Inverter, control method thereof, and power supply system

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 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. The first terminal of the multi-terminal gating switch is connected to the input terminal of the DC / DC conversion circuit, the second terminal of the multi-terminal gating switch is connected to the direct current input source, and the other terminal of the multi-terminal gating switch is connected to the output terminal of the inverter unit. The controller controls the first terminal to be connected to the second terminal to establish the connection between the DC / DC conversion circuit and the direct current input source. When the output parameter of the inverter 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 controller controls the first terminal to be connected to the other terminal, so that the DC / DC conversion circuit and the inverter unit are connected in parallel. The inverter overload capacity can be improved by using the application, and the structure is simple and applicable.

Description

Technical Field

[0001] This application relates to the field of electronic power technology, and in particular to an inverter and its control method, as well as a power supply system. Background Technology

[0002] In existing technologies, a two-level bridge arm can be added to a traditional three-phase bridge arm inverter to form a fault-tolerant control inverter. For example, when phase A of the three-phase bridge arm inverter fails, the fast-acting fuse of phase A disconnects the faulty phase, and the added bridge arm takes over the operation of phase A, keeping the motor's output power unaffected before and after fault tolerance. However, the inventors of this application have found in their research and practice that adding an extra bridge arm for fault tolerance is costly, and the added bridge arm increases the inverter's size, complicates its structure, and reduces its stability. Summary of the Invention

[0003] This application provides an inverter and its control method, as well as a power supply system, which can improve the inverter's inverter overload capacity, has a simple structure, thereby improving the inverter's working efficiency and safety, and has strong adaptability.

[0004] In a first aspect, this 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 includes a DC input source, a DC / DC conversion circuit, and a multi-terminal selection switch. A first terminal of the multi-terminal selection switch is connected to the input terminal of the DC / DC conversion circuit, and the output terminal of the DC / DC conversion circuit serves as the output terminal of the DC / DC conversion unit, connected to the input terminal of the inverter unit. A second terminal of the multi-terminal selection switch is connected to the DC input source, and the other terminals of the multi-terminal selection switch are connected to the output terminal of the inverter unit. The controller is used to control the first terminal of the multi-terminal selection switch in the DC / DC conversion unit to connect to the second terminal, thereby establishing a connection between the DC / DC conversion circuit and the DC input source in the DC / DC conversion unit. The controller is also used to control the first terminal of the multi-terminal selection switch in the DC / DC conversion unit to connect to the other terminals when the output parameter of the inverter 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 inverter unit are connected in parallel. The DC / DC conversion circuit is used to shunt or replace the input current of the inverter unit.

[0005] In the solution provided in this application, the inverter may include a multi-terminal selection switch. The controller can connect the first terminal of the multi-terminal selection switch to the second terminal to establish a connection between the DC / DC conversion circuit and the DC input source. This ensures that the DC / DC conversion circuit uses the electrical energy provided by the DC input source to supply power to the AC load (e.g., the AC power grid). When the inverter unit experiences transient overload, the controller can connect the first terminal of the multi-terminal selection switch to other terminals to establish a parallel connection between the idle DC / DC conversion circuit and the inverter unit. This ensures that the idle DC / DC conversion circuit is used to shunt or replace the input current of the inverter unit, thereby improving the inverter's inverter overload capacity. The structure is simple, which improves the inverter's working efficiency and safety, and it has strong adaptability.

[0006] As one possible implementation, the inverter unit is an N-phase inverter unit, and the other terminals of the multi-terminal selection switch are 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; the M other terminals of the multi-terminal selection switch are connected to any one or more of the N-phase output terminals of the inverter unit.

[0007] The solution provided in this application offers possible connection methods between the other terminals of the multi-terminal gating switch and the multi-phase output terminals of the inverter unit, thereby improving the circuit topology flexibility of the inverter.

[0008] As one possible implementation, the inverter unit includes N first inductors, and one of the N-phase output terminals of the inverter unit is connected to an AC load through one of the first inductors.

[0009] In the solution provided in this application, the inverter unit may include an inductor, which can enhance the reactance capability and thus improve the stability of the inverter.

[0010] As one possible implementation, the M other terminals of the multi-terminal selector switch are connected to one end of the first inductor connected to any one or more of the N-phase output terminals of the inverter unit.

[0011] In the solution provided in this application, the inverter unit may include an inductor, and the other terminals of the multi-terminal selection switch may be connected to one end of the inductor. The inductor can improve the reactance capability of the inverter unit, thereby improving the stability of the inverter.

[0012] As one possible implementation, the DC / DC converter unit also includes a second inductor; the first terminal of the multi-terminal selection switch is connected to the input terminal of the DC / DC converter circuit through the second inductor.

[0013] In the solution provided in this application, the DC / DC conversion unit may include an inductor. The first terminal of the multi-terminal selection switch can be connected to the input terminal of the DC / DC conversion circuit through the inductor. The inductor can improve the reactance capability of the DC / DC conversion unit, thereby improving the stability of the inverter.

[0014] As one possible implementation, the DC / DC converter unit also includes a second inductor; the second terminal of the multi-terminal selector switch is connected to the DC input source through the second inductor.

[0015] In the solution provided in this application, the DC / DC conversion unit may include an inductor, and the second terminal of the multi-terminal selection switch is connected to the DC input source through the inductor. The inductor can improve the reactance capability of the DC / DC conversion unit, thereby improving the stability of the inverter.

[0016] As one possible implementation, the multi-terminal gating switch is any one or a combination of the following: a mechanical switch, an active semiconductor device, or a passive semiconductor device.

[0017] As one possible implementation, the output parameters of the inverter unit and / or DC / DC converter unit are any one or more of the following: current, voltage, active power, reactive power, phase angle, and AC output frequency.

[0018] The second aspect provides a power supply system comprising a power supply unit and an inverter provided in the first aspect or any of the possible embodiments of the first aspect, which is connected (e.g., directly or indirectly) to the power supply unit.

[0019] In one possible implementation, the power supply unit is a photovoltaic array, and the inverter is a photovoltaic inverter. During the process of supplying power to an AC load, the photovoltaic inverter can convert the DC voltage provided by the photovoltaic array into AC voltage and supply power to the AC load based on the AC voltage. When the photovoltaic inverter includes a multi-terminal selector switch and a controller, the controller can control the multi-terminal selector switch to change the connection method between the DC / DC conversion circuit and the inverter unit. This allows the DC / DC conversion circuit to shunt or replace the input current of the inverter unit when it is overloaded, thereby increasing the inverter's overload capacity. This improves the power supply efficiency and safety of the power supply system, and enhances its adaptability.

[0020] In one possible implementation, the power supply unit is a wind turbine or an energy storage battery, and the inverter is an energy storage inverter. During the supply of power to an AC load, the energy storage inverter can convert the DC voltage provided by the wind turbine or energy storage battery into AC voltage and supply power to the AC load based on this AC voltage. When the energy storage inverter includes a multi-terminal selector switch and a controller, the controller can control the multi-terminal selector switch to change the connection method between the DC / DC converter circuit and the inverter unit. This allows the DC / DC converter circuit to shunt or replace the input current of the inverter unit when it is overloaded, increasing the inverter's overload capacity. This, in turn, improves the power supply efficiency and safety of the power supply system, and provides strong adaptability.

[0021] As one possible implementation, the power supply system also includes a DC combiner box. The power supply unit can be connected to the input terminal of the inverter through the DC combiner box. During the process of supplying power to the AC load, the DC combiner box can combine the DC voltage provided by the power supply unit and output it to the inverter. At this time, the inverter (such as a centralized inverter) can supply power to the AC load based on the combined DC voltage. In this power supply process, since the inverter has higher operating efficiency and power supply safety, the power supply efficiency and power supply safety of the power supply system can be improved, and the adaptability is stronger.

[0022] As one possible implementation, the power supply system also includes a grid-connected transformer, through which the output of the inverter can be connected to an AC load. During the supply of power to the AC load, the DC combiner box can combine the DC voltage provided by the power supply unit and output it to the inverter. At this time, the inverter (such as a centralized inverter) can supply power to the AC load based on the combined DC voltage and through the grid-connected transformer. In this power supply process, because the inverter has higher operating efficiency and power supply security, the power supply efficiency and security of the photovoltaic system can be improved, and its adaptability is enhanced.

[0023] In this application, the controller can connect the first terminal of the multi-terminal selection switch to the second terminal to establish a connection between the DC / DC conversion circuit and the DC input source. This ensures that the DC / DC conversion circuit uses the power provided by the DC input source to supply power to the AC load. When the inverter unit experiences transient overload, the controller can connect the first terminal of the multi-terminal selection switch to other terminals to establish a parallel connection between the idle DC / DC conversion circuit and the inverter unit. This ensures that the idle DC / DC conversion circuit can be used to shunt or replace the input current of the inverter unit, increasing the inverter's overload capacity. This improves the inverter's efficiency and safety, and enhances its adaptability.

[0024] The third aspect provides a control method for an inverter, which can be applied to an inverter including one or more DC / DC conversion units, an inverter unit, and a controller. The DC / DC conversion unit includes a DC input source, a DC / DC conversion circuit, and a multi-terminal selection switch. A first terminal of the multi-terminal selection switch is connected to the input terminal of the DC / DC conversion circuit, and the output terminal of the DC / DC conversion circuit serves as the output terminal of the DC / DC conversion unit, connected to the input terminal of the inverter unit. A second terminal of the multi-terminal selection switch is connected to the DC input source, and the other terminals of the multi-terminal selection switch are connected to the output terminal of the inverter unit. The method includes: controlling the first terminal of the multi-terminal selection switch in the DC / DC conversion unit to connect to the second terminal via the controller, thereby establishing a connection between the DC / DC conversion circuit and the DC input source in the DC / DC conversion unit; when the output parameter of the inverter 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, controlling the first terminal of the multi-terminal selection switch in the DC / DC conversion unit to connect to the other terminals via the controller, so that the DC / DC conversion circuit and the inverter unit are connected in parallel, and the DC / DC conversion circuit is used to shunt or replace the input current of the inverter unit.

[0025] In the solution provided in this application, the controller can connect the first terminal of the multi-terminal selection switch to the second terminal to establish a connection between the DC / DC conversion circuit and the DC input source. This ensures that the DC / DC conversion circuit uses the power provided by the DC input source to supply power to the AC load. When the inverter unit experiences transient overload, the controller can connect the first terminal of the multi-terminal selection switch to other terminals to establish a parallel connection between the idle DC / DC conversion circuit and the inverter unit. This ensures that the idle DC / DC conversion circuit is used to shunt or replace the input current of the inverter unit, thereby improving the inverter's inverter overload capacity. The structure is simple, which improves the inverter's working efficiency and safety, and it has strong adaptability. Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the application scenario of the inverter provided in this application;

[0027] Figure 2 This is a structural schematic diagram of the power supply system provided in this application;

[0028] Figure 3 This is another structural schematic diagram of the power supply system provided in this application;

[0029] Figure 4 This is a structural schematic diagram of the inverter provided in this application;

[0030] Figure 5 This is a schematic diagram of the structure of the multi-terminal selection switch provided in the embodiments of this application;

[0031] Figure 6This is a schematic diagram of the controller provided in an embodiment of this application;

[0032] Figure 7 This is another structural schematic diagram of the inverter provided in this application;

[0033] Figure 8 This is another structural schematic diagram of the inverter provided in this application;

[0034] Figure 9 This is another structural schematic diagram of the inverter provided in this application;

[0035] Figure 10 This is another structural schematic diagram of the inverter provided in this application;

[0036] Figure 11 This is a schematic diagram of the DC / DC converter circuit and inverter unit provided in this application;

[0037] Figure 12 This is a flowchart illustrating the control method for the inverter provided in this application. Detailed Implementation

[0038] The inverter (an AC / DC converter) provided in this application is applicable to various fields, including new energy smart microgrids, power transmission and distribution, new energy (such as photovoltaic grid connection or wind power grid connection), photovoltaic power generation (such as photovoltaic inverters), wind power generation, high-power converters (such as converting DC voltage to high-power high-voltage AC), and electric equipment (such as various electric equipment). The specific application can be determined according to the actual application scenario, and no restrictions are imposed here.

[0039] The inverter provided in this application is adaptable to both high-power and low-to-medium power inverter applications, such as photovoltaic power supply, wind power grid-connected power supply, electric vehicle charging, and other applications. The following explanation will use a photovoltaic power supply application as an example; further details will not be provided here. Please refer to [link to relevant documentation]. Figure 1 , Figure 1 This is a schematic diagram illustrating the application scenario of the inverter provided in this application. For example... Figure 1As shown, this application scenario can include a power supply unit, a positive DC bus, a negative DC bus, and an inverter. The power supply unit can be connected to the input terminal of the inverter via the positive and negative DC buses, and the output terminal of the inverter can be used to connect AC loads. Optionally, the AC load can be an AC power grid or other sources. The power supply unit can be a wind turbine, a photovoltaic array, or an energy storage battery. The photovoltaic array can be a photovoltaic module group, which can consist of one or more photovoltaic modules connected in series and parallel. A photovoltaic string can be formed by one or more photovoltaic modules connected in series. The photovoltaic modules can be solar panels or photovoltaic panels, etc. An inverter includes a DC / DC conversion circuit, a multi-terminal selection switch, an inverter unit, and a controller. The controller can connect the first terminal of the multi-terminal selection switch to the second terminal, establishing a connection between the DC / DC conversion circuit and the DC input source (power supply unit). This ensures that the DC / DC conversion circuit uses the power provided by the DC input source to supply AC loads. During transient overload of the inverter unit, the controller can connect the first terminal of the multi-terminal selection switch to other terminals, establishing a parallel connection between the idle DC / DC conversion circuit and the inverter unit. This ensures that the idle DC / DC conversion circuit can be used to shunt or replace the input current of the inverter unit, improving the inverter's overload capacity. The inverter has a simple structure, thus improving its efficiency and safety, and offering strong adaptability. The following will combine... Figures 2 to 9 The inverter, power supply system, and their working principle provided in this application are illustrated with examples.

[0040] In some feasible implementations, an example of a power supply system including an inverter will be described below; please refer to [link / reference]. Figure 2 , Figure 2 This is a structural schematic diagram of the power supply system provided in this application. For example... Figure 2As shown, the power supply system 10 includes a power supply unit 101 and an inverter 102 (hereinafter referred to as inverter 20) connected to the power supply unit 101 (e.g., directly or indirectly). The output terminal of the inverter 102 can be connected (e.g., directly or indirectly) to an AC load. During the process of supplying power to the AC load, the inverter 102 can convert the DC voltage provided by the power supply unit 101 into an AC voltage and supply power to the AC load based on the AC voltage. If the inverter 102 includes a controller, the controller can connect the first terminal of a multi-terminal selection switch to the second terminal to establish a connection between the DC / DC conversion circuit and the DC input source. This ensures that the DC / DC conversion circuit uses the electrical energy provided by the DC input source to supply power to the AC load. In the event of a transient overload of the inverter unit, the controller can connect the first terminal of the multi-terminal selection switch to other terminals to establish a parallel connection between the idle DC / DC conversion circuit and the inverter unit. This ensures that the idle DC / DC conversion circuit is used to shunt or replace the input current of the inverter unit, improving the inverter's overload capacity. This, in turn, improves the inverter's operating efficiency and safety, and enhances its adaptability.

[0041] In this system, the power supply unit 101 can be a photovoltaic array, and the inverter 102 is a photovoltaic inverter. During the supply of power to an AC load, the photovoltaic inverter converts the DC voltage provided by the photovoltaic array into AC voltage and supplies power to the AC load based on this AC voltage. When the photovoltaic inverter includes a multi-terminal selection switch and a controller, the controller can control the multi-terminal selection switch to change the connection method between the DC / DC conversion circuit and the inverter unit. This allows the DC / DC conversion circuit to shunt or replace the input current of the inverter unit when it is overloaded, improving the inverter's overload capacity. This, in turn, improves the power supply efficiency and safety of the power supply system, and provides strong adaptability.

[0042] The power supply unit 101 can be a wind turbine generator or an energy storage battery, and the inverter 102 is an energy storage inverter. During the supply of power to an AC load, the energy storage inverter can convert the DC voltage provided by the wind turbine generator or energy storage battery into AC voltage and supply power to the AC load based on the AC voltage. When the energy storage inverter includes a multi-terminal selection switch and a controller, the controller can control the multi-terminal selection switch to change the connection method between the DC / DC conversion circuit and the inverter unit. This allows the DC / DC conversion circuit to shunt or replace the input current of the inverter unit when the inverter unit is overloaded, improving the inverter's overload capacity. This, in turn, improves the power supply efficiency and safety of the power supply system, and provides strong adaptability.

[0043] In some feasible implementations, the above Figure 2The power supply system 10 shown also includes a DC combiner box 103. The power supply unit 101 can be connected to the input terminal of the inverter 102 via the DC combiner box 103. The output terminal of the inverter 102 can be connected (e.g., directly or indirectly) to an AC load. During the process of supplying power to the AC load, the DC combiner box 103 can combine the DC voltage provided in the power supply unit 101 and output it to the inverter 102. At this time, the inverter 102 (such as a centralized photovoltaic inverter) can supply power to the AC load based on the combined DC voltage. During this power supply process, since the inverter 102 has higher operating efficiency and power supply safety, the power supply efficiency and power supply safety of the power supply system 10 can be improved, and its adaptability is stronger.

[0044] Optional, please see also Figure 3 , Figure 3 This is another structural schematic diagram of the power supply system provided in this application. In some feasible implementations, such as… Figure 3 As shown, the power supply system 10 also includes a grid-connected transformer 104. The output of the inverter 102 can be connected to an AC load through the grid-connected transformer 104. The grid-connected transformer 104 refers to a substation (or distribution station) that combines high-voltage switchgear, distribution transformers, and low-voltage distribution equipment according to a specific wiring scheme and installs them in a box-type enclosure. During the process of supplying power to the AC load, the inverter 102 (such as a centralized photovoltaic inverter) can output AC voltage to the grid-connected transformer 104 based on the combined DC voltage. At this time, the grid-connected transformer 104 can supply power to the AC load based on the AC voltage input to the inverter 102. During this power supply process, because the inverter 102 has higher operating efficiency and power supply safety, the power supply efficiency and safety of the power supply system 10 can be improved, and its adaptability is stronger.

[0045] See Figure 4 , Figure 4 This is a structural schematic diagram of the inverter provided in this application. Figure 4As shown, the inverter 20 includes one or more DC / DC conversion units 201, an inverter unit 202, and a controller 203. The DC / DC conversion unit 201 includes a DC input source 2011, a multi-terminal selection switch 2012, and a DC / DC conversion circuit 2013. The first terminal of the multi-terminal selection switch 2012 is connected to the input terminal of the DC / DC conversion circuit 2013. The output terminal of the DC / DC conversion circuit 2013 serves as the output terminal of the DC / DC conversion unit 201 and is connected to the input terminal of the inverter unit 202. The second terminal of the multi-terminal selection switch 2012 is connected to the DC input source 2011. The other terminals of the multi-terminal selection switch 2012 are connected to the output terminal of the inverter unit 202. The output terminal of the inverter unit 202 can be connected to an AC load. The multi-terminal selection switch 2012 can also be called a multiplexer or a selector. During multi-channel electrical connection, it can select one or more channels to be active as needed, thereby achieving channel expansion or multiplexing. Examples include 4-to-1, dual 4-to-1, and 8-to-1 selection switches. The multi-terminal gating switch 2012 can be any one or a combination of mechanical switches, active semiconductor devices, and passive semiconductor devices. For example, please refer to... Figure 5 , Figure 5 This is a schematic diagram of the structure of the multi-terminal selection switch provided in an embodiment of this application. For example... Figure 5 As shown, Figure 5 (a) and (b) are mechanical switches. Figure 5 (c) and (g) are active semiconductor devices. Figure 5 (d) is a passive semiconductor device. Figure 5 (e) represents a combination of active and passive semiconductor devices. Figure 5 (f) is a combination of mechanical switch and active semiconductor device. The multi-terminal selector switch 2012 can also be a combination of mechanical and active semiconductor device (not shown in the figure), or a combination of mechanical switch, active semiconductor device and passive semiconductor device (not shown in the figure), etc.

[0046] Figure 4 The illustration shows an example where each DC / DC conversion unit in one or more DC / DC conversion units 201 is first connected in parallel and then connected to the input terminal of inverter unit 202. It can be understood that each DC / DC conversion unit can also be connected to different input ports of inverter unit 202 to achieve parallel connection within inverter unit 202. This application embodiment does not make specific limitations.

[0047] In some feasible implementations, the controller 203 can be used to control the first terminal of the multi-terminal selection switch 2012 in the DC / DC converter unit 201 to connect the second terminal, thereby establishing a connection between the DC / DC converter circuit 2013 and the DC input source 2011 in the DC / DC converter unit 201. The controller 203 can also be used to control the first terminal of the multi-terminal selection switch 2012 in the DC / DC converter unit 201 to connect other terminals when the output parameter of the inverter unit 202 is greater than or equal to a first threshold and the output parameter of the DC / DC converter unit 201 is less than or equal to a second threshold, so that the DC / DC converter circuit 2013 and the inverter unit 202 are connected in parallel, wherein the DC / DC converter circuit 2013 is used to shunt or replace the input current of the inverter unit 202. The first threshold and the second threshold can be predefined values, and the first threshold and the second threshold can be the same or different.

[0048] Specifically, when the output parameters of inverter unit 202 reach a certain stable value, this process can be called steady state. When the output parameters of inverter unit 202 change from a certain stable value, this process can be called transient state. When the output of inverter unit 202 is in steady state, for example when the output parameters of inverter unit 202 are at a stable value, the first terminal of multi-terminal selector switch 2012 is connected to the second terminal, establishing a connection between DC / DC conversion circuit 2013 in DC / DC conversion unit 201 and DC input source 2011. That is, the DC input source's electrical energy is transferred to inverter unit 202 through DC / DC conversion circuit 2013 in one or more DC / DC conversion units, and then inverter unit 202 supplies power to AC load. When the output of inverter unit 202 is transient, such as when the grid voltage suddenly rises or falls, and the output parameter of inverter unit 202 is greater than or equal to a first threshold (e.g., the first threshold is a stable value of the output parameter), the first terminal of multi-terminal selector switch 2012 can be disconnected from the second terminal, and the first terminal can be connected to the other terminals. This allows the DC / DC conversion circuit 2013 in the DC / DC conversion unit 201, which is idle or has low operating intensity (e.g., the output parameter of DC / DC conversion unit 201 is less than or equal to the second threshold; if the second threshold is 0, the output voltage of DC / DC conversion unit 201 is 0, indicating that DC / DC conversion unit 201 is in an idle state), to be connected in parallel with inverter unit 202. This allows the DC / DC conversion circuit 2013 in the idle or low operating intensity DC / DC conversion unit 201 to shun or replace the input current (overload current) of inverter unit 202, thereby improving the transient overcurrent capability of inverter unit 202. Furthermore, the number of DC / DC conversion circuits from one or more DC / DC conversion units that need to be connected in parallel to inverter unit 202 can be determined based on the magnitude of the overload current of the inverter unit, thereby mitigating overload or transient situations in inverter unit 202. By connecting the DC / DC conversion circuits in parallel to inverter unit 202, idle DC / DC conversion circuits can be continuously connected to the grid, thus achieving the effect of rapid power restoration for the branch of the DC / DC conversion unit.

[0049] Furthermore, one or more DC / DC conversion units 201 can be connected to inverter units 202 via bus capacitors. These bus capacitors can be a single bus capacitor or multiple bus capacitors connected in series, and can be used for energy storage. Figure 4In the inverter shown, when the output parameter of the inverter unit 202 is greater than or equal to the first threshold and the output parameter of the DC / DC conversion unit 201 is less than or equal to the second threshold, the controller 203 controls the first terminal of the multi-terminal selection switch 2012 in the DC / DC conversion unit 201 to connect to the other terminals, so that the DC / DC conversion circuit 2013 in the DC / DC conversion unit 201 and the inverter unit 202 are connected in parallel. Since the connection between the first terminal and the second terminal of the multi-terminal selection switch 2012 is broken, that is, the DC / DC conversion circuit 2013 in the DC / DC conversion unit 201 and the DC input source 2011 are disconnected, the input terminal of the DC / DC conversion circuit 2013 is connected to the output terminal of the inverter unit 202. At this time, a voltage can be maintained by the bus capacitor, and no energy enters or leaves.

[0050] Further optionally, when the output parameter of the inverter unit 202 recovers from being greater than or equal to the first threshold to being less than the first threshold, the controller 203 can also be used to control the first terminal of the multi-terminal selection switch 2012 in the DC / DC converter unit 201 to disconnect from other terminals and connect the first terminal to the second terminal, so as to establish the connection between the DC / DC converter circuit 2013 and the DC input source 2011 in the DC / DC converter unit 201.

[0051] The output parameters of inverter unit 202 can be any one or more of the following: current, voltage, active power, reactive power, phase angle, and AC output frequency. The output parameters of DC / DC converter unit 201 can be any one or more of the following: current, voltage, active power, reactive power, phase angle, and AC output frequency. For example, the output parameter of both inverter unit 202 and DC / DC converter unit 201 can be voltage. Optionally, please refer to [link to relevant documentation]. Figure 6 , Figure 6 This is a schematic diagram of the controller provided in an embodiment of this application, as shown below. Figure 6 As shown, the controller 203 may specifically include a control module 2031 and a voltage detection module 2032. The control module 2031 is connected to the control terminal of the multi-terminal selector switch 2012, and the controller 203 can control the multi-terminal selector switch 2012 to be turned on or off through the control module 2031. The control module 2031 is also connected to the voltage detection module 2032. The voltage detection module 2032 can be connected to the output terminals of the DC / DC converter unit 201 and the inverter unit 202, respectively. The voltage detection module 2032 is used to detect the output voltage of the DC / DC converter unit 201 and the inverter unit 202, and provides the corresponding voltage detection results to the control module 2031. It is understood that... Figure 6The controller 203 specifically includes a voltage detection module 2032, which is described exemplarily using only the output parameters of the inverter unit 202 and the DC / DC conversion unit 201 as voltage. If the output parameters of the inverter unit 202 and the DC / DC conversion unit 201 can also be any one of current, active power, reactive power, phase angle, AC output frequency, etc., then the voltage detection module 2032 can 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. This embodiment does not impose any limitations.

[0052] Optionally, the controller 203 can also control the first terminal of the multi-terminal selection switch 2012 to connect with the second terminal or with other terminals according to the grid command. In some feasible implementations, the grid command is independent of the output parameters of the inverter unit 202. That is, regardless of whether the output parameters of the inverter unit 202 are greater than or equal to a first threshold, or less than the first threshold, the controller 203 can detect the grid command or dispatch command issued by the superior authority and control the first terminal of the multi-terminal selection switch 2012 to connect with the second terminal or with other terminals according to the grid command or dispatch command. In some feasible implementations, the grid command is related to the output parameters of the inverter unit 202. That is, when the output parameters of the inverter unit 202 are greater than or equal to the first threshold, the superior authority can issue a power grid command or dispatch command to the controller 203. The controller 203 can detect the grid command or dispatch command issued by the superior authority and control the first terminal of the multi-terminal selection switch 2012 to connect with the second terminal or with other terminals according to the grid command or dispatch command.

[0053] In the inverter 20 provided in this embodiment, the controller 203 can connect the first terminal of the multi-terminal selection switch 2012 to the second terminal to establish a connection between the DC / DC conversion circuit 2013 and the DC input source 2011 (power supply unit). This ensures that the DC / DC conversion circuit 2013 uses the power provided by the DC input source 2011 to supply power to the AC load. When the inverter unit experiences transient overload, the controller can connect the first terminal of the multi-terminal selection switch 2012 to other terminals to establish a parallel connection between the idle DC / DC conversion circuit 2013 and the inverter unit 202. This ensures that the idle DC / DC conversion circuit 2013 is used to shunt or replace the input current of the inverter unit 202. In other words, the redundant DC / DC conversion circuit during the transient period of the power grid can be fully utilized and converted to inverter mode. It can be connected in parallel with the inverter unit to increase the overload capacity of the inverter side, thereby improving the efficiency and safety of the inverter 20 and making it highly adaptable.

[0054] In some feasible implementations, Figure 4The inverter unit 202 can be an N-phase inverter unit, and the other terminals of the multi-terminal selection switch 2012 can 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. The M other terminals of the multi-terminal selection switch 2012 are connected to any one or more of the N-phase output terminals of the inverter unit 202.

[0055] For example, such as Figure 4 As shown, M is 1 and N is 1, meaning that there is one other terminal of the multi-terminal selection switch 2012. The inverter unit 202 is a single-phase inverter unit, so one other terminal of the multi-terminal selection switch 2012 is connected to the single-phase output terminal of the inverter unit 202.

[0056] For example, please see Figure 7 , Figure 7 This is another structural schematic diagram of the inverter provided in this application. For example... Figure 7 As shown, M is 1 and N is 3, meaning that there is one other terminal of the multi-terminal selection switch 2012. The inverter unit 202 is a three-phase inverter unit, including phase A inverter bridge arm, phase B inverter bridge arm and phase C inverter bridge arm. One other terminal of the multi-terminal selection switch 2012 in the DC / DC conversion unit 201 is connected to any one of the three phase output terminals of the inverter unit 202.

[0057] For example, please see Figure 8 , Figure 8 This is yet another structural schematic diagram of the inverter provided in this application. For example... Figure 8 As shown, M is 2 and N is 3, meaning that the multi-terminal selection switch 2012 has 2 other terminals. The inverter unit 202 is a three-phase inverter unit, including phase A inverter bridge arm, phase B inverter bridge arm and phase C inverter bridge arm. The two other terminals of the multi-terminal selection switch 2012 in the DC / DC conversion unit 201 are connected to any two of the three-phase output terminals of the inverter unit 202.

[0058] For example, please see Figure 9 , Figure 9 This is yet another structural schematic diagram of the inverter provided in this application. For example... Figure 9 As shown, M is 3 and N is 3, meaning that the multi-terminal selection switch 2012 has 3 other terminals. The inverter unit 202 is a three-phase inverter unit, including phase A inverter bridge arm, phase B inverter bridge arm and phase C inverter bridge arm. The three other terminals of the multi-terminal selection switch 2012 in the DC / DC conversion unit 201 are respectively connected to the three-phase output terminals of the inverter unit 202.

[0059] It is understandable that the above Figure 4 , Figures 7-9For illustrative purposes, this application embodiment does not limit the number of other terminals of the multi-terminal selection switch 2012 or the number of output phases of the inverter unit 202. For example, the inverter unit can also be a four-phase inverter unit, a six-phase inverter unit, or a twelve-phase inverter unit, etc. The number of other terminals of the multi-terminal selection switch 2012 can be determined according to the connection with the multi-phase output terminals of the inverter unit.

[0060] In the inverter 20 provided in this embodiment, the controller 203 can connect the first terminal of the multi-terminal selection switch 2012 to the second terminal to establish a connection between the DC / DC conversion circuit 2013 and the DC input source 2011 (power supply unit). This ensures that the DC / DC conversion circuit 2013 uses the power provided by the DC input source 2011 to supply power to the AC load. When the inverter unit experiences transient overload, the controller can connect the first terminal of the multi-terminal selection switch 2012 to other terminals to establish a parallel connection between the idle DC / DC conversion circuit 2013 and the inverter unit 202. This ensures that the idle DC / DC conversion circuit 2013 is used to shunt or replace the input current of the inverter unit 202. In other words, the redundant DC / DC conversion circuit during the transient period of the power grid can be fully utilized and converted to inverter mode. It can be connected in parallel with the inverter unit to increase the overload capacity of the inverter side, thereby improving the efficiency and safety of the inverter 20 and making it highly adaptable. Secondly, exemplary connection descriptions are provided for the other terminals of the multi-terminal gating switch 2012 and the multi-phase output terminals of the inverter unit 202, thereby improving the circuit topology flexibility of the inverter 20.

[0061] In some feasible implementations, in Figure 4 Based on the inverter 20 shown, please refer to Figure 10 , Figure 10 This is yet another structural schematic diagram of the inverter provided in this application. For example... Figure 10 As shown, the inverter unit 202 can be an N-phase inverter unit, which may include N first inductors. One phase output terminal of the N-phase output terminal of the inverter unit 202 is connected to an AC load through one of the first inductors. The M other terminals of the multi-terminal selector switch 2012 are connected to one end of the first inductor connected to any one or more of the N-phase output terminals of the inverter unit 202.

[0062] In some further feasible embodiments, the DC / DC conversion unit 201 may also include a second inductor, with the first terminal of the multi-terminal selection switch 2012 connected to the input terminal of the DC / DC conversion circuit 2013 through the second inductor, or the second terminal of the multi-terminal selection switch 2012 connected to the DC input source 2011 through the second inductor.

[0063] Some feasible implementation methods, such as Figure 10The inverter 20 shown in (a) and (b) includes a second inductor L2 in the DC / DC conversion unit 201. The first terminal of the multi-terminal selector switch 2012 is connected to the input terminal of the DC / DC conversion circuit 2013 via the second inductor L2. The inverter unit 202 is a single-phase inverter unit, including a first inductor L1. The single-phase output terminal of the inverter unit 202 is connected to an AC load via the first inductor L1. One other terminal of the multi-terminal selector switch 2012 is connected to one end of the first inductor L1 connected to the single-phase output terminal of the inverter unit 202. Specifically, it can be as follows... Figure 10 One other terminal of the multi-terminal selector switch 2012 shown in (a) is connected to the first terminal of the first inductor L1 connected in the single-phase output terminal of the inverter unit 202, or as shown in (a). Figure 10 One of the other terminals of the multi-terminal selector switch 2012 shown in (b) is connected to the second terminal of the first inductor L1 connected in the single-phase output terminal of the inverter unit 202.

[0064] Some feasible implementation methods, such as Figure 10 Inverter 20, as shown in (c) and (d), includes a second inductor L2 in DC / DC conversion unit 201. The second terminal of multi-terminal selector switch 2012 is connected to DC input source 2011 via the second inductor L2. Inverter unit 202 is a single-phase inverter unit, including a first inductor L1. The single-phase output terminal of inverter unit 202 is connected to an AC load via the first inductor L1. One other terminal of multi-terminal selector switch 2012 is connected to one end of the first inductor L1 connected to the single-phase output terminal of inverter unit 202. Specifically, it can be as follows... Figure 10 One other terminal of the multi-terminal selector switch 2012 shown in (c) is connected to the first terminal of the first inductor L1 connected in the single-phase output terminal of the inverter unit 202, or as shown in (c). Figure 10 One of the other terminals of the multi-terminal selector switch 2012 shown in (d) is connected to the second terminal of the first inductor L1 connected in the single-phase output terminal of the inverter unit 202.

[0065] Understandable. Figure 10 The inverter unit 202 is used as an example of a single-phase inverter unit. The inverter unit 202 can be an N-phase inverter unit, such as a three-phase inverter unit, a four-phase inverter unit, a six-phase inverter unit, or a twelve-phase inverter unit, etc. It includes N first inductors L1. One of the N-phase output terminals of the inverter unit is connected to the AC load through one of the first inductors L1. The M other terminals of the multi-terminal selector switch are connected to one end of the first inductor connected to any one or more of the N-phase output terminals of the inverter unit. These will not be illustrated in detail here.

[0066] 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. When the DC / DC conversion circuit 2013 and the inverter unit 202 are connected in parallel by the controller 203, the first inductor L1 and / or the second inductor L2 can be connected into the parallel circuit. The complexity of implementation is different. Connecting the first inductor L1 and / or the second inductor L2 can improve the reactance capability, thereby improving the stability of the inverter 20.

[0067] For some feasible implementation methods, please refer to Figure 11 , Figure 11 This is a schematic diagram of the DC / DC converter circuit and inverter unit provided in this application. Figure 11 As shown, the DC / DC converter circuit 2013 and the inverter unit 202 can be multi-level, such as two-level, four-level, six-level, etc. The embodiments of this application do not limit the number of levels of the DC / DC converter circuit 2013 and the inverter unit 202.

[0068] The following section will provide an example illustrating the inverter's control method; please refer to [link / reference]. Figure 12 , Figure 12 This is a flowchart illustrating the control method for the inverter provided in this application. This method is applicable to inverters (such as those described above). Figures 2-8 The inverter 20 shown is a controller. The inverter includes one or more DC / DC conversion units, an inverter unit, and a controller. The DC / DC conversion unit includes a DC input source, a DC / DC conversion circuit, and a multi-terminal selection switch. The first terminal of the multi-terminal selection switch is connected to the input terminal of the DC / DC conversion circuit, and the output terminal of the DC / DC conversion circuit serves as the output terminal of the DC / DC conversion unit, connected to the input terminal of the inverter unit. The second terminal of the multi-terminal selection switch is connected to the DC input source, and the other terminals of the multi-terminal selection switch are connected to the output terminal of the inverter unit. The output terminal of the inverter unit is connected to an AC load. Figure 12 As shown, the method includes the following steps S1201 to S1202:

[0069] Step S1201: Control the first terminal of the multi-terminal selection switch in the DC / DC converter unit to connect the second terminal, so as to establish the connection between the DC / DC converter circuit and the DC input source in the DC / DC converter unit.

[0070] In some feasible implementations, the controller 203 can be used to control the first terminal of the multi-terminal selector switch 2012 in the DC / DC converter unit 201 to connect the second terminal, thereby establishing a connection between the DC / DC converter circuit 2013 and the DC input source 2011 in the DC / DC converter unit 201. Specifically, when the output parameters of the inverter unit 202 reach a certain stable value, this process can be called steady state. When the output parameters of the inverter unit 202 change from a certain stable value, this process can be called transient state. When the output of the inverter unit 202 is in steady state, for example, when the output parameters of the inverter unit 202 are at a stable value, the first terminal of the multi-terminal selector switch 2012 connects the second terminal, establishing a connection between the DC / DC converter circuit 2013 and the DC input source 2011 in the DC / DC converter unit 201. That is, the DC power from their respective DC input sources is transferred to the inverter unit 202 through one or more DC / DC converter circuits 2013, and then the inverter unit 202 supplies power to the AC load.

[0071] Step S1202: When the output parameter of the inverter unit is greater than or equal to the first threshold and the output parameter of the DC / DC converter unit is less than or equal to the second threshold, control the first terminal of the multi-terminal selection switch in the DC / DC converter unit to connect to the other terminals, so that the DC / DC converter circuit and the inverter unit are connected in parallel.

[0072] In some feasible implementations, the controller 203 can also be used to control the first terminal of the multi-terminal selection switch 2012 in the DC / DC converter 201 to connect to other terminals when the output parameter of the inverter unit 202 is greater than or equal to a first threshold and the output parameter of the DC / DC converter 201 is less than or equal to a second threshold, so that the DC / DC converter circuit 2013 in the DC / DC converter 201 and the inverter unit 202 are connected in parallel, wherein the DC / DC converter circuit is used to shunt or replace the input current of the inverter unit. Specifically, when the output of inverter unit 202 is transient, such as when the grid voltage suddenly rises or falls, and the output parameter of inverter unit 202 is greater than or equal to a first threshold (e.g., the first threshold is a stable value of the output parameter), the first terminal of multi-terminal selector switch 2012 can be disconnected from the second terminal, and the first terminal can be connected to the other terminals. This allows the DC / DC conversion circuit 2013 in the DC / DC conversion unit 201, which is idle or has low operating intensity (e.g., the output parameter of DC / DC conversion unit 201 is less than or equal to the second threshold; if the second threshold is 0, the output voltage of DC / DC conversion unit 201 is 0, indicating that DC / DC conversion unit 201 is in an idle state), to be connected in parallel with inverter unit 202. This allows the DC / DC conversion circuit 2013 in the DC / DC conversion unit 201, which is idle or has low operating intensity, to shun or replace the input current (overload current) of inverter unit 202, thereby improving the transient overcurrent capability of inverter unit 202. By connecting the DC / DC converter circuit in parallel to the inverter unit 202, the idle DC / DC converter circuit can be continuously connected to the grid, thereby achieving the effect of fast power restoration of the DC / DC converter unit branch.

[0073] Further optionally, when the output parameter of the inverter unit 202 recovers from being greater than or equal to the first threshold to being less than the first threshold, the controller 203 can also be used to control the first terminal of the multi-terminal selection switch 2012 in the DC / DC converter unit 201 to disconnect from other terminals and connect the first terminal to the second terminal, so as to establish the connection between the DC / DC converter circuit 2013 and the DC input source 2011 in the DC / DC converter unit 201.

[0074] In specific implementation, further operations performed by the controller in the inverter control method provided in this application can be found in the above-mentioned... Figures 4 to 10 The implementation method of the inverter 20 and its working principle by the controller 203 shown will not be described in detail here.

[0075] In the method provided in this application, the controller can connect the first terminal of the multi-terminal selection switch to the second terminal to establish a connection between the DC / DC conversion circuit and the DC input source, thereby ensuring that the DC / DC conversion circuit uses the electrical energy provided by the DC input source to supply power to the AC load. When the inverter unit experiences transient overload, the controller can connect the first terminal of the multi-terminal selection switch to other terminals to establish a parallel connection between the idle DC / DC conversion circuit and the inverter unit, thereby ensuring that the idle DC / DC conversion circuit is used to shunt or replace the input current of the inverter unit. This can improve the inverter's inverter overload capacity, thereby improving the inverter's working efficiency and safety, and providing strong adaptability.

[0076] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An inverter, characterized in that, The inverter includes one or more DC / DC conversion units, an inverter unit, and a controller. The DC / DC conversion unit includes a DC input source, a DC / DC conversion circuit, and a multi-terminal selection switch. The first terminal of the multi-terminal selection switch is connected to the input terminal of the DC / DC conversion circuit, and the output terminal of the DC / DC conversion circuit serves as the output terminal of the DC / DC conversion unit and is connected to the input terminal of the inverter unit. The second terminal of the multi-terminal selection switch is connected to the DC input source, and the other terminals of the multi-terminal selection switch are connected to the output terminal of the inverter unit. The controller is used to control the first terminal of the multi-terminal selection switch in the DC / DC converter unit to connect the second terminal, so as to establish the connection between the DC / DC converter circuit and the DC input source in the DC / DC converter unit; The controller is further configured to, when the output parameter of the inverter unit is greater than or equal to a first threshold and the output parameter of the DC / DC converter unit is less than or equal to a second threshold, control the first terminal of the multi-terminal selection switch in the DC / DC converter unit to connect to the other terminals, so that the DC / DC converter circuit and the inverter unit are connected in parallel; the DC / DC converter circuit is switched to inverter mode to shunt or replace the input current of the inverter unit.

2. The inverter according to claim 1, characterized in that, The inverter unit is an N-phase inverter unit, and the other terminals of the multi-terminal selection switch are 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. The M other terminals of the multi-terminal selector switch are connected to any one or more of the N phase output terminals of the inverter unit.

3. The inverter according to claim 2, characterized in that, The inverter unit includes N first inductors, and one of the N phase output terminals of the inverter unit is connected to an AC load through one of the first inductors.

4. The inverter according to claim 3, characterized in that, The M other terminals of the multi-terminal selector switch are connected to one end of the first inductor, which is connected to any one or more of the N-phase output terminals of the inverter unit.

5. The inverter according to claim 2 or 3, characterized in that, The DC / DC conversion unit also includes a second inductor; the first terminal of the multi-terminal selector switch is connected to the input terminal of the DC / DC conversion circuit through the second inductor.

6. The inverter according to claim 2 or 3, characterized in that, The DC / DC converter unit also includes a second inductor; the second terminal of the multi-terminal selector switch is connected to the DC input source through the second inductor.

7. The inverter according to any one of claims 1-4, characterized in that, The multi-terminal selection switch is any one or a combination of the following: Mechanical switches, active semiconductor devices, passive semiconductor devices.

8. The inverter according to any one of claims 1-4, characterized in that, The output parameters of the inverter unit and / or the DC / DC converter unit are any one or more of the following: Current, voltage, active power, reactive power, phase angle, and AC output frequency.

9. A control method for an inverter, characterized in that, The inverter includes one or more DC / DC conversion units, an inverter unit, and a controller. The DC / DC conversion unit includes a DC input source, a DC / DC conversion circuit, and a multi-terminal selection switch. The first terminal of the multi-terminal selection switch is connected to the input terminal of the DC / DC conversion circuit, and the output terminal of the DC / DC conversion circuit serves as the output terminal of the DC / DC conversion unit and is connected to the input terminal of the inverter unit. The second terminal of the multi-terminal selection switch is connected to the DC input source, and the other terminals of the multi-terminal selection switch are connected to the output terminal of the inverter unit. The method includes: The controller controls the first terminal of the multi-terminal selection switch in the DC / DC converter unit to connect to the second terminal, thereby establishing the connection between the DC / DC converter circuit and the DC input source in the DC / DC converter unit. When the output parameter of the inverter unit is greater than or equal to a first threshold and the output parameter of the DC / DC converter unit is less than or equal to a second threshold, the controller controls the first terminal of the multi-terminal selection switch in the DC / DC converter unit to connect to the other terminals, so that the DC / DC converter circuit and the inverter unit are connected in parallel; the DC / DC converter circuit is switched to inverter mode to shunt or replace the input current of the inverter unit.

10. A power supply system, characterized in that, The power supply system includes a power supply unit and an inverter as described in any one of claims 1-8.

11. The power supply system according to claim 10, characterized in that, The power supply unit is a photovoltaic array, and the inverter is a photovoltaic inverter; or, the power supply unit is a wind turbine or an energy storage battery, and the inverter is an energy storage inverter.

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