Switching device, inverter system, and energy storage system

Abstract

The present application provides a switching device, an inverter system, and an energy storage system. A first electromagnetic switch and a second normally-closed auxiliary switch in the switching device and a grid-connected interface of an inverter form a first control loop. A second electromagnetic switch and a first normally-closed auxiliary switch in the switching device and an off-grid interface of the inverter form a second control loop. The first electromagnetic switch and the first normally-closed auxiliary switch are mechanically interlocked. The first electromagnetic switch and the second electromagnetic switch are mechanically interlocked. The second electromagnetic switch and the second normally-closed auxiliary switch are mechanically interlocked. The first control loop is used for, when the inverter is grid-connected, controlling the first electromagnetic switch to be closed and controlling the first normally-closed auxiliary switch to be open, so as to disconnect the second control loop. The second control loop is used for, when the inverter is off-grid, controlling the second electromagnetic switch to be closed and controlling the second normally-closed auxiliary switch to be open, so as to disconnect the first control loop. The switching device of the present application can switch a power supply source for a load.

Description

Switching devices, inverter systems and energy storage systems

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 9, 2024, with application number 202420054441.9 and entitled “Switching device, inverter system and energy storage system”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of power supply technology, and in particular to a switching device, an inverter system and an energy storage system. Background Art

[0003] Inverters and the grid often serve as dual power sources for loads. In the event of a single fault or fault recovery in either power source, the two power sources must be switched. Furthermore, during this switching process, the switch from the grid to the load and the switch from the inverter's off-grid side to the load must be electrically and mechanically interlocked to prevent voltage from the off-grid side from being applied to the grid, and vice versa.

[0004] Therefore, how to achieve effective switching of load power supply is a technical problem that needs to be solved.

[0005] Summary of the Invention

[0006] In view of this, the present application provides a switching device, an inverter system and an energy storage system, which can switch the power supply for the load to ensure uninterrupted power supply and power supply safety of the load.

[0007] A first aspect of the present application provides a switching device. The switching device includes: a first electromagnetic switch, a second electromagnetic switch, a first normally closed auxiliary switch, and a second normally closed auxiliary switch;

[0008] The first electromagnetic switch is used to connect the second normally closed auxiliary switch, the grid-connected interface of the inverter, and the load, wherein the grid-connected interface is used to connect to the power grid; the second normally closed auxiliary switch is used to connect to the grid-connected interface, thereby forming a first control loop together with the grid-connected interface and the first electromagnetic switch;

[0009] The second electromagnetic switch is used to connect the first normally closed auxiliary switch, the off-grid interface of the inverter and the load; the first normally closed auxiliary switch is used to connect to the off-grid interface, thereby forming a second control loop together with the off-grid interface and the second electromagnetic switch;

[0010] Wherein, the first electromagnetic switch is mechanically interlocked with the first normally closed auxiliary switch, the first electromagnetic switch is mechanically interlocked with the second electromagnetic switch, and the second electromagnetic switch is mechanically interlocked with the second normally closed auxiliary switch;

[0011] The first control loop is used to control the first electromagnetic switch to close when the inverter is in grid-connected operation, so as to connect the grid-connected interface to the load, and to control the first normally closed auxiliary switch to open, so as to disconnect the second control loop, so that the inverter and the grid can supply power to the load through the grid-connected interface;

[0012] The second control loop is used to control the second electromagnetic switch to close when the inverter is operating off-grid to connect the off-grid interface and the load, and to control the second normally closed auxiliary switch to open to disconnect the first control loop, so that the inverter can supply power to the load through the off-grid interface.

[0013] In one embodiment, the first electromagnetic switch includes a first main contact and a first induction coil, wherein the first main contact is connected between the grid-connected interface and the load, the first induction coil is connected in series with the second normally closed auxiliary switch, and the first induction coil and the second normally closed auxiliary switch are also connected to the grid-connected interface, thereby forming a first control loop together with the grid-connected interface;

[0014] The second electromagnetic switch includes a second main contact and a second induction coil, wherein the second main contact is connected between the off-grid interface and the load, the second induction coil is connected in series with the first normally closed auxiliary switch, and the second induction coil and the first normally closed auxiliary switch are also connected to the off-grid interface, thereby forming a second control loop together with the off-grid interface.

[0015] In one embodiment, the first main contact is mechanically interlocked with the first normally closed auxiliary switch, the first main contact is mechanically interlocked with the second main contact, and the second main contact is mechanically interlocked with the second normally closed auxiliary switch;

[0016] The first control circuit is used to energize when the inverter is in grid-connected operation, so that the first induction coil generates a first electromagnetic signal. The first electromagnetic signal is used to control the closure of the first main contact to connect the grid-connected interface and the load. When the first main contact is closed, the first normally closed auxiliary switch is opened to disconnect the second control circuit.

[0017] The second control circuit is used to energize when the inverter is operating off-grid, so that the second induction coil generates a second electromagnetic signal. The second electromagnetic signal is used to control the closure of the second main contact to conduct the off-grid interface and the load. When the second main contact is closed, the second normally closed auxiliary switch is opened to disconnect the first control circuit.

[0018] In one embodiment, the first induction coil is connected to one of the phase line and the neutral line of the grid-connected interface, and the second normally closed auxiliary switch is connected to the other of the phase line and the neutral line of the grid-connected interface;

[0019] The first main contact includes a first phase line main contact and a first neutral line main contact, wherein the first phase line main contact is connected to the phase line of the grid-connected interface in a one-to-one correspondence, and the first neutral line main contact is connected to the neutral line of the grid-connected interface in a corresponding manner.

[0020] In one embodiment, the second induction coil is connected to one of the phase line and the neutral line of the off-grid interface, and the first normally closed auxiliary switch is connected to the other of the phase line and the neutral line of the off-grid interface;

[0021] The second main contacts include a second phase line main contact and a second neutral line main contact, wherein the second phase line main contact is connected to the phase line of the off-grid interface in a one-to-one correspondence, and the second neutral line main contact is connected to the neutral line of the off-grid interface in a corresponding manner.

[0022] In one embodiment, the switching device further includes a mechanical interlocking accessory, which is disposed between the first electromagnetic switch and the second electromagnetic switch, mechanically connecting the first electromagnetic switch and the second electromagnetic switch into one, and mechanically interlocking the first electromagnetic switch and the second electromagnetic switch.

[0023] In one embodiment, the first normally closed auxiliary switch is mounted on the first electromagnetic switch, and the second normally closed auxiliary switch is mounted on the second electromagnetic switch.

[0024] In one embodiment, the first electromagnetic switch and the second electromagnetic switch are AC contactors, and the first normally closed auxiliary switch and the second normally closed auxiliary switch are normally closed auxiliary contacts;

[0025] The rated voltages of the first electromagnetic switch, the second electromagnetic switch, the first normally closed auxiliary switch, and the second normally closed auxiliary switch are all within the grid voltage range.

[0026] A second aspect of the present application provides an inverter system. The inverter system includes an inverter and a switching device as described in the first aspect or any embodiment of the first aspect, wherein the inverter is connected to the switching device, the switching device is further configured to be connected to a load, and the inverter is configured to output AC power to the load via the switching device.

[0027] A third aspect of the present application provides an energy storage system. The energy storage system includes a battery pack, an inverter, and a switching device as described in the first aspect or any embodiment of the first aspect, wherein the battery pack and the switching device are both connected to the inverter, and the switching device is further configured to be connected to a load. The inverter is configured to convert the direct current (DC) power provided by the battery pack into alternating current (AC) power and output the AC power to the load via the switching device.

[0028] Compared with the prior art, this application has the following advantages:

[0029] 1. The switching device of the present application can be applied to the power supply scenario of the load and used in conjunction with the inverter. It can realize the function of switching the load to be powered by the power grid and / or inverter, and also realize the function of switching the inverter to the grid-connected interface or the off-grid interface to carry the load. The switching efficiency is high and the safety is high, which is conducive to ensuring uninterrupted power supply to the load and safe operation of the inverter.

[0030] 2. The switching device of the present application is configured such that the first electromagnetic switch and the second normally closed auxiliary switch are located in the same control circuit, and the second electromagnetic switch and the first normally closed auxiliary switch are located in another control circuit, so that the on-off state of the first electromagnetic switch can depend on the power supply status of the first control circuit, and the on-off state of the second electromagnetic switch can depend on the power supply status of the second control circuit. In addition, the first electromagnetic switch and the first normally closed auxiliary switch are mechanically interlocked, and the second electromagnetic switch and the second normally closed auxiliary switch are mechanically interlocked. Therefore, when the first control circuit is energized, the first electromagnetic switch can connect the grid-connected interface and the load, and the second normally closed auxiliary switch can synchronously disconnect the second control circuit, so that The second electromagnetic switch cannot connect the off-grid interface and the load; when the second control circuit is energized, the second electromagnetic switch can connect the off-grid interface and the load, and the first normally closed auxiliary switch can synchronously disconnect the first control circuit, so that the first electromagnetic switch cannot connect the grid-connected interface and the load. In this way, the grid-connected interface and the off-grid interface of the inverter can be used to select one to supply power to the load, thereby automatically switching the power supply for the load without the need for remote control of the upper computer or the need for an additional controller. Therefore, the switching efficiency of the switching device of the present application is high and the cost is low. In addition, the interlocking design also ensures the effective switching and safety of use of the switching device.

[0031] 3. The switching device of the present application can be composed of contactors, auxiliary contact devices, and mechanical accessories. The contactors and auxiliary contact devices can be attracted and separated very quickly, so the switching time of the switching device can be very short (such as within 100ms). In addition, it is easy to integrate into one and is cheap. Therefore, the switching device of the embodiment of the present application has the advantages of high switching efficiency, simple structure, small space occupation, low cost, and easy implementation.

[0032] 4. The switching device of the present application can achieve mechanical and electrical interlocking between the switch from the grid side to the load side (i.e., the first electromagnetic switch) and the switch from the off-grid side to the load side (i.e., the second electromagnetic switch), and in the event of a single fault, the off-grid side voltage will not be applied to the grid side (i.e., the AC voltage output by the inverter off-grid interface will not be transmitted to the inverter grid-connected interface), or the grid side voltage will not be applied to the off-grid side (i.e., the AC voltage output by the inverter grid-connected interface will not be transmitted to the off-grid interface). In this way, the safety of grid-side inspection and maintenance can be guaranteed when the inverter is off-grid, avoiding the occurrence of safety accidents. In addition, overstress of the electronic components of the inverter can also be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a schematic diagram of an application scenario of the switching device provided in an embodiment of the present application.

[0034] FIG2 is a schematic structural diagram of the switching device in FIG1 .

[0035] FIG. 3 is a connection diagram of the switching device in FIG. 1 .

[0036] FIG4 is a schematic diagram of an inverter system provided in an embodiment of the present application.

[0037] FIG5 is a schematic diagram of an energy storage system provided in an embodiment of the present application.

[0038] Key Component Symbols Description Switching Device 100 First Electromagnetic Switch 10 Second Electromagnetic Switch 20 First Normally Closed Auxiliary Switch 30 Second Normally Closed Auxiliary Switch 40 Mechanical Interlocking Accessory 50 Inverter 200 Battery Interface 201 PV Interface 202 Grid-Connected Interface 203 Off-Grid Interface 204 Battery Pack 300 PV Panel 400 Load 500 Grid 600 Inverter System 1000 Energy Storage System 2000 DETAILED DESCRIPTION

[0039] Please refer to Figure 1, which is a schematic diagram of an application scenario of the switching device provided in an embodiment of the present application. The scenario in Figure 1 includes a switching device 100, an inverter 200, a battery pack 300, a photovoltaic module 400, a load 500 and a power grid 600.

[0040] The inverter 200 includes a battery interface 201, a photovoltaic interface 202, a grid-connected interface 203, and an off-grid interface 204. The battery interface 201 is used to connect to the positive and negative poles of the battery pack 300. The photovoltaic interface 202 is used to connect to the output interface of the photovoltaic component 400. The grid-connected interface 203 is used to connect to the power grid 600, wherein the phase line L' of the grid-connected interface 203 corresponds to the phase line L connected to the power grid 600, and the neutral line N' of the grid-connected interface 203 corresponds to the neutral line N connected to the power grid 600. The grid-connected interface 203 is also used to connect to the switching device 100 through the phase line L' and the neutral line N'. Similarly, the off-grid interface 204 is also used to connect to the switching device 100 through its phase line L" and neutral line N". The switching device 100 is also connected to the phase line L'' and neutral line N'' of the load 500.

[0041] The inverter 200 can access the DC power provided by the battery pack 300 through the battery interface 201, or can access the DC power provided by the photovoltaic module 400 through the photovoltaic interface 202. The inverter 200 can output AC power through the grid-connected interface 203 or the off-grid interface 204. In one embodiment, the inverter 200 can also omit either the battery interface 201 or the photovoltaic interface 202. When the inverter 200 transmits AC power through the grid-connected interface 203, the inverter 200 is in a grid-connected state. When the inverter 200 transmits AC power through the off-grid interface 204, the inverter 200 is in an off-grid state.

[0042] The load 500 can be a single-phase, two-phase or three-phase load, and no limitation is made here. That is to say, the phase line L'' of the load 500 can be a single-phase, two-phase or three-phase phase line. Correspondingly, the AC power provided to the load 500 by the inverter 200 and the grid 600 can also be single-phase, two-phase or three-phase AC power. Among them, the phase line L' of the grid-connected interface 203 of the inverter 200, the phase line L'' of the off-grid interface 204, the phase line L of the grid 600 and the phase line L'' of the load 500 are consistent in number and phase sequence.

[0043] The switching device 100 can be integrated separately. In actual application, the switching device 100 can first establish connections with the grid-connected interface 203, the off-grid interface 204, the power grid 600, and the load 500, and then can be used in conjunction with the inverter 200 to switch the corresponding power supply source for the load 500 when the inverter 200 is in grid-connected or off-grid operation. The control logic for the on-grid and off-grid operation of the inverter 200 can be pre-set, but this does not constitute a limitation of this application.

[0044] Next, the switching device 100 according to the embodiment of the present application is further introduced.

[0045] Please also refer to FIG. 2 , the switching device 100 includes a first electromagnetic switch 10 , a second electromagnetic switch 20 , a first normally closed auxiliary switch 30 , a second normally closed auxiliary switch 40 and a mechanical interlocking accessory 50 .

[0046] As shown in Figure 2, the first normally closed auxiliary switch 30 can be mounted on the first electromagnetic switch 10 to form an integral assembly with the first electromagnetic switch 10. The second normally closed auxiliary switch 40 can be mounted on the second electromagnetic switch 20 to form an integral assembly with the second electromagnetic switch 20. A mechanical interlocking assembly 50 can be positioned between the first and second electromagnetic switches 10, 20, or on the same side of the first and second electromagnetic switches 10, 20, thereby connecting the first and second electromagnetic switches 10, 20 and integrating the entire switching device 100. This facilitates implementation, reduces space requirements, and reduces wiring requirements in practical applications.

[0047] In an embodiment of the present application, the first electromagnetic switch 10 is connected to the second normally closed auxiliary switch 40, the grid-connected interface 203 of the inverter 200 and the load 500, and the second normally closed auxiliary switch 40 is also connected to the grid-connected interface 203, so that the first electromagnetic switch 10, the second normally closed auxiliary switch 40 and the grid-connected interface 203 together constitute a first control loop.

[0048] The second electromagnetic switch 20 is connected to the first normally closed auxiliary switch 30, the off-grid interface 204 of the inverter 200 and the load 500. The first normally closed auxiliary switch 30 is also connected to the off-grid interface 204, so that the second electromagnetic switch 20, the first normally closed auxiliary switch 30 and the off-grid interface 204 together constitute a second control loop.

[0049] Specifically, referring to Figure 3 , the first electromagnetic switch 10 includes first main contacts TL1, TN1, and a first induction coil A1. For ease of distinction, TL1 may also be referred to as the first phase main contact, and TN1 as the first neutral main contact.

[0050] The first main contacts TL1 and TN1 are connected between the grid-connected interface 203 and the load 500. Specifically, the first end of the first main contact TL1 (denoted as 1 in FIG. 3 as the first end) is connected in a one-to-one correspondence with the phase line L' of the grid-connected interface 203, and the first end of the first main contact TN1 is connected in a one-to-one correspondence with the neutral line N' of the grid-connected interface 203. The second end of the first main contact TL1 (denoted as 2 in FIG. 3 as the second end) is connected in a one-to-one correspondence with the phase line L'' of the load 500, and the second end of the first main contact TN1 is connected in a one-to-one correspondence with the neutral line N'' of the load 500.

[0051] It should be understood that since the phase line L' of the grid-connected interface 203 is also connected to the phase line L of the grid 600, and the neutral line N' of the grid-connected interface 203 is also connected to the neutral line N of the grid 600, the first end of the first main contact TL1 will also be connected one-to-one with the phase line L of the grid 600, and the first end of the first main contact TN1 will also be connected one-to-one with the neutral line N of the grid 600.

[0052] The first induction coil A1 is connected in series with the second normally closed auxiliary switch 40 (corresponding to K2 in FIG. 3 ). Furthermore, the first induction coil A1 and the second normally closed auxiliary switch 40 are both connected to the grid-connected interface 203, thereby forming a first control loop with the grid-connected interface 203. Specifically, the first end of the first induction coil A1 is connected to the phase line L' of the grid-connected interface 203, the second end of the first induction coil A1 is connected to the second end of the second normally closed auxiliary switch 40, and the first end of the second normally closed auxiliary switch 40 is connected to the neutral line N' of the grid-connected interface 203. Alternatively, the first end of the first induction coil A1 is connected to the neutral line N' of the grid-connected interface 203, the second end of the first induction coil A1 is connected to the second end of the second normally closed auxiliary switch 40, and the first end of the second normally closed auxiliary switch 40 is connected to the phase line L' of the grid-connected interface 203. The first induction coil A1, the second normally closed auxiliary switch 40, and the grid-connected interface 203 are thus connected to form the first control loop.

[0053] 3 , the second electromagnetic switch 20 includes second main contacts TL2, TN2, and a second induction coil A2. For ease of distinction, TL2 may also be referred to as the second phase line main contact, and TN2 as the second neutral line main contact.

[0054] The second main contacts TL2 and TN2 are connected between the off-grid interface 204 and the load 500. Specifically, the first end of the second main contact TL" is connected in a one-to-one correspondence with the phase line L" of the off-grid interface 204, and the first end of the second main contact TN" is connected in a one-to-one correspondence with the neutral line N" of the off-grid interface 204. The second end of the second main contact TL" is connected in a one-to-one correspondence with the phase line L"' of the load 500, and the second end of the second main contact TN" is connected in a one-to-one correspondence with the neutral line N"' of the load 500.

[0055] The second induction coil A2 is connected in series with the first normally closed auxiliary switch 30 (corresponding to K1 in FIG. 3 ). Furthermore, the second induction coil A2 and the first normally closed auxiliary switch 30 are also connected to the off-grid interface 204, thereby forming a second control loop together with the off-grid interface 204. Specifically, the first end of the second induction coil A2 is connected to the phase line L'' of the off-grid interface 204, the second end of the second induction coil A2 is connected to the second end of the first normally closed auxiliary switch 30, and the first end of the first normally closed auxiliary switch 30 is connected to the neutral line N'' of the off-grid interface 204. Alternatively, the first end of the second induction coil A2 is connected to the neutral line N'' of the off-grid interface 204, the second end of the second induction coil A2 is connected to the second end of the first normally closed auxiliary switch 30, and the first end of the first normally closed auxiliary switch 30 is connected to the phase line L'' of the off-grid interface 204. The second induction coil A2, the first normally closed auxiliary switch 30, and the off-grid interface 204 are thus connected to form a second control loop.

[0056] In the embodiment of the present application, the first electromagnetic switch 10 and the second electromagnetic switch 20 are normally open switches, and the first normally closed auxiliary switch 30 and the second normally closed auxiliary switch 40 are both normally closed switches. The types of the first electromagnetic switch 10, the second electromagnetic switch 20, the first normally closed auxiliary switch 30, and the second normally closed auxiliary switch 40 are not limited, as long as they can achieve the corresponding functions. For example, in this embodiment, the first electromagnetic switch 10 and the second electromagnetic switch 20 can be AC ​​contactors, where the first main contact of the first electromagnetic switch 10 and the second main contact of the second electromagnetic switch 20 are normally open contacts. The first normally closed auxiliary switch 30 and the second normally closed auxiliary switch 40 can also use normally closed auxiliary contacts.

[0057] In the embodiment of the present application, since the switching device 100 is used in conjunction with an inverter 200 capable of both grid-connected and off-grid operation with load, the rated voltages of the first electromagnetic switch 10, the second electromagnetic switch 20, the first normally closed auxiliary switch 30, and the second normally closed auxiliary switch 40 are all within the voltage range of the power grid 600. For example, when the power grid 600 is a 220V mains, the rated voltages of the first electromagnetic switch 10, the second electromagnetic switch 20, the first normally closed auxiliary switch 30, and the second normally closed auxiliary switch 40 can be within the range of 210 to 230V. This design prevents the first electromagnetic switch 10, the second electromagnetic switch 20, the first normally closed auxiliary switch 30, and the second normally closed auxiliary switch 40 from overstress and damage, thereby preventing them from affecting the normal operation of the inverter 200, the power grid 600, and the load 500.

[0058] In the embodiment of the present application, the first electromagnetic switch 10 and the first normally closed auxiliary switch 30 are mechanically interlocked, the second electromagnetic switch 20 and the second normally closed auxiliary switch 40 are mechanically interlocked, and the first electromagnetic switch 10 and the second electromagnetic switch 20 are mechanically interlocked.

[0059] Specifically, as shown in Figure 3, the first main contacts TL1 and TN1 of the first electromagnetic switch 10 are mechanically interlocked with the first normally closed auxiliary switch 30. Therefore, the first main contacts TL1 and TN1 and the first normally closed auxiliary switch 30 are never closed simultaneously. Therefore, when the first main contacts TL1 and TN1 switch from open to closed, the first normally closed auxiliary switch 30 switches from closed to open. This prevents short circuits in the grid-connected interface 203 of the inverter 200.

[0060] Similarly, the second main contacts TL2 and TN2 of the second electromagnetic switch 20 are mechanically interlocked with the second normally closed auxiliary switch 40. Therefore, the second main contacts TL2 and TN2 and the second normally closed auxiliary switch 40 will not close simultaneously. Therefore, when the second main contacts TL2 and TN2 switch from open to closed, the second normally closed auxiliary switch 40 switches from closed to open. This prevents short circuits in the off-grid interface 204 of the inverter 200.

[0061] The first main contact TL1 and the second main contact TL2 are mechanically interlocked.

[0062] It will be appreciated that the embodiments of the present application do not limit the implementation method of the mechanical interlock. Taking the first main contact TL1 and the second main contact TL2 as an example, for example, the first main contact TL1 and the second main contact TL2 can be mechanically connected via a mechanical interlocking accessory 50, thereby achieving mechanical interlocking between the first main contact TL1 and the second main contact TL2.

[0063] The structure of the mechanical interlocking assembly 50 is not limited. For example, the mechanical interlocking assembly 50 can be a mechanical link. When one of the first and second main contacts is conducting, the other is locked and prevented from closing. This ensures that only one of the first and second main contacts is closed. Therefore, even if the electrical interlock fails, the first and second main contacts are prevented from closing simultaneously. This further ensures the effective switching of the switching device 100 and the normal and safe operation of the switching device 100 and the circuit to which it is connected.

[0064] Based on the above design, when inverter 200 is grid-connected and operating, grid 600 is supplying power normally, and inverter 200 outputs the AC current required by load 500 via grid-connection interface 203. Of course, in some cases, grid 600 and inverter 200 can jointly output AC current to meet load demand. In general, inverter 200 and grid 600 supply power to load 500 via grid-connection interface 203.

[0065] When grid-connected interface 203 outputs AC current, the second normally closed auxiliary switch 40 is closed, energizing the first control loop. The first induction coil A1 receives the output of grid-connected interface 203, generating a first electromagnetic signal. Under the control of the first electromagnetic signal, the first main contacts TL1 and TN1 switch to a closed state, thereby connecting the grid-connected interface 203 and the load 500 to the first electromagnetic switch 10. Simultaneously, because the first normally closed auxiliary switch 30 is mechanically interlocked with the first electromagnetic switch 10, it switches to an open state, disconnecting the second control loop.

[0066] It will be appreciated that once the second control circuit is disconnected, power cannot be supplied to close the second main contacts TL2 and TN2. Therefore, the first electromagnetic switch 10 and the second electromagnetic switch 20 are now electrically interlocked. Furthermore, because the first main contact TL1 and the second main contact TL2 are mechanically interlocked, when the first main contact TL1 is closed, even if power is accidentally re-energized due to a single fault in the second control circuit, the second main contacts TL2 and TN2 will not close and will remain open.

[0067] Therefore, at this time, the AC current output by the grid-connected interface 203 is transmitted to the load 500 through the closed first main contacts TL1 and TN1. That is, at this time, at least one of the inverter 200 and the grid 600 serves as a power supply source to supply power to the load 500.

[0068] When inverter 200 needs to operate off-grid, perhaps due to a power outage on grid 600 or other reasons, disconnection between grid 600 and inverter 200 is necessary to ensure safety during grid 600 maintenance. Therefore, inverter 200 outputs AC voltage through off-grid interface 204, while grid-connected interface 203 is de-energized. Consequently, first induction coil A1 loses power and cannot generate the first electromagnetic signal. Therefore, first main contacts TL1 and TN1 are both switched to an open state, and first normally closed auxiliary switch 30 is switched to a closed state. Therefore, the second control loop containing second induction coil A2 and first normally closed auxiliary switch 30 is connected, allowing access to the output of off-grid interface 204. Consequently, second induction coil A2 can receive the output of off-grid interface 204, generating a second electromagnetic signal. Controlled by the second electromagnetic signal, second main contacts TL2 and TN2 are switched to a closed state, thereby connecting second electromagnetic switch 200 to off-grid interface 204 and load 500. At the same time, since the second normally closed auxiliary switch 40 and the second electromagnetic switch 20 are mechanically interlocked, the second normally closed auxiliary switch 40 is switched to an open state, thereby disconnecting the first control loop.

[0069] As can be understood, once the first control circuit is disconnected, power cannot be supplied to close the first main contacts TL1 and TN1. Therefore, the second electromagnetic switch 20 and the first electromagnetic switch 10 are electrically interlocked. Furthermore, because the first main contact TL1 and the second main contact TL2 are mechanically interlocked, when the second main contact TL2 is closed, even if power is accidentally restored due to a single fault in the first control circuit, the first main contacts TL1 and TN1 will not close and will remain open.

[0070] Therefore, at this time, the output of the off-grid interface 204 is transmitted to the load 500 through the closed second main contacts TL2 and TN2. That is, at this time, the inverter 200 serves as the power supply source and supplies power to the load 500 through the off-grid interface 204.

[0071] If the power grid 600 loses power and then recovers during the above process, the second normally closed auxiliary switch 40 is in the open state. Therefore, the first control loop containing the second normally closed auxiliary switch 40 and the first induction coil A1 cannot be connected. Therefore, the first main contacts TL1 and TN1 remain open, and the second main contacts TL2 and TN2 remain closed. Therefore, the second electromagnetic switch 20 maintains connection between the off-grid interface 204 and the load 500, while the second normally closed auxiliary switch 40 remains disconnected from the first control loop. The inverter 200 is in the off-grid operating state, and the load 500 is still powered by the inverter 200.

[0072] Furthermore, if the subsequent inverter 200 stops outputting AC voltage through the off-grid interface 204, that is, the off-grid interface 204 is powered off, the switching device 100 can be switched to access the output of the grid-connected interface 203, so that the power grid 600 and the inverter 200 supply power to the load 500 through the grid-connected interface 203. The specific process can be found in the relevant description of the switching device 100 when the grid-connected interface 203 is output, which will not be repeated here.

[0073] As can be seen, when the grid 600 resumes power supply, when the switching device 100 switches back to outputting AC voltage to the load 500 through the grid-connected interface 203 may depend on when the off-grid interface 204 of the inverter 200 loses power. Therefore, the inverter 200 can determine whether the grid 600 has lost power by sampling the voltage between the phase line L and the neutral line N, or by sampling the voltage of the grid-connected interface 203, through the voltage sampling circuit. This can then control its own operating state (i.e., whether it is grid-connected or off-grid, in other words, whether it outputs through the grid-connected interface 203 or the off-grid interface 204), thereby affecting the switching behavior of the switching device 100. For example, the inverter 200 may stop outputting AC voltage through the off-grid interface 204 after a preset time period has passed since the grid 600 resumes power supply, so that the switching device 100 switches back to having the grid 600 provide AC current to the load 500 through the grid-connected interface 203 only after a period of time has passed since the grid 600 resumes power supply. Such a design can ensure that power is supplied to the load 500 only after the power supply of the power grid 600 is stable, thereby ensuring the stable and normal operation of the load 500. The preset time length can be set to 5 seconds or other time lengths, for example.

[0074] To sum up, the switching device of the embodiment of the present application can be used in conjunction with the inverter to switch the power supply for the load, and switch the grid-connected interface load or the off-grid interface load of the inverter (referred to as on-grid and off-grid load), with high switching efficiency and high safety, which is conducive to ensuring uninterrupted power supply to the load and safe operation of the inverter.

[0075] Compared with manual two-way knife switches and professional dual-power switching switches (ATS, Automatic Transfer Switching Equipment), manual two-way knife switches require manual operation, which is cumbersome to operate and poses safety hazards. In addition, the switching time is long, making it difficult to switch immediately when the power grid is out of power or restored. ATS is expensive, and the switching is also relatively slow, generally requiring more than 1 second of switching time. The switching device of the embodiment of the present application can be composed of contactors, auxiliary contact devices, and mechanical accessories. The contactors and auxiliary contact devices can be attracted and separated very quickly, so the switching time of the switching device can be very short (such as within 100ms). In addition, the contactors, auxiliary contact devices, and mechanical accessories are cheap, simple in structure, and easy to integrate into one. Therefore, the switching device of the embodiment of the present application has the advantages of high switching efficiency, low cost, simple structure, easy implementation, and small space occupation.

[0076] Moreover, the switching device of the embodiment of the present application can realize mechanical interlocking and electrical interlocking between the switch from the grid side to the load side (i.e., the first electromagnetic switch) and the switch from the off-grid side to the load side (i.e., the second electromagnetic switch), wherein the mechanical interlocking can prevent the failure of the electrical interlocking from causing the switching function of the switching device to fail. And in the case of a single fault, the off-grid side voltage will not be applied to the grid side, or the grid side voltage will not be applied to the off-grid side. In this way, when the inverter is off-grid, the safety of the grid side inspection and maintenance can be guaranteed to avoid the occurrence of safety accidents. In addition, overstress of the electronic components of the inverter can also be avoided.

[0077] Please refer to FIG. 4 . The embodiment of the present application also provides an inverter system.

[0078] As shown in FIG. 4 , the inverter system 1000 includes a switching device 100 and an inverter 200 .

[0079] The switching device 100 is connected to the inverter 200. The switching device 100 is also connected to the load, and the inverter 200 is also connected to the power grid. The switching device 100 may be the switching device 100 of the embodiment shown in FIG. 1 to FIG. 3 .

[0080] It can be understood that the switching device 100 , the inverter 200 , the power grid and the load can refer to the relevant description in the aforementioned switching device 100 , which will not be repeated here.

[0081] Please refer to FIG5 as well. This embodiment of the present application also provides an energy storage system.

[0082] As shown in FIG5 , the energy storage system 2000 includes a switching device 100 , an inverter 200 and a battery pack 300 .

[0083] The description of the switching device 100 and inverter 200 can be found in the relevant description in FIG4 and will not be repeated here. The battery pack 300 is connected to the inverter 200, thereby providing DC power to the inverter 200. The inverter 200 can then convert the DC power provided by the battery pack 300 into AC power and transmit the AC power to the load connected to the inverter 200 through the switching device 100.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A switching device, characterized in that, Including: A first electromagnetic switch, a second electromagnetic switch, a first normally-closed auxiliary switch, and a second normally-closed auxiliary switch; The first electromagnetic switch is used to connect the second normally-closed auxiliary switch, the grid connection interface of the inverter, and the load, where the grid connection interface is used to connect to the power grid; the second normally-closed auxiliary switch is used to connect to the grid connection interface, so as to jointly form a first control loop with the grid connection interface and the first electromagnetic switch; The second electromagnetic switch is used to connect the first normally-closed auxiliary switch, the off-grid interface of the inverter, and the load; the first normally-closed auxiliary switch is used to connect to the off-grid interface, so as to jointly form a second control loop with the off-grid interface and the second electromagnetic switch; Wherein, the first electromagnetic switch and the first normally-closed auxiliary switch are mechanically interlocked, the first electromagnetic switch and the second electromagnetic switch are mechanically interlocked, and the second electromagnetic switch and the second normally-closed auxiliary switch are mechanically interlocked; The first control loop is used to control the first electromagnetic switch to close when the inverter is operating in grid-connected mode, so as to conduct the grid connection interface and the load, and control the first normally-closed auxiliary switch to open, so as to disconnect the second control loop, so that the inverter and the power grid supply power to the load through the grid connection interface; The second control loop is used to control the second electromagnetic switch to close when the inverter is operating in off-grid mode, so as to conduct the off-grid interface and the load, and control the second normally-closed auxiliary switch to open, so as to disconnect the first control loop, so that the inverter supplies power to the load through the off-grid interface.

2. The switching device according to claim 1, wherein The first electromagnetic switch includes a first main contact and a first induction coil. Wherein, the first main contact is connected between the grid connection interface and the load, the first induction coil is connected in series with the second normally-closed auxiliary switch, and the first induction coil and the second normally-closed auxiliary switch are also both connected to the grid connection interface, so as to jointly form the first control loop with the grid connection interface; The second electromagnetic switch includes a second main contact and a second induction coil. Wherein, the second main contact is connected between the off-grid interface and the load, the second induction coil is connected in series with the first normally-closed auxiliary switch, and the second induction coil and the first normally-closed auxiliary switch are also both connected to the off-grid interface, so as to jointly form the second control loop with the off-grid interface.

3. The switching device according to claim 2, wherein The first main contact and the first normally-closed auxiliary switch are mechanically interlocked, the first main contact and the second main contact are mechanically interlocked, and the second main contact and the second normally-closed auxiliary switch are mechanically interlocked; The first control loop is used to be powered on when the inverter is operating in grid-connected mode, so that the first induction coil generates a first electromagnetic signal, and the first electromagnetic signal is used to control the first main contact to close, so as to conduct the grid connection interface and the load; when the first main contact closes, the first normally-closed auxiliary switch opens, so as to disconnect the second control loop; The second control loop is used to be powered on when the inverter operates off-grid, so that the second induction coil generates a second electromagnetic signal, and the second electromagnetic signal is used to control the closing of the second main contact to conduct the off-grid interface and the load; when the second main contact is closed, the second normally closed auxiliary switch is opened to disconnect the first control loop.

4. The switching device according to claim 2, characterized in that, The first induction coil is connected to one of the phase line and the neutral line of the grid-connected interface, and the second normally closed auxiliary switch is connected to the other of the phase line and the neutral line of the grid-connected interface; The first main contact includes a first phase line main contact and a first neutral line main contact, wherein the first phase line main contact is connected to the phase line of the grid-connected interface in one-to-one correspondence, and the first neutral line main contact is connected to the neutral line of the grid-connected interface correspondingly.

5. The switching device according to claim 2, characterized in that, The second induction coil is connected to one of the phase line and the neutral line of the off-grid interface, and the first normally closed auxiliary switch is connected to the other of the phase line and the neutral line of the off-grid interface; The second main contact includes a second phase line main contact and a second neutral line main contact, wherein the second phase line main contact is connected to the phase line of the off-grid interface in one-to-one correspondence, and the second neutral line main contact is connected to the neutral line of the off-grid interface correspondingly.

6. The switching device according to claim 1, wherein The switching device further includes a mechanical interlock fitting, which is arranged between the first electromagnetic switch and the second electromagnetic switch, mechanically connects the first electromagnetic switch and the second electromagnetic switch into one body, and mechanically interlocks the first electromagnetic switch and the second electromagnetic switch.

7. The switching device according to claim 1, wherein The first normally closed auxiliary switch is installed on the first electromagnetic switch, and the second normally closed auxiliary switch is installed on the second electromagnetic switch.

8. The switching device according to claim 1, wherein The first electromagnetic switch and the second electromagnetic switch adopt AC contactors, and the first normally closed auxiliary switch and the second normally closed auxiliary switch adopt normally closed auxiliary contacts; Wherein, the rated voltages of the first electromagnetic switch, the second electromagnetic switch, the first normally closed auxiliary switch and the second normally closed auxiliary switch are all within the range of the grid voltage.

9. An inverter system, characterized in that, The inverter system includes an inverter and the switching device according to any one of claims 1 to 8, the inverter is connected to the switching device, the switching device is further used to be connected to a load, and the inverter is used to output alternating current to the load through the switching device.

10. A energy storage system, characterized in that, The energy storage system includes a battery pack, an inverter and the switching device according to any one of claims 1 to 8, the battery pack and the switching device are both connected to the inverter, the switching device is further used to be connected to a load, and the inverter is used to convert the direct current provided by the battery pack into alternating current and output the alternating current to the load through the switching device.

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