CN116505781A

CN116505781A - Inverter and control method thereof

Info

Publication number: CN116505781A
Application number: CN202310360087.2A
Authority: CN
Inventors: 辛德锋; 王晨; 付明晓
Original assignee: Huawei Digital Power Technologies Co Ltd
Current assignee: Huawei Digital Power Technologies Co Ltd
Priority date: 2023-03-31
Filing date: 2023-03-31
Publication date: 2023-07-28

Abstract

The application provides an inverter and a control method of the inverter, and the method can be applied to the field of inverters. The method comprises the following steps: controlling the output voltage of the inverter bridge, and closing the second switch; opening the second switch in response to the current flowing through the second switch being greater than or equal to the current threshold; the first switch is closed in response to the current flowing through the second switch being less than the current threshold. The inverter comprises a bus capacitor, an inverter bridge, a first switch and a second switch, wherein the bus capacitor is used for supplying power to the inverter bridge. The bus capacitor is connected with the direct current input end of the inverter bridge, the alternating current output end of the inverter bridge is connected with one end of the first switch and one end of the second switch, the other end of the first switch is connected with the power grid, and the other end of the second switch is connected with the load. Through above-mentioned scheme and inverter structure, this application can reduce the volume and the weight of dc-to-ac converter when realizing carrying out the short circuit detection's of the port that is used for connecting the load to the dc-to-ac converter function.

Description

Inverter and control method thereof

Technical Field

The present application relates to the field of inverters, and more particularly, to an inverter and a control method of the inverter.

Background

The inverter comprises two direct current ports and two alternating current ports, wherein the two direct current ports are respectively used for connecting the photovoltaic module and the energy storage system, and the two alternating current ports are respectively used for connecting the power grid and the load. When both the photovoltaic module and the energy storage system are in a power-down state and the power grid is switched from power-down to power-up, if the ac port (which may also be referred to as an external port) for connecting the load is not short-circuited, damage to the inverter may be caused.

In order to realize the function of short circuit detection of the external port of the inverter, the structure of the inverter is changed to a large extent, which increases the manufacturing cost of the inverter and also increases the volume and weight of the inverter. Therefore, how to implement the short circuit detection function of the external port by the inverter at a low cost is a technical problem to be solved.

Disclosure of Invention

The application provides an inverter and a control method of the inverter, which can reduce the volume and weight of the inverter while realizing the function of short circuit detection on a port of the inverter for connecting a load.

In a first aspect, an inverter is provided, comprising: the device comprises a bus capacitor, an inverter bridge, a first switch, a second switch, a direct current auxiliary source and a controller. The bus capacitor is connected with the direct current input end of the inverter bridge, the alternating current output end of the inverter bridge is connected with one end of the first switch and one end of the second switch, the other end of the first switch is connected with the power grid, the other end of the second switch is connected with the load, and the two ends of the direct current auxiliary source are respectively connected with the bus capacitor and the controller. The bus capacitor supplies power to the controller through the direct current auxiliary source. The controller is used for controlling the output voltage of the inverter bridge and controlling the second switch to be closed; the controller is configured to open the second switch in response to the current flowing through the second switch being greater than or equal to the current threshold; the controller is configured to close the first switch in response to the current flowing through the second switch being less than the current threshold.

Specifically, the bus capacitance is the source of power for the controller and inverter bridge. After the bus capacitor supplies power to the controller through the direct current auxiliary source, the controller can control the output voltage of the inverter bridge. When the inverter bridge outputs voltage, the circuit between the bus capacitor and the inverter bridge and between the inverter bridge and the second switch and the load is in a conducting state, and the controller can respond to the magnitude of the current flowing through the circuit. For example, when the current flowing through the circuit is greater than or equal to a current threshold, the controller determines that a short circuit fault exists at a port of the inverter connected to the load and opens the second switch; when the current flowing through the circuit is less than the current threshold, the controller determines that there is no short circuit fault at the port of the inverter connected to the load and closes the first switch. In this way, detection of a short circuit condition of the port for connecting the load in the inverter can be completed.

The controller and the inverter bridge are powered through the bus capacitor, and when short circuit detection is carried out, the current flowing through the inverter bridge, the second switch and the load is smaller, so that the second switch is conveniently disconnected when the short circuit fault is determined, damage to the place where the second switch is connected with the load can be avoided, and meanwhile, the overall circuit loss can be reduced.

Through above-mentioned inverter structure, this application can reduce the volume and the weight of dc-to-ac converter when realizing the short circuit condition's of the port that is used for connecting the load in the dc-to-ac converter detection function, can also reduce the overall manufacturing cost of dc-to-ac converter.

In a possible implementation, the inverter further includes: AC auxiliary source and rectifying circuit. One end of the rectifying circuit is connected with one end of the alternating current auxiliary source, the other end of the rectifying circuit is connected with the bus capacitor, and the other end of the alternating current auxiliary source is connected with the power grid.

Through foretell exchanging auxiliary source and rectifier circuit, this application can be when photovoltaic module and energy storage system all are in the outage, can charge for the busbar electric capacity through the electric wire netting, and then can accomplish the short circuit condition's of the port that is used for connecting the load in the dc-to-ac converter detection.

In one possible implementation, the dc input side of the inverter is used to connect a photovoltaic module that is used to charge the bus capacitor.

Through the device, the photovoltaic module can charge the bus capacitor, and then the detection of the short circuit condition of the port used for connecting the load in the inverter can be completed.

In one possible implementation, the dc input side of the inverter is used to connect an energy storage system for charging the bus capacitor.

Through the device, the energy storage system can charge the bus capacitor, and then detection of the short circuit condition of the port used for connecting the load in the inverter can be completed.

In a possible implementation, the inverter further includes: and a current detection device for detecting the magnitude of the current flowing through the second switch.

It will be appreciated that there is communication between the current sensing device and the controller. The controller can acquire the magnitude of the current flowing through the second switch through the current detection device and perform corresponding operation.

In one possible implementation, the ac auxiliary source is used to charge the bus capacitor in response to power from the grid.

Therefore, after the energy storage system and the photovoltaic module are both in power failure, the bus capacitor can be charged through the power grid, the alternating current auxiliary source and the rectifying circuit.

In a second aspect, there is provided a control method of an inverter, including; controlling the output voltage of the inverter bridge, and closing the second switch; opening the second switch in response to the current flowing through the second switch being greater than or equal to the current threshold; the first switch is closed in response to the current flowing through the second switch being less than the current threshold. The inverter comprises a bus capacitor, an inverter bridge, a first switch and a second switch, wherein the bus capacitor is used for supplying power to the inverter bridge. The bus capacitor is connected with the direct current input end of the inverter bridge, the alternating current output end of the inverter bridge is connected with one end of the first switch and one end of the second switch, the other end of the first switch is connected with the power grid, and the other end of the second switch is connected with the load.

In a possible implementation, the method further includes: the bus capacitor is charged through the alternating current auxiliary source and the rectifying circuit. The inverter also comprises an alternating current auxiliary source and a rectifying circuit, one end of the alternating current auxiliary source is connected with one end of the rectifying circuit, the other end of the alternating current auxiliary source is connected with a power grid, and the other end of the rectifying circuit is connected with a bus capacitor.

In a possible implementation, the method further includes: the bus capacitor is charged through the photovoltaic module. The direct current input side of the inverter is used for being connected with the photovoltaic module.

In a possible implementation, the method further includes: the bus capacitor is charged by an energy storage system. The direct current input side of the inverter is used for being connected with the energy storage system.

In a possible implementation, the method further includes: the magnitude of the current flowing through the second switch is detected.

In a third aspect, there is provided an optical storage system comprising: an energy storage system, a photovoltaic module, and an inverter of any of the first aspect and the first aspect. The energy storage system is connected with the direct current input side of the inverter, and the photovoltaic module is connected with the direct current input side of the inverter. The inverter is used for converting direct current from a photovoltaic module or an energy storage system into alternating current and transmitting the alternating current to a power grid or a load.

For a description of the advantageous effects of the second aspect and the third aspect, reference may be made to the description of the advantageous effects of the first aspect, which is not repeated here.

Drawings

Fig. 1 is a schematic diagram of a light storage system 100 according to an embodiment of the present application.

Fig. 2 is a schematic diagram of an inverter 200.

Fig. 3 is a schematic diagram of an inverter 300 according to an embodiment of the present application.

Fig. 4 is a flowchart of a control method 400 of an inverter according to an embodiment of the present application.

Fig. 5 is a schematic diagram of an architecture of an inverter 500 according to an embodiment of the present application.

Fig. 6 is a schematic diagram of an architecture of an inverter 600 according to an embodiment of the present application.

Fig. 7 is a schematic diagram of an architecture of an inverter 700 according to an embodiment of the present application.

Fig. 8 is a schematic diagram of an architecture of an inverter 800 according to an embodiment of the present application.

Detailed Description

The technical solutions in the present application will be described below with reference to the accompanying drawings.

With the continuous development of the modern industry, the desire for energy is endless. Solar energy, which is one of renewable energy sources, is widely pursued by people due to its excellent characteristics of being general, harmless, huge, long-lasting, etc.

Photovoltaic modules are a popular way for people to utilize solar energy. Through photovoltaic module, people can realize converting solar energy into electric energy to this satisfies our power consumption demand. In order to effectively store the electric energy output by the photovoltaic module, a light storage system is designed, and in particular, reference is made to fig. 1.

Fig. 1 is a schematic diagram of a light storage system 100 according to an embodiment of the present application. As shown in fig. 1, the apparatus in the optical storage system 100 includes: photovoltaic module, dc-to-ac converter and energy storage system.

Optionally, the optical storage system 100 may further include: grid and load.

Specifically, the inverter is capable of converting direct current from the photovoltaic module into alternating current and delivering the alternating current to a power grid or load. The inverter is capable of delivering direct current from the photovoltaic module to the energy storage system for charging the energy storage system. The inverter is capable of converting direct current from the energy storage system to alternating current and delivering the alternating current to a power grid or load.

It will be appreciated that when the photovoltaic system 100 includes a photovoltaic module, an inverter, and an energy storage system, the inverter is mainly used to connect the photovoltaic module and the energy storage system so as to charge the energy storage system. When the light storage system 100 includes a photovoltaic module, an inverter, an energy storage system, a grid, and a load, the inverter can be used to connect the devices. For example, an inverter connects the photovoltaic module with an energy storage system; the inverter connects the photovoltaic module with a power grid; the inverter connects the photovoltaic module with a load; the inverter connects the load with the energy storage system, etc.

The energy storage system in the optical storage system 100 is capable of storing and releasing electrical energy. For example, the energy storage system may store dc electrical energy from the photovoltaic module, and the energy storage system may power a grid or a load through an inverter. Accordingly, energy storage systems have a wide range of applications including, but not limited to: a household scene, an industry green electricity scene, an intelligent photovoltaic power station scene and the like. In one example, when applied to a consumer scenario, the energy storage system is mainly used as a standby power supply, which can facilitate the adjustment of peak-to-valley electricity prices by the consumer. For example, the energy storage system is charged when the electricity price is low, and is discharged when the electricity price is high, so that the household electricity cost can be saved.

As is apparent from the above description, an inverter is a converter capable of converting direct current into alternating current. Specifically, the inverter generally includes two dc ports (such as dc port 1 and dc port 2) and two ac ports (such as ac port 1 and ac port 2) for connecting the photovoltaic module and the energy storage system, respectively, and for connecting the grid and the load, respectively. Illustratively, dc port 1 is used to connect the photovoltaic module, dc port 2 is used to connect the energy storage system, ac port 1 is used to connect the grid, and ac port 2 is used to connect the load.

The photovoltaic module can feed the grid through the dc port 1 and power the load. The energy storage system may supply power to the load through the dc port 2. The grid may supply power to the load through ac port 1. In other words, the inverter is the connection hub between the load and the energy module (which may include the photovoltaic module, the energy storage system, and the grid).

When the photovoltaic module and the energy storage system connected with the inverter are both in power failure, and the power grid connected with the inverter is switched from power-down to power-up, the short circuit condition of the alternating current port 2 is unknown at the moment. If the power grid is directly used to supply power to the load without detecting the short circuit condition of the ac port 2, if the ac port 2 does have a short circuit fault, the inverter may be damaged. Therefore, the inverter needs to have a function of detecting a short circuit of a port for connecting a load.

Fig. 2 is a schematic diagram of an inverter 200. As shown in fig. 2, the inverter 200 includes: port 211-port 214, switch 221-switch 225, resistor 226, current hall device 230, ac auxiliary source 240, and controller 250.

Specifically, port 211 is used to connect the photovoltaic module, port 212 is used to connect the energy storage system, port 213 is used to connect the grid, and port 214 is used to connect the load. The grid to which port 213 is connected needs to be powered through switch 224, switch 223, switch 222, and switch 221. The controller 250 may control the switches 221 to 225 and the current hall device 230. The principle of short circuit detection of the port for connecting the load with respect to the inverter 200 is as follows:

step 1: switch 224 and switch 222 are closed, and switch 223 and switch 221 are opened.

Specifically, through step 1, the ac auxiliary source 240 starts to operate after power is supplied from the power grid, and further supplies power to the controller 250.

Step 2: switch 225 is closed.

Specifically, controller 250 closes switch 225 after being powered by ac auxiliary source 240 to enable electrical communication between port 213 and port 214.

Step 3: the current hall device 230 detects the current between the port 213 and the port 214.

The controller 250 may control the current hall device 240 to detect the current flowing between the port 213 and the port 214. If a large current is observed, it is determined that a short circuit fault exists at port 214; if no large current value is observed, it is determined that no short circuit fault exists at port 214.

Step 4: upon determining that the port 214 has no short-circuit fault, the switches 223-221 are closed, and the switch 225 is opened; any one of the switches 225 ～ 224 ～ 222 is opened upon determining that a short circuit fault exists at the port 214.

The inverter 200 can have a function of detecting a short circuit at a port for connecting a load by means of the newly added switch 225, resistor 226, current hall device 230, and the like. However, the above approach requires the addition of a larger number of switches, resistors, and current hall devices, which makes the overall cost of the inverter 200 higher, and also increases the volume and weight of the inverter 200.

In view of the above technical problems, the present application provides an inverter and a control method of the inverter, which can realize a function of short-circuit detection of a port for connecting a load by the inverter at a low cost.

The control method of the inverter and the inverter according to the embodiments of the present application will be described below with reference to other drawings.

Fig. 3 is a schematic diagram of an inverter 300 according to an embodiment of the present application. As shown in fig. 3, the inverter 300 includes: bus capacitor 310, inverter bridge 320, switch 331 (e.g., a first switch), switch 332 (e.g., a second switch), dc auxiliary source 340, controller 350, and current sensing device 360 (which are optional devices). The bus capacitor 310 is connected to the dc input of the inverter bridge 320, the ac output of the inverter bridge 320 is connected to one end of the switch 331 and one end of the switch 332, the other end of the switch 331 is connected to the power grid, and the other end of the switch 332 is connected to the load. The bus capacitor 310 provides power to the controller 350 via the dc auxiliary source 340. Bus capacitor 310 also provides power to inverter bridge 320. The controller 350 can control the inverter bridge 320, the current detection device 360, the switch 331, and the switch 332.

Specifically, the current detection device 360 can be used to perform a current detection function. For example, when the bus capacitor 310 to the inverter bridge 320 to the current detection device 360 to a circuit between the switch 332 and the load (hereinafter simply referred to as a circuit a) is in a conductive state, the current detection device 360 can detect the value of the current flowing through the circuit a. Wherein there is communication between the current sensing device 360 and the controller 350. The controller 350 may obtain the current value flowing through the aforementioned circuit a, i.e., obtain the magnitude of the current flowing through the switch 332, through the current detecting device 360. Accordingly, the controller 350 may issue instructions or signals to the current detection device 360 to detect the current.

The inverter 300 is understood by way of example only, and the internal configuration of the modules in the inverter 300 is not limited. In one example, the current detecting device 360 may be a current hall device, or may be another device having similar or identical functions, which is not limited thereto. Similarly, the current detecting device 360 may be located at any position in the circuit a, and is not limited to the circuit position shown in fig. 3.

In addition, compared with the structure of the inverter 200, the current hall device and the resistor do not need to be added on the power grid side, so that the size and the weight of the inverter 300 can be effectively reduced. Meanwhile, when short circuit detection is carried out, the whole circuit loss can be reduced.

Fig. 4 is a flow chart of a control method 400 of an inverter according to an embodiment of the present application. The control method 400 may be applied to the inverter 300 shown in fig. 3 and the inverter described later. As shown in fig. 4, the method 400 includes:

s410, controlling the inverter bridge 320 to output the voltage 1, and closing the switch 332.

Specifically, when the output voltage of the bus capacitor 310 is the voltage threshold 1 (or the design voltage value), the bus capacitor 310 supplies power to the controller 350 through the dc auxiliary source 340 and directly supplies power to the inverter bridge 320. Accordingly, the controller 350 controls the inverter bridge 320 to output the voltage 1, the voltage 1 is less than or equal to the voltage threshold 2, and the voltage threshold 2 is used for protecting the circuit a between the bus capacitor 310, the inverter bridge 320, the current detection device 360, the switch 332 and the load from being damaged.

As described above, when the inverter 300 performs short-circuit detection on the port for connecting the load, the voltage 1 output by the inverter bridge 320 cannot be excessively large, and when there is a short-circuit fault at the port for connecting the load in the inverter 300, the excessive voltage 1 output by the inverter bridge 320 may damage the port for connecting the load in the inverter 300, and thus may affect the load. Accordingly, the present application protects the port in the inverter 300 for connecting the load by setting the voltage threshold 2.

S420, in response to the current 1 flowing through the switch 332 being less than or equal to the current threshold 1, closing the switch 331; in response to current 1 flowing through switch 332 being greater than or equal to current threshold 1, switch 332 is opened.

Specifically, when the controller 350 controls the switch 332 to be closed, the circuit a is in a conductive state, and the controller 350 can obtain the magnitude of the current 1 flowing through the circuit a. In one example, the controller 350 obtains the magnitude of the current 1 flowing through the circuit a through interaction with the current detecting device 360, and performs a corresponding operation according to the magnitude of the current 1 flowing through the circuit a.

Illustratively, in response to the current 1 flowing through the switch 332 being less than the current threshold 1, the controller 350 determines that the aforementioned circuit a is free of a short circuit fault, and the controller 350 controls the switch 331 to be closed. Accordingly, the inverter 300 may safely supply power to the load through the power grid. Also illustratively, in response to the current 1 flowing through the switch 332 being greater than or equal to the current threshold 1, the controller 350 determines that the circuit a has a short circuit fault, and the controller 350 controls the switch 332 to open.

Specifically, the current detection device 360 can be used to perform a current detection function. For example, when the circuit a between the bus capacitor 310 to the inverter bridge 320 to the current detection device 360 to the switch 332 to the load is in the on state, the current detection device 360 can detect the current value of the circuit a. Wherein there is communication between the current sensing device 360 and the controller 350. The controller 350 may obtain the current value of the aforementioned circuit a, i.e., obtain the magnitude of the current 1 flowing through the switch 332, through the current detection device 360. Accordingly, the controller 350 may issue instructions or signals to the current detection device 360 to detect the current.

The inverter 300 is understood by way of example only, and the internal configuration of the modules in the inverter 300 is not limited. The current detection device 360 may be, for example, a current hall device, or may be another device having a function of a current hall device, which is not limited thereto. Similarly, the current detecting device 360 may be located at any position in the circuit a, and is not limited to the circuit position shown in fig. 3.

It can be appreciated that the bus capacitor 310, the inverter bridge 320, the switch 331, the switch 332, the current detection device 360, the dc auxiliary source 340 and the controller 350 are all existing structures, and no additional devices are needed.

The controller 350 and the inverter bridge 320 are powered by the bus capacitor 310, and when short circuit detection is performed, the current flowing through the inverter bridge 320, the switch 332 and the load is smaller, which is convenient for disconnecting the switch 332 when the short circuit fault is determined, so that damage to the connection place of the switch 332 and the load can be avoided, and meanwhile, the overall circuit loss can be reduced.

Specifically, the controller 350 compares the current 1 flowing through the switch 332 with the current threshold 1, and detects a short circuit condition of a port for connecting a load in the inverter 300 according to the magnitudes of the two. For one example, when the current threshold 1 is 1A and the controller 350 determines that the current 1 is greater than or equal to 1A, the control module 350 determines that a short circuit fault exists at a port in the inverter 300 for connecting the load; when the controller 350 determines that the current value 1 is less than 1A, the controller 350 determines that there is no short-circuit fault at the port for connecting the load in the inverter 300.

It is understood that, when the current value 1 is equal to 1A, the controller 350 may determine that there is a short-circuit fault at the port for connecting the load in the inverter 300, or may determine that there is no short-circuit fault at the port for connecting the load in the inverter 300, which is not limited.

Alternatively, the current threshold 1 may also have other values, such as 2A, which is not limited thereto.

In one possible implementation, the method 400 may further include:

s410a, the bus capacitor 310 is charged through the AC auxiliary source and the rectifying circuit.

Specifically, the inverter 300 may further include an ac auxiliary source and a rectifying circuit. One end of the rectifying circuit is connected with the bus capacitor 310, the other end of the rectifying circuit is connected with an alternating current auxiliary source, and the other end of the alternating current auxiliary source is connected with a power grid. See in particular the description of fig. 5.

Fig. 5 is a schematic diagram of an architecture of an inverter 500 according to an embodiment of the present application. As shown in fig. 5, the inverter 500 includes: bus capacitor 510, inverter bridge 520, switch 531 (e.g., a first switch), switch 532 (e.g., a second switch), dc auxiliary source 540, controller 550, current detection device 560 (which is an optional device), ac auxiliary source 570, and rectifying circuit 580. The bus capacitor 510 is connected to the dc input of the inverter bridge 520, the ac output of the inverter bridge 520 is connected to one end of the switch 531 and one end of the switch 532, the other end of the switch 531 is connected to the grid, and the other end of the switch 532 is connected to the load. Bus capacitor 510 provides power to controller 550 through dc auxiliary source 540. Bus capacitor 510 also provides power to inverter bridge 520. The controller 550 can control the inverter bridge 520, the current detection device 560, the switch 531, and the switch 532.

Specifically, one end of the rectifying circuit 580 is connected to the bus capacitor 510, the other end of the rectifying circuit 580 is connected to the ac auxiliary source 570, and the other end of the ac auxiliary source 570 is connected to the power grid. Specifically, the inverter 500 may charge the bus capacitor 510 through the grid-ac auxiliary source 570-rectifying circuit 580.

It can be appreciated that when the inverter 500 is capable of charging the bus capacitor 510 through the ac auxiliary source 570 and the rectifying circuit 580, the photovoltaic module or the energy storage system connected to the dc input side of the inverter 500 can be in a power-off state.

In one possible implementation, the method 400 may further include:

s410b, charging the bus capacitor 310 through the photovoltaic module.

Specifically, the inverter 300 may be connected to the photovoltaic module through the dc input side. See in particular the description of fig. 6.

Fig. 6 is a schematic diagram of an architecture of an inverter 600 according to an embodiment of the present application. As shown in fig. 6, the inverter 600 includes: bus capacitor 610, inverter bridge 620, switch 631 (e.g., a first switch), switch 632 (e.g., a second switch), dc auxiliary source 640, controller 650, current detection device 660 (which is an optional device), and dc input port 670. The bus capacitor 610 is connected to the dc input of the inverter bridge 620, the ac output of the inverter bridge 620 is connected to one end of the switch 631 and one end of the switch 632, the other end of the switch 631 is connected to the power grid, and the other end of the switch 632 is connected to the load. The bus capacitor 610 provides power to the controller 650 via the dc auxiliary source 640. Bus capacitor 610 also provides power to inverter bridge 620. The controller 650 can control the inverter bridge 620, the current detection device 660, the switch 631, and the switch 632.

It will be appreciated that the inverter 600 can be connected to a photovoltaic module through a dc input port, which can enable charging of the bus capacitor 610, which in turn can enable detection of a short circuit condition at the port of the inverter 600 for connecting a load.

In one possible implementation, the method 400 may further include:

s410c, the bus capacitor 310 is charged by the energy storage system.

Specifically, the inverter 300 may be connected to the energy storage system through a dc input side. See in particular the description of fig. 7.

Fig. 7 is a schematic diagram of an architecture of an inverter 700 according to an embodiment of the present application. As shown in fig. 7, the inverter 700 includes: bus capacitor 710, inverter bridge 720, switch 731 (e.g., a first switch), switch 732 (e.g., a second switch), dc auxiliary source 740, controller 750, current sensing device 760 (which is an optional device), and dc input port 770. The bus capacitor 710 is connected to the dc input of the inverter bridge 720, the ac output of the inverter bridge 720 is connected to one end of the switch 731 and one end of the switch 732, the other end of the switch 731 is connected to the power grid, and the other end of the switch 732 is connected to the load. Bus capacitor 710 powers controller 750 through dc auxiliary source 740. Bus capacitor 710 also provides power to inverter bridge 720. The controller 750 can control the inverter bridge 720, the current detection device 760, the switch 731, and the switch 732.

It will be appreciated that inverter 700 can be connected to an energy storage system via a dc input port, which can enable charging of bus capacitor 710, which in turn can enable detection of a short circuit condition at the port of inverter 700 used to connect a load.

The execution order between S410a to S410c is not limited, and may include only one item, and is not limited. The energy storage system and the photovoltaic module are supported to charge the bus capacitor at the same time, one of the energy storage system and the photovoltaic module is also supported to charge the bus capacitor, and the power grid is also supported to charge the bus capacitor.

Inverter 300 and method 400 are further described below in conjunction with other figures.

Fig. 8 is a schematic diagram of an architecture of an inverter 800 according to an embodiment of the present application. As shown in fig. 8, the inverter 800 includes: bus capacitor 810, inverter bridge 820, switch 831 and switch 832, dc auxiliary source 840, controller 850, current hall device 860, ac auxiliary source 870, and diode 880.

Specifically, the current hall device 860 may be the aforementioned current sensing device 360. The functions and connection relationships of the devices in the inverter 800 may be referred to in the foregoing description, and are not repeated here.

It will be appreciated that when the inverter 800 includes the diode 843, it can be used to enable the grid to power the unidirectional nature of the bus capacitor 820 through the ac auxiliary source 842. Meanwhile, the diode 880 may convert the ac power output from the ac auxiliary source 870 into dc power and charge the bus capacitor 810.

Optionally, the inverter 800 may also include a resistor that can be used so that the current value between the ac auxiliary source 870 and the bus capacitor 810 is not excessive.

It should be noted that the device structure of the inverter 800 is understood by way of example only, and may also include other devices, such as electromagnetic compatibility (electronmagnetic compatibility, EMC) devices, for reducing electromagnetic interference, etc.

It should also be noted that the above listed modules are described by way of example only and are not intended to be limiting. However, the control method of the inverter according to the embodiment of the present application is not limited to this, and other devices or modules capable of implementing similar functions may be supported.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It will be clear to those skilled in the art that, for convenience and brevity of description, reference may be made to the corresponding process in the foregoing method embodiment for the specific working process of the apparatus described above, which is not described herein again.

In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a read-only memory (ROM), a random access memory (random access memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The foregoing is merely specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes and substitutions are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. An inverter, comprising:

the system comprises a bus capacitor, an inverter bridge, a first switch, a second switch, a direct current auxiliary source and a controller;

the bus capacitor is connected with a direct current input end of the inverter bridge, an alternating current output end of the inverter bridge is connected with one end of the first switch and one end of the second switch, the other end of the first switch is connected with a power grid, the other end of the second switch is connected with a load, one end of the direct current auxiliary source is connected with the bus capacitor, and the other end of the direct current auxiliary source is connected with the controller;

the controller is used for controlling the output voltage of the inverter bridge and controlling the second switch to be closed;

the controller is configured to open the second switch in response to the current flowing through the second switch being greater than or equal to a current threshold;

the controller is configured to close the first switch in response to a current flowing through the second switch being less than the current threshold.

2. The inverter of claim 1, wherein the inverter further comprises:

an alternating current auxiliary source and a rectifying circuit;

one end of the rectifying circuit is connected with one end of the alternating current auxiliary source, the other end of the rectifying circuit is connected with the bus capacitor, and the other end of the alternating current auxiliary source is connected with the power grid.

3. The inverter according to claim 1 or 2, wherein the dc input side of the inverter is used for connecting a photovoltaic module for charging the bus capacitor.

4. An inverter according to any one of claims 1 to 3, characterized in that the dc input side of the inverter is used for connection to an energy storage system for charging the bus capacitance.

5. The inverter according to any one of claims 1 to 4, characterized in that the inverter further comprises:

and a current detection device for detecting the magnitude of the current flowing through the second switch.

6. The inverter of any one of claims 1-5, wherein the ac auxiliary source is configured to charge the bus capacitor in response to the grid being powered.

7. A control method of an inverter, characterized by comprising;

controlling the output voltage of the inverter bridge, and closing the second switch;

opening the second switch in response to the current flowing through the second switch being greater than or equal to a current threshold;

closing a first switch in response to a current flowing through the second switch being less than the current threshold;

the inverter comprises a bus capacitor, the inverter bridge, the first switch and the second switch;

the bus capacitor is connected with a direct current input end of the inverter bridge, an alternating current output end of the inverter bridge is connected with one end of the first switch and one end of the second switch, the other end of the first switch is connected with a power grid, and the other end of the second switch is connected with a load.

8. The method of claim 7, wherein the method further comprises:

charging the bus capacitor through an alternating current auxiliary source and a rectifying circuit;

the inverter further comprises an alternating current auxiliary source and a rectifying circuit, one end of the alternating current auxiliary source is connected with one end of the rectifying circuit, the other end of the alternating current auxiliary source is connected with the power grid, and the other end of the rectifying circuit is connected with the bus capacitor.

9. The method according to claim 7 or 8, characterized in that the method further comprises:

charging the bus capacitor through a photovoltaic module;

the direct current input side of the inverter is used for being connected with the photovoltaic module.

10. The method according to any one of claims 7 to 9, further comprising:

charging the bus capacitor through an energy storage system;

the direct current input side of the inverter is used for being connected with the energy storage system.

11. An optical storage system, comprising:

an energy storage system and the inverter of any one of claims 1 to 6;

the energy storage system is connected with the direct current input side of the inverter, and the photovoltaic module is connected with the direct current input side of the inverter;

the inverter is used for converting direct current from the photovoltaic assembly or the energy storage system into alternating current and transmitting the alternating current to the power grid or the load.