Inverter, method and power supply system

Abstract

The invention discloses an inverter, a method and a power supply system, the inverter comprises an inverter circuit, a first group of switches and a second group of switches, and a path between an alternating current side of the inverter circuit and a power grid comprises less than or equal to one group of switches; the first group of switches and the second group of switches are arranged on a path between the direct current side of the inverter circuit and the direct current source; or, the first group of switches are arranged on the path between the direct current side of the inverter circuit and the direct current source, and the second group of switches are arranged on the path between the alternating current side of the inverter circuit and the power grid. According to the scheme, the number of switches can be reduced, switching loss is reduced, and the power generation efficiency of the inverter is improved.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically to an inverter, method, and power supply system. Background Technology

[0002] An inverter can convert direct current (DC) to alternating current (AC) for grid connection. The AC side of the inverter is generally connected to the grid through two sets of AC switches connected in series. The purpose of setting two sets of AC switches is to achieve redundancy protection. When performing maintenance on the AC side, it is necessary to ensure that the inverter is disconnected from the DC source. Therefore, if one set of AC switches fails, the remaining set of AC switches can operate reliably, avoiding the risk of electric shock to maintenance personnel.

[0003] However, setting two sets of AC switches on the AC side has the following disadvantages: First, each phase of the three-phase inverter needs to be set, resulting in a large number of switches. Summary of the Invention

[0004] In view of this, this application provides an inverter, method, and power supply system that can save the number of switches, reduce switching losses, and improve the power generation efficiency of the inverter.

[0005] This application provides an inverter, including: an inverter circuit, a first set of switches and a second set of switches, wherein the number of switch sets in the path between the AC side of the inverter circuit and the power grid is less than or equal to one; both the first set of switches and the second set of switches are disposed in the path between the DC side of the inverter circuit and the DC source; or, the first set of switches is disposed in the path between the DC side of the inverter circuit and the DC source, and the second set of switches is disposed in the path between the AC side of the inverter circuit and the power grid.

[0006] One possible implementation further includes: a DC bus capacitor; a first end of the DC bus capacitor is connected to the DC positive terminal of the inverter circuit, and a second end of the DC bus capacitor is connected to the DC negative terminal of the inverter circuit; a second set of switches is disposed in the path between the DC bus capacitor and the DC side of the inverter circuit, and the first set of switches is disposed in the path between the DC bus capacitor and the DC source; or, both the first set of switches and the second set of switches are disposed in the path between the DC bus capacitor and the DC side of the inverter circuit; or, both the first set of switches and the second set of switches are disposed in the path between the DC bus capacitor and the DC source.

[0007] One possible implementation further includes: a DC / DC / DC circuit; a first terminal of the DC / DC circuit is connected to the DC source, the positive terminal of the second terminal of the DC / DC circuit is connected to the first terminal of the DC bus capacitor, and the negative terminal of the second terminal of the DC / DC circuit is connected to the second terminal of the DC bus capacitor; both the first set of switches and the second set of switches are disposed in the path between the DC bus capacitor and the DC source, specifically: both the first set of switches and the second set of switches are disposed in the path between the DC bus capacitor and the DC / DC circuit; or, the first set of switches is disposed in the path between the DC bus capacitor and the second terminal of the DC / DC circuit, and the second set of switches is disposed in the path between the first terminal of the DC / DC circuit and the DC source.

[0008] In one possible implementation, the DC bus capacitor includes a first DC bus capacitor and a second DC bus capacitor. A first terminal of the first DC bus capacitor is connected to the positive DC terminal of the inverter circuit, and a second terminal of the first DC bus capacitor is connected to the midpoint of the DC bus. A first terminal of the second DC bus capacitor is connected to the midpoint of the DC bus, and a second terminal of the second DC bus capacitor is connected to the negative DC terminal of the inverter circuit. The midpoint of the DC bus is connected to the midpoint of the DC side of the inverter circuit. When one set of switches (either the first set of switches or the second set of switches) is installed in the path between the DC bus capacitor and the DC side of the inverter circuit, the set of switches includes a switch connected between the midpoint of the DC bus and the midpoint of the DC side.

[0009] One possible implementation further includes: a filter circuit; the filter circuit is connected between the AC side of the inverter circuit and the power grid; the common terminal of the filter capacitor in the filter circuit is connected to the midpoint of the DC side of the inverter circuit.

[0010] One possible implementation further includes: a controller; a first terminal of the first set of switches is connected to the DC source, a second terminal of the first set of switches is connected to the DC bus capacitor, and a second set of switches is disposed on the path between the AC side of the inverter circuit and the power grid; the controller is used to control the first set of switches to close before the inverter is connected to the grid, so that the DC source charges the DC bus capacitor; and to control the second set of switches to close when the voltage of the DC bus capacitor reaches a first voltage threshold.

[0011] One possible implementation further includes: a pre-charging circuit; the pre-charging circuit is connected in parallel across the first set of switches; the controller is further configured to, when charging the DC bus capacitor, first control the pre-charging circuit to be turned on before controlling the first set of switches to be closed, and then control the first set of switches to be closed after a preset time or when the voltage of the DC bus capacitor reaches a second voltage threshold, wherein the second voltage threshold is less than or equal to the first voltage threshold.

[0012] One possible implementation further includes: a controller; a first terminal of the first set of switches is connected to a second terminal of the DC / DC circuit, and a second terminal of the first set of switches is connected to the DC bus capacitor; the controller is configured to change the voltage of the first terminal or the voltage of the second terminal of the DC / DC circuit when the first set of switches is controlled to be disconnected, and determine whether the first set of switches has been successfully disconnected by the voltage difference between the first terminal and the second terminal of the first set of switches.

[0013] One possible implementation further includes: a controller; the second set of switches is disposed on the path between the AC side of the inverter circuit and the power grid; the controller is used to change the AC side voltage of the inverter circuit when the second set of switches is controlled to be disconnected, and to determine whether the second set of switches has been successfully disconnected by the voltage difference between the first and second terminals of the second set of switches.

[0014] In one possible implementation, a discharge load is connected in parallel to the DC bus capacitor or the filter capacitor via a controllable switch; the inverter further includes: a controller; a first terminal of the first set of switches is connected to the DC source, and a second terminal of the first set of switches is connected to the DC bus capacitor; the controller is used to control the DC / DC circuit to operate when the first set of switches is closed, transferring the energy of the DC bus capacitor or the energy of the filter capacitor connected to the AC side of the inverter circuit to the DC source or the load; or, the controller is used to control the controllable switch to close, so that the discharge load consumes the energy on the DC bus capacitor or the filter capacitor.

[0015] In one possible implementation, the inverter further includes: a controller; a first terminal of the first set of switches is connected to the DC source, and a second terminal of the first set of switches is connected to the DC bus capacitor; the controller is used to control at least one of the DC / DC circuits in the inverter or the inverter circuit to operate when the first set of switches is closed, thereby consuming the energy of the DC bus capacitor; or, the inverter further includes: an auxiliary power supply; the controller is also used to increase the energy drawn by the auxiliary power supply from the DC bus capacitor.

[0016] This application also provides a control method for an inverter, wherein the path between the AC side of the inverter circuit and the power grid includes one or fewer sets of switches. The method includes: when the output terminal of the inverter needs to be disconnected from the DC source, controlling at least one set of a first set of switches or a second set of switches to disconnect; both the first set of switches and the second set of switches are located on the path between the DC side of the inverter circuit and the DC source; or, the first set of switches is located on the path between the DC side of the inverter circuit and the DC source, and the second set of switches is located on the path between the AC side of the inverter circuit and the power grid.

[0017] In one possible implementation, the inverter further includes a DC bus capacitor; a first terminal of the DC bus capacitor is connected to the DC positive terminal of the inverter circuit, and a second terminal of the DC bus capacitor is connected to the DC negative terminal of the inverter circuit; a first terminal of the first set of switches is connected to the DC source, and a second terminal of the first set of switches is connected to the DC bus capacitor; the second set of switches is located on the path between the AC side of the inverter circuit and the power grid; the method further includes: before the inverter is connected to the grid, controlling the first set of switches to close, so that the DC source charges the DC bus capacitor; and controlling the second set of switches to close when the voltage of the DC bus capacitor reaches a first voltage threshold.

[0018] In one possible implementation, the first set of switches is connected between the DC side and the DC bus capacitor; the method further includes: when charging the DC bus capacitor, before controlling the first set of switches to close, controlling the pre-charging circuit to be turned on, and after a preset time or when the voltage of the DC bus capacitor reaches a second voltage threshold, controlling the first set of switches to close, wherein the second voltage threshold is less than or equal to the first voltage threshold.

[0019] In one possible implementation, the inverter further includes a DC / DC circuit connected between the DC bus capacitor and the inverter circuit; the first set of switches is connected between the DC / DC circuit and the DC bus capacitor; the method further includes: when the first set of switches is controlled to be open, changing the first terminal voltage or the second terminal voltage of the DC / DC circuit, and determining whether the first set of switches has been successfully opened by the voltage difference between the first terminal and the second terminal of the first set of switches.

[0020] One possible implementation is that the second set of switches is located on the path between the AC side of the inverter circuit and the power grid; the method further includes: when the second set of switches is controlled to be open, changing the AC side voltage of the inverter circuit, and determining whether the second set of switches has been successfully opened by the voltage difference between the first and second terminals of the second set of switches.

[0021] In one possible implementation, the inverter further includes a DC / DC circuit connected between the DC bus capacitor and the inverter circuit; the first set of switches is connected between the DC source and the DC bus capacitor; the method further includes: when the first set of switches is closed, controlling the DC / DC circuit to operate, transferring the energy of the DC bus capacitor or the energy of the filter capacitor connected to the AC side of the inverter circuit to the DC source or load; or, discharging the load in parallel through a controllable switch on the DC bus capacitor or the filter capacitor; the method further includes: controlling the controllable switch to close, causing the discharge load to consume the energy on the DC bus capacitor or the filter capacitor.

[0022] In one possible implementation, the inverter further includes a DC / DC circuit connected between the DC bus capacitor and the inverter circuit; the first set of switches is connected between the DC source and the DC bus capacitor; the method further includes: when the first set of switches is closed, controlling at least one of the DC / DC circuit or the inverter circuit to operate, consuming the energy of the DC bus capacitor; or, the inverter further includes: an auxiliary power supply; the method further includes: increasing the energy drawn by the auxiliary power supply from the DC bus capacitor.

[0023] This application also provides a power supply system including the inverter described in the above embodiments, wherein the DC side of the inverter is used to connect to a DC source; the DC source includes at least one of photovoltaic or battery.

[0024] This application provides a control device, including a processor and a memory. The memory is used to store programs, instructions, or code, and the processor is used to execute the programs, instructions, or code in the memory to perform the methods described above.

[0025] This application provides a computer-readable storage medium storing a computer program, which is loaded by a processor to execute the method described above.

[0026] The inverter provided in this application embodiment requires disconnecting the AC output terminal from the DC power source during maintenance. A redundant first and second set of switches are configured; for example, either the first or second set of switches can be controlled to disconnect, thereby protecting personal safety. Furthermore, the inverter provided in this application embodiment has no switches or only one set of switches on the AC side, reducing the number of AC side switches and thus the inverter's size and cost. On the other hand, during normal operation, because the DC side voltage is higher than the AC side voltage, the DC side current is smaller, resulting in lower losses in the DC side switches and improved power generation efficiency. Attached Figure Description

[0027] Figure 1 A schematic diagram of an inverter provided in an embodiment of this application;

[0028] Figure 2 A schematic diagram of yet another inverter provided in the embodiments of this application;

[0029] Figure 3 A schematic diagram of another inverter provided in the embodiments of this application;

[0030] Figure 4 An inverter circuit diagram provided for an embodiment of this application;

[0031] Figure 5 A schematic diagram of a pre-charging circuit provided for an embodiment of this application;

[0032] Figure 6 A circuit diagram of another inverter provided in the embodiments of this application;

[0033] Figure 7 A circuit diagram of another inverter provided in the embodiments of this application;

[0034] Figure 8 A circuit diagram of another inverter provided in the embodiments of this application;

[0035] Figure 9 A circuit diagram of another inverter provided in an embodiment of this application;

[0036] Figure 10 A circuit diagram of another inverter provided in the embodiments of this application;

[0037] Figure 11 A schematic diagram of another inverter provided in the embodiments of this application;

[0038] Figure 12 A schematic diagram of a power supply system provided in an embodiment of this application;

[0039] Figure 13 A flowchart of an inverter control method provided in an embodiment of this application;

[0040] Figure 14 This is a schematic diagram of a control device provided in an embodiment of this application. Detailed Implementation

[0041] See Figure 1 The figure is a schematic diagram of an inverter provided in an embodiment of this application.

[0042] The inverter provided in this application includes: an inverter DC / AC circuit 100, a first set of switches, and a second set of switches. The path between the AC side of the inverter circuit and the power grid includes at most one set of switches; that is, the path between the AC side of the inverter circuit and the power grid includes at most one set of switches. The first set of switches and the second set of switches are redundant; if one set fails to open, the other set can open, disconnecting the DC source from the power grid. The first set of switches includes at least two switches, and the second set of switches includes at least two switches, connected in series at the positive and negative terminals, respectively.

[0043] Both the first and second sets of switches are located in the path between the DC side 30 of the DC / AC circuit 100 and the DC source, i.e., connected in series in the power transmission path; that is, the two sets of switches are connected in series at the position of the DC side 30 of the DC / AC circuit 100.

[0044] or,

[0045] The first set of switches is installed on the path between the DC side 30 of the DC / AC circuit 100 and the DC source, and the second set of switches is installed on the path between the AC side 40 of the DC / AC circuit 100 and the power grid. That is, one set of switches is installed on each of the DC side 30 and AC side 40 of the DC / AC circuit 100. All of the above paths refer to those connected in series in the power transmission path; when the switch is open, the power transmission path is broken. It should be understood that when the second set of switches is installed on the AC side 40 of the DC / AC circuit 100, the second set of switches includes three switches, one in series on each of the three phases L1, L2, and L3. The first set of switches, installed on the DC side 30, includes at least two switches: one in series with the positive DC terminal of the DC / AC circuit 100, and one in series with the negative DC terminal of the DC / AC circuit 100.

[0046] The embodiments of this application do not specifically limit the types of the first group of switches and the second group of switches, such as relays, contactors or circuit breakers.

[0047] The inverter provided in this application embodiment allows for disconnection of the DC power source from the AC side of the DC / AC circuit 100 during maintenance. This can be achieved by controlling the first or second set of switches to disconnect, thus protecting personal safety. Furthermore, the inverter provided in this application embodiment eliminates or eliminates switches on the AC side of the DC / AC circuit 100, reducing the number of AC side switches and lowering the inverter's size and cost. On the other hand, during normal operation, the DC side voltage is higher than the AC side voltage, resulting in a smaller DC side current. Consequently, the losses of the switches on the DC side are lower, improving the inverter's power generation efficiency.

[0048] In traditional technology, two sets of switches are connected in series at position 40 on the AC side of the DC / AC circuit 100 to achieve redundant protection. However, this method involves a large number of switches and significant losses.

[0049] The following diagram illustrates the various possible positions when the switch is set on the DC side of a DC / AC circuit.

[0050] See Figure 2 This figure is a schematic diagram of another inverter provided in an embodiment of this application.

[0051] The inverter provided in this application embodiment further includes a DC bus capacitor. The first terminal of the DC bus capacitor is connected to the positive DC terminal of the inverter circuit, and the second terminal of the DC bus capacitor is connected to the negative DC terminal of the inverter circuit.

[0052] Figure 2 The following example illustrates the process using two DC bus capacitors connected in series. Specifically, the DC bus capacitors include a first DC bus capacitor C1 and a second DC bus capacitor C2. The first terminal of the first DC bus capacitor C1 is connected to the positive DC terminal of the inverter circuit, and the second terminal of the first DC bus capacitor C1 is connected to the midpoint of the DC bus. The first terminal of the second DC bus capacitor C2 is connected to the midpoint of the DC bus, and the second terminal of the second DC bus capacitor C2 is connected to the negative DC terminal of the inverter circuit.

[0053] This application embodiment uses the example of both sets of switches being located on the DC side of the DC / AC circuit 100. This can include the following three scenarios:

[0054] The first method involves setting the second set of switches between the DC bus capacitor and the DC side of the DC / AC circuit 100, and setting the first set of switches between the DC bus capacitor and the DC source, i.e., setting one set of switches at positions 20 and 30 respectively.

[0055] This application does not specifically limit the type of DC source; it can be at least one of photovoltaic or battery. The embodiments of this application do not specifically limit the type of battery; for example, it can be at least one of lead-acid battery, lithium-ion battery, or fuel cell.

[0056] The second type:

[0057] Both the first and second sets of switches are located between the DC bus capacitor and the DC / AC circuit 100; that is, two sets of switches are connected in series at position 30.

[0058] The third type:

[0059] Both the first and second sets of switches are located between the DC bus capacitor and the DC source, that is, two sets of switches are connected in series at position 20.

[0060] The inverters described above use DC / AC circuits as an example. The following section introduces the implementation methods of inverters that include DC / AC circuits as well as DC / DC / DC circuits.

[0061] See Figure 3 This figure is a schematic diagram of another inverter provided in an embodiment of this application.

[0062] The inverter provided in this application embodiment further includes: a DC / DC circuit 200; the first terminal of the DC / DC circuit 200 is used to connect to a DC source, the positive terminal of the second terminal of the DC / DC circuit 200 is connected to the first terminal A of the DC bus capacitor, and the negative terminal of the second terminal of the DC / DC circuit 200 is connected to the second terminal B of the DC bus capacitor.

[0063] Both the first and second sets of switches are located between the DC bus capacitor and the DC source, and can include the following two situations.

[0064] The first type: Both the first and second sets of switches are located between the DC bus capacitor and the DC / DC circuit 200; that is, both are located between... Figure 3 Position 20 in the middle.

[0065] The second type: The first set of switches is set between the DC bus capacitor and the second terminal of the DC / DC circuit 200, that is, set between the DC bus capacitor and the second terminal of the DC / DC circuit 200. Figure 3 Position 20. The second set of switches is located between the first terminal of the DC / DC circuit 200 and the DC source, i.e., it is set at... Figure 3 The position of 10 in the middle.

[0066] Normally, a manual switch is provided between the DC source and the first terminal of the DC / DC circuit 200. However, the switch in this application needs to be automatically controllable, so that the inverter controller can control the switch to open and cut off the power supply when needed. Therefore, in order to meet the connection requirements of the DC source and the DC / DC circuit 200, a 10-position switch can be set to be both manually operable and automatically controlled.

[0067] The embodiments of this application do not specifically limit the specific topology of DC / DC circuits and DC / AC circuits. A specific implementation method is described below with reference to the accompanying drawings.

[0068] See Figure 4 This figure is an inverter circuit diagram provided in an embodiment of this application.

[0069] The inverter provided in this application embodiment, taking its application in a photovoltaic system as an example, can use a photovoltaic string as the DC source. This application does not specifically limit the number of photovoltaic strings, nor does it specifically limit the number of DC / DC circuits 200. Figure 4The diagram only illustrates three DC / DC circuits 200. The first end of each of the three DC / DC circuits 200 can be connected to the corresponding photovoltaic string, and the second ends of the three DC / DC circuits 200 are connected in parallel. Figure 4 The DC / DC circuit shown is a Boost circuit. In addition, the DC / DC circuit can also be a Buck circuit, a bidirectional Buckboost circuit, an isolated DC / DC circuit, or other topologies, without specific limitations.

[0070] This application does not specifically limit the specific type of DC / AC circuit 100. Figure 4 The following section uses DC / AC circuit 100 as an example of a three-phase T-type three-level inverter circuit. However, DC / AC circuit 100 can also be used for other topologies such as type I three-level inverter, single-phase full-bridge inverter, etc., and is not limited to these.

[0071] The inverter provided in this application embodiment further includes: a filter circuit 300; the DC bus capacitors include a first DC bus capacitor C1 and a second DC bus capacitor C2, the first end of the first DC bus capacitor C1 is connected to the DC positive terminal A of the inverter circuit, the second end of the first DC bus capacitor C1 is connected to the midpoint of the DC bus, the first end of the second DC bus capacitor C2 is connected to the midpoint O of the DC bus, and the second end of the second DC bus capacitor C2 is connected to the DC negative terminal B of the inverter circuit 100.

[0072] The filter circuit 300 is connected between the AC side of the inverter circuit 100 and the power grid.

[0073] The common terminal M of the filter capacitor in the filter circuit 300 is connected to the midpoint E of the DC side of the inverter circuit 100.

[0074] Figure 4 The first set of switches, K1, is connected between the second terminal of the DC / DC circuit 200 and the DC bus capacitor. The second set of switches, K2, is connected to the AC side of the inverter circuit 100, specifically between the filter circuit 300 and the power grid.

[0075] The inverter provided in this application embodiment can also detect whether the first set of switches K1 is reliably disconnected. Specifically, the inverter provided in this application embodiment further includes a controller (not shown in the figure).

[0076] The first terminal of the first switch K1 is connected to the second terminal of the DC / DC circuit, and the second terminal of the first switch K1 is connected to the DC bus capacitor. The controller, when the first switch K1 is controlled to open, changes the voltage at either the first or second terminal of the DC / DC circuit, and determines whether the first switch K1 has successfully opened by measuring the voltage difference Vm between the first and second terminals of the first switch K1. It should be understood that when the first switch K1 is reliably opened, the voltage difference Vm between the first and second terminals of the first switch K1 is large; when the first switch K1 fails to open due to problems such as sticking, the voltage difference Vm between the first and second terminals of the first switch K1 is almost zero. The controller can compare the voltage difference Vm with a preset value to determine whether the first switch K1 has successfully opened. The inverter provided in this application, by operating the DC / DC circuit to change the voltage across the first switch K1, can effectively determine whether K1 has successfully opened. When it is determined that K1 has not successfully opened, the redundant K2 can be controlled to open.

[0077] The above describes how the controller determines whether the first set of switches K1 has been successfully disconnected. The following describes how the controller determines whether the second set of switches K2 has been successfully disconnected.

[0078] The second set of switches K2 is set on the path between the AC side of the inverter circuit and the power grid;

[0079] The controller is used to change the AC side voltage of the inverter circuit when the second set of switches K2 is controlled to be open, and to determine whether the second set of switches K2 has been successfully opened by measuring the voltage difference between the first and second terminals of the second set of switches K2. The inverter provided in this application embodiment can effectively determine whether K2 has been successfully opened by changing the voltage across the second set of switches K2 through the operation of the inverter circuit. When it is determined that K2 has not been successfully opened, the redundant K1 can be controlled to open.

[0080] The inverter provided in this embodiment of the application has a first set of switches K1 on the DC side, from... Figure 4 As can be seen, the first set of switches K1 contains two switches, which reduces the number of switches by one compared to the three-phase path on the AC side, thus saving circuit size and cost. Furthermore, since the DC voltage is typically higher than the AC voltage, a switch on the DC side will draw less current, resulting in lower losses for the same internal resistance and thus improving the inverter's power generation efficiency.

[0081] The following will continue to combine Figure 4 The timing sequence of the operation of the first set of switches K1 and the second set of switches K2 is introduced.

[0082] The inverter provided in this application embodiment also includes a controller.

[0083] The first terminal of the first set of switches K1 is connected to a DC source through the DC / DC circuit 200, and the second terminal of the first set of switches K1 is connected to the DC bus capacitor. The second set of switches K2 is set on the path between the AC side of the DC / AC circuit 100 and the power grid. Specifically, when the inverter includes a filter circuit 300, the first terminal of the filter circuit 300 is connected to the AC side of the DC / AC circuit, and the second terminal of the filter circuit 300 is connected to the power grid through the second set of switches K2.

[0084] The controller is used to close the first set of switches K1 before the inverter is connected to the grid, allowing the DC source to charge the DC bus capacitors (C1 and C2), thus establishing the DC bus voltage. When the voltage of the DC bus capacitors reaches a voltage threshold, the controller closes the second set of switches K2, allowing the inverter to start generating electricity. When the inverter circuit 100 needs to be disconnected from the grid, the connection between the grid and the DC source is disconnected. The controller can simultaneously open the first set of switches K1 and the second set of switches K2. Alternatively, it can open only one set of switches. For example, the controller can open the first set of switches K1, disconnecting the grid from the DC source, thus de-energizing the inverter circuit 100. Similarly, the controller can open the second set of switches K2, disconnecting the grid from the DC source.

[0085] The inverter provided in this application embodiment has energy storage components such as DC bus capacitors and filter capacitors between the first set of switches K1 and the second set of switches K2. To ensure that the AC port will not be energized after the second set of switches K2 fails, the DC bus capacitors or AC capacitors can be actively discharged. Several possible discharge methods are described below.

[0086] The first type:

[0087] A discharge load is connected in parallel to the DC bus capacitor or filter capacitor via a controllable switch. The filter capacitor is the capacitor connected to the AC side of the inverter circuit. The first terminal of the first set of switches K1 is connected to a DC source through the DC / DC circuit 200, and the second terminal of the first set of switches K1 is connected to the DC bus capacitor. The controller is used to control the DC / DC circuit 200 to operate when the first set of switches K1 is closed, transferring the energy of the DC bus capacitor or the filter capacitor to the DC source or load. The load here can be connected to the DC side. The DC source can be a battery connected to the DC / DC circuit 200, charging the battery with the energy of the DC bus capacitor or the filter capacitor connected to the AC side of the inverter circuit. The load can be a resistor, i.e., an energy-consuming element, which directly consumes energy to discharge the energy of the DC bus capacitor or the filter capacitor connected to the AC side of the inverter circuit.

[0088] Alternatively, in another implementation, a controller is used to control the closing of the controllable switch, causing the discharge load to consume the energy on the DC bus capacitor or the filter capacitor. For example, the discharge load can be a resistor. The energy on the DC bus capacitor or the filter capacitor is released by the discharge load consuming energy.

[0089] The second type:

[0090] The first terminal of the first set of switches K1 is connected to a DC power source. Figure 4 This example illustrates the connection of the first terminal of the first set of switches K1 to a DC source via DC / DC circuit 200. The second terminal of the first set of switches K1 is connected to a DC bus capacitor. A controller is used to control the operation of at least one of the DC / DC circuit 200 or DC / AC circuit 100 when the first set of switches K1 is closed, thereby consuming the energy of the DC bus capacitor.

[0091] The third type:

[0092] Increase the energy drawn by the auxiliary power supply from the DC bus capacitor. Most inverters include an auxiliary power supply, which draws power from the DC bus capacitor to power control circuits such as the controller. The auxiliary power supply also powers cooling devices, such as fans, increasing their speed to accelerate energy dissipation from the DC bus capacitor. This ensures that the voltage on the DC bus capacitor or filter capacitor does not exceed the set voltage value after the first switch K1 is opened.

[0093] When the DC side of the inverter circuit 100 is connected to the first set of switches K1, the inverter circuit provided in this application embodiment may further include a pre-charging circuit, see [link to relevant documentation]. Figure 5 The figure is a schematic diagram of a pre-charging circuit provided in an embodiment of this application.

[0094] The pre-charge circuit is connected in parallel across the two ends of the first set of switches; the controller is also used to control the pre-charge circuit to be turned on before controlling the first set of switches K1 to be closed when charging the DC bus capacitor, and then control the first set of switches K1 to be closed after a preset time or when the voltage of the DC bus capacitor reaches the second voltage threshold, wherein the second voltage threshold is less than or equal to the first voltage threshold.

[0095] This application does not specifically limit the form of the pre-charge circuit, but it generally includes at least a resistor and a switch. In one specific implementation, the pre-charge circuit provided in this application includes: a pre-charge resistor R and a pre-charge switch S.

[0096] The pre-charge resistor R is connected in series with the pre-charge switch S and then in parallel across the two ends of the first set of switches K1.

[0097] The controller is also used to, when charging the DC bus capacitors (i.e., charging the first DC bus capacitor C1 and the second DC bus capacitor C2), first control the pre-charge switch S to close before controlling the first set of switches K1 to close, and then control the first set of switches K1 to close after a preset time. After the first set of switches K1 is closed, the pre-charge switch S can be controlled to open.

[0098] Due to the current-limiting effect of the pre-charge resistor R, the DC source can reduce the current surge and protect the safety of the DC bus capacitor when charging it.

[0099] When the midpoint of the DC bus is connected to the midpoint of the DC side of the inverter, in addition to one switch connected in series with the positive and negative terminals, a switch also needs to be connected in series at the midpoint to completely block the electrical connection and disconnect it from the DC source.

[0100] See Figure 6 This figure is a circuit diagram of another inverter provided in an embodiment of this application.

[0101] The inverter provided in this application embodiment, when one of the first group of switches or the second group of switches is located between the DC bus capacitor and the DC side of the inverter circuit, Figure 6 The first set of switches K1 is located between the DC side and the DC bus capacitor of the DC / AC circuit 100. This set of switches includes a switch connected between the midpoint of the DC bus and the midpoint of the DC side. Figure 6 As can be seen, K1 includes three switches, two of which are connected in series on the positive bus and the negative bus, respectively, and the remaining switch is connected between the midpoint O of the DC bus and the midpoint E of the DC side. When the first set of switches K1 is opened, the connection between the DC source and the power grid can be completely disconnected.

[0102] In addition, the inverter provided in this application embodiment also includes: a filter circuit; the filter circuit is connected between the AC side of the inverter circuit and the power grid; the common terminal M of the filter capacitor in the filter circuit 300 is connected to the midpoint E of the DC side of the inverter circuit 100. When the first set of switches K1 is opened, the connection between the filter capacitor and the DC source can also be completely disconnected.

[0103] The following description, with reference to the accompanying drawings, illustrates that one set of switches can be installed on the path between the DC source and the DC / DC circuit, while the other set of switches can be installed on the path between the AC side of the DC / AC circuit and the power grid.

[0104] See Figure 7 This figure is a circuit diagram of another inverter provided in an embodiment of this application.

[0105] This application uses a photovoltaic string as the DC source for illustration. It describes an example where each input terminal of three DC / DC circuits 200 is connected to two photovoltaic strings, without specifically limiting the number of photovoltaic strings connected to each DC / DC circuit 200. The three DC / DC circuits 200 connect a total of six photovoltaic strings, with their positive terminals connected to PV1+ and PV2+, PV3+ and PV4+, and PV5+ and PV6+, respectively, and their negative terminals connected to PV1- and PV2-, PV3- and PV4-, and PV5- and PV6-, respectively.

[0106] The first set of switches K1 is connected in the path between the DC / DC circuit 200 and the photovoltaic string.

[0107] The first set of switches K1 is positioned on the DC source side and directly connected to the DC source. It can be configured to support both manual and automatic disconnection. This placement of the first set of switches K1 is particularly effective for inverters with a limited number of DC / DC circuits. For example, if the inverter only includes one DC / DC circuit, the number of switches K1 is reduced by one compared to placing them on the three-phase AC path.

[0108] When the inverter includes a large number of DC / DC circuits 200, although the first set of switches K1 is set Figure 7 The location of the switches results in a larger number of switches, but the current of each switch is greatly reduced, allowing for the use of smaller and larger switches, more flexible circuit layout, and a reduction in the overall cost of the inverter.

[0109] The second set of switches, K2, is connected to the path between the AC side of the DC / AC circuit and the power grid.

[0110] The following description, with reference to the accompanying diagram, illustrates the scenario where both sets of switches are connected in the path between the DC side of the DC / AC circuit and the DC source.

[0111] See Figure 8 This figure is a circuit diagram of another inverter provided in an embodiment of this application.

[0112] Figure 8 The inverter shown has a first set of switches K1 and a second set of switches K2 connected in series in the path between the DC bus capacitor and the second terminal of the DC / DC circuit 200. When one set of switches fails, the other set of switches ensures that the grid and the DC source can be reliably disconnected.

[0113] See Figure 9 This figure is a circuit diagram of another inverter provided in an embodiment of this application.

[0114] Figure 9The inverter shown has a first set of switches K1 and a second set of switches K2 connected in series in the path between the DC bus capacitor and the DC side of the DC / AC circuit 100. When one set of switches fails, the other set of switches ensures that the grid and the DC source can be reliably disconnected.

[0115] See Figure 10 This figure is a circuit diagram of another inverter provided in an embodiment of this application.

[0116] Figure 10 The inverter shown has a first set of switches, K1, connected in the path between the DC bus capacitor and the second terminal of the DC / DC circuit 200. A second set of switches, K2, is connected in the path between the DC bus capacitor and the DC side of the DC / AC circuit 100. When one set of switches fails, the other set of switches ensures reliable disconnection between the grid and the DC source.

[0117] See Figure 11 This figure is a schematic diagram of another inverter provided in an embodiment of this application.

[0118] Figure 11 The inverter shown has a first set of switches K1 connected to the path between the first terminal of the DC / DC circuit 200 and the DC source. A second set of switches K2 is connected to the path between the DC side of the DC / AC circuit 100 and the second terminal of the DC / DC circuit 200. When one set of switches fails, the other set of switches ensures reliable disconnection between the power grid and the DC source.

[0119] Based on the inverter provided in the above embodiments, this application also provides a power supply system, which will be described in detail below with reference to the accompanying drawings.

[0120] See Figure 12 This figure is a schematic diagram of a power supply system provided in an embodiment of this application.

[0121] The power supply system provided in this application embodiment includes the inverter 1000 described in the above embodiment, and the DC side of the inverter 1000 is used to connect to the DC source 2000.

[0122] The DC source 200 includes at least one of photovoltaic or battery.

[0123] The power supply system provided in this application embodiment allows for the disconnection of the inverter's AC side from the DC power source during maintenance. This can be achieved by controlling the first or second set of switches in the inverter to disconnect, thus protecting personal safety. Furthermore, the power supply system provided in this application embodiment eliminates or eliminates switches on the AC side of the inverter, reducing the number of AC side switches and lowering the inverter's cost and size. On the other hand, during normal inverter operation, the DC side voltage is higher than the AC side voltage, resulting in a smaller DC side current. Consequently, the losses of the switches on the DC side are lower, improving the inverter's power generation efficiency and thus the overall power supply system's power generation efficiency.

[0124] Based on the inverter provided in the above embodiments, this application also provides a power supply system, which will be described in detail below with reference to the accompanying drawings.

[0125] See Figure 13 The figure is a flowchart of the inverter control method provided in the embodiment of this application.

[0126] The inverter control method provided in this application embodiment includes a switch group of less than or equal to one on the path between the AC side of the inverter circuit and the power grid. The method includes:

[0127] S1001: Determine whether it is necessary to disconnect the inverter's output from the DC source; if yes, execute S1002.

[0128] S1002: When the inverter output needs to be disconnected from the DC source, control at least one of the first or second set of switches to disconnect. It should be understood that since the first and second sets of switches function identically and are redundant, when one set of switches cannot reliably disconnect, the other set of switches is activated to disconnect the inverter output from the DC source, ensuring isolation and power outage.

[0129] Both the first and second sets of switches are located on the path between the DC side of the inverter circuit and the DC source in the inverter; or, the first set of switches is located on the path between the DC side of the inverter circuit and the DC source, and the second set of switches is located on the path between the AC side of the inverter circuit and the power grid.

[0130] In one possible implementation, the inverter also includes a DC bus capacitor; the first end of the DC bus capacitor is connected to the DC positive terminal of the inverter circuit, and the second end of the DC bus capacitor is connected to the DC negative terminal of the inverter circuit; the first end of the first set of switches is connected to the DC source, the second end of the first set of switches is connected to the DC bus capacitor, and the second set of switches is set on the path between the AC side of the inverter circuit and the power grid.

[0131] The method also includes:

[0132] Before the inverter is connected to the grid, the first set of switches is closed to charge the DC bus capacitor from the DC source; when the voltage of the DC bus capacitor reaches a first voltage threshold, the second set of switches is closed. One possible implementation is that the first set of switches is connected between the DC side and the DC bus capacitor.

[0133] The method also includes:

[0134] When charging the DC bus capacitor, before closing the first set of switches, the pre-charging circuit is first turned on. After a preset time or when the voltage of the DC bus capacitor reaches the second voltage threshold, the first set of switches is then closed. The second voltage threshold is less than or equal to the first voltage threshold.

[0135] In one possible implementation, the inverter also includes a DC / DC circuit connected between the DC bus capacitor and the inverter circuit; a first set of switches is connected between the DC / DC circuit and the DC bus capacitor.

[0136] The method also includes:

[0137] When the first set of switches is controlled to be open, the voltage at the first or second terminal of the DC / DC circuit is changed, and the voltage difference between the first and second terminals of the first set of switches is used to determine whether the first set of switches has been successfully opened.

[0138] One possible implementation is that the second set of switches is placed on the path between the AC side of the inverter circuit and the power grid;

[0139] The method also includes: when the second set of switches is controlled to be disconnected, changing the AC side voltage of the inverter circuit, and determining whether the second set of switches has been successfully disconnected by the voltage difference between the first and second terminals of the second set of switches.

[0140] In one possible implementation, the inverter also includes a DC / DC circuit connected between the DC bus capacitor and the inverter circuit; a first set of switches is connected between the DC source and the DC bus capacitor;

[0141] The method also includes: when the first set of switches is closed, controlling the DC / DC circuit to work, transferring the energy of the DC bus capacitor or the energy of the filter capacitor connected to the AC side of the inverter circuit to the DC source or load;

[0142] Alternatively, a discharge load can be connected in parallel to the DC bus capacitor or filter capacitor via a controllable switch;

[0143] The method also includes: controlling the closing of a controllable switch to allow the discharge load to consume the energy on the DC bus capacitor or filter capacitor.

[0144] In one possible implementation, the inverter also includes a DC / DC circuit connected between the DC bus capacitor and the inverter circuit; a first set of switches is connected between the DC source and the DC bus capacitor;

[0145] The method also includes:

[0146] When the first set of switches is closed, it controls the operation of at least one of the DC / DC circuit or DC / AC circuit, consuming the energy of the DC bus capacitor.

[0147] Alternatively, the inverter may also include: an auxiliary power supply;

[0148] The method also includes increasing the energy that the auxiliary power supply draws from the DC bus capacitor.

[0149] In one possible implementation, see Figure 14 The figure is a schematic diagram of a control device provided in an embodiment of this application.

[0150] The control device may include a memory 1011 and a processor 1012. The processor 1012 may be connected to the inverter and can drive the switches in the various power conversion circuits within the inverter. Figure 14 As shown, the memory can be random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (Electronic Programmable ROM), registers, hard disks, removable disks, etc.

[0151] The memory 1011 can store computer instructions. When the computer instructions stored in the memory 1011 are executed by the processor 1012, the processor 1012 can be used to execute the control method of the inverter. The memory 1011 can also store data.

[0152] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape) or a semiconductor medium (e.g., solid-state disk (SSD)).

[0153] This application also provides a readable storage medium for storing the methods provided in the above embodiments. Examples include random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (EPROM), registers, hard disks, removable disks, or any other form of storage medium in the art.

[0154] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0155] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An inverter, characterized in that, include: The inverter circuit, the first set of switches, and the second set of switches, wherein the path between the AC side of the inverter circuit and the power grid includes one or fewer sets of switches. Both the first set of switches and the second set of switches are located on the path between the DC side of the inverter circuit and the DC source. or, The first set of switches is located on the path between the DC side of the inverter circuit and the DC source, and the second set of switches is located on the path between the AC side of the inverter circuit and the power grid.

2. The inverter according to claim 1, characterized in that, Also includes: DC bus capacitor; The first end of the DC bus capacitor is connected to the positive DC terminal of the inverter circuit, and the second end of the DC bus capacitor is connected to the negative DC terminal of the inverter circuit. The second set of switches is disposed in the path between the DC bus capacitor and the DC side of the inverter circuit, and the first set of switches is disposed in the path between the DC bus capacitor and the DC source. or, Both the first set of switches and the second set of switches are located on the path between the DC bus capacitor and the DC side of the inverter circuit; or, Both the first set of switches and the second set of switches are located on the path between the DC bus capacitor and the DC source.

3. The inverter according to claim 2, characterized in that, Also includes: A DC / DC / DC circuit; the first terminal of the DC / DC circuit is used to connect to the DC source, the positive terminal of the second terminal of the DC / DC circuit is connected to the first terminal of the DC bus capacitor, and the negative terminal of the second terminal of the DC / DC circuit is connected to the second terminal of the DC bus capacitor. Both the first set of switches and the second set of switches are installed on the path between the DC bus capacitor and the DC source, specifically: Both the first set of switches and the second set of switches are located on the path between the DC bus capacitor and the DC / DC circuit. or, The first set of switches is disposed in the path between the DC bus capacitor and the second terminal of the DC / DC circuit, and the second set of switches is disposed in the path between the first terminal of the DC / DC circuit and the DC source.

4. The inverter according to claim 2 or 3, characterized in that, The DC bus capacitor includes a first DC bus capacitor and a second DC bus capacitor. The first end of the first DC bus capacitor is connected to the positive DC terminal of the inverter circuit, the second end of the first DC bus capacitor is connected to the midpoint of the DC bus, the first end of the second DC bus capacitor is connected to the midpoint of the DC bus, and the second end of the second DC bus capacitor is connected to the negative DC terminal of the inverter circuit. The midpoint of the DC bus is connected to the midpoint of the DC side of the inverter circuit; When one of the first group of switches or one of the second group of switches is located on the path between the DC bus capacitor and the DC side of the inverter circuit, the group of switches includes a switch connected between the midpoint of the DC bus and the midpoint of the DC side.

5. The inverter according to claim 4, characterized in that, Also includes: Filtering circuit; The filter circuit is connected between the AC side of the inverter circuit and the power grid; The common terminal of the filter capacitor in the filter circuit is connected to the midpoint of the DC side of the inverter circuit.

6. The inverter according to claim 2, characterized in that, Also includes: Controller; The first end of the first set of switches is connected to the DC source, the second end of the first set of switches is connected to the DC bus capacitor, and the second set of switches is located on the path between the AC side of the inverter circuit and the power grid. The controller is used to control the first set of switches to close before the inverter is connected to the grid, so that the DC source charges the DC bus capacitor; and to control the second set of switches to close when the voltage of the DC bus capacitor reaches a first voltage threshold.

7. The inverter according to claim 6, characterized in that, Also includes: Pre-charge circuit; The pre-charging circuit is connected in parallel across the two ends of the first set of switches; The controller is further configured to, when charging the DC bus capacitor, first control the pre-charging circuit to be turned on before controlling the first set of switches to be closed, and then control the first set of switches to be closed after a preset time or when the voltage of the DC bus capacitor reaches a second voltage threshold, wherein the second voltage threshold is less than or equal to the first voltage threshold.

8. The inverter according to claim 3, characterized in that, Also includes: Controller; The first terminal of the first set of switches is connected to the second terminal of the DC / DC circuit, and the second terminal of the first set of switches is connected to the DC bus capacitor. The controller is used to change the voltage at the first or second terminal of the DC / DC circuit when the first set of switches is controlled to be disconnected, and to determine whether the first set of switches has been successfully disconnected by the voltage difference between the first and second terminals of the first set of switches.

9. The inverter according to claim 1, characterized in that, Also includes: Controller; The second set of switches is installed on the path between the AC side of the inverter circuit and the power grid; The controller is used to change the AC side voltage of the inverter circuit when the second set of switches is controlled to be disconnected, and to determine whether the second set of switches has been successfully disconnected by the voltage difference between the first and second terminals of the second set of switches.

10. The inverter according to claim 3, characterized in that, A discharge load is connected in parallel to the DC bus capacitor or the filter capacitor via a controllable switch. The inverter also includes: a controller; The first terminal of the first set of switches is connected to the DC source, and the second terminal of the first set of switches is connected to the DC bus capacitor. The controller is configured to control the DC / DC circuit to operate when the first set of switches is closed, transferring the energy of the DC bus capacitor or the energy of the filter capacitor connected to the AC side of the inverter circuit to the DC source or load; or, The controller is used to control the closing of the controllable switch so that the discharge load consumes the energy on the DC bus capacitor or the filter capacitor.

11. The inverter according to any one of claims 1-3, characterized in that, The inverter also includes: a controller; The first end of the first set of switches is connected to the DC source, and the second end of the first set of switches is connected to the DC bus capacitor. The controller is used to control the operation of at least one of the DC / DC circuits in the inverter or the inverter circuit when the first set of switches is closed, thereby consuming the energy of the DC bus capacitor. Alternatively, the inverter may further include: an auxiliary power supply; the controller is also used to increase the energy drawn by the auxiliary power supply from the DC bus capacitor.

12. A control method for an inverter, characterized in that, The method includes: The path between the AC side of the inverter circuit and the power grid in the inverter includes one or fewer switch groups. When the output of the inverter needs to be disconnected from the DC source, at least one of the first or second sets of switches is controlled to disconnect. Both the first set of switches and the second set of switches are located on the path between the DC side of the inverter circuit and the DC source in the inverter; or, the first set of switches is located on the path between the DC side of the inverter circuit and the DC source, and the second set of switches is located on the path between the AC side of the inverter circuit and the power grid.

13. The method according to claim 11, characterized in that, The inverter also includes a DC bus capacitor; the first end of the DC bus capacitor is connected to the DC positive terminal of the inverter circuit, and the second end of the DC bus capacitor is connected to the DC negative terminal of the inverter circuit; the first end of the first set of switches is connected to the DC source, the second end of the first set of switches is connected to the DC bus capacitor, and the second set of switches is located on the path between the AC side of the inverter circuit and the power grid. The method further includes: Before the inverter is connected to the grid, the first set of switches is controlled to close, so that the DC source charges the DC bus capacitor; when the voltage of the DC bus capacitor reaches the first voltage threshold, the second set of switches is controlled to close.

14. The method according to claim 12, characterized in that, The first set of switches is connected between the DC side and the DC bus capacitor; The method further includes: When charging the DC bus capacitor, before controlling the first set of switches to close, the pre-charging circuit is first turned on. After a preset time or when the voltage of the DC bus capacitor reaches the second voltage threshold, the first set of switches is then controlled to close. The second voltage threshold is less than or equal to the first voltage threshold.

15. The method according to claim 11, characterized in that, The inverter also includes a DC / DC circuit connected between the DC bus capacitor and the inverter circuit. The first set of switches is connected between the DC / DC circuit and the DC bus capacitor; The method further includes: When the first set of switches is controlled to be disconnected, the voltage at the first or second terminal of the DC / DC circuit is changed, and the voltage difference between the first and second terminals of the first set of switches is used to determine whether the first set of switches has been successfully disconnected.

16. The method according to claim 11, characterized in that, The second set of switches is installed on the path between the AC side of the inverter circuit and the power grid; The method further includes: when the second set of switches is controlled to be disconnected, changing the AC side voltage of the inverter circuit, and determining whether the second set of switches has been successfully disconnected by the voltage difference between the first and second terminals of the second set of switches.

17. The method according to claim 11, characterized in that, The inverter further includes a DC / DC circuit connected between the DC bus capacitor and the inverter circuit; the first set of switches is connected between the DC source and the DC bus capacitor; The method further includes: when the first set of switches is closed, controlling the DC / DC circuit to operate, transferring the energy of the DC bus capacitor or the energy of the filter capacitor connected to the AC side of the inverter circuit to the DC source or load; Alternatively, a discharge load may be connected in parallel to the DC bus capacitor or the filter capacitor via a controllable switch; The method further includes: controlling the controllable switch to close, so that the discharge load consumes the energy on the DC bus capacitor or the filter capacitor.

18. The method according to claim 11, characterized in that, The inverter also includes a DC / DC circuit connected between the DC bus capacitor and the inverter circuit. The first set of switches is connected between the DC source and the DC bus capacitor; The method further includes: When the first set of switches is closed, at least one of the DC / DC circuit or the inverter circuit is controlled to operate, consuming the energy of the DC bus capacitor. Alternatively, the inverter may further include: an auxiliary power supply; The method further includes: increasing the energy that the auxiliary power supply draws from the DC bus capacitor.

19. A power supply system, characterized in that, Including the inverter according to any one of claims 1-11, wherein the DC side of the inverter is used to connect to a DC source; The DC source includes at least one of photovoltaic or battery.

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