CN116154837A

CN116154837A - Inverter, control method thereof, and power supply system

Info

Publication number: CN116154837A
Application number: CN202211097544.5A
Authority: CN
Inventors: 陆丰隆; 陈东; 石磊; 唐云宇; 辛凯
Original assignee: Huawei Digital Power Technologies Co Ltd
Current assignee: Huawei Digital Power Technologies Co Ltd
Priority date: 2022-09-08
Filing date: 2022-09-08
Publication date: 2023-05-23

Abstract

The application provides an inverter, a control method thereof and a power supply system. The inverter comprises one or more DC/DC conversion units, an inversion unit and a controller; the DC/DC conversion unit comprises a direct current input source, a DC/DC conversion circuit and a multi-terminal gating switch, wherein a first end of the multi-terminal gating switch is connected with the input end of the DC/DC conversion circuit, a second end of the multi-terminal gating switch is connected with the direct current input source, and other ends of the multi-terminal gating switch are connected with the output end of the inversion unit; the controller controls the first end to be communicated with the second end so as to establish connection between the DC/DC conversion circuit and the direct current input source; when the output parameter of the inversion unit is larger than or equal to a first threshold value and the output parameter of the DC/DC conversion unit is smaller than or equal to a second threshold value, the controller controls the first end to be communicated with other ends so that the DC/DC conversion circuit and the inversion unit are connected in parallel. By adopting the inverter, the inverter overload capacity of the inverter can be improved, and the inverter has a simple structure and strong applicability.

Description

Inverter, control method thereof, and power supply system

Technical Field

The present disclosure relates to the field of electronic power technology, and in particular, to an inverter, a control method thereof, and a power supply system.

Background

In the prior art, a two-level bridge arm can be additionally added in the inverter of the traditional three-phase bridge arm to form a fault-tolerant control inverter, for example, when an A-phase bridge arm in the inverter of the three-phase bridge arm breaks down, the A-phase fast fuse works to disconnect a fault phase, and the added bridge arm replaces the A-phase bridge arm to work, so that the output power of the motor is not influenced before and after fault tolerance. However, the inventor of the application finds that in the research and practice process, the realization cost of additionally adding a bridge arm to realize fault tolerance is high, and the added bridge arm can enlarge the size of the inverter, and has a complex structure and poor stability.

Disclosure of Invention

The inverter, the control method thereof and the power supply system can improve the inversion overload capacity of the inverter, and are simple in structure, so that the working efficiency and the safety of the inverter can be improved, and the adaptability is high.

In a first aspect, the present application provides an inverter comprising one or more Direct Current (DC)/DC conversion units, an inverter unit, and a controller; the DC/DC conversion unit comprises a direct current input source, a DC/DC conversion circuit and a multi-terminal gating switch, wherein a first end of the multi-terminal gating switch is connected with the input end of the DC/DC conversion circuit, an output end of the DC/DC conversion circuit is used as an output end of the DC/DC conversion unit to be connected with the input end of the inversion unit, a second end of the multi-terminal gating switch is connected with the direct current input source, and other ends of the multi-terminal gating switch are connected with the output end of the inversion unit; the controller is used for controlling the first end of the multi-end gating switch in the DC/DC conversion unit to be communicated with the second end so as to establish connection between the DC/DC conversion circuit in the DC/DC conversion unit and a direct current input source; and the controller is also used for controlling the first ends of the multi-end gating switches in the DC/DC conversion unit to be communicated with other ends when the output parameters of the inversion unit are larger than or equal to a first threshold value and the output parameters of the DC/DC conversion unit are smaller than or equal to a second threshold value so as to enable the DC/DC conversion circuit to be connected with the inversion unit in parallel, and the DC/DC conversion circuit is used for shunting or replacing the input current of the inversion unit.

In the scheme provided by the application, the inverter can comprise a multi-port gating switch, the controller can establish connection between the DC/DC conversion circuit and the direct current input source by controlling the first end of the multi-port gating switch to connect the second end, so that the DC/DC conversion circuit can supply power to an alternating current load (such as an alternating current power grid) by using electric energy provided by the direct current input source, when the inverter unit is in transient overload, the first end of the multi-port gating switch can be controlled to connect other ends, and parallel connection of the idle DC/DC conversion circuit and the inverter unit can be established, so that the idle DC/DC conversion circuit is ensured to be used for shunting or replacing input current of the inverter unit, the inversion overload capacity of the inverter can be improved, the structure is simple, the working efficiency and the safety of the inverter can be improved, and the adaptability is strong.

As one possible implementation manner, the inversion unit is an N-phase inversion unit, the other ends of the multi-end gating switch are M, N is a positive integer greater than or equal to 1, and M is a positive integer less than or equal to N; m other ends of the multi-end gating switch are connected with any one or multiple phases of output ends of N phases of the inversion unit.

In the scheme provided by the application, the possible connection mode of the other ends of the multi-end gating switch and the multiphase output end of the inversion unit is provided, so that the circuit topology flexibility of the inverter can be improved.

As a possible embodiment, the inverter unit comprises N first inductors, and one of the N phase outputs of the inverter unit is connected to the ac load through one first inductor.

In the scheme that this application provided, the contravariant unit can include the inductance, can promote the ability of reactance to improve the stability of dc-to-ac converter.

As a possible implementation manner, M other terminals of the multi-terminal gating switch are connected to one terminal of the first inductor connected to any one or more of the N-phase output terminals of the inverter unit.

In the scheme that this application provided, the contravariant unit can include the inductance, and the one end of inductance can be connected to the other ends of multiport gating switch, and the reactance ability of contravariant unit can be promoted to the inductance to improve the stability of dc-to-ac converter.

As a possible implementation manner, the DC/DC conversion unit further includes a second inductor; the first end of the multi-end gating switch is connected with the input end of the DC/DC conversion circuit through the second inductor.

In the scheme provided by the application, the DC/DC conversion unit can comprise an inductor, the first end of the multi-end gating switch can be connected with the input end of the DC/DC conversion circuit through the inductor, and the inductor can improve the reactance capacity of the DC/DC conversion unit, so that the stability of the inverter is improved.

As a possible implementation manner, the DC/DC conversion unit further includes a second inductor; the second end of the multi-end gating switch is connected with a direct current input source through a second inductor.

In the scheme provided by the application, the DC/DC conversion unit can comprise an inductor, the second end of the multi-end gating switch is connected with a direct current input source through the inductor, and the inductor can improve the reactance capacity of the DC/DC conversion unit, so that the stability of the inverter is improved.

As one possible implementation, the multi-port gating switch is any one or a combination of any one or more of the following: mechanical switches, active semiconductor devices, passive semiconductor devices.

As a possible implementation manner, the output parameters of the inversion unit and/or the DC/DC conversion unit are any one or more of the following: current, voltage, active power, reactive power, phase angle, ac output frequency.

A second aspect provides a power supply system comprising a power supply unit and an inverter as provided in any one of the possible implementations of the first aspect or the first aspect described above connected (e.g. directly connected or indirectly connected) to the power supply unit.

As a possible implementation, the power supply unit is a photovoltaic array and the inverter is a photovoltaic inverter. In the process of supplying power to an ac load, the photovoltaic inverter may convert a dc voltage provided by the photovoltaic array into an ac voltage and supply power to the ac load based on the ac voltage. Under the condition that the photovoltaic inverter comprises a multi-end gating switch and a controller, the controller can control the multi-end gating switch to change the connection mode of the DC/DC conversion circuit and the inversion unit, so that the DC/DC conversion circuit can shunt or replace the input current of the inversion unit when the inversion unit is overloaded, the inversion overload capacity is increased, the power supply efficiency and the power supply safety of a power supply system can be improved, and the adaptability is high.

As a possible embodiment, the power supply unit is a wind power generator or an energy storage battery, and the inverter is an energy storage inverter. In the process of supplying power to an alternating-current load, the energy storage inverter can convert direct-current voltage provided by the wind power generator or the energy storage battery into alternating-current voltage and supply power to the alternating-current load based on the alternating-current voltage. Under the condition that the energy storage inverter comprises the multi-port gating switch and the controller, the controller can control the multi-port gating switch to change the connection mode of the DC/DC conversion circuit and the inversion unit, so that the DC/DC conversion circuit can shunt or replace the input current of the inversion unit when the inversion unit is overloaded, the inversion overload capacity is increased, the power supply efficiency and the power supply safety of a power supply system can be improved, and the adaptability is high.

As a possible implementation manner, the power supply system further includes a dc combiner box, the power supply unit may be connected to an input end of the inverter through the dc combiner box, and in a process of supplying power to the ac load, the dc combiner box may combine the dc voltages provided by the power supply unit and output the combined dc voltages to the inverter, where the inverter (e.g., the centralized inverter) may supply power to the ac load based on the combined dc voltages. In the power supply process, the working efficiency and the power supply safety of the inverter are higher, so that the power supply efficiency and the power supply safety of a power supply system can be improved, and the adaptability is higher.

As a possible implementation manner, the power supply system further includes a grid-connected transformer, and the output end of the inverter may be connected to an ac load through the grid-connected transformer. In the process of supplying power to an alternating-current load, the direct-current combiner box can combine direct-current voltages provided by the power supply unit and output the combined direct-current voltages to the inverter, and at the moment, the inverter (such as a centralized inverter) can supply power to the alternating-current load based on the combined direct-current voltages through the grid-connected transformer. In the power supply process, the working efficiency and the power supply safety of the inverter are higher, so that the power supply efficiency and the power supply safety of the photovoltaic system can be improved, and the adaptability is higher.

In the application, the controller can establish connection between the DC/DC conversion circuit and the direct current input source by controlling the first end of the multi-end gating switch to connect the second end, so that the DC/DC conversion circuit is ensured to supply power to the alternating current load by using electric energy provided by the direct current input source, when the inverter unit is in transient overload, the first end of the multi-end gating switch is controlled to connect other ends, and parallel connection between the idle DC/DC conversion circuit and the inverter unit is established, so that the idle DC/DC conversion circuit is ensured to be used for shunting or replacing the input current of the inverter unit, the inversion overload capacity is increased, and the efficiency and the safety of the inverter can be improved, and the adaptability is strong.

A third aspect provides a control method of an inverter, the control method being applicable to an inverter including one or more DC/DC conversion units, an inverter unit, and a controller; the DC/DC conversion unit comprises a direct current input source, a DC/DC conversion circuit and a multi-terminal gating switch, wherein a first end of the multi-terminal gating switch is connected with the input end of the DC/DC conversion circuit, an output end of the DC/DC conversion circuit is used as an output end of the DC/DC conversion unit to be connected with the input end of the inversion unit, a second end of the multi-terminal gating switch is connected with the direct current input source, and other ends of the multi-terminal gating switch are connected with the output end of the inversion unit; the method comprises the following steps: the first end of the multi-end gating switch in the DC/DC conversion unit is controlled by the controller to be communicated with the second end so as to establish connection between the DC/DC conversion circuit in the DC/DC conversion unit and a direct current input source; when the output parameter of the inversion unit is larger than or equal to a first threshold value and the output parameter of the DC/DC conversion unit is smaller than or equal to a second threshold value, the controller is used for controlling the first ends of the multi-end gating switches in the DC/DC conversion unit to be communicated with other ends so that the DC/DC conversion circuit and the inversion unit are connected in parallel, and the DC/DC conversion circuit is used for shunting or replacing the input current of the inversion unit.

In the scheme provided by the application, the controller can be used for controlling the first end of the multi-end gating switch to be connected with the second end, so that the connection between the DC/DC conversion circuit and the direct current input source is established, the DC/DC conversion circuit is ensured to supply power to the alternating current load by using the electric energy provided by the direct current input source, when the transient overload of the inversion unit occurs, the first end of the multi-end gating switch is controlled to be connected with other ends, the parallel connection between the idle DC/DC conversion circuit and the inversion unit is established, the idle DC/DC conversion circuit is ensured to be used for shunting or replacing the input current of the inversion unit, the inversion overload capacity of the inverter can be improved, the structure is simple, the working efficiency and the safety of the inverter can be improved, and the adaptability is strong.

Drawings

Fig. 1 is a schematic diagram of an application scenario of an inverter provided in the present application;

FIG. 2 is a schematic diagram of a power supply system according to the present disclosure;

FIG. 3 is another schematic diagram of the power supply system provided herein;

fig. 4 is a schematic structural diagram of an inverter provided in the present application;

FIG. 5 is a schematic diagram of a multi-port gating switch according to an embodiment of the present application;

FIG. 6 is a schematic diagram of a controller according to an embodiment of the present disclosure;

Fig. 7 is another schematic structural view of the inverter provided herein;

fig. 8 is a schematic view of still another configuration of the inverter provided herein;

fig. 9 is a schematic view of still another structure of the inverter provided herein;

fig. 10 is a schematic view of still another structure of the inverter provided herein;

fig. 11 is a schematic diagram of a DC/DC conversion circuit and an inverter unit provided in the present application;

fig. 12 is a flowchart of a control method of the inverter provided in the present application.

Detailed Description

The inverter (an alternating current-direct current converter) provided by the application is suitable for various application fields such as the new energy intelligent micro-grid field, the power transmission-distribution field or the new energy field (such as the photovoltaic grid-connected field or the wind power grid-connected field), the photovoltaic power generation field (such as the photovoltaic inverter), the wind power generation field, the high-power converter field (such as the field of converting direct current voltage into high-power high-voltage alternating current), the electric equipment field (such as various electric equipment) and the like, and can be specifically determined according to practical application scenes, and the application is not limited.

The inverter provided by the application can be suitable for high-power inverter application scenes and medium-low-power inverter application scenes, such as photovoltaic power supply application scenes, wind power grid-connected power supply scenes, electric automobile charging scenes or other application scenes, and the photovoltaic power supply application scenes are taken as an example for illustration and are not repeated. Referring to fig. 1 together, fig. 1 is a schematic view of an application scenario of an inverter provided in the present application. As shown in fig. 1, the application scenario may include a power supply unit, a positive dc bus, a negative dc bus, and an inverter, where the power supply unit may be connected to an input end of the inverter through the positive dc bus and the negative dc bus, and an output end of the inverter may be used to connect to an ac load. Alternatively, the ac load may be an ac grid, or other. The power supply unit can be a wind driven generator, a photovoltaic array or an energy storage battery, the photovoltaic array can be a photovoltaic module group, one photovoltaic module group can be formed by connecting one or more photovoltaic modules in series and one photovoltaic module group can be obtained by connecting one or more photovoltaic modules in series. The photovoltaic module may be a solar panel or a photovoltaic panel, etc. The inverter comprises a DC/DC conversion circuit, a multi-port gating switch, an inversion unit and a controller, wherein the controller can establish connection between the DC/DC conversion circuit and a direct current input source (a power supply unit) by controlling the first end of the multi-port gating switch to be connected with the second end, so that the DC/DC conversion circuit is ensured to supply power to an alternating current load by using electric energy provided by the direct current input source, and when the inversion unit is in transient overload, the first end of the multi-port gating switch can be controlled to be connected with other ends to establish parallel connection between the idle DC/DC conversion circuit and the inversion unit, thereby ensuring that the idle DC/DC conversion circuit is used for shunting or replacing input current of the inversion unit, improving the inversion overload capacity of the inverter, having simple structure, improving the working efficiency and safety of the inverter and strong adaptability. The inverter, the power supply system, and the operation principle thereof provided in the present application will be exemplified with reference to fig. 2 to 9.

In some possible embodiments, an example of a power supply system including an inverter will be described below, referring to fig. 2, and fig. 2 is a schematic structural diagram of the power supply system provided in the present application. As shown in fig. 2, the power supply system 10 includes a power supply unit 101 and an inverter 102 (such as the inverter 20 described below) connected (e.g., directly connected or indirectly connected) to the power supply unit 101, and an output terminal of the inverter 102 may be connected (e.g., directly connected or indirectly connected) to an ac load. In supplying power to the ac load, the inverter 102 may convert the dc voltage supplied from the power supply unit 101 into an ac voltage and supply power to the ac load based on the ac voltage. In the case that the inverter 102 includes a controller, the controller may establish connection between the DC/DC conversion circuit and the DC input source by controlling the first end of the multi-port gating switch to connect the second end, thereby ensuring that the DC/DC conversion circuit uses the electric energy provided by the DC input source to supply power to the ac load, and when the inverter unit is in transient overload, may establish parallel connection between the idle DC/DC conversion circuit and the inverter unit by controlling the first end of the multi-port gating switch to connect the other ends, thereby ensuring that the idle DC/DC conversion circuit is used to shunt or replace the input current of the inverter unit, improving the inversion overload capability of the inverter, thereby improving the working efficiency and safety of the inverter, and having strong adaptability.

The power supply unit 101 may be a photovoltaic array, and the inverter 102 is a photovoltaic inverter. In the process of supplying power to an ac load, the photovoltaic inverter may convert a dc voltage provided by the photovoltaic array into an ac voltage and supply power to the ac load based on the ac voltage. Under the condition that the photovoltaic inverter comprises a multi-port gating switch and a controller, the controller can control the multi-port gating switch to change the connection mode of the DC/DC conversion circuit and the inversion unit, so that the DC/DC conversion circuit can shunt or replace the input current of the inversion unit when the inversion unit is overloaded, the inversion overload capacity of the inverter is improved, the power supply efficiency and the power supply safety of a power supply system can be improved, and the adaptability is high.

The power supply unit 101 may be a wind power generator or an energy storage battery, and the inverter 102 is an energy storage inverter. In the process of supplying power to an alternating-current load, the energy storage inverter can convert direct-current voltage provided by the wind power generator or the energy storage battery into alternating-current voltage and supply power to the alternating-current load based on the alternating-current voltage. Under the condition that the energy storage inverter comprises the multi-port gating switch and the controller, the controller can control the multi-port gating switch to change the connection mode of the DC/DC conversion circuit and the inversion unit, so that the DC/DC conversion circuit can shunt or replace the input current of the inversion unit when the inversion unit is overloaded, the inversion overload capacity of the inverter is improved, the power supply efficiency and the power supply safety of a power supply system can be improved, and the adaptability is high.

In some possible embodiments, the power supply system 10 shown in fig. 2 further includes a dc combiner box 103, where the power supply unit 101 may be connected to an input terminal of the inverter 102 through the dc combiner box 103, and an output terminal of the inverter 102 may be connected (e.g., directly connected or indirectly connected) to an ac load. In the process of supplying power to an ac load, the dc combiner box 103 may combine the dc voltages supplied from the power supply unit 101 and output the combined dc voltages to the inverter 102, and at this time, the inverter 102 (e.g., a centralized photovoltaic inverter) may supply power to the ac load based on the combined dc voltages. In this power supply process, since the working efficiency and the power supply safety of the inverter 102 are higher, the power supply efficiency and the power supply safety of the power supply system 10 can be improved, and the adaptability is higher.

Optionally, referring to fig. 3, fig. 3 is another schematic structural diagram of the power supply system provided in the present application. In some possible embodiments, as shown in fig. 3, the power supply system 10 further includes a grid-connected transformer 104, where the output end of the inverter 102 may be connected to an ac load through the grid-connected transformer 104, where the grid-connected transformer 104 refers to a transformer substation (or a distribution substation) that combines high-voltage switching devices, distribution transformers, and low-voltage distribution devices according to a certain wiring scheme, and is installed in a box-type housing. In the process of supplying power to the ac load, the inverter 102 (e.g., a centralized photovoltaic inverter) may output an ac voltage to the grid-connected transformer 104 based on the converged dc voltage, and at this time, the grid-connected transformer 104 may supply power to the ac load based on the ac voltage input from the inverter 102. In this power supply process, since the working efficiency and the power supply safety of the inverter 102 are higher, the power supply efficiency and the power supply safety of the power supply system 10 can be improved, and the adaptability is higher.

Referring to fig. 4, fig. 4 is a schematic structural diagram of an inverter provided in the present application. As shown in fig. 4, the inverter 20 includes one or more DC/DC conversion units 201, an inverter unit 202, and a controller 203, where the DC/DC conversion unit 201 includes a DC input source 2011, a multi-port gating switch 2012, and a DC/DC conversion circuit 2013, a first end of the multi-port gating switch 2012 is connected to an input end of the DC/DC conversion circuit 2013, an output end of the DC/DC conversion circuit 2013 is connected to an input end of the inverter unit 202 as an output end of the DC/DC conversion unit 201, a second end of the multi-port gating switch 2012 is connected to the DC input source 2011, and other ends of the multi-port gating switch 2012 are connected to an output end of the inverter unit 202, where an output end of the inverter unit 202 may be connected to an ac load. The multi-port gating switch 2012 may also be referred to as a multiplexing switch or a multiplexer, and may gate one or more paths as required in the multi-path electrical connection process, so as to achieve the purpose of channel expansion or multiplexing. For example, 1-out-of-4, 1-out-of-two, 1-out-of-8, etc. The multi-port gating switch 2012 may be any one or a combination of any of a mechanical switch, an active semiconductor device, and a passive semiconductor device. For example, referring to fig. 5, fig. 5 is a schematic structural diagram of a multi-terminal gating switch according to an embodiment of the present application. As shown in fig. 5, fig. 5 (a) and (b) are mechanical switches, fig. 5 (c) and (g) are active semiconductor devices, fig. 5 (d) is a passive semiconductor device, fig. 5 (e) is a combination of an active semiconductor device and a passive semiconductor device, fig. 5 (f) is a combination of a mechanical switch and an active semiconductor device, the multi-port switch 2012 may be a combination of a mechanical switch and an active semiconductor device (not shown), a combination of a mechanical switch, an active semiconductor device and a passive semiconductor device (not shown), or the like.

Fig. 4 illustrates that each of the one or more DC/DC conversion units 201 is connected in parallel and then connected to an input end of the inverter unit 202, and it is understood that each DC/DC conversion unit may be connected to a different input port of the inverter unit 202, and the parallel connection is implemented inside the inverter unit 202, which is not specifically limited in the embodiment of the present application.

In some possible embodiments, the controller 203 may be configured to control the first terminal of the multi-terminal gating switch 2012 in the DC/DC conversion unit 201 to communicate with the second terminal to establish a connection between the DC/DC conversion circuit 2013 and the DC input source 2011 in the DC/DC conversion unit 201; the controller 203 may also be configured to control the first terminal of the multi-terminal gating switch 2012 in the DC/DC conversion unit 201 to communicate with the other terminal when the output parameter of the inverter unit 202 is greater than or equal to the first threshold value and the output parameter of the DC/DC conversion unit 201 is less than or equal to the second threshold value, so that the DC/DC conversion circuit 2013 in the DC/DC conversion unit 201 and the inverter unit 202 are connected in parallel, wherein the DC/DC conversion circuit 2013 is configured to shunt or replace the input current of the inverter unit 202. The first threshold value and the second threshold value may be predefined values, and the first threshold value and the second threshold value may be the same or different.

Specifically, when the output parameter of the inverter unit 202 reaches a certain stable value, this process may be referred to as a steady state. When the output parameter of the inverter unit 202 changes from a certain stable value, this process may be referred to as a transient. When the output of the inverter unit 202 is in a steady state, for example, when the output parameter of the inverter unit 202 is at a steady value, the first end of the multi-port gating switch 2012 is connected to the second end, and a connection between the DC/DC conversion circuit 2013 in the DC/DC conversion unit 201 and the DC input source 2011 is established, that is, the electric energy of the respective DC input source is transmitted to the inverter unit 202 through the DC/DC conversion circuits 2013 in one or more DC/DC conversion units, and then the inverter unit 202 supplies power to the ac load. In the case where the output of the inverter unit 202 is in a transient state, for example, the grid voltage suddenly increases or suddenly decreases, and the output parameter of the inverter unit 202 is greater than or equal to a first threshold (for example, the first threshold is a stable value of the output parameter), the first end of the multi-port gating switch 2012 may be disconnected from the second end, and the first end is connected to the other end, so that the DC/DC conversion circuit 201 that is in an idle state or has a smaller operation intensity (for example, when the output parameter of the DC/DC conversion unit 201 is less than or equal to the second threshold, for example, the second threshold is 0, and the output voltage of the DC/DC conversion unit 201 is 0, it may be determined that the DC/DC conversion unit 201 is in an idle state), and the DC/DC conversion circuit 2013 and the inverter unit 202 are connected in parallel, so that the input current (overload current) of the inverter unit 202 may be shunted or replaced by the DC/DC conversion circuit 2013 in the DC/DC conversion unit 201 that is in the idle state or has a smaller operation intensity, thereby achieving an improvement of the transient overcurrent capability of the inverter unit 202. Further, it may be determined how many DC/DC conversion circuits of one or more DC/DC conversion units are required to be connected in parallel to the inverter unit 202 according to the magnitude of the overload current of the inverter unit, so that the overload or transient condition of the inverter unit 202 can be alleviated. By connecting the DC/DC conversion circuit in parallel to the inverter unit 202, the idle DC/DC conversion circuit can be continuously connected to the grid, so that the effect of recovering the power supply quickly by the branch of the DC/DC conversion unit can be achieved.

Further, the one or more DC/DC conversion units 201 may be connected to the inverter unit 202 through a bus capacitor, which may be one bus capacitor or a plurality of bus capacitors connected in series to each other, and may be used for energy storage. In the inverter shown in fig. 4, when the output parameter of the inverter unit 202 is greater than or equal to the first threshold value and the output parameter of the DC/DC conversion unit 201 is less than or equal to the second threshold value, the controller 203 controls the first end of the multi-port switch 2012 in the DC/DC conversion unit 201 to be connected to the other end so that the DC/DC conversion circuit 2013 in the DC/DC conversion unit 201 and the inverter unit 202 are connected in parallel, and since the connection between the first end and the second end of the multi-port switch 2012 is disconnected, that is, the DC/DC conversion circuit 2013 in the DC/DC conversion unit 201 is disconnected from the DC input source 2011, the input end of the DC/DC conversion circuit 2013 is connected to the output end of the inverter unit 202, and at this time, a voltage can be maintained by the bus capacitor without energy ingress or egress.

Further alternatively, when the output parameter of the inverter unit 202 is recovered from being greater than or equal to the first threshold value to be less than the first threshold value, the controller 203 may be further configured to control a first terminal of the multi-terminal gating switch 2012 in the DC/DC conversion unit 201 to disconnect from other terminals, the first terminal being connected to a second terminal, so as to establish connection between the DC/DC conversion circuit 2013 and the DC input source 2011 in the DC/DC conversion unit 201.

The output parameter of the inverter unit 202 may be any one or more of current, voltage, active power, reactive power, phase angle, ac output frequency, and the like. The output parameter of the DC/DC conversion unit 201 may be any one or more of current, voltage, active power, reactive power, phase angle, ac output frequency, and the like. For example, the output parameters of the inverter unit 202 and the DC/DC conversion unit 201 are voltages. Optionally, referring to fig. 6, fig. 6 is a schematic structural diagram of a controller provided in the embodiment of the present application, and as shown in fig. 6, the controller 203 may specifically include a control module 2031, and a voltage detection module 2032. Wherein, the control module 2031 is connected with a control terminal of the multi-terminal gating switch 2012, and the controller 203 can control on or off of the multi-terminal gating switch 2012 through the control module 2031. The control module 2031 is also connected to a voltage detection module 2032. The voltage detection module 2032 may be connected to the output terminals of the DC/DC conversion unit 201 and the inverter unit 202, respectively, and the voltage detection module 2032 is configured to detect output voltages of the DC/DC conversion unit 201 and the inverter unit 202 and provide corresponding voltage detection results to the control module 2031. It is to be understood that, in fig. 6, only the output parameters of the inverter unit 202 and the DC/DC conversion unit 201 are taken as voltages, and the controller 203 specifically includes the voltage detection module 2032 for illustration, if the output parameters of the inverter unit 202 and the DC/DC conversion unit 201 may also be any one of current, active power, reactive power, phase angle, ac output frequency, etc., the voltage detection module 2032 may be replaced with a corresponding current detection module, active power detection module, reactive power detection module, phase angle detection module, ac output frequency detection module, etc., which is not limited in this embodiment.

Further alternatively, the controller 203 may also control the first end of the multi-port gating switch 2012 to communicate with the second end or the first end to communicate with other ends according to a grid command. In some possible embodiments, the power grid command is independent of the output parameter of the inverter unit 202, that is, whether the output parameter of the inverter unit 202 is greater than or equal to the first threshold value, or whether the output parameter of the inverter unit 202 is less than the first threshold value, the controller 203 detects the power grid command or the scheduling command issued by the upper stage, and may control the first end of the multi-port gating switch 2012 to communicate with the second end or the first end to communicate with the other end according to the power grid command or the scheduling command. In some possible embodiments, the power grid command relates to an output parameter of the inverter unit 202, that is, when the output parameter of the inverter unit 202 is greater than or equal to the first threshold, the upper level may issue a power grid command or a scheduling command to the controller 203, and when the controller 203 detects the power grid command or the scheduling command issued by the upper level, the first end of the multi-port gating switch 2012 may be controlled to communicate with the second end or the first end may be controlled to communicate with the other end according to the power grid command or the scheduling command.

In the inverter 20 provided in this embodiment, the controller 203 may connect the first end of the multi-port gating switch 2012 to the second end to establish connection between the DC/DC conversion circuit 2013 and the DC input source 2011 (power supply unit), so as to ensure that the DC/DC conversion circuit 2013 uses the electric energy provided by the DC input source 2011 to supply power to the ac load, and when the inverter unit is in transient overload, may connect the first end of the multi-port gating switch 2012 to other ends to establish parallel connection between the idle DC/DC conversion circuit 2013 and the inverter unit 202, so as to ensure that the idle DC/DC conversion circuit 2013 is used for shunting or replacing the input current of the inverter unit 202, i.e. the redundant DCDC conversion circuit can be fully utilized during the power grid transient period and is changed into an inverter mode to work and connected in parallel with the inverter unit, thereby increasing the overload capability of the inverter side, so as to improve the efficiency and safety of the inverter 20, and strong adaptability.

In some possible embodiments, the inverter unit 202 in fig. 4 may be an N-phase inverter unit, and the other terminals of the multi-terminal gating switch 2012 may be M, where N is a positive integer greater than or equal to 1, and M is a positive integer less than or equal to N. Wherein the M other terminals of the multi-terminal gating switch 2012 are connected to any one of the N-phase output terminals or the multi-phase output terminal of the inverter unit 202.

Illustratively, as shown in fig. 4, M is 1, n is 1, i.e., 1 is at the other end of the multi-port gating switch 2012, and the inverter unit 202 is a single-phase inverter unit, then 1 is at the other end of the multi-port gating switch 2012 connected to the single-phase output end of the inverter unit 202.

For example, referring to fig. 7, fig. 7 is another schematic structural diagram of the inverter provided in the present application. As shown in fig. 7, M is 1, n is 3, i.e. 1 is at the other end of the multi-end gating switch 2012, and the inverter unit 202 is a three-phase inverter unit including an a-phase inverter arm, a B-phase inverter arm, and a C-phase inverter arm, where 1 other end of the multi-end gating switch 2012 in the DC/DC converter 201 is connected to any one of three-phase output ends of the inverter unit 202.

For example, referring to fig. 8, fig. 8 is a schematic diagram of another structure of the inverter provided in the present application. As shown in fig. 8, M is 2, n is 3, that is, 2 other ends of the multi-end gating switch 2012, the inverter unit 202 is a three-phase inverter unit, including an a-phase inverter leg, a B-phase inverter leg, and a C-phase inverter leg, where 2 other ends of the multi-end gating switch 2012 in the DC/DC converter unit 201 are connected to any two of three-phase output ends of the inverter unit 202.

For example, referring to fig. 9, fig. 9 is a schematic diagram of still another structure of the inverter provided in the present application. As shown in fig. 9, M is 3, n is 3, that is, 3 other ends of the multi-end gating switch 2012 are provided, the inverter unit 202 is a three-phase inverter unit including an a-phase inverter arm, a B-phase inverter arm, and a C-phase inverter arm, where 3 other ends of the multi-end gating switch 2012 in the DC/DC converter 201 are respectively connected to three-phase output ends of the inverter unit 202.

It can be appreciated that fig. 4 and fig. 7 to fig. 9 are exemplary illustrations, the number of other ends of the multi-end gate switch 2012 and the number of output end phases of the inverter unit 202 are not limited in the embodiments of the present application, for example, the inverter unit may be a four-phase inverter unit, a six-phase inverter unit, or a twelve-phase inverter unit, etc., and the number of other ends of the multi-end gate switch 2012 may be determined according to the connection situation with the multi-phase output end of the inverter unit.

In the inverter 20 provided in this embodiment, the controller 203 may connect the first end of the multi-port gating switch 2012 to the second end to establish connection between the DC/DC conversion circuit 2013 and the DC input source 2011 (power supply unit), so as to ensure that the DC/DC conversion circuit 2013 uses the electric energy provided by the DC input source 2011 to supply power to the ac load, and when the inverter unit is in transient overload, may connect the first end of the multi-port gating switch 2012 to other ends to establish parallel connection between the idle DC/DC conversion circuit 2013 and the inverter unit 202, so as to ensure that the idle DC/DC conversion circuit 2013 is used for shunting or replacing the input current of the inverter unit 202, i.e. the redundant DCDC conversion circuit can be fully utilized during the power grid transient period and is changed into an inverter mode to work and connected in parallel with the inverter unit, thereby increasing the overload capability of the inverter side, so as to improve the efficiency and safety of the inverter 20, and strong adaptability. Second, an exemplary connection illustration of the other terminals of the multi-terminal gating switch 2012 with the multiphase output terminals of the inverter unit 202 is provided, thereby increasing the circuit topology flexibility of the inverter 20.

In some possible embodiments, please refer to fig. 10 on the basis of the inverter 20 shown in fig. 4, fig. 10 is a schematic diagram of another structure of the inverter provided in the present application. As shown in fig. 10, the inverter unit 202 may be an N-phase inverter unit, and the inverter unit 202 may include N first inductors, where one phase output end of N phase output ends of the inverter unit 202 is connected to an ac load through one first inductor. The M other terminals of the multi-terminal gating switch 2012 are connected to one terminal of the first inductor connected to any one or more of the N-phase output terminals of the inverter unit 202.

Further in some possible embodiments, the DC/DC conversion unit 201 may further include a second inductor, where a first end of the multi-port gating switch 2012 is connected to an input end of the DC/DC conversion circuit 2013 through the second inductor, or where a second end of the multi-port gating switch 2012 is connected to the DC input source 2011 through the second inductor.

In some possible embodiments, as shown in fig. 10 (a) and (b) of the inverter 20, the DC/DC conversion unit 201 includes a second inductor L2, and the first terminal of the multi-port gating switch 2012 is connected to the input terminal of the DC/DC conversion circuit 2013 through the second inductor L2. The inverter unit 202 is a single-phase inverter unit, and includes a first inductor L1, and a single-phase output end of the inverter unit 202 is connected to an ac load through the first inductor L1. 1 other terminal of the multi-terminal gating switch 2012 is connected to one terminal of the first inductor L1 connected in the single-phase output terminal of the inverter unit 202. Specifically, 1 other terminal of the multi-terminal gating switch 2012 shown in fig. 10 (a) may be connected to a first terminal of the first inductor L1 connected to the single-phase output terminal of the inverter unit 202, or 1 other terminal of the multi-terminal gating switch 2012 shown in fig. 10 (b) may be connected to a second terminal of the first inductor L1 connected to the single-phase output terminal of the inverter unit 202.

In some possible embodiments, as shown in the inverter 20 of fig. 10 (c) and (d), the DC/DC conversion unit 201 includes a second inductor L2, and the second terminal of the multi-terminal gating switch 2012 is connected to the DC input source 2011 through the second inductor L2. The inverter unit 202 is a single-phase inverter unit, and includes a first inductor L1, and a single-phase output end of the inverter unit 202 is connected to an ac load through the first inductor L1. 1 other terminal of the multi-terminal gating switch 2012 is connected to one terminal of the first inductor L1 connected in the single-phase output terminal of the inverter unit 202. Specifically, 1 other terminal of the multi-terminal gating switch 2012 shown in fig. 10 (c) may be connected to a first terminal of the first inductor L1 connected to the single-phase output terminal of the inverter unit 202, or 1 other terminal of the multi-terminal gating switch 2012 shown in fig. 10 (d) may be connected to a second terminal of the first inductor L1 connected to the single-phase output terminal of the inverter unit 202.

It should be understood that, in fig. 10, the inverter unit 202 is exemplified as a single-phase inverter unit, and the inverter unit 202 may be an N-phase inverter unit, for example, a three-phase inverter unit, a four-phase inverter unit, a six-phase inverter unit, or a twelve-phase inverter unit, and includes N first inductors L1, where one of the N-phase output ends of the inverter unit is connected to the ac load through one of the first inductors L1, and the M other ends of the multi-port gating switch are connected to one end of the first inductor connected to any one of the N-phase output ends or the multi-phase output ends of the inverter unit, which is not illustrated herein.

In this embodiment, the inverter unit 202 may include a first inductor L1, and the DC/DC conversion unit 201 may include a second inductor L2, and when the controller 203 connects the DC/DC conversion circuit 2013 and the inverter unit 202 in parallel, the first inductor L1 and/or the second inductor L2 may be connected into the parallel circuit, which has different implementation complexity, and the connection of the first inductor L1 and/or the second inductor L2 may improve the reactance capability, so as to improve the stability of the inverter 20.

In some possible embodiments, please refer to fig. 11, fig. 11 is a schematic structural diagram of the DC/DC conversion circuit and the inverter unit provided in the present application. As shown in fig. 11, the DC/DC conversion circuit 2013 and the inverter unit 202 may be multi-level, such as two-level, four-level, six-level, etc., and the number of levels of the DC/DC conversion circuit 2013 and the inverter unit 202 is not limited in the embodiment of the present application.

Next, an example of a control method of the inverter will be described, referring to fig. 12, and fig. 12 is a schematic flow chart of the control method of the inverter provided in the present application. The method is applicable to a controller in an inverter, such as inverter 20 shown in fig. 2-8 described above. Wherein the inverter comprises one or more DC/DC conversion units, an inversion unit and a controller; the DC/DC conversion unit comprises a direct current input source, a DC/DC conversion circuit and a multi-terminal gating switch, wherein a first end of the multi-terminal gating switch is connected with the input end of the DC/DC conversion circuit, an output end of the DC/DC conversion circuit is used as an output end of the DC/DC conversion unit to be connected with the input end of the inversion unit, a second end of the multi-terminal gating switch is connected with the direct current input source, other ends of the multi-terminal gating switch are connected with the output end of the inversion unit, and the output end of the inversion unit is connected with an alternating current load. As shown in fig. 12, the method includes the following steps S1201 to S1202:

Step S1201: the first end of the multi-terminal gating switch in the DC/DC conversion unit is controlled to be communicated with the second end so as to establish connection between the DC/DC conversion circuit in the DC/DC conversion unit and a direct current input source.

In some possible embodiments, the controller 203 may be configured to control the first terminal of the multi-terminal gating switch 2012 in the DC/DC conversion unit 201 to communicate with the second terminal to establish a connection between the DC/DC conversion circuit 2013 and the DC input source 2011 in the DC/DC conversion unit 201. Specifically, when the output parameter of the inverter unit 202 reaches a certain stable value, this process may be referred to as a steady state. When the output parameter of the inverter unit 202 changes from a certain stable value, this process may be referred to as a transient. When the output of the inverter unit 202 is in a steady state, for example, when the output parameter of the inverter unit 202 is at a steady value, the first end of the multi-port gating switch 2012 is connected to the second end, and a connection between the DC/DC conversion circuit 2013 in the DC/DC conversion unit 201 and the DC input source 2011 is established, that is, the electric energy of the respective DC input source is transmitted to the inverter unit 202 through the DC/DC conversion circuits 2013 in one or more DC/DC conversion units, and then the inverter unit 202 supplies power to the ac load.

Step S1202: when the output parameter of the inversion unit is larger than or equal to a first threshold value and the output parameter of the DC/DC conversion unit is smaller than or equal to a second threshold value, the first ends of the multi-end gating switches in the DC/DC conversion unit are controlled to be communicated with other ends, so that the DC/DC conversion circuit and the inversion unit are connected in parallel.

In some possible embodiments, the controller 203 may be further configured to control the first terminal of the multi-terminal gating switch 2012 in the DC/DC conversion unit 201 to communicate with the other terminal when the output parameter of the inverter unit 202 is greater than or equal to the first threshold value and the output parameter of the DC/DC conversion unit 201 is less than or equal to the second threshold value, so that the DC/DC conversion circuit 2013 in the DC/DC conversion unit 201 and the inverter unit 202 are connected in parallel, wherein the DC/DC conversion circuit is configured to shunt or replace the input current of the inverter unit. Specifically, when the output of the inverter unit 202 is in a transient state, for example, the grid voltage suddenly increases or suddenly decreases, and the output parameter of the inverter unit 202 is greater than or equal to a first threshold (for example, the first threshold is a stable value of the output parameter), the first end of the multi-port gating switch 2012 may be disconnected from the second end, and the first end is connected to the other end, so that the DC/DC conversion circuit 201 in an idle state or a low working strength is enabled (for example, when the output parameter of the DC/DC conversion unit 201 is less than or equal to the second threshold, for example, the second threshold is 0, and when the output voltage of the DC/DC conversion unit 201 is 0, it may be determined that the DC/DC conversion unit 201 is in an idle state), the DC/DC conversion circuit 2013 and the inverter unit 202 are connected in parallel, so that the input current (overload current) of the inverter unit 202 may be shunted or replaced by the DC/DC conversion circuit 2013 in the idle state or the low working strength DC/DC conversion unit 201, thereby achieving the transient overcurrent capability of the inverter unit 202. By connecting the DC/DC conversion circuit in parallel to the inverter unit 202, the idle DC/DC conversion circuit can be continuously connected to the grid, so that the effect of recovering the power supply quickly by the branch of the DC/DC conversion unit can be achieved.

In specific implementation, for more operations executed by the controller in the control method of the inverter provided in the present application, reference may be made to the implementation manner executed by the controller 203 in the inverter 20 and the working principle thereof shown in fig. 4 to 10, which is not described herein.

In the method provided by the application, the controller can establish connection between the DC/DC conversion circuit and the direct current input source by controlling the first end of the multi-end gating switch to be connected with the second end, so that the DC/DC conversion circuit is ensured to supply power to the alternating current load by using electric energy provided by the direct current input source, and when the inverter unit is in transient overload, the first end of the multi-end gating switch is controlled to be connected with other ends, so that parallel connection between the idle DC/DC conversion circuit and the inverter unit is established, thereby ensuring that the idle DC/DC conversion circuit is used for shunting or replacing the input current of the inverter unit, improving the inversion overload capacity of the inverter, improving the working efficiency and safety of the inverter, and having strong adaptability.

The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An inverter, characterized in that the inverter comprises one or more Direct Current (DC)/DC conversion units, an inversion unit and a controller; the DC/DC conversion unit comprises a direct current input source, a DC/DC conversion circuit and a multi-terminal gating switch, wherein a first end of the multi-terminal gating switch is connected with the input end of the DC/DC conversion circuit, the output end of the DC/DC conversion circuit is used as the output end of the DC/DC conversion unit to be connected with the input end of the inversion unit, a second end of the multi-terminal gating switch is connected with the direct current input source, and other ends of the multi-terminal gating switch are connected with the output end of the inversion unit;

the controller is used for controlling the first end of the multi-end gating switch in the DC/DC conversion unit to be communicated with the second end so as to establish connection between the DC/DC conversion circuit in the DC/DC conversion unit and the direct current input source;

The controller is further configured to control the first end of the multi-port gating switch in the DC/DC conversion unit to communicate with the other end when the output parameter of the inversion unit is greater than or equal to a first threshold and the output parameter of the DC/DC conversion unit is less than or equal to a second threshold, so that the DC/DC conversion circuit and the inversion unit are connected in parallel, and the DC/DC conversion circuit is configured to shunt or replace an input current of the inversion unit.

2. The inverter according to claim 1, wherein the inverter unit is an N-phase inverter unit, the other ends of the multi-port gating switch are M, N is a positive integer greater than or equal to 1, and M is a positive integer less than or equal to N;

and M other ends of the multi-end gating switch are connected with any one or more phase output ends of N-phase output ends of the inversion unit.

3. The inverter of claim 2, wherein the inverter unit comprises N first inductors, and one of the N phase outputs of the inverter unit is connected to an ac load through one of the first inductors.

4. An inverter according to claim 3, wherein the M other terminals of the multi-terminal gating switch are connected to one terminal of the first inductor to which any one or more of the N-phase output terminals of the inverter unit are connected.

5. An inverter according to claim 2 or 3, characterized in that the DC/DC conversion unit further comprises a second inductance; the first end of the multi-end gating switch is connected with the input end of the DC/DC conversion circuit through the second inductor.

6. An inverter according to claim 2 or 3, characterized in that the DC/DC conversion unit further comprises a second inductance; the second end of the multi-end gating switch is connected with the direct current input source through the second inductor.

7. The inverter of any of claims 1-6, wherein the multi-port gating switch is any one or a combination of any of the following:

mechanical switches, active semiconductor devices, passive semiconductor devices.

8. The inverter according to any one of claims 1-5, wherein the output parameters of the inverter unit and/or the DC/DC conversion unit are any one or more of the following:

current, voltage, active power, reactive power, phase angle, ac output frequency.

9. A control method of an inverter, characterized in that the inverter comprises one or more Direct Current (DC)/DC conversion units, an inversion unit and a controller; the DC/DC conversion unit comprises a direct current input source, a DC/DC conversion circuit and a multi-terminal gating switch, wherein a first end of the multi-terminal gating switch is connected with the input end of the DC/DC conversion circuit, the output end of the DC/DC conversion circuit is used as the output end of the DC/DC conversion unit to be connected with the input end of the inversion unit, a second end of the multi-terminal gating switch is connected with the direct current input source, and other ends of the multi-terminal gating switch are connected with the output end of the inversion unit;

The method comprises the following steps:

controlling the first end of the multi-end gating switch in the DC/DC conversion unit to be communicated with the second end through the controller so as to establish connection between the DC/DC conversion circuit in the DC/DC conversion unit and the direct current input source;

when the output parameter of the inversion unit is greater than or equal to a first threshold value and the output parameter of the DC/DC conversion unit is less than or equal to a second threshold value, the first end of the multi-end gating switch in the DC/DC conversion unit is controlled by the controller to be communicated with the other ends, so that the DC/DC conversion circuit and the inversion unit are connected in parallel, and the DC/DC conversion circuit is used for shunting or replacing the input current of the inversion unit.

10. A power supply system, characterized in that the power supply system comprises a power supply unit and an inverter as claimed in any one of claims 1-8.

11. The power supply system of claim 10, wherein the power supply unit is a photovoltaic array and the inverter is a photovoltaic inverter; or the power supply unit is a wind power generator or an energy storage battery, and the inverter is an energy storage inverter.