be understood that the leakage current has a direct relationship with the common-mode voltage, and the larger the common-mode voltage jump is, the larger the corresponding leakage current is; in the bipolar PWM modulation mode, the common mode voltage is a fixed value and hardly jumps, so that the leakage current can be effectively reduced.

In the above embodiment, when the leakage current is greater than the preset current threshold, the first end of the switching circuit 1231 is controlled to be conducted with the third end of the switching circuit 1231 so that the second bridge arm H2 and the third bridge arm H3 form the inverter module, and the inverter module formed by the second bridge arm H2 and the third bridge arm H3 is controlled to work based on the bipolar PWM modulation mode, so that the leakage current can be effectively reduced.

Referring to fig. 13, fig. 13 is a schematic diagram illustrating a structure of another power conversion circuit 123 according to an embodiment of the present application. As shown in fig. 13, in an off-network pure resistive load scenario, a turn-on signal may be sent to a first switch S1 (not shown in the figure) and a fourth switch S4 (not shown in the figure), so that the first switch S1 turns on a first end and a second end of a switching circuit 1231 (not shown in the figure), the fourth switch S4 turns on an ac interface 1232 and a load 15, the first leg H1 and the second leg H2 form a first inverter module, and the first leg H1 and the third leg H3 form a second inverter module. At this time, the photovoltaic panel 11 may supply power to the load 15 via the power conversion circuit 123.

For example, the second bridge arm H2 may be controlled to operate with a first high frequency PWM signal and the third bridge arm H3 may be controlled to operate with a second high frequency PWM signal based on a unipolar PWM modulation scheme. The control principle of the first, second and third bridge arms H1, H2 and H3 in the off-grid pure resistive load scenario is similar to the control principle of the first, second and third bridge arms H1, H2 and H3 in the scenario that the reactive power output instruction is not received and the reactive power output instruction is fed in a grid-connected mode, and the specific control principle is not described herein.

In the above embodiment, in the off-grid pure resistive load scenario, the first bridge arm H1 and the second bridge arm H2 are controlled to form the first inverter module, and the first bridge arm H1 and the third bridge arm H3 form the second inverter module, so that two paths of inverter modules can be used for discharging the load 15 at the same time, and the discharging power can be effectively improved.

Referring to fig. 14, fig. 14 is a schematic flowchart of another control method of a power conversion circuit according to an embodiment of the present application. As shown in fig. 14, the control method of the power conversion circuit includes step S501 and step S502.

Step S501, determining a temperature value of an inverter circuit, where the inverter circuit includes a second bridge arm and a third bridge arm.

In the embodiment of the present application, when the inverter module formed by the second bridge arm H2 and the third bridge arm H3 in the inverter circuit 1230 is controlled to operate based on the unipolar PWM modulation mode, the temperature value of the inverter circuit 1230 may be detected; when the temperature value of the inverter circuit 1230 is too high, the second arm H2 and the third arm H3 can be controlled to operate in turn, so as to reduce the temperature of the inverter circuit 1230.

For example, the temperature value of the inverter circuit 1230 may be detected by a temperature sensor.

Step S502, if the temperature value of the inverter circuit is greater than a preset temperature threshold value, the first inverter module and the second inverter module are controlled to work in turn, wherein the working states of the first inverter module and the second inverter module are switched at the voltage zero crossing point every preset time.

For example, when the temperature value of the inverter circuit 1230 is greater than a preset temperature threshold, the first inverter module and the second inverter module may be controlled to operate alternately. And switching the working states of the first inversion module and the second inversion module at the voltage zero crossing point every preset time. The preset time may be set according to actual conditions, and specific values are not limited herein. For example, the preset time may be one or more power frequency cycles.

Referring to fig. 15, fig. 15 is a schematic diagram of a driving signal waveform of a switching tube according to an embodiment of the present application. As shown in fig. 15, the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4 are all turned on or off by PWM wave driving. Vac represents the ac side voltage of the power conversion circuit 123, i.e., the voltage at the ac interface 1232, the dashed line is the voltage zero point, and T1, T2 … … Tn are the times corresponding to the Vac zero crossing points. As shown in fig. 15, controlling the first inverter module and the second inverter module to operate alternately means: in the period of 0-T1, the first switching tube Q1 and the second switching tube Q2 in the second bridge arm H2 can be driven to work, and the third switching tube Q3 and the fourth switching tube Q4 in the third bridge arm H3 are simultaneously not driven to work; and in the period of T1-T2, driving the third switching tube Q3 and the fourth switching tube Q4 in the third bridge arm H3 to work, and enabling the first switching tube Q1 and the second switching tube Q2 in the second bridge arm H2 to not work, and so on.

In the above embodiment, when the temperature value of the inverter circuit 1230 is greater than the preset temperature threshold, the first inverter module and the second inverter module are controlled to work alternately at the voltage zero crossing point every preset time, so that the temperature of the inverter circuit 1230 can be effectively reduced, and the damage to the device caused by the influence of the too high temperature can be avoided.

Embodiments of the present application further provide a computer readable storage medium storing a computer program, where the computer program includes program instructions, and a processor executes the program instructions to implement a method for controlling any one of the power conversion circuits provided in the embodiments of the present application.

For example, the program is loaded by a processor, and the following steps may be performed:

The computer readable storage medium may be an internal storage unit of the power conversion apparatus of the foregoing embodiment, for example, a hard disk or a memory of the power conversion apparatus. The computer readable storage medium may also be an external storage device of the power conversion apparatus, such as a plug-in hard disk, a Smart Media Card (SMC), a secure digital Card (Secure Digital Card, SD Card), a Flash memory Card (Flash Card) or the like, which are provided on the power conversion apparatus.

Further, the computer-readable storage medium may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, a program required for at least one function, and the like; the storage data area may store data created according to each program, and the like.

The foregoing is merely a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any equivalent modifications or substitutions will be apparent to those skilled in the art within the scope of the present application, and these modifications or substitutions should be covered in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. The power conversion circuit is characterized by comprising an inverter circuit, a switching circuit, an alternating current interface and a direct current interface, wherein the inverter circuit comprises a first bridge arm, a second bridge arm and a third bridge arm;

The first end of the first bridge arm, the first end of the second bridge arm and the first end of the third bridge arm are all connected with a positive direct current bus, the second end of the first bridge arm, the second end of the second bridge arm and the second end of the third bridge arm are all connected with a negative direct current bus, a first neutral point of the first bridge arm is connected with a zero line end of the alternating current interface, a second neutral point of the second bridge arm is connected with the first end of the switching circuit through a first inductor, and a third neutral point of the third bridge arm is connected with a live line end of the alternating current interface through a second inductor;

the alternating current interface is used for being connected with a power grid and/or a load, and the direct current interface is used for being connected with energy storage equipment;

the second end of the switching circuit is connected with the live wire end of the alternating current interface, the third end of the switching circuit is connected with the zero line end of the alternating current interface, and the switching circuit is used for conducting the first end of the switching circuit and the second end of the switching circuit when the alternating current interface is charged or discharged, so that the first bridge arm and the second bridge arm form a first inversion module, and the first bridge arm and the third bridge arm form a second inversion module.

2. The power conversion circuit of claim 1, wherein the first leg comprises a first diode and a second diode, a cathode of the first diode is connected to the positive dc bus, an anode of the first diode is connected to the first neutral point, a cathode of the second diode is connected to the first neutral point, and an anode of the second diode is connected to the negative dc bus.

3. The power conversion circuit of claim 1, wherein the switching circuit comprises a first switch and a second switch, the first switch connected between a first terminal of the switching circuit and a second terminal of the switching circuit, the second switch connected between the first terminal of the switching circuit and a third terminal of the switching circuit.

4. A method of controlling a power conversion circuit according to any one of claims 1 to 3, the method comprising:

in a grid-connected mode, a first end of the switching circuit is controlled to be conducted with a second end of the switching circuit, so that the first bridge arm and the second bridge arm form a first inversion module, and the first bridge arm and the third bridge arm form a second inversion module;

The first high-frequency PWM signal is used for controlling the second bridge arm to work and the second high-frequency PWM signal is used for controlling the third bridge arm to work; the frequencies of the first high frequency PWM signal and the second high frequency PWM signal are determined by the frequency of the power grid to which the ac interface is connected.

5. The method of controlling a power conversion circuit according to claim 4, further comprising:

when grid-connected charging and reactive power output instructions are received, a first end of the switching circuit is controlled to be conducted with a third end of the switching circuit, so that the second bridge arm and the third bridge arm form an inversion module;

and controlling the inverter module formed by the second bridge arm and the third bridge arm to work based on a unipolar PWM modulation mode.

6. The method of controlling a power conversion circuit according to claim 4, further comprising:

when grid-connected feeding and a reactive power output request is received, a first end of the switching circuit is controlled to be conducted with a third end of the switching circuit, so that the second bridge arm and the third bridge arm form an inversion module;

and controlling the inverter module formed by the second bridge arm and the third bridge arm to work based on a bipolar PWM modulation mode.

7. The method of controlling a power conversion circuit according to claim 4, further comprising:

detecting leakage current of the power conversion circuit during grid-connected feeding;

when the leakage current is larger than a preset current threshold value, a first end of the switching circuit is controlled to be conducted with a third end of the switching circuit, so that the second bridge arm and the third bridge arm form an inversion module;

8. The method of controlling a power conversion circuit according to claim 4, further comprising:

determining a temperature value of an inverter circuit, wherein the inverter circuit comprises the second bridge arm and the third bridge arm;

and if the temperature value of the inverter circuit is larger than a preset temperature threshold value, controlling the first inverter module and the second inverter module to work in turn, wherein the working states of the first inverter module and the second inverter module are switched at voltage zero crossing points every preset time.

9. A power conversion device, comprising a processor, a memory, and a power conversion circuit;

The memory is used for storing a computer program;

the processor being configured to implement the control method of the power conversion circuit according to any one of claims 4 to 8 when executing the computer program.

10. A photovoltaic power supply system comprising a photovoltaic panel, an energy storage device, an electrical grid, a load, and a power conversion apparatus as claimed in claim 9.