WO2020182083A1

WO2020182083A1 - Photovoltaic power supply system, inverter, and inverter device and control method therefor

Info

Publication number: WO2020182083A1
Application number: PCT/CN2020/078300
Authority: WO
Inventors: 尹韶文; 黄伟; 李程; 翁宏达
Original assignee: 比亚迪股份有限公司
Priority date: 2019-03-11
Filing date: 2020-03-06
Publication date: 2020-09-17
Also published as: CN111697867A; CN111697867B

Abstract

Disclosed are a photovoltaic power supply system, an inverter, and an inverter device and a control method therefor. The inverter device comprises: a power supply circuit; an inverter circuit, the inverter circuit comprising a plurality of switch tubes and being configured to converting a direct current voltage input by a direct current power source to an alternating current voltage; and a filter circuit, the filter circuit being configured to filter the alternating current voltage and output the filtered alternating current voltage to an alternating current power grid, and the filter circuit comprising a filter inductor and a filter capacitor. Within each half cycle of the alternating current voltage, one switch tube of the inverter circuit is controlled to be turned on or off by a high frequency pulse, and when one switch tube is turned off, the inverter circuit, the filter circuit, and the alternating current power grid constitute a freewheeling loop to isolate a freewheeling current after the switch tube is turned off from the direct current power source. The inverter device can reduce losses of switches and magnetic components, improve output power quality, reduce voltage stress, reduce output current ripple, and improve inversion efficiency.

Description

Photovoltaic power supply system, inverter, inverter device and control method thereof

Cross references to related applications

This application is filed based on a Chinese patent application with an application number of 201910180907.3 and an application date of March 11, 2019, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby incorporated by reference into this application.

Technical field

This application relates to the field of inverter technology, in particular to a photovoltaic power supply system, an inverter, an inverter device and a control method thereof.

Background technique

As the core part of the photovoltaic power generation system, the inverter's performance will directly affect the stability, reliability, efficiency and cost of the photovoltaic power system. In the related art, a common H4 single-phase full-bridge inverter system is shown in Figure 1. Among them, the switching tube Q1 and the switching tube Q4 are a set of bridge arms, and the switching tube Q2 and the switching tube Q3 are a set of bridge arms. The conduction of the bridge arm obtains a positive pulse, and the conduction of the other group of bridge arms obtains a negative pulse. Therefore, the system obtains high frequency through the alternate conduction of the switching tube Q1 and the switching tube Q4, and the switching tube Q2 and the switching tube Q3. Chopping, the chopping wave passes through the filter circuit to obtain the AC voltage that can be connected to the AC power grid.

However, in the circuit diagram shown in Figure 1, when one of the bridge arms is turned off, since the inductor current in the filter circuit will not change suddenly, a part of the energy will be stored in the inductor, and part of the energy will be fed back to the DC power supply. During the feedback process, oscillation will occur, which is easy to produce high voltage impulse. The next time the switching tube is activated, it may cause damage to the switching tube, and at the same time, it will cause the output current to fluctuate, resulting in a large current ripple. When the power level is increased, the switching stress of the H4 bridge is also relatively large, there is a big problem in heat dissipation, and the efficiency is difficult to improve.

Summary of the invention

This application aims to solve one of the technical problems in the related technology at least to a certain extent. To this end, one purpose of the present application is to provide an inverter device that can reduce switching loss and magnetic element loss, improve output power quality, reduce voltage stress, and reduce output current ripple, thereby reducing output current ripple. A filter inductor with a smaller inductance is needed to improve the inverter efficiency.

The second purpose of this application is to provide a control method of the inverter device.

The third purpose of this application is to propose an inverter.

The fourth purpose of this application is to propose a photovoltaic power system.

In order to achieve the above objective, an embodiment of the first aspect of the present application proposes an inverter device, including: a power supply circuit, the input end of the power supply circuit is connected to a DC power supply; an inverter circuit, the input end of the inverter circuit is connected to The output terminal of the power supply circuit is connected, the inverter circuit includes a plurality of switch tubes, the inverter circuit is used to convert the DC voltage input by the DC power supply into an AC voltage; a filter circuit, the input terminal of the filter circuit is connected to The output terminal of the inverter circuit is connected, the output terminal of the filter circuit is connected to the AC power grid, and the filter circuit is used to filter the AC voltage and output the filtered AC voltage to the AC The power grid, wherein the filter circuit includes a filter inductor and a filter capacitor; wherein, in each half cycle of the AC voltage, a switch in the inverter circuit is turned on and off by high-frequency pulse control, And when the one switch tube is turned off, the inverter circuit, the filter circuit, and the AC power grid form a freewheeling loop, so that the freewheeling current after the one switch tube is turned off and the DC power supply isolation.

According to the inverter device of the embodiment of the present application, during each half cycle of the AC voltage, a switch tube in the inverter circuit is turned on and off by high-frequency pulse control, which can reduce switching loss and magnetic element loss, Improve the output power quality and reduce the voltage stress; the freewheeling current after a switch tube is turned off can be isolated from the DC power supply to reduce the output current ripple, so that the inverter device only needs a filter inductor with a small inductance, which improves the inverse Variable efficiency.

In addition, the inverter device according to the foregoing embodiment of the present application may also have the following additional technical features:

According to an embodiment of the present application, the power supply circuit includes: a first capacitor, one end of the first capacitor is connected to the first pole of the DC power supply; a second capacitor, one end of the second capacitor is connected to the The other end of the first capacitor is connected to form a first node, and the other end of the second capacitor is connected to the second pole of the DC power supply.

According to an embodiment of the present application, the inverter circuit includes: a first diode, an anode of the first diode is connected to the first node; a second diode, the second diode The cathode of the tube is connected to the first node; the first switching tube, the first end of the first switching tube is connected to the first pole of the DC power supply; the second switching tube, the first terminal of the second switching tube One end is connected to the first pole of the DC power supply; a third switch tube, the first end of the third switch tube is connected to the second end of the first switch tube, and a second node is formed. The second end of the three switch tube is connected to the second pole of the DC power supply; the fourth switch tube, the first end of the fourth switch tube is connected to the second end of the second switch tube, and forms a third switch tube. Node, the second end of the fourth switch tube is connected to the second pole of the DC power supply; the fifth switch tube, the first end of the fifth switch tube is connected to the cathode of the first diode, The second end of the fifth switch tube is connected to the second node; the sixth switch tube, the first end of the sixth switch tube is connected to the second node, and the second end of the sixth switch tube Terminal is connected to the anode of the second diode, and forms a fourth node; a seventh switch tube, the first terminal of the seventh switch tube is connected to the third node, the seventh switch tube The two ends are connected with the fourth node.

According to an embodiment of the present application, the filter inductor includes a first inductor, one end of the first inductor is connected to the second node, and the other end of the first inductor is connected to the first pole of the AC power grid. Connected; a second inductor, one end of the second inductor is connected to the third node, and the other end of the second inductor is connected to the second pole of the AC power grid.

According to an embodiment of the present application, the filter capacitor includes a third capacitor, one end of the third capacitor is connected to the other end of the first inductor, and the other end of the third capacitor is connected to the second inductor. Connected to the other end.

According to an embodiment of the present application, the inverter device controls the fifth switching tube and the seventh switching tube to be continuously turned on during a period of 0<Uo≦Udc/2, where Uo is the AC voltage , Udc is the DC voltage, when the fourth switch tube is controlled by a high-frequency pulse to turn on, the first diode, the fifth switch tube, the first inductor, the AC power grid, The second inductor, the fourth switch tube, and the second capacitor in turn form a current loop. When the fourth switch tube is turned off by a high-frequency pulse, the first inductor, the AC power grid, The second inductor, the seventh switch tube and the anti-parallel diodes in the sixth switch tube in turn form a freewheeling loop; during the period Udc/2<Uo≤Udc, the first switch tube, the The seventh switching tube is continuously turned on, wherein, when the fourth switching tube is turned on under the control of a high-frequency pulse, the first switching tube, the first inductor, the AC power grid, the second inductor, The fourth switch tube and the second capacitor in turn form a current loop. When the fourth switch tube is turned off by high-frequency pulse control, the first inductor, the AC power grid, the second inductor, The anti-parallel diodes in the seventh switch tube and the sixth switch tube in turn form a freewheeling loop; during the period -Udc/2≤Uo<0, the sixth switch tube is controlled to be continuously turned on. When the second switching tube is controlled by a high-frequency pulse to turn on, the second switching tube, the second inductor, the AC power grid, the first inductor, the sixth switching tube, and the second second The pole tube and the first capacitor in turn form a current loop. When the second switch tube is turned off by high-frequency pulse control, the second inductor, the AC grid, the first inductor, and the sixth The switch tube and the anti-parallel diodes in the seventh switch tube in turn form a freewheeling loop; during the period -Udc≤Uo<-Udc/2, the third switch tube is controlled to be continuously turned on, wherein, when the second When the switching tube is turned on by the high-frequency pulse control, the second switching tube, the second inductor, the AC power grid, the first inductor, the third switching tube, the second capacitor, the The first capacitor in turn forms a current loop. When the second switch tube is turned off by high-frequency pulse control, the second inductor, the AC power grid, the first inductor, the third switch tube and the The anti-parallel diodes in the fourth switch tube sequentially form a freewheeling loop.

According to an embodiment of the present application, the first diode and the second diode are both silicon carbide diodes or fast recovery diodes, and the first to sixth switching tubes are all cool MOS Tube, the seventh switch tube is an IGBT tube.

In order to achieve the above objective, an embodiment of the second aspect of the present application proposes a control method of an inverter device, which includes the following steps: controlling a switch tube in the inverter circuit to conduct through high frequency pulses, and controlling through power frequency pulses The other switching tubes in the inverter circuit are turned on or off to convert the DC voltage input by the DC power supply into AC voltage; the one switching tube is controlled to be turned off by high-frequency pulses, and the power frequency pulse is used to control all The other switching tubes are turned on or off, and the inverter circuit, the filter inductor, and the AC power grid are used to form a freewheeling loop, so that the freewheeling current after the one switching tube is turned off and the DC Power isolation.

According to the control method of the inverter device of the embodiment of the present application, the control method of the inverter device of the embodiment of the present application controls the on and off of a switch tube in the inverter circuit through high-frequency pulses to realize the inverter process , Can reduce switching loss and magnetic element loss, improve output power quality, reduce voltage stress; can isolate the freewheeling current after a switch tube is turned off from the DC power supply, thereby reducing the output current ripple, making the inverter device only A filter inductor with a smaller inductance is needed to improve the inverter efficiency.

To achieve the foregoing objective, an embodiment of the third aspect of the present application proposes an inverter, including the inverter device proposed in the embodiment of the first aspect of the present application.

According to the inverter of the embodiment of the present application, the inverter device of the embodiment of the present application can reduce switching loss and magnetic element loss, improve output power quality, reduce voltage stress, and reduce output current ripple, thereby only requiring Filter inductance with smaller inductance improves inverter efficiency.

In order to achieve the above objective, the embodiment of the fourth aspect of the present application proposes a photovoltaic power supply system, including: a photovoltaic device as a DC power source for outputting a DC voltage; an AC power grid; The input terminal of the inverter is connected to the photoelectric device, the output terminal of the inverter is connected to the AC power grid, and the inverter is used to convert the DC voltage into an AC voltage and output to The AC power grid.

According to the photovoltaic power supply system of the embodiment of the present application, through the inverter of the embodiment of the present application, switching loss and magnetic element loss can be reduced, output power quality can be improved, voltage stress can be reduced, and output current ripple can be reduced. Filter inductance with smaller inductance improves inverter efficiency.

The additional aspects and advantages of this application will be partly given in the following description, and some will become obvious from the following description, or be understood through the practice of this application.

Description of the drawings

The above and/or additional aspects and advantages of the present application will become obvious and easy to understand from the following description of the embodiments in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic diagram of the structure of an inverter device in the related art;

Fig. 2 is a schematic structural diagram of an inverter device according to an embodiment of the present application;

Figure 3 is a schematic structural diagram of an inverter device according to an example of the present application;

Fig. 4 is a current loop diagram of the inverter device according to an example of the present application during the period 0<Uo≤Udc/2;

Fig. 5 is a current freewheeling circuit diagram of the inverter device according to an example of the present application during the period 0<Uo≤Udc;

Fig. 6 is a current loop diagram of the inverter device according to an example of the present application during the period Udc/2<Uo≤Udc;

Fig. 7 is a current loop diagram of an inverter device according to an example of the present application during -Udc/2≤Uo＜0;

Fig. 8 is a current freewheeling circuit diagram of an inverter device according to an example of the present application during -Udc/2≤Uo＜0;

Fig. 9 is a current loop diagram of the inverter device according to an example of the present application during -Udc≤Uo<-Udc/2;

Fig. 10 is a current freewheeling circuit diagram of an inverter device according to an example of the present application during -Udc≤Uo<-Udc/2;

Fig. 11 is a flowchart of a control method of an inverter device according to an embodiment of the present application;

Fig. 12 is a structural block diagram of an inverter according to an embodiment of the present application;

Fig. 13 is a structural block diagram of a photovoltaic power supply system according to an embodiment of the present application.

detailed description

The embodiments of the present application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary, and are intended to explain the application, but should not be understood as a limitation to the application.

The photovoltaic power system, inverter, inverter device and control method thereof according to the embodiments of the present application are described below with reference to FIGS. 2 to 13.

Fig. 2 is a schematic structural diagram of an inverter device according to an embodiment of the present application.

As shown in FIG. 2, the inverter device 10 of the embodiment of the present application includes: a power supply circuit 11, an inverter circuit 12 and a filter circuit 13.

Among them, the input end of the power supply circuit 11 is connected to the DC power supply 1; the input end of the inverter circuit 12 is connected to the output end of the power supply circuit 11, and the inverter circuit 12 includes a plurality of switch tubes (switch tube Q1-switch tube Qn, n> 1) The inverter circuit 12 is used to convert the DC voltage input by the DC power supply 1 into AC voltage; the input end of the filter circuit 13 is connected to the output end of the inverter circuit 12, and the output end of the filter circuit 13 is connected to the AC power grid 2. The filter circuit 13 is used to filter the AC voltage and output the filtered AC voltage to the AC power grid 2. The filter circuit 13 includes a filter inductor L and a filter capacitor C; wherein, in each half cycle of the AC voltage, A switch tube Qi (1≤i≤n) in the inverter circuit 12 is turned on and off by the high-frequency pulse control, and when the switch tube Qi is turned off, the inverter circuit 12, the filter circuit 13 and the AC power grid 2 A freewheeling loop is formed to isolate the freewheeling current after the switch Qi is turned off from the DC power supply 1.

In this embodiment, the DC power supply 1 may be a DC voltage generating device, such as a solar panel, which can convert the energy generated by renewable energy solar energy into grid voltage to realize solar power supply.

In an embodiment of the present application, as shown in FIG. 3, the power supply circuit 11 may include: a first capacitor C1 and a second capacitor C2.

Among them, one end of the first capacitor C1 is connected to the first pole of the DC power supply 1; one end of the second capacitor C2 is connected to the other end of the first capacitor C1 to form a first node d1, and the other end of the second capacitor C2 is connected to the DC The second pole of the power supply 1 is connected.

In an example, referring to FIG. 3, the inverter circuit 12 may include: a first diode D1, a second diode D2, a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, a fourth The switching tube Q4, the fifth switching tube Q5, the sixth switching tube Q6, and the seventh switching tube Q7.

Wherein, the anode of the first diode D1 is connected to the first node d1; the cathode of the second diode D2 is connected to the first node d1; the first end of the first switching tube Q1 is connected to the first pole of the DC power supply 1 The first end of the second switching tube Q2 is connected to the first pole of the DC power supply 1; the first end of the third switching tube Q3 is connected to the second end of the first switching tube Q1, and forms a second node d2, the third The second terminal of the switching tube Q3 is connected to the second pole of the DC power supply 1; the first terminal of the fourth switching tube Q4 is connected to the second terminal of the second switching tube Q2 to form a third node d3, and the fourth switching tube Q4 The second terminal of the fifth switch tube Q5 is connected to the second pole of the DC power supply 1; the first terminal of the fifth switch tube Q5 is connected to the cathode of the first diode D1, and the second terminal of the fifth switch tube Q5 is connected to the second node d2; The first terminal of the sixth switch tube Q6 is connected to the second node d2, and the second terminal of the sixth switch tube Q6 is connected to the anode of the second diode D2 to form a fourth node d4; the seventh terminal of the seventh switch tube Q7 One end is connected to the third node d3, and the second end of the seventh switch tube Q7 is connected to the fourth node d4.

In this example, referring to FIG. 3, the first diode D1 and the second diode D2 can be silicon carbide diodes or fast recovery diodes, and the first switch tube Q1 to the sixth switch tube Q6 can be cool MOS ( Metal Oxide Semiconductor, metal oxide semiconductor) tube, the seventh switch tube Q7 can be an IGBT tube (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor).

Further, referring to FIG. 3, the filter inductor L may include: a first inductor L1 and a second inductor L2.

One end of the first inductor L1 is connected to the second node d2, the other end of the first inductor L1 is connected to the first pole of the AC power grid 2; one end of the second inductor L2 is connected to the third node d3, and the second inductor L2 The other end is connected to the second pole of the AC grid 2.

Furthermore, referring to FIG. 3, the filter capacitor C may further include a third capacitor C3. One end of the third capacitor C3 is connected to the other end of the first inductor L1, and the other end of the third capacitor C3 is connected to the other end of the second inductor L2. Connected.

Specifically, the DC power supply 1 outputs a DC voltage to the power supply circuit 11. The first capacitor C1 and the second capacitor C2 in the power supply circuit 11 absorb spikes and surge voltages in the DC voltage and then output them to the inverter circuit 12. The variable circuit 12 converts the DC voltage into an AC voltage by turning on and off the first diode D1, the second diode D2, and the first switching tube Q1 to the seventh switching tube Q7. In each half cycle of the voltage, one of the first switching tube Q1-seventh switching tube Q7 is turned on and off by high-frequency pulse control. When the switching tube Qi is turned on, the inverter process is realized. That is, the DC voltage is converted into AC voltage and output to the filter circuit 13. After the AC voltage is filtered by the first inductor L1, the second inductor L2 and the third capacitor C3 in the filter circuit 13, its waveform becomes Smooth curve and closer to a sine wave, and finally output the filtered AC voltage to the AC grid 2 to meet the power demand; when the switch tube Qi is turned off, the inductor current in the filter inductor L will not change suddenly Therefore, a part of the energy is stored in the filter inductor L. In order to prevent this part of energy from being fed back to the DC power supply 1, the inverter circuit 11, the filter inductor L and the AC power grid 2 form a freewheeling loop to turn off a switch tube Qi. The freewheeling current is isolated from the DC power supply 1. Therefore, the damage of the switching tube is avoided when the switching tube is turned on next time, and the output current ripple is reduced at the same time, and only a filter inductor with a smaller inductance is required.

Specifically, when the inverter device 10 of the embodiment of the present application is inverted through the inverter circuit 12, one of its inverter cycles can be divided into the following parts according to the magnitude of the AC voltage, which is described below with reference to FIGS. 4 to 10 The working process of the inverter device 10 in one inverter cycle (the direction indicated by the arrow on the thick dashed line drawn in FIGS. 4 to 10 indicates the current flow direction, and the thick dashed line is a schematic diagram of the current loop).

During the period of 0＜Uo≤Udc/2, the fifth switching tube Q5 and the seventh switching tube Q7 can be controlled to be continuously turned on. Among them, Uo is an AC voltage and Udc is a DC voltage. When the fourth switching tube Q4 is controlled by a high-frequency pulse When turned on, the first diode D1, the fifth switch tube Q5, the first inductor L1, the AC power grid 2, the second inductor L2, the fourth switch tube Q4, and the second capacitor C2 in turn form a current loop, which is as As shown in Figure 4; when the fourth switching tube Q4 is turned off by high-frequency pulse control, the first inductor L1, the AC grid 2, the second inductor L2, the seventh switching tube Q7 and the anti-parallel diode in the sixth switching tube Q6 The freewheeling loop is formed in turn, which is shown in Figure 5.

During the period of Udc/2<Uo≤Udc, the first switching tube Q1 and the seventh switching tube Q7 can be controlled to be continuously turned on. Among them, when the fourth switching tube Q4 is controlled by the high-frequency pulse to turn on, the first switching tube Q1, The first inductor L1, the AC grid 2, the second inductor L2, the fourth switching tube Q4 and the second capacitor C2 in turn form a current loop, which is shown in Figure 6; when the fourth switching tube Q4 is controlled by a high-frequency pulse to turn off When it is off, the first inductor L1, the AC power grid 2, the second inductor L2, the seventh switching tube Q7, and the anti-parallel diodes in the sixth switching tube Q6 sequentially form a freewheeling loop, which is shown in FIG. 5.

During the period -Udc/2≤Uo<0, the sixth switching tube Q6 can be controlled to be continuously turned on. When the second switching tube Q2 is controlled by the high-frequency pulse to turn on, the second switching tube Q2, the second inductor L2, and The AC power grid 2, the first inductor L1, the sixth switching tube Q6, the second diode D2, and the first capacitor C1 in turn form a current loop, which is shown in Figure 7; when the second switching tube Q2 receives high-frequency pulses When the control is turned off, the second inductor L2, the AC grid 2, the first inductor L1, the sixth switching tube Q6, and the anti-parallel diodes in the seventh switching tube Q7 sequentially form a freewheeling loop, which is shown in Figure 8. .

During the period -Udc≤Uo<-Udc/2, the third switching tube Q3 can be controlled to be continuously turned on. When the second switching tube Q2 is controlled by the high-frequency pulse to turn on, the second switching tube Q2 and the second inductor L2 , AC power grid 2, the first inductor L1, the third switching tube Q3, the second capacitor C2 and the first capacitor C1 in turn form a current loop, which is shown in Figure 9; when the second switching tube Q2 is controlled by a high-frequency pulse When turned off, the second inductor L2, the AC power grid 2, the first inductor L1, the third switching tube Q3, and the anti-parallel diodes in the fourth switching tube Q4 sequentially form a freewheeling loop, as shown in FIG. 10.

That is to say, during the period of 0<Uo≤Udc, that is, during the positive half cycle of the AC voltage Uo waveform, the power frequency pulse can be used to control the on and off of the other switching tubes except the fourth switching tube Q4, that is, the first A switching tube Q1 to a third switching tube Q3, a fifth switching tube Q5 to a seventh switching tube Q7, the fourth switching tube Q4 is controlled to be turned on and off through high-frequency pulses to realize the inverter process of the inverter device 10 ; During the period -Udc≤Uo＜0, that is, during the negative half cycle of the AC voltage Uo waveform, the power frequency pulse can be used to control the on and off of other switching tubes except the second switching tube Q2, that is, the first switch The tube Q1 and the second switching tube Q2 to the seventh switching tube Q7 control the on and off of the second switching tube Q2 through high-frequency pulses, so as to realize the inverter process of the inverter device 10. Therefore, when the fourth switching tube and the second switching tube are controlled by the high-frequency pulse to turn on, the voltages borne by the fourth switching tube and the second switching tube are both half of the DC voltage, thereby reducing switching loss and improving reverse Variable efficiency.

In summary, in the inverter device of the embodiment of the present application, in each half cycle of the AC voltage, the inverter circuit has only one switch tube controlled by high-frequency pulses to turn on and off, which can reduce switching losses and magnetic components. Loss, improve the output power quality; reduce the voltage stress of the switching tube, so that the selection range of the switching tube is increased, and thus the cost of the inverter device is reduced; by isolating the freewheeling current after a switching tube is turned off from the DC power supply, It can reduce the output current ripple, and then only need a filter inductor with a small inductance, which improves the inverter efficiency; the first diode and the second diode in the inverter circuit can be both on and off Silicon carbide diodes or fast recovery diodes with very fast conversion speeds can reduce the power loss during inversion and improve the utilization rate of power; it has good electromagnetic compatibility and low noise.

Fig. 11 is a flowchart of a control method of an inverter device according to an embodiment of the present application.

As shown in FIG. 11, the control method of the inverter device in the embodiment of the present application includes the following steps:

In S1, one switch tube in the inverter circuit is controlled to be turned on by high-frequency pulses, and other switch tubes in the inverter circuit are controlled to be turned on or off by power frequency pulses to convert the DC voltage input by the DC power supply into AC voltage.

S2: Control one switch tube to turn off by high-frequency pulse, control other switch tubes to turn on or off by power frequency pulse, and use inverter circuit, filter inductor and AC grid to form a freewheeling loop to turn off one switch tube The subsequent freewheeling current is isolated from the DC power supply.

It should be noted that the expanded explanation of the control method of the inverter device of this embodiment can refer to the foregoing explanation of the embodiment of the inverter device, which will not be repeated here.

The control method of the inverter device of the embodiment of the present application controls the on and off of a switch tube in the inverter circuit through high-frequency pulses to realize the inverter process, which can reduce switching losses and magnetic element losses, and improve output Power quality, reduce voltage stress; can isolate the freewheeling current after a switch tube is turned off from the DC power supply, thereby reducing the output current ripple, so that the inverter device only needs a filter inductor with a small inductance, which improves the inverter efficiency .

Fig. 12 is a structural block diagram of an inverter according to an embodiment of the present application.

As shown in FIG. 12, the inverter 100 of the embodiment of the present application includes the inverter device 10 of the foregoing embodiment of the present application.

The inverter of the embodiment of the present application, using the inverter device of the embodiment of the present application, can reduce switching loss and magnetic element loss, improve output power quality, reduce voltage stress, and reduce output current ripple, so that the inverse The variable device only needs a filter inductor with a smaller inductance, which improves the inverter efficiency.

As shown in FIG. 13, the photovoltaic power supply system 1000 of the embodiment of the present application includes: a photovoltaic device 200, an AC power grid 2 and the inverter 100 of the foregoing embodiment of the present application.

Among them, the photovoltaic device 200 is used as a DC power source 1 to output a DC voltage; the input end of the inverter 100 is connected to the photovoltaic device 200, the output end of the inverter 100 is connected to the AC power grid 2, and the inverter 100 is used to The voltage is converted into AC voltage and output to the AC grid 2.

The photoelectric device 200 can convert renewable energy into an electrical signal to output a DC voltage. The inverter 200 converts the DC voltage into an AC voltage with a waveform similar to a sine wave and then outputs it to the AC grid 2 to realize power supply from renewable energy. The renewable energy can be solar energy, wind energy, etc.

It should be noted that the explanation of the voltage conversion performed by the inverter 200 in this embodiment can be referred to the foregoing explanation of the embodiment of the inverter device, which will not be repeated here.

The photovoltaic power supply system of the embodiment of the present application, through the inverter of the embodiment of the present application, can reduce switching loss and magnetic element loss, improve output power quality, reduce voltage stress, and reduce output current ripple, so that the reverse The variable device only needs a filter inductor with a smaller inductance, which improves the inverter efficiency.

In the description of this specification, descriptions with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean specific features described in conjunction with the embodiment or example , The structure, materials, or characteristics are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above-mentioned terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner.

In the description of this application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " "Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise", "Axial", The orientation or positional relationship indicated by "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the application and simplifying the description, and does not indicate or imply the pointed device or element It must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the application.

In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "a plurality of" means at least two, such as two, three, etc., unless specifically defined otherwise.

In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , Or integrated; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, it can be the internal communication of two components or the interaction relationship between two components, unless otherwise specified The limit. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

In this application, unless expressly stipulated and defined otherwise, the “on” or “under” of the first feature on the second feature may be in direct contact with the first and second features, or indirectly through an intermediary. contact. Moreover, the "above", "above" and "above" of the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the level of the first feature is higher than the second feature. The first feature "below", "below" and "below" the second feature can mean that the first feature is directly below or obliquely below the second feature, or it simply means that the level of the first feature is smaller than the second feature.

Although the embodiments of the present application have been shown and described above, it can be understood that the above-mentioned embodiments are exemplary and should not be construed as limiting the present application. A person of ordinary skill in the art can comment on the foregoing within the scope of the present application. The embodiment undergoes changes, modifications, substitutions and modifications.

Claims

An inverter device is characterized by comprising:

A power supply circuit, the input end of the power supply circuit is connected to a DC power supply;

An inverter circuit, the input terminal of the inverter circuit is connected to the output terminal of the power supply circuit, the inverter circuit includes a plurality of switch tubes, and the inverter circuit is used to convert the DC voltage input by the DC power supply into AC Voltage;

A filter circuit, the input end of the filter circuit is connected to the output end of the inverter circuit, the output end of the filter circuit is connected to the AC power grid, and the filter circuit is used to filter the AC voltage, and The filtered AC voltage is output to the AC power grid, wherein the filter circuit includes a filter inductor and a filter capacitor;

Wherein, in each half cycle of the AC voltage, one switch tube in the inverter circuit is turned on and off under high-frequency pulse control, and when the one switch tube is turned off, the inverter The circuit, the filter circuit, and the AC power grid form a freewheeling loop to isolate the freewheeling current after the one switch tube is turned off from the DC power supply.
The inverter device according to claim 1, wherein the power supply circuit comprises:

A first capacitor, one end of the first capacitor is connected to the first pole of the DC power supply;

A second capacitor, one end of the second capacitor is connected to the other end of the first capacitor to form a first node, and the other end of the second capacitor is connected to the second pole of the DC power supply.
3. The inverter device of claim 2, wherein the inverter circuit comprises:

A first diode, the anode of the first diode is connected to the first node;

A second diode, the cathode of the second diode is connected to the first node;

A first switch tube, the first end of the first switch tube is connected to the first pole of the DC power supply;

A second switch tube, the first end of the second switch tube is connected to the first pole of the DC power supply;

The third switch tube, the first end of the third switch tube is connected to the second end of the first switch tube to form a second node, and the second end of the third switch tube is connected to the DC power supply The second pole is connected;

A fourth switch tube, the first end of the fourth switch tube is connected to the second end of the second switch tube to form a third node, and the second end of the fourth switch tube is connected to the DC power supply The second pole is connected;

A fifth switch tube, the first end of the fifth switch tube is connected to the cathode of the first diode, and the second end of the fifth switch tube is connected to the second node;

A sixth switch tube, the first end of the sixth switch tube is connected to the second node, and the second end of the sixth switch tube is connected to the anode of the second diode to form a fourth node ；

A seventh switch tube, the first end of the seventh switch tube is connected to the third node, and the second end of the seventh switch tube is connected to the fourth node.
8. The inverter device of claim 3, wherein the filter inductor comprises:

A first inductor, one end of the first inductor is connected to the second node, and the other end of the first inductor is connected to the first pole of the AC power grid;

A second inductor, one end of the second inductor is connected to the third node, and the other end of the second inductor is connected to the second pole of the AC power grid.
The inverter device according to claim 3 or 4, wherein the filter capacitor comprises:

A third capacitor, one end of the third capacitor is connected to the other end of the first inductor, and the other end of the third capacitor is connected to the other end of the second inductor.
The inverter device according to claim 4, wherein:

During the period of 0<Uo≤Udc/2, control the fifth switch tube and the seventh switch tube to continuously conduct, where Uo is the AC voltage, Udc is the DC voltage, and when the fourth switch When controlled by a high-frequency pulse, the first diode, the fifth switch, the first inductor, the AC power grid, the second inductor, the fourth switch and the The second capacitor in turn forms a current loop. When the fourth switch tube is turned off by high-frequency pulse control, the first inductor, the AC power grid, the second inductor, the seventh switch tube and the The anti-parallel diodes in the sixth switch tube sequentially form a freewheeling loop;

During the period Udc/2<Uo≤Udc, the first switch tube and the seventh switch tube are controlled to be continuously turned on, wherein, when the fourth switch tube is controlled to be turned on by a high-frequency pulse, the first The switch tube, the first inductor, the AC power grid, the second inductor, the fourth switch tube, and the second capacitor in turn form a current loop. When the fourth switch tube is controlled by a high-frequency pulse to turn off When off, the anti-parallel diodes in the first inductor, the AC power grid, the second inductor, the seventh switch tube, and the sixth switch tube sequentially form a freewheeling loop;

During the period -Udc/2≤Uo<0, the sixth switch tube is controlled to be continuously turned on, wherein, when the second switch tube is controlled to conduct by a high-frequency pulse, the second switch tube and the first switch tube are turned on. The two inductors, the AC power grid, the first inductor, the sixth switch tube, the second diode, and the first capacitor in turn form a current loop. When the second switch tube receives a high-frequency pulse When the control is turned off, the anti-parallel diodes in the second inductor, the AC power grid, the first inductor, the sixth switch tube and the seventh switch tube sequentially form a freewheeling loop;

During the period -Udc≤Uo<-Udc/2, the third switching tube is controlled to be continuously turned on. When the second switching tube is controlled to be turned on by a high-frequency pulse, the second switching tube, the The second inductor, the AC power grid, the first inductor, the third switch tube, the second capacitor, and the first capacitor in turn form a current loop. When the second switch tube is controlled by a high-frequency pulse When turned off, the second inductor, the AC power grid, the first inductor, the third switch tube and the anti-parallel diodes in the fourth switch tube sequentially form a freewheeling loop.
The inverter device of claim 3, wherein the first diode and the second diode are both silicon carbide diodes or fast recovery diodes, and the first switch tube to the second diode The six switching tubes are all cool MOS tubes, and the seventh switching tube is an IGBT tube.
A method for controlling an inverter device according to any one of claims 1-7, characterized by comprising the following steps:

One switch tube in the inverter circuit is controlled to be turned on by high-frequency pulses, and other switch tubes in the inverter circuit are controlled to be turned on or off by power frequency pulses to convert the DC voltage input by the DC power supply Into AC voltage;

The one switching tube is controlled to be turned off by high-frequency pulses, the other switching tubes are controlled to be turned on or off by power frequency pulses, and the inverter circuit, the filter inductor and the AC power grid are used to form a freewheeling loop , So as to isolate the freewheeling current after the one switch tube is turned off from the DC power supply.
An inverter, characterized by comprising the inverter device according to any one of claims 1-7.
A photovoltaic power system, characterized in that it comprises:

A photoelectric device, which is used as a DC power supply for outputting a DC voltage;

AC grid

The inverter according to claim 9, wherein the input end of the inverter is connected to the photoelectric device, the output end of the inverter is connected to the AC grid, and the inverter is used to connect the The DC voltage is converted into AC voltage and output to the AC power grid.