Power conversion device and switching apparatus

Abstract

Provided in the present application are a power conversion device and a switching apparatus. A switching apparatus and a controller are provided in the power conversion device. The switching apparatus comprises a first contact, a second contact, a piston and an electromagnetic driving mechanism. The first contact may come into contact with or be separated from the second contact. The piston is movable relative to a housing. When the switching apparatus is turned on, the first contact comes into contact with the second contact, and the piston is disposed away from the first contact and the second contact. When a fault occurs in a circuit where the switching apparatus is located, the controller may control the electromagnetic driving mechanism to be turned on, such that the electromagnetic driving mechanism drives the piston to move towards the first contact and the second contact, so as to separate the first contact from the second contact, thereby disconnecting the power conversion device from a direct-current bus. The electromagnetic driving mechanism drives, in an electromagnetic manner, the piston to separate the first contact from the second contact, and can quickly respond to a fault signal, so as to improve the high-efficiency breaking speed between the power conversion device and the direct-current bus, thereby preventing fault spreading.

Description

A power conversion device and a switching device

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202510382158.8, filed on March 27, 2025, entitled "A Power Conversion Device and Switching Device", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of power technology, and in particular to a power conversion device and a switching device. Background Technology

[0004] With the rapid development of new energy sources, the integration of photovoltaic, energy storage, and charging systems has become a current research hotspot. Among these, since both energy storage batteries and photovoltaic modules operate on DC voltage, and DC systems offer advantages over AC systems such as higher conversion efficiency and lower equipment costs, they have a greater application advantage in charging stations and photovoltaic power plants. Typically, connecting devices are equipped with mechanical switches, which connect to a common DC bus. In the event of a short circuit fault on the common DC bus or in the connecting devices, it is necessary to quickly disconnect the common DC bus and the connecting devices to prevent the fault from spreading.

[0005] Existing mechanical switches consist of two contacts that conduct electricity when in contact and disconnect when separated. The mechanical switch can use a spring mechanism to drive the two contacts apart. Alternatively, it can use high-pressure gas or impact force generated by a small explosive to separate the two contacts. However, the driving speed of the aforementioned spring mechanisms still cannot meet the breaking rate requirements of the mechanical switch, and small explosives also have high requirements for manufacturing and maintenance. Therefore, improving the breaking speed of the switch has become an important direction in current switch development. Summary of the Invention

[0006] This application provides a power conversion device and a switching device to send a disconnect signal to the switching device when a short circuit fault occurs in the power conversion circuit or DC bus, and to separate two contacts by electromagnetic drive, thereby realizing the rapid disconnection of the power conversion circuit and the DC bus to prevent the fault from spreading.

[0007] In a first aspect, this application provides a power conversion device. The power conversion device includes a power conversion circuit, a switching device, and a controller. The input / output terminal of the power conversion circuit is connected to the aforementioned switching device. The switching device includes a housing, a first contact, a second contact, a piston, and an electromagnetic drive mechanism. The first contact, the second contact, and the piston are located within the housing. The first contact is electrically connected to the corresponding power conversion circuit, and the second contact is electrically connected to a DC bus. At least one of the first and second contacts is rotatable relative to the housing to allow the first and second contacts to contact or separate. The piston is movable relative to the housing. The electromagnetic drive mechanism includes a first fixed conductor and a movable conductor. The first fixed conductor is fixedly connected to the housing, and the movable conductor is fixedly connected to the piston. The first fixed conductor and the movable conductor are sequentially electrically connected. The first fixed conductor includes a first conductor portion disposed opposite to the movable conductor. When the electromagnetic drive mechanism is energized, the current conduction direction of the first conductor portion is opposite to the current direction of the movable conductor. When the power conversion device is operating normally, the piston is held away from the first and second contacts, and the first and second contacts are in contact. When a short circuit fault occurs in the circuit where the switching device is located, the controller controls the first fixed conductor and the moving conductor to conduct, so that the first magnetic field generated by the first conductor drives the moving conductor to move, thereby driving the piston to move toward the first contact and the second contact and separating the first contact and the second contact.

[0008] The switching device of this application can connect or disconnect the power conversion circuit from the DC bus or the AC power grid / AC load. Taking the switching device located between the power conversion circuit and the DC bus as an example, the power conversion equipment can include multiple power conversion circuits and multiple switching devices. The power conversion circuits and switching devices can be configured one-to-one and connected to the DC bus. In some cases, the power conversion circuits and switching devices can also have a many-to-one relationship. When a short-circuit fault occurs in the line where the switching device is located, the short-circuit current flows through the power conversion equipment. The controller can control the supply of electrical energy to the electromagnetic drive mechanism of the switching device corresponding to the faulty line to control the switching device corresponding to the faulty line to turn off, thereby preventing the fault from spreading. Specifically, a short-circuit fault in the line where the switching device is located can include a short-circuit fault in the power conversion circuit connected to the switching device, an external load, or its connecting lines. In this case, since the current in the moving conductor is opposite to the current in the first conductor, the direction of the magnetic field generated by the moving conductor is opposite to the direction of the magnetic field generated by the first conductor. In this way, through electromagnetic drive of the magnetic field, the moving conductor moves under the influence of the magnetic field generated by the first conductor, thereby driving the piston towards the two contacts, thus separating the first and second contacts to disconnect the power conversion circuit from the DC bus. The aforementioned electromagnetic drive mechanism uses electromagnetic means to drive the piston to separate the first and second contacts, enabling rapid response to short-circuit faults, thereby increasing the breaking speed between the power conversion circuit and the DC bus and preventing fault propagation. Similarly, when the switching device is located between the power conversion circuit and the AC power grid / AC load, a similar principle can be used to quickly disconnect the power conversion circuit and the AC power grid / AC load, preventing fault propagation. This electromagnetic drive mechanism has a simple structure and low manufacturing cost. Furthermore, the contact between the first and second contacts to achieve the switching function enhances the current-carrying capacity, and the piston easily pushes open the first and second contacts, achieving rigid separation of the switching device.

[0009] Furthermore, the switching device may also include a second fixed conductor, which is fixedly connected to the housing. The first fixed conductor, the moving conductor, and the second fixed conductor are sequentially electrically connected. The second fixed conductor includes a second conductor portion disposed opposite to the moving conductor. When the electromagnetic drive mechanism is energized, the current direction of the first conductor portion is the same as the current direction of the second conductor portion. When a short-circuit fault occurs in the circuit where the switching device is located, the controller controls the first fixed conductor, the moving conductor, and the second fixed conductor to conduct, so that the first magnetic field generated by the first conductor portion and the second magnetic field generated by the second conductor portion jointly drive the moving conductor to move, thereby driving the piston to move toward the first and second contacts and separating the first and second contacts. By adding a second fixed conductor and making the current direction of the first conductor portion and the current direction of the second conductor portion the same when the electromagnetic drive mechanism is energized, the first conductor portion of the first fixed conductor and the second conductor portion of the second fixed conductor can jointly generate a superimposed magnetic field. In this way, compared with a single fixed conductor, the moving conductor can be driven to move at a faster speed, thereby driving the piston to separate the first and second contacts more quickly. Alternatively, at the same breaking speed, the current excitation for energizing the electromagnetic drive mechanism can be smaller, and the volume of the excitation system can be relatively reduced.

[0010] The aforementioned movable conductor can be a strip conductor. The first conductor portion and the second conductor portion are parallel to the movable conductor, respectively, and the first fixed conductor and the second fixed conductor are located on the side of the piston away from the first contact and the second contact. In this embodiment, the first conductor portion, the second conductor portion, and the movable conductor are all strip conductors. By designing the dimensions of the first conductor portion and the second conductor portion, the force exerted by the magnetic field generated by the first conductor portion and the second conductor portion on the conductive movable conductor can be adjusted.

[0011] Furthermore, since the movable conductor can move relative to the first and second fixed conductors, the connecting wires between the movable conductor and the first fixed conductor, and between the movable conductor and the second fixed conductor, need to be made of flexible materials. Specifically, the electromagnetic drive mechanism also includes a first flexible conductor and a second flexible conductor. The first flexible conductor connects the first fixed conductor and the movable conductor, and the second flexible conductor connects the second fixed conductor and the movable conductor to achieve electrical connection between the first fixed conductor, the movable conductor, and the second fixed conductor. When the piston moves away from the first and second contacts, the first and second flexible conductors bend respectively. When the piston moves towards the first and second contacts, the first and second flexible conductors stretch respectively.

[0012] The switching device may also include a fuse. One end of the fuse is electrically connected to the power conversion circuit, and the other end is electrically connected to the DC bus. The resistance of the fuse is greater than the resistance of the first and second contacts. Therefore, when the power conversion device is operating normally, the first and second contacts are in contact and conducting. At this time, the operating current flows through the path with lower resistance, i.e., the operating current flows through the first and second contacts. When the piston separates the first and second contacts, the current between the first and second contacts flows into the fuse to melt it. In this embodiment, the fuse provides dual protection to the switching device. When the power conversion device is used in a high-voltage power supply system, when the piston separates the first and second contacts, the short-circuit current switches to the circuit where the fuse is located, so the separation of the first and second contacts may not generate an arc. Even if the speed of the current switching circuit is slower than the speed at which an arc is generated when the first and second contacts separate, the arc can still be conducted to the fuse and extinguished by melting the fuse. In addition, the fuse can also melt when the current flowing through it is greater than its rated current. Therefore, fuses have the function of extinguishing arcs or limiting current.

[0013] The switching device of this application may further include an arc-extinguishing chamber, which is located on the side of the first contact and the second contact away from the electromagnetic drive mechanism. The arc-extinguishing chamber is used to eliminate the electric arc generated when the first contact and the second contact separate.

[0014] The rotation of the first and second contacts can be achieved by springs, thus simplifying the structure of the switching device. Specifically, the switching device may further include a first spring and a second spring located within the housing. One end of the first spring is fixedly connected to the housing, and the other end is fixedly connected to the first contact. One end of the second spring is fixedly connected to the housing, and the other end is fixedly connected to the second contact. The first and second contacts are rotatably connected to the housing. The first spring applies a first force to the first contact, and the second spring applies a second force to the second contact. When the power conversion device is operating normally, the first force drives the first contact to rotate toward the second contact, and the second force drives the second contact to rotate toward the first contact. When the piston separates the first and second contacts, the first and second springs are compressed, and after the piston returns to its original position, the first and second springs reset the first and second contacts.

[0015] Furthermore, the switching device may also include a first flexible electrical connection wire and a second flexible electrical connection wire located within the housing. The switching device has a first connecting piece and a second connecting piece. The first flexible electrical connection wire can connect the first connecting piece to a first contact, and the second flexible electrical connection wire can connect the second connecting piece to a second contact. The first connecting piece is used for electrical connection with a corresponding power conversion circuit, and the second connecting piece is used for electrical connection with a DC bus. The first and second flexible electrical connection wires allow for minute movement and / or deformation, thereby improving connection reliability.

[0016] A sealing ring can also be provided between the piston and the housing in the switching device to prevent the electric arc generated by the separation of the first contact and the second contact from entering the electromagnetic drive mechanism.

[0017] The power conversion device of this application also includes a capacitor and a fault switch. One end of the capacitor is electrically connected to a first fixed conductor via the fault switch, and the other end of the capacitor is electrically connected to a second fixed conductor. The fault switch is used to conduct when the controller detects a short circuit in the power conversion device, so that the capacitor supplies power to the electromagnetic drive mechanism. This technical solution uses a capacitor to supply power to the electromagnetic drive mechanism, which can reduce the energy consumption of the power conversion device and has a lower cost.

[0018] In the case of only the first fixed conductor, one end of the capacitor can be electrically connected to one end of the first fixed conductor through a fault switch, and the other end of the capacitor can be electrically connected to the moving conductor.

[0019] In one embodiment, the power conversion circuit can be specifically applied to DC / DC conversion. Specifically, the power conversion circuit includes a DC / DC conversion circuit, the DC input terminal of which is connected to a DC bus via a corresponding switching device, and the DC output terminal of which is used to connect to a DC load.

[0020] In one embodiment, the power conversion circuit can be specifically applied to AC / DC conversion. Specifically, the power conversion circuit includes an AC / DC conversion circuit, the AC input terminal of which is used to connect to the AC power grid, and the DC output terminal of which is connected to the DC bus through a corresponding switching device.

[0021] In one embodiment, the power conversion circuit can be specifically applied to DC / AC conversion. Specifically, the power conversion circuit includes a DC / AC conversion circuit, the DC input terminal of which is connected to a DC bus via a corresponding switching device, and the AC output terminal of which is used to connect to an AC load.

[0022] In one embodiment, the power conversion device includes multiple switching devices, one of which is connected between the photovoltaic string and the DC bus, and / or another of which is connected between the energy storage device and the DC bus. The at least one switching device can connect or disconnect the electrical connection between the DC bus and the photovoltaic module and / or the energy storage device. In this case, a short-circuit fault in the line where the switching device is located can also include a short-circuit fault in the photovoltaic string, the energy storage device, or their connecting lines.

[0023] In one embodiment, the power conversion circuit includes a DC / AC conversion circuit, the AC output of which is connected to the AC power grid via a switching device.

[0024] Secondly, this application provides a switching device. The switching device includes a housing, a first contact, a second contact, a piston, and an electromagnetic drive mechanism. The first contact, the second contact, and the piston are located within the housing. The first contact is electrically connected to a corresponding power conversion circuit, and the second contact is electrically connected to a DC bus. At least one of the first and second contacts is rotatable relative to the housing to allow the first and second contacts to contact or separate. The piston is movable relative to the housing. The electromagnetic drive mechanism includes a first fixed conductor and a movable conductor. The first fixed conductor is fixedly connected to the housing, and the movable conductor is fixedly connected to the piston. The first fixed conductor and the movable conductor are electrically connected in sequence. The first fixed conductor includes a first conductor portion disposed opposite to the movable conductor. When the electromagnetic drive mechanism is energized, the current conduction direction of the first conductor portion is opposite to the current direction of the movable conductor. When the power conversion device is operating normally, the piston is held away from the first and second contacts, and the first and second contacts are in contact. When a short circuit fault occurs in the circuit where the switching device is located, the controller controls the first fixed conductor and the moving conductor to conduct, so that the first magnetic field generated by the first conductor drives the moving conductor to move, thereby driving the piston to move toward the first contact and the second contact and separating the first contact and the second contact.

[0025] The switching device of this application can be applied to power conversion equipment. The switching device can connect or disconnect the power conversion circuit from the DC bus or the AC power grid / AC load. Taking the switching device located between the power conversion circuit and the DC bus as an example, the power conversion equipment can include multiple power conversion circuits and multiple switching devices. The power conversion circuits and switching devices can be configured one-to-one and connected to the DC bus. In some cases, the power conversion circuits and switching devices can also have a many-to-one relationship. When a short-circuit fault occurs in the line where the switching device is located, the short-circuit current flows through the power conversion equipment. The controller can control the supply of electrical energy to the electromagnetic drive mechanism of the switching device corresponding to the faulty line to control the switching device corresponding to the faulty line to turn off, thereby preventing the fault from spreading. Specifically, a short-circuit fault in the line where the switching device is located can include a short-circuit fault in the power conversion circuit connected to the switching device, an external load, or its connecting lines. In this case, since the current in the moving conductor is opposite to the current in the first conductor, the direction of the magnetic field generated by the moving conductor is opposite to the direction of the magnetic field generated by the first conductor. In this way, through electromagnetic drive of the magnetic field, the moving conductor moves under the influence of the magnetic field generated by the first conductor, thereby driving the piston towards the two contacts, thus separating the first and second contacts to disconnect the power conversion circuit from the DC bus. The aforementioned electromagnetic drive mechanism uses electromagnetic means to drive the piston to separate the first and second contacts, enabling rapid response to short-circuit faults, thereby increasing the breaking speed between the power conversion circuit and the DC bus and preventing fault propagation. Similarly, when the switching device is located between the power conversion circuit and the AC power grid, a similar principle can be used to quickly disconnect the power conversion circuit and the AC power grid / AC load, preventing fault propagation. This electromagnetic drive mechanism has a simple structure and low manufacturing cost. Furthermore, the contact between the first and second contacts to achieve the switching function enhances the current-carrying capacity, and the piston easily pushes open the first and second contacts, achieving rigid separation of the switching device.

[0026] Furthermore, the switching device may also include a second fixed conductor, which is fixedly connected to the housing. The first fixed conductor, the moving conductor, and the second fixed conductor are sequentially electrically connected. The second fixed conductor includes a second conductor portion disposed opposite to the moving conductor. When the electromagnetic drive mechanism is energized, the current direction of the first conductor portion is the same as the current direction of the second conductor portion. When a short-circuit fault occurs in the circuit where the switching device is located, the controller controls the first fixed conductor, the moving conductor, and the second fixed conductor to conduct, so that the first magnetic field generated by the first conductor portion and the second magnetic field generated by the second conductor portion jointly drive the moving conductor to move, thereby driving the piston to move toward the first and second contacts and separating the first and second contacts. By adding a second fixed conductor and making the current direction of the first conductor portion and the current direction of the second conductor portion the same when the electromagnetic drive mechanism is energized, the first conductor portion of the first fixed conductor and the second conductor portion of the second fixed conductor can jointly generate a superimposed magnetic field. In this way, compared with a single fixed conductor, the moving conductor can be driven to move at a faster speed, thereby driving the piston to separate the first and second contacts more quickly. Alternatively, at the same breaking speed, the current excitation for energizing the electromagnetic drive mechanism can be smaller, and the volume of the excitation system can be relatively reduced.

[0027] The aforementioned movable conductor can be a strip conductor. The first conductor portion and the second conductor portion are parallel to the movable conductor, respectively, and the first fixed conductor and the second fixed conductor are located on the side of the piston away from the first contact and the second contact. In this embodiment, the first conductor portion, the second conductor portion, and the movable conductor are all strip conductors. By designing the dimensions of the first conductor portion and the second conductor portion, the force exerted by the magnetic field generated by the first conductor portion and the second conductor portion on the conductive movable conductor can be adjusted.

[0028] Furthermore, since the movable conductor can move relative to the first and second fixed conductors, the connecting wires between the movable conductor and the first fixed conductor, and between the movable conductor and the second fixed conductor, need to be made of flexible materials. Specifically, the electromagnetic drive mechanism also includes a first flexible conductor and a second flexible conductor. The first flexible conductor connects the first fixed conductor and the movable conductor, and the second flexible conductor connects the second fixed conductor and the movable conductor to achieve electrical connection between the first fixed conductor, the movable conductor, and the second fixed conductor. When the piston moves away from the first and second contacts, the first and second flexible conductors bend respectively. When the piston moves towards the first and second contacts, the first and second flexible conductors stretch respectively.

[0029] The switching device may also include a fuse. One end of the fuse is electrically connected to the power conversion circuit, and the other end is electrically connected to the DC bus. The resistance of the fuse is greater than the resistance of the first and second contacts. Therefore, when the power conversion device is operating normally, the first and second contacts are in contact to conduct the power conversion circuit and the DC bus. At this time, the operating current flows through the path of lower resistance, i.e., the operating current flows through the first and second contacts. When the piston separates the first and second contacts, the current between the first and second contacts flows into the fuse to blow the fuse. In this embodiment, the fuse provides dual protection to the switching device. When the power conversion device is used in a high-voltage power supply system, when the piston separates the first and second contacts, the short-circuit current switches to the circuit where the fuse is located, so the separation of the first and second contacts may not generate an arc. Even if the current switching circuit is slower than the speed at which an arc is generated when the first and second contacts separate, the arc can be conducted to the fuse and extinguished by blowing the fuse. In addition, the fuse can also blow when the current flowing through it is greater than its rated current. Therefore, fuses have the function of extinguishing arcs or limiting current.

[0030] The switching device of this application may further include an arc-extinguishing chamber, which is located on the side of the first contact and the second contact away from the electromagnetic drive mechanism. The arc-extinguishing chamber is used to eliminate the electric arc generated when the first contact and the second contact separate.

[0031] The rotation of the first and second contacts can be achieved by springs, thus simplifying the structure of the switching device. Specifically, the switching device may further include a first spring and a second spring located within the housing. One end of the first spring is fixedly connected to the housing, and the other end is fixedly connected to the first contact. One end of the second spring is fixedly connected to the housing, and the other end is fixedly connected to the second contact. The first and second contacts are rotatably connected to the housing. The first spring applies a first force to the first contact, and the second spring applies a second force to the second contact. When the power conversion device is operating normally, the first force drives the first contact to rotate toward the second contact, and the second force drives the second contact to rotate toward the first contact. When the piston separates the first and second contacts, the first and second springs are compressed, and after the piston returns to its original position, the first and second springs reset the first and second contacts.

[0032] Furthermore, the switching device may also include a first flexible electrical connection wire and a second flexible electrical connection wire located within the housing. The switching device has a first connecting piece and a second connecting piece. The first flexible electrical connection wire can connect the first connecting piece to a first contact, and the second flexible electrical connection wire can connect the second connecting piece to a second contact. The first connecting piece is used for electrical connection with a corresponding power conversion circuit, and the second connecting piece is used for electrical connection with a DC bus. The first and second flexible electrical connection wires allow for minute movement and / or deformation, thereby improving connection reliability.

[0033] A sealing ring can also be provided between the piston and the housing in the switching device to prevent the electric arc generated by the separation of the first contact and the second contact from entering the electromagnetic drive mechanism. Attached Figure Description

[0034] Figure 1 is a schematic diagram of an application scenario of the switching device provided in an embodiment of this application;

[0035] Figure 2 is a schematic diagram of another application scenario of the switching device provided in the embodiment of this application;

[0036] Figure 3 is a schematic diagram of another application scenario of the switching device provided in the embodiment of this application;

[0037] Figure 4 is a schematic diagram of the connection structure of the charging system in Figure 2;

[0038] Figure 5 is a schematic diagram of a switching device provided in an embodiment of this application;

[0039] Figure 6 is an exploded view of a switching device provided in an embodiment of this application;

[0040] Figure 7 is another schematic diagram of the switching device provided in an embodiment of this application;

[0041] Figure 8 is a schematic diagram of the switching device provided in the embodiment of this application in the on state;

[0042] Figure 9 is another schematic diagram of the switching device in Figure 8;

[0043] Figure 10 is a schematic diagram of the switching device provided in the embodiment of this application in the open state;

[0044] Figure 11 is another schematic diagram of the switching device in Figure 10;

[0045] Figure 12 is a schematic diagram of the current when the switching device provided in the embodiment of this application is in the open state;

[0046] Figure 13 is another schematic diagram of the switching device provided in the embodiment of this application in the open state;

[0047] Figure 14 is a schematic diagram of a piston provided in an embodiment of this application;

[0048] Figure 15 is a cross-sectional schematic diagram of the shell provided in an embodiment of this application;

[0049] Figure 16 is another schematic diagram of the switching device provided in an embodiment of this application;

[0050] Figure 17 is a schematic diagram of the current when the switching device provided in the embodiment of this application switches from the on state to the off state;

[0051] Figure 18 is another schematic diagram of the switching device provided in the embodiment of this application.

[0052] Reference numerals: 11-DC bus; 12-Photovoltaic string; 13-Energy storage device; 14-Charging system; 15-Grid; 20-Switch device; 21-Housing; 22-First contact; 23-Second contact; 24-Piston; 25-Electromagnetic drive mechanism; 26-First spring; 27-Second spring; 28-First flexible electrical connection wire; 29-Second flexible electrical connection wire; 30-Capacitor; 141-Charging equipment; 142-Electric vehicle; 143-Charging host; 144-Charging terminal; 145-Charging gun; 146-AC / DC conversion circuit; 147-DC / DC conversion circuit; 148-Power distribution device; 201-Fuse; 202-Arc extinguishing chamber; 211-First connecting piece; 212-Second connecting piece; 213-Receiving cavity; 214-Slide groove; 241-Sealing ring; 251-First fixed conductor; 252-First flexible conductor; 253-Moving conductor; 254-Second flexible conductor; 255-Second fixed conductor; 2511-First conductor section; 2551-Second conductor section. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this application clearer, the application will now be described in further detail with reference to the accompanying drawings.

[0054] To facilitate understanding of the power conversion device and switching device provided in this application embodiment, their application scenarios are described below. The switching device can be applied to the power conversion device, which can be applied to power supply systems such as photovoltaic strings, energy storage devices, and charging systems. Figure 1 is a schematic diagram of an application scenario of the switching device provided in this application embodiment. As shown in Figure 1, this application embodiment provides a power supply system, which includes a power conversion device 10. The power conversion device 10 is used to receive AC power output from the power grid 15 and convert the AC power into DC power before transmitting it to the DC load. Specifically, the power conversion device 10 includes multiple DC / DC conversion circuits (DC / DC 1-DC / DC n), multiple AC / DC conversion circuits (AC / DC 1-AC / DC n), and a DC bus 11. The AC input terminal of each AC / DC conversion circuit is connected to the power grid 15, and the DC output terminal of each DC / DC conversion circuit (DC / DC 1-DC / DC n) is connected to the DC bus 11. The DC input terminal of each DC / DC conversion circuit is connected to the DC bus 11, and the DC output terminal of each DC / DC conversion circuit is connected to the DC load. Multiple AC / DC conversion circuits are used to receive AC power output from the power grid 15, convert the AC power into DC power, and then output it to the DC bus 11. Multiple DC / DC conversion circuits are used to obtain DC power from the DC bus 11, and further convert the obtained DC power into DC power suitable for DC loads before outputting it to the DC load.

[0055] In some possible implementation scenarios, the specifications of some AC loads are not suitable for the AC output of the power grid. In this case, the power conversion device 10 can also be used to convert the AC output of the power grid 15 into DC, and then convert the DC into AC that is suitable for the AC load through multiple DC / AC conversion circuits (DC / AC 1-DC / AC n) and output it to multiple AC loads. At this time, the DC input terminal of each DC / AC conversion circuit is connected to the DC bus 11, and the AC output terminal of each DC / AC conversion circuit is connected to the AC load.

[0056] In addition, current power supply systems also include scenarios of "overlapping photovoltaic and energy storage," where photovoltaic and energy storage are further combined. Specifically, the photovoltaic string 12 is connected to the DC bus 11, and the DC power it generates can be output to the DC bus 11, and then output to DC or AC loads through the DC bus 11. At the same time, the energy storage device 13 is also connected to the DC bus 11. In some scenarios, the energy from the energy storage device can be supplied to DC or AC loads through the DC bus, and the DC power can also be obtained through the DC bus 11 to charge the energy storage battery in the energy storage device 13.

[0057] As can be seen from the power supply system described above, the power conversion device 10 in this embodiment may include multiple power conversion circuits, specifically including at least one of DC / DC conversion circuits, AC / DC conversion circuits, and DC / AC conversion circuits. In one embodiment of this application, the input / output terminals of each power conversion circuit are connected to the DC bus 11 through a corresponding switch device 20 among multiple switch devices 20. The photovoltaic string 12 or energy storage device 13 can also be connected to the DC bus 11 through a switch device 20, so that in the event of a short circuit detected in the line where the switch device 20 is located, the switch device 20 can be disconnected in time to cut off the faulty line and maintain the stability of the bus voltage. Specifically, the switch device 20 and the power conversion circuit can be in a one-to-one correspondence, or multiple power conversion circuits can correspond to one switch device 20.

[0058] Therefore, the switching device 20 of this application can be installed between the DC bus 11 and the power conversion circuit, photovoltaic string 12, and energy storage device 13 connected to the DC bus, so as to disconnect the electrical connection between the DC bus 11 and the power conversion circuit, external load (AC or DC load) or external system (photovoltaic string or energy storage device) when a short circuit fault occurs.

[0059] The above implementation scenarios mainly illustrate the application of the switching device 20 of this application in DC-side disconnection scenarios. In another embodiment of this application, the switching device 20 can also be located between the power conversion circuit and the AC power grid / AC load, that is, the switching device 20 can also be applied to AC-side disconnection scenarios. For example, when the power conversion circuit is a DC / AC conversion circuit, the switching device 20 can be set between the DC / AC conversion circuit and the AC power grid so that it can be disconnected in time when a short circuit fault occurs on the AC side.

[0060] Since the switching device 20 is applied to both the AC and DC sides in principle, the following description of the embodiments in this application will mainly focus on the DC side as an example.

[0061] Figure 2 is a schematic diagram of a specific application scenario of the switching device provided in this application embodiment. As shown in Figure 2, the switching device 20 can be applied to the charging system 14. The charging system 14 may include a charging device 141 and an electric vehicle 142. The charging device 141 is used to receive AC power output from the power grid 15, convert the AC power into stable DC power, and then supply it to the electric vehicle 142 to charge the electric vehicle 142. Alternatively, the electric vehicle 142 can also output electrical energy back to the power grid 15 through the charging device 141.

[0062] As shown in Figure 2, the charging device 141 is a split-type charging device. Specifically, the charging device 141 includes a charging host 143, at least one charging terminal 144, and at least one charging gun 145. The charging host 143 is connected to each charging terminal 144, and at least one charging terminal 144 is connected to at least one charging gun 145. Each charging gun 145 is used to connect to an electric vehicle 142. In a specific implementation, one charging terminal 144 is connected to one or more charging guns 145, and one or more charging guns 145 are connected to one electric vehicle 142.

[0063] The charging host 143 includes multiple power conversion devices that convert the AC power output from the power grid 15 into stable DC power before supplying it to the charging terminal 144. These power conversion devices may include, for example, AC / DC conversion circuits and DC / DC conversion circuits. The charging terminal 144 then supplies this stable DC power to the electric vehicle 142 via a connected charging gun 145.

[0064] The charging terminal 144 includes a housing, a human-machine interface, a charging control unit, and a metering and billing unit, and is used for information exchange, energy transmission, and metering and billing with the electric vehicle 142.

[0065] Electric vehicle 142 is a means of transportation that is powered by electricity. Electric vehicle 142 includes pure electric vehicle (pure electric vehicle / battery electric vehicle, pure EV / battery EV), hybrid electric vehicle (HEV), range-extended electric vehicle (REEV), or plug-in hybrid electric vehicle (PHEV), etc.

[0066] Figure 3 is a schematic diagram of another application scenario of the switching device provided in the embodiment of this application. As shown in Figure 3, the charging device 141 can also be an integrated charging device. Specifically, the human-machine interface, charging control unit, and metering and billing unit in the charging device 141 are directly set in the charging host 143, so the charging device 141 only includes the charging host 143 and at least one charging gun 145 connected to the charging host 143, and does not include the charging terminal 144. In a specific implementation, multiple power conversion devices in the charging host 143 convert the AC power output from the grid 15 into stable DC power, which is then directly transmitted to the electric vehicle 142 through the charging gun 145.

[0067] Figure 4 is a schematic diagram of the connection structure of the charging system in Figure 2. As shown in Figure 4, the charging host 143 includes multiple AC / DC conversion circuits 146, multiple DC / DC conversion circuits 147, a DC bus 11, and a power distribution device 148. The input terminal of each AC / DC conversion circuit 146 is connected to the power grid 15, and the output terminal of each AC / DC conversion circuit 146 is connected to the DC bus 11 via a switch device 20. The input terminal of each DC / DC conversion circuit 147 is connected to the DC bus 11 via a switch device 20, and the output terminal of each DC / DC conversion circuit 147 is connected to the input terminal of the power distribution device 148. Optionally, a switch device 20 may also be provided between the output terminal of the DC / DC conversion circuit 147 and the input terminal of the power distribution device 148. The output terminal of the power distribution device 148 is connected to the charging gun 145 via a charging terminal 144.

[0068] Multiple AC / DC conversion circuits 146 are used to receive AC power output from the power grid 15, convert the AC power into DC power, and output it to the DC bus 11. Multiple DC / DC conversion circuits 147 are used to obtain DC power from the DC bus 11, further convert the obtained DC power into DC power suitable for the electric vehicle 142, and output it to the power distribution device 148. The power distribution device 148 is used to dynamically distribute the DC power output from the multiple DC / DC conversion circuits 147 according to the actual charging power required by the electric vehicle 142, and transmit the distributed charging power to the electric vehicle 142 through the charging gun 145.

[0069] Existing switching devices use spring mechanisms or small explosives to achieve contact separation. However, the spring mechanism's extension / retraction time limits the contact separation speed required for high breaking rates. While using high-pressure gas or impact force from small explosives can achieve millisecond- or even microsecond-level switching actions, the manufacturing cost of the explosives is high, and safety and maintenance requirements are also stringent.

[0070] In view of this, this application provides a power conversion device and a switching device that sends a disconnect signal to the switching device corresponding to the faulty line when a short circuit fault occurs in the power conversion circuit, external load or external system (photovoltaic string or energy storage device), and separates the two contacts by electromagnetic drive, thereby realizing the rapid disconnection of the power conversion circuit or external load or external system from the DC bus 11 to prevent the fault from spreading.

[0071] It should be noted that the terminology used in the following embodiments is for the purpose of describing specific embodiments only and is not intended to be a limitation of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise.

[0072] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0073] Taking the application of the switching device 20 in a power conversion device as an example, the switching device 20 can be installed in the power conversion device. The power conversion device has an input terminal and an output terminal. The power conversion device includes multiple power conversion circuits, a DC bus 11, multiple switching devices 20, and a controller. The DC input / output terminal of each power conversion circuit is connected to the DC bus 11 through a corresponding switching device 20 among the multiple switching devices 20. When a short-circuit fault occurs in the power conversion circuit or the external system, the controller can control the switching device 20 to quickly disconnect the faulty power conversion circuit or external system from the DC bus 11.

[0074] The structure of the switching device 20 will be described in detail below.

[0075] Figure 5 is a schematic diagram of a switching device provided in an embodiment of this application, and Figure 6 is an exploded view of a switching device provided in an embodiment of this application. As shown in Figures 5 and 6, the switching device 20 includes a housing 21, a first contact 22, a second contact 23, a piston 24, and an electromagnetic drive mechanism 25. Specifically, the first contact 22, the second contact 23, and the piston 24 are located inside the housing 21, and the electromagnetic drive mechanism 25 is at least partially located inside the housing 21. The switching device 20 is provided with a first connecting piece 211 and a second connecting piece 212, which extend into the housing 21. The first connecting piece 211 is connected to the first contact 22, and the second connecting piece 212 is connected to the second contact 23. The first connecting piece 211 can be used to connect to a power conversion circuit, a photovoltaic string 12, or an energy storage device 13, and the second connecting piece 212 can be used to connect to a DC bus 11. When the power conversion device is working normally, the first contact 22 and the second contact 23 are in contact, so that the DC input / output terminal of the power conversion circuit, the first connecting piece 211, the first contact 22, the second contact 23, the second connecting piece 212, and the DC bus 11 are connected in sequence.

[0076] In the aforementioned switching device 20, the first contact 22 can rotate relative to the housing 21, and / or the second contact 23 can rotate relative to the housing 21, thereby allowing the first contact 22 and the second contact 23 to contact or separate. That is, in one embodiment, the first contact 22 can rotate relative to the housing 21, and the second contact 23 can be fixed relative to the housing 21. In another embodiment, the first contact 22 can be fixed relative to the housing 21, and the second contact 23 can rotate relative to the housing 21. In still other embodiments, the first contact 22 can rotate relative to the housing 21, and the second contact 23 can rotate relative to the housing 21.

[0077] As shown in Figure 6, the electromagnetic drive mechanism 25 includes a first fixed conductor 251, a second fixed conductor 255, and a movable conductor 253. The first fixed conductor 251 and the second fixed conductor 255 are fixedly connected to the housing 21, and the movable conductor 253 is fixedly connected to the piston 24. The first fixed conductor 251, the movable conductor 253, and the second fixed conductor 255 are electrically connected in sequence. The first fixed conductor 251 includes a first conductor portion 2511 disposed opposite to the movable conductor 253, and the second fixed conductor 255 includes a second conductor portion 2551 disposed opposite to the movable conductor 253.

[0078] When the electromagnetic drive mechanism 25 is turned on, the current direction of the first fixed conductor 251 is in the same direction as the current direction of the second fixed conductor 255, and the current conduction direction of the first fixed conductor 251 is opposite to the current direction of the moving conductor 253. When the power conversion device is working normally, the first contact 22 and the second contact 23 are in contact to conduct the power conversion circuit and the output terminal of the power conversion device. At this time, the piston 24 is held away from the first contact 22 and the second contact 23. When the controller detects a short-circuit current passing through the first contact 22 and the second contact 23, the controller can control the first fixed conductor 251, the moving conductor 253 and the second fixed conductor 255 to conduct, so that the first magnetic field generated by the first fixed conductor 251 and the second magnetic field generated by the second fixed conductor 255 jointly drive the moving conductor 253 to move, thereby moving the piston 24 toward the first contact 22 and the second contact 23 and separating the first contact 22 and the second contact 23.

[0079] Figure 7 is another schematic diagram of the switching device provided in an embodiment of this application. As shown in Figure 7, the power conversion device may further include a capacitor 30. Specifically, the electromagnetic drive mechanism 25 may be connected to the capacitor 30. A fault switch K may be provided between the first fixed conductor 251 and the capacitor 30, or a fault switch K may be provided between the second fixed conductor 255 and the capacitor 30. The fault switch K is used to connect or disconnect the electromagnetic drive mechanism 25 and the capacitor. When the controller detects a short-circuit current, the controller controls the fault switch K to conduct, thereby connecting the capacitor 30 and the electromagnetic drive mechanism 25 to supply power to the electromagnetic drive mechanism 25.

[0080] The aforementioned electromagnetic drive mechanism 25 uses electromagnetic means to drive the piston 24 to separate the first contact 22 and the second contact 23, enabling a rapid response to fault signals and improving the efficient disconnection speed between the power conversion circuit or external system and the DC bus 11, thereby preventing further fault propagation. Furthermore, the electromagnetic drive mechanism 25 has a simple structure and low manufacturing cost.

[0081] Figure 8 is a schematic diagram of the switching device provided in the embodiment of this application in the on state, and Figure 9 is another schematic diagram of the switching device in Figure 8. As shown in Figures 8 and 9, when the controller controls the electromagnetic drive mechanism 25 to be on, the first fixed conductor 251, the second fixed conductor 255, and the moving conductor 253 are electrically connected in sequence. The moving conductor 253 can be a strip conductor, and the first conductor portion 2511 and the second conductor portion 2551 are respectively arranged parallel to the moving conductor 253. Therefore, the portion of the first fixed conductor 251 parallel to the moving conductor 253, the portion of the second fixed conductor 255 parallel to the moving conductor 253, and the moving conductor 253 are all strip conductors. In addition, the first fixed conductor 251 and the second fixed conductor 255 are located on the side of the piston 24 away from the first contact 22 and the second contact 23. In this way, by designing the dimensions of the portion of the first fixed conductor 251 parallel to the moving conductor 253 and the portion of the second fixed conductor 255 parallel to the moving conductor 253, the force exerted by the magnetic field generated by the first fixed conductor 251 and the second fixed conductor 255 on the conductive moving conductor 253 can be adjusted.

[0082] In one specific embodiment, the first fixed conductor 251 and the second fixed conductor 255 can also be strip conductors, so the first fixed conductor 251, the second fixed conductor 255 and the moving conductor 253 are arranged in parallel. As shown in Figures 5 and 8, in another embodiment, the first fixed conductor 251 and the second fixed conductor 255 can be bent structures, and the first fixed conductor 251 and the second fixed conductor 255 each have a portion arranged parallel to the strip moving conductor 253.

[0083] As shown in Figures 5, 8, and 9, since the movable conductor 253 can move relative to the first fixed conductor 251 and the second fixed conductor 255, the connecting lines between the movable conductor 253 and the first fixed conductor 251, and between the movable conductor 253 and the second fixed conductor 255, need to be made of flexible materials. Specifically, the electromagnetic drive mechanism 25 also includes a first flexible conductor 252 and a second flexible conductor 254. The first flexible conductor 252 is connected between the first fixed conductor 251 and the movable conductor 253, and the second flexible conductor 254 is connected between the second fixed conductor 255 and the movable conductor 253. Figure 10 is a schematic diagram of the switching device provided in the embodiment of this application in the open state, and Figure 11 is another schematic diagram of the switching device in Figure 10. As shown in Figures 10 and 11, when the piston 24 moves away from the first contact 22 and the second contact 23, the first flexible conductor 252 and the second flexible conductor 254 bend respectively. When the piston 24 moves toward the first contact 22 and the second contact 23, the first flexible conductor 252 and the second flexible conductor 254 stretch respectively.

[0084] As shown in Figures 8 and 9, when the switching device 20 is operating normally, the first contact 22 and the second contact 23 are in contact, and the piston 24 is in its initial position, that is, the piston 24 is kept away from the contact point of the first contact 22 and the second contact 23. At this time, the switch between the first fixed conductor 251 and the capacitor 30 is open, and the current I flows in from the first connecting piece 211 (i.e., Iin), and flows out from the second connecting piece 212 (i.e., Iout) after passing through the first contact 22 and the second contact 23.

[0085] Figure 12 is a schematic diagram of the current when the switching device provided in the embodiment of this application is in the open state. As shown in Figures 10, 11 and 12, when the controller detects a short circuit fault, the fault switch K is turned on, making the capacitor 30 and the electromagnetic drive mechanism 25 conductive. At this time, taking the current flowing through the first fixed conductor 251, the first flexible conductor 252, the moving conductor 253, the second flexible conductor 254 and the second fixed conductor 255 in sequence as an example, as shown in Figure 12, the direction of the current flowing through the first fixed conductor 251 is I1, the direction of the current flowing through the moving conductor 253 is I2, and the direction of the current flowing through the second fixed conductor 255 is I3. I1 and I3 are in the same direction and I1 and I3 are opposite to I2 respectively.

[0086] Figure 13 is another schematic diagram of the switching device provided in the embodiment of this application in the open state. As shown in Figure 13, when current is applied to the electromagnetic drive mechanism 25, since I1 and I2 are in opposite directions, under the action of the magnetic field generated by the first fixed conductor 251 and the magnetic field generated by the moving conductor 253, a repulsive force is generated between the first fixed conductor 251 and the moving conductor 253. Therefore, the first fixed conductor 251 generates a first force F1 on the moving conductor 253. Similarly, since I3 and I2 are in opposite directions, under the action of the magnetic field generated by the second fixed conductor 255 and the magnetic field generated by the moving conductor 253, a repulsive force is generated between the second fixed conductor 255 and the moving conductor 253. Therefore, the second fixed conductor 255 generates a second force F2 on the moving conductor 253. Under the combined force of the first force F1 and the second force F2, the moving conductor 253 can drive the piston 24 to move towards the contact point between the first contact 22 and the second contact 23 to separate the first contact 22 and the second contact 23.

[0087] As shown in Figures 11 and 13, when the first contact 22 is rotatable relative to the housing 21, the switching device 20 may further include a first spring 26 located within the housing 21. One end of the first spring 26 may be fixedly connected to the housing 21, and the other end of the first spring 26 may be fixedly connected to the first contact 22. The first spring 26 is used to drive the first contact 22 to rotate counterclockwise to contact the second contact 23. When the second contact 23 is rotatable relative to the housing 21, the switching device 20 may further include a second spring 27. One end of the second spring 27 may be fixedly connected to the housing 21, and the other end of the second spring 27 may be fixedly connected to the second contact 23. The second spring 27 is used to drive the second contact 23 to rotate clockwise to contact the first contact 22.

[0088] When the first contact 22 is rotatable relative to the housing 21, and the second contact 23 is rotatable relative to the housing 21, during the process of the piston 24 separating the first contact 22 and the second contact 23, the first contact 22 rotates clockwise under the push of the piston 24 and resists the force of the first spring 26 to compress the first spring 26. The second contact 23 rotates counterclockwise under the push of the piston 24 and resists the force of the second spring 27 to compress the second spring 27.

[0089] In some embodiments, the switching device 20 can be used for single-use scenarios. In other embodiments, to enable the switching device 20 to be used multiple times, after the short-circuit fault disappears, the piston 24 can be manually reset to a position away from the contact point of the first contact 22 and the second contact 23. At this time, the first contact 22 rotates counterclockwise under the action of the first spring 26, and the second contact 23 rotates clockwise under the action of the second spring 27, thereby causing the first contact 22 and the second contact 23 to contact again, thus achieving automatic reset of the first contact 22 and the second contact 23. Of course, the reset of the piston 24 can also be controlled by a controller. For example, the switching device 20 also includes a connecting rod, which is fixedly connected to the piston 24. When the controller detects that the short-circuit fault has disappeared, the controller can control the connecting rod to drive the piston 24 to reset.

[0090] In the switching device 20 of this application, the first contact 22 and the second contact 23 can be made of metals or alloys with good conductivity, such as silver, copper, or silver alloys. This can reduce the resistance of the first contact 22 and the second contact 23, reduce heat generation, and thus improve the current carrying capacity.

[0091] As shown in Figures 9 and 11, the switching device 20 may further include a first flexible electrical connection line 28 and a second flexible electrical connection line 29 located within the housing 21. The first flexible electrical connection line 28 connects the first connecting piece 211 and the first contact 22, and the second flexible electrical connection line 29 connects the second connecting piece 212 and the second contact 23. During the rotation of the first contact 22 and the second contact 23, the first flexible electrical connection line 28 and the second flexible electrical connection line 29 are allowed to make slight movements and / or deformations, thereby improving connection reliability.

[0092] Figure 14 is a schematic diagram of a piston provided in an embodiment of this application. As shown in Figure 14, the piston 24 can slide relative to the housing 21. When the switching device 20 is turned on, the piston 24 is held at a position away from the contact point of the first contact 22 and the second contact 23. When the controller controls the switching device 20 to turn off, the electromagnetic drive mechanism 25 receives the turn-off signal from the controller and drives the piston 24 to move in a direction close to the aforementioned contact point to separate the first contact 22 and the second contact 23, thereby disconnecting the power conversion circuit or external system from the DC bus 11. The piston 24 easily pushes open the first contact 22 and the second contact 23 to ensure the stability and accuracy of the separation process, thereby achieving rigid separation.

[0093] In addition, piston 24 may also be provided with a sealing ring 241. The sealing ring 241 is located between piston 24 and housing 21, and can prevent the electric arc generated by the separation of first contact 22 and second contact 23 from entering electromagnetic drive mechanism 25.

[0094] Figure 15 is a cross-sectional schematic diagram of the housing provided in an embodiment of this application. As shown in Figure 15, a receiving cavity 213 is provided inside the housing 21. The size and shape of the receiving cavity 213 can be set according to the layout of the first contact 22, the second contact 23, and the piston 24. Specifically, the receiving cavity 213 is provided with a sliding groove 214. One end of the sliding groove 214 extends between the first contact 22 and the second contact 23, and the other end of the sliding groove 214 is disposed towards the first fixed conductor 251 and the second fixed conductor 255. When the piston 24 is driven by the electromagnetic drive mechanism 25, the piston 24 moves along the extension direction of the sliding groove 214 to the contact point of the first contact 22 and the second contact 23 and separates the first contact 22 and the second contact 23.

[0095] Figure 16 is another schematic diagram of the switching device provided in an embodiment of this application. As shown in Figure 16, the switching device 20 may further include a fuse 201. One end of the fuse 201 is connected to the first connecting piece 211, and the other end of the fuse 201 is connected to the second connecting piece 212. The resistance of the fuse 201 is greater than the resistance of the first contact 22 and the second contact 23.

[0096] Figure 17 is a schematic diagram of the current switching device provided in this embodiment of the application when switching from the on state to the off state. As shown in Figure 17, when the power conversion device is working normally, the operating current flows through the path with lower resistance, that is, the operating current flows through the first contact 22 and the second contact 23. When the piston 24 separates the first contact 22 and the second contact 23, the short-circuit current between the first contact 22 and the second contact 23 flows into the circuit where the fuse 201 is located, so as to melt the fuse 201. In this embodiment, the fuse 201 can provide dual protection for the switching device 20. When the power conversion device is applied to a high-voltage power supply system, when the piston 24 separates the first contact 22 and the second contact 23, the short-circuit current switches to the circuit where the fuse 201 is located, so the separation of the first contact 22 and the second contact 23 may not generate an arc. Even if the speed of the current switching circuit is slower than the speed at which an arc is generated when the first contact 22 and the second contact 23 separate, the arc can still be introduced into the fuse 201, and the arc is extinguished by melting the fuse 201. In addition, when the current flowing through fuse 201 exceeds the rated current of fuse 201, fuse 201 can also melt. Therefore, fuse 201 has the function of extinguishing arcs or limiting current.

[0097] Figure 18 is another schematic diagram of the switching device provided in an embodiment of this application. As shown in Figure 18, in another embodiment, the switching device 20 may also employ an arc-extinguishing chamber 202. Specifically, the arc-extinguishing chamber 202 is located on the side of the first contact 22 and the second contact 23 away from the electromagnetic drive mechanism 25. The arc-extinguishing chamber 202 can eliminate the electric arc generated when the first contact 22 and the second contact 23 separate. In this embodiment, the arc-extinguishing chamber 202 can be reused, thereby enabling the switching device 20 to be used multiple times.

[0098] In the above embodiments, the electromagnetic drive mechanism 25, piston 24, first contact 22 and second contact 23, and fuse 201 / arc extinguishing chamber 202 are arranged sequentially in one direction within the housing 21 to achieve a longitudinal layout of the switching device 20, making the structure more compact and facilitating the miniaturization of the switching device 20.

[0099] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A power conversion device, characterized in that, It includes a power conversion circuit, a switching device, and a controller, wherein the input / output terminals of the power conversion circuit are connected to the switching device; The switching device includes a housing, a first contact, a second contact, a piston, and an electromagnetic drive mechanism. The first contact, the second contact, and the piston are located within the housing. At least one of the first contact and the second contact is rotatable relative to the housing to allow the first contact and the second contact to contact or separate. The piston is movable relative to the housing. The electromagnetic drive mechanism includes a first fixed conductor and a movable conductor. The first fixed conductor is fixedly connected to the housing, and the movable conductor is fixedly connected to the piston. The first fixed conductor and the movable conductor are electrically connected in sequence. The first fixed conductor includes a first conductor portion disposed opposite to the movable conductor. When the electromagnetic drive mechanism is energized, the current direction of the first conductor portion is opposite to that of the movable conductor. When the power conversion device is working normally, the piston is held away from the first contact and the second contact, and the first contact and the second contact are in contact to conduct the corresponding power conversion circuit and the DC bus; When a short circuit fault occurs in the circuit where the switching device is located, the controller controls the first fixed conductor and the moving conductor to conduct, so that the first magnetic field generated by the first conductor drives the moving conductor to move, thereby driving the piston to move toward the first contact and the second contact and separating the first contact and the second contact.

2. The power conversion device as described in claim 1, characterized in that, The switching device further includes a second fixed conductor, which is fixedly connected to the housing, and the first fixed conductor, the movable conductor, and the second fixed conductor are electrically connected in sequence. The second fixed conductor includes a second conductor portion disposed opposite to the movable conductor; when the electromagnetic drive mechanism is energized, the current direction of the first conductor portion is the same as the current direction of the second conductor portion; When a short circuit fault occurs in the circuit where the switching device is located, the controller controls the first fixed conductor, the moving conductor and the second fixed conductor to conduct, so that the first magnetic field generated by the first conductor and the second magnetic field generated by the second conductor jointly drive the moving conductor to move, thereby driving the piston to move toward the first contact and the second contact and separating the first contact and the second contact.

3. The power conversion device as described in claim 2, characterized in that, The moving conductor is a strip conductor; the first conductor portion and the second conductor portion are parallel to the moving conductor respectively; the first fixed conductor and the second fixed conductor are located on the side of the piston away from the first contact and the second contact.

4. The power conversion device as described in claim 2 or 3, characterized in that, The electromagnetic drive mechanism further includes a first flexible conductor and a second flexible conductor; the first flexible conductor is connected between the first fixed conductor and the moving conductor, and the second flexible conductor is connected between the second fixed conductor and the moving conductor, so as to realize the electrical connection between the first fixed conductor, the moving conductor and the second fixed conductor.

5. The power conversion device as described in any one of claims 1 to 4, characterized in that, The switching device further includes a fuse, one end of which is electrically connected to the power conversion circuit, and the other end of which is electrically connected to the DC bus; the resistance of the fuse is greater than the resistance of the first contact and the second contact. When the power conversion device is working normally, the first contact and the second contact are in contact and conducting; when the piston separates the first contact and the second contact, the current between the first contact and the second contact flows into the fuse to melt the fuse.

6. The power conversion device as described in any one of claims 1 to 4, characterized in that, The switching device further includes an arc-extinguishing chamber located on the side of the first contact and the second contact away from the electromagnetic drive mechanism. The arc-extinguishing chamber is used to eliminate the electric arc generated when the first contact and the second contact separate.

7. The power conversion device according to any one of claims 1 to 6, characterized in that, The switching device may further include a first spring and a second spring located within the housing; one end of the first spring is fixedly connected to the housing, and the other end of the first spring is fixedly connected to the first contact; one end of the second spring is fixedly connected to the housing, and the other end of the second spring is fixedly connected to the second contact; the first contact and the second contact are respectively rotatably connected to the housing; the first spring is used to apply a first force to the first contact, and the second spring is used to apply a second force to the second contact; When the power conversion device is working normally, the first force drives the first contact to rotate toward the second contact, and the second force drives the second contact to rotate toward the first contact; when the piston separates the first contact and the second contact, the first spring and the second spring are compressed.

8. The power conversion device according to any one of claims 1 to 7, characterized in that, The switching device may further include a first flexible electrical connection line and a second flexible electrical connection line located within the housing; the switching device has a first connecting piece and a second connecting piece, the first flexible electrical connection line connects the first connecting piece and the first contact, the second flexible electrical connection line connects the second connecting piece and the second contact, the first connecting piece is used for electrical connection with the corresponding power conversion circuit, and the second connecting piece is used for electrical connection with the DC bus.

9. The power conversion device as described in any one of claims 1 to 8, characterized in that, A sealing ring is provided between the piston and the inner wall of the housing.

10. The power conversion device according to any one of claims 2 to 9, characterized in that, The power conversion device further includes a capacitor and a fault switch. One end of the capacitor is electrically connected to the first fixed conductor through the fault switch, and the other end of the capacitor is electrically connected to the second fixed conductor. The fault switch is used to turn on when the controller detects a short circuit in the power conversion device, so that the capacitor supplies power to the electromagnetic drive mechanism.

11. The power conversion device as described in claim 1, characterized in that, The power conversion device further includes a capacitor and a fault switch. One end of the capacitor is electrically connected to one end of the first fixed conductor through the fault switch, and the other end of the capacitor is electrically connected to the moving conductor. The fault switch is used to turn on when the controller detects a short circuit in the power conversion device, so that the capacitor supplies power to the electromagnetic drive mechanism.

12. The power conversion device according to any one of claims 1 to 11, characterized in that, The power conversion circuit includes a DC / DC conversion circuit. The DC input terminal of the DC / DC conversion circuit is connected to the DC bus through the switching device, and the DC output terminal of the DC / DC conversion circuit is used to connect to a DC load.

13. The power conversion device according to any one of claims 1 to 11, characterized in that, The power conversion circuit includes an AC / DC conversion circuit. The AC input terminal of the AC / DC conversion circuit is used to connect to the AC power grid, and the DC output terminal of the AC / DC conversion circuit is connected to the DC bus through the switching device.

14. The power conversion device according to any one of claims 1 to 11, characterized in that, The power conversion circuit includes a DC / AC conversion circuit. The DC input terminal of the DC / AC conversion circuit is connected to the DC bus through the switching device, and the AC output terminal of the DC / AC conversion circuit is used to connect to an AC load.

15. The power conversion device according to any one of claims 1 to 14, characterized in that, The power conversion device includes multiple switching devices, one of which is used to connect between the photovoltaic string and the DC bus, and / or another of which is used to connect between the energy storage device and the DC bus.

16. The power conversion device according to any one of claims 1 to 11, characterized in that, The power conversion circuit includes a DC / AC conversion circuit, and the AC output terminal of the DC / AC conversion circuit is connected to an AC power grid or an AC load through the switching device.

17. A switching device, characterized in that, It includes a housing, a first contact, a second contact, a piston, and an electromagnetic drive mechanism, wherein: The first contact, the second contact, and the piston are located within the housing; at least one of the first contact and the second contact is rotatable relative to the housing to make the first contact and the second contact contact or separate; the piston is movable relative to the housing. The electromagnetic drive mechanism includes a first fixed conductor and a movable conductor. The first fixed conductor is fixedly connected to the housing, and the movable conductor is fixedly connected to the piston. The first fixed conductor and the movable conductor are electrically connected in sequence. The first fixed conductor includes a first conductor portion disposed opposite to the movable conductor. When the electromagnetic drive mechanism is energized, the current direction of the first conductor portion is opposite to that of the movable conductor. When the switching device is turned on, the piston is held away from the first contact and the second contact, and the first contact and the second contact are in contact and connected; When the first fixed conductor and the moving conductor are connected, the first magnetic field generated by the first conductor drives the moving conductor to move, thereby moving the piston toward the first contact and the second contact and separating the first contact and the second contact.

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