Power-converter protection apparatus and power conversion system

Abstract

Provided in the embodiments of the present utility model are a power-converter protection apparatus and a power conversion system. The power-converter protection apparatus comprises a protection element and a mechanical switch, wherein the protection element is connected to the mechanical switch; a control end of the protection element and a control end of the mechanical switch respectively receive corresponding control signals; when a power converter is overloaded, the control signal received by the mechanical switch is a turn-off signal, such that load switching and arc extinguishing inside the power converter are realized; and when the power converter short circuits, the control signal received by the protection element is a turn-off signal, such that the power converter is disconnected from a direct-current power source. The present utility model can ensure the safety of a power conversion system when a power converter is faulty.

Description

A power converter protection device and a power conversion system

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 11, 2023, with application number 202322464710.7 and invention name “A power converter protection device and power conversion system”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The utility model relates to the technical field of power electronics, in particular to a power converter protection device and a power conversion system. Background Art

[0003] Currently, when a power converter short-circuit fault occurs, interrupting the short-circuit current carries the risk of arcing. In severe cases, this can burn out the entire power converter, even compromising the safety of the entire power conversion system. Furthermore, when a power converter short-circuit fault occurs, the long protection action time poses a safety hazard to the power conversion system.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a power converter protection device and a power conversion system, which can ensure the safety of the power conversion system when the power converter fails. The specific technical solution is as follows:

[0006] The utility model provides a power converter protection device, comprising:

[0007] Protection components and mechanical switches;

[0008] The protection element is connected to the mechanical switch;

[0009] The protection element and the control end of the mechanical switch receive corresponding control signals respectively;

[0010] When the power converter is overloaded, the control signal received by the mechanical switch is a shutdown signal, thereby realizing on-load disconnection and arc extinguishing inside the power converter;

[0011] When the power converter is short-circuited, the control signal received by the protection element is a shutdown signal, which disconnects the power converter from the DC power supply.

[0012] Optionally, the number of the protection elements is 1 or 2;

[0013] When the number of the protection element is 1, the protection element is connected in series to the positive electrode or the negative electrode of the DC power supply;

[0014] When the number of the protection elements is two, each protection element is connected in series to the positive electrode and the negative electrode of the DC power supply, or two protection elements are connected in series to any one electrode of the DC power supply.

[0015] Optionally, the number of the mechanical switches is 2, and each mechanical switch is connected to the positive pole and the negative pole of the DC side of the power converter respectively.

[0016] Optionally, the protection element is a solid-state switch.

[0017] Optionally, the solid-state switch includes an IGBT or a MOS tube.

[0018] Optionally, the mechanical switch includes a circuit breaker.

[0019] Optionally, also include:

[0020] Controller;

[0021] The protection element and the mechanical switch are both controlled by the controller;

[0022] The input end of the controller receives a sampling signal, and the output end of the controller is connected to the protection element and the control end of the mechanical switch respectively.

[0023] Optionally, also include:

[0024] Sampling circuit;

[0025] The output end of the sampling circuit is connected to the input end of the controller;

[0026] The controller receives the sampling signal transmitted by the sampling circuit, and outputs a shutdown signal to the mechanical switch when the sampling signal indicates that the power converter is overloaded, and outputs a shutdown signal to the protection element when the sampling signal indicates that the power converter is short-circuited.

[0027] Optionally, the sampling circuit includes:

[0028] Current sampling unit and voltage sampling unit;

[0029] The current sampling unit is connected in series on the DC side of the power converter;

[0030] The voltage sampling unit is connected in parallel to the DC side of the power converter.

[0031] Optionally, the current sampling unit is a current sensor or a shunt.

[0032] The utility model also provides a power conversion system, comprising:

[0033] DC power supplies and power converters;

[0034] The power converter includes the power converter protection device as described above;

[0035] The DC power supply is connected to the power converter protection device.

[0036] The embodiments of the present invention provide a power converter protection device and a power conversion system, which disconnect the connection between the power converter and the DC power supply through a protection element when the power converter is short-circuited, and realize on-load disconnection and arc extinguishing inside the power converter by a mechanical switch when the power converter is overloaded. The risk of arcing can be avoided when the power converter fails, and the connection between the power converter and the DC power supply can be disconnected in time by the protection element, thereby ensuring the safety of the power conversion system.

[0037] Of course, any product or method implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] FIG1 is a schematic structural diagram of a power converter protection device provided by an embodiment of the present utility model;

[0040] FIG2( a ) is a schematic structural diagram of another power converter protection device provided by an embodiment of the present utility model;

[0041] FIG2( b ) is a schematic structural diagram of another power converter protection device provided by an embodiment of the present utility model;

[0042] FIG2( c ) is a schematic structural diagram of another power converter protection device provided by an embodiment of the present utility model;

[0043] FIG3 is a schematic structural diagram of another power converter protection device provided by an embodiment of the present utility model;

[0044] FIG4 is a schematic structural diagram of another power converter protection device provided by an embodiment of the present utility model;

[0045] FIG5 is a schematic structural diagram of another power converter protection device provided by an embodiment of the present utility model;

[0046] FIG6 is a schematic diagram of the structure of a power converter provided by an embodiment of the present utility model;

[0047] FIG7( a ) is a schematic diagram of another power converter structure provided by an embodiment of the present utility model;

[0048] FIG7( b ) is a schematic diagram of another power converter structure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] The present invention provides a power converter protection device, as shown in FIG1 , the power converter protection device 1 includes:

[0051] Protection element 11 and mechanical switch 12.

[0052] The protection element 11 and the mechanical switch 12 are connected.

[0053] The control terminals of the protection element 11 and the mechanical switch 12 receive corresponding control signals respectively.

[0054] When the power converter is overloaded, the control signal received by the mechanical switch 12 is a shut-off signal, thereby achieving on-load disconnection and arc extinguishing inside the power converter 22 .

[0055] When the power converter is short-circuited, the control signal received by the protection element 11 is a shutdown signal, which disconnects the power converter 22 from the DC power source 21 .

[0056] To prevent the risk of arcing caused by short-circuit faults when a power converter fault occurs, a mechanical switch with an arc extinguishing function can be disconnected when the power converter is overloaded to cut off the connection between the power converter and the DC power supply, avoiding the risk of arcing and ensuring the safety of the entire power conversion system. In addition, the mechanical switch can achieve on-load disconnection when disconnecting overload current. Specifically, when a power converter overload fault occurs, the mechanical switch can receive a shutdown signal. When the mechanical switch receives the shutdown signal, the mechanical switch opens to disconnect the power converter from the DC power supply.

[0057] If a mechanical switch is used to disconnect the power converter from the DC power supply when a short circuit occurs, the protective action time is relatively long. To shorten this time, a protective element can be used to disconnect the power converter from the DC power supply, thereby ensuring the safety of the power conversion system. Specifically, when a short circuit occurs in the power converter, the protective element can receive a shutdown signal. Upon receiving the shutdown signal, the protective element disconnects, thereby disconnecting the power converter from the DC power supply.

[0058] The power converter protection device of the present invention, through the cooperation between the mechanical switch and the protection element, can not only avoid the problem of long protection action time in the event of a short circuit fault caused by using only a mechanical switch, but also avoid the risk of arcing in the event of a power converter fault, which may burn the entire power converter and even affect the safety of the entire power conversion system.

[0059] Optionally, the protection element is a solid-state switch.

[0060] This solid-state switch, primarily composed of power electronic components, offers fast protection, enabling rapid disconnection in the event of a short-circuit fault in the power converter. The protection time of a solid-state switch is shorter than that of a fuse, and fuses require prompt replacement after a fault. However, a solid-state switch is less susceptible to damage and does not require replacement after a short-circuit, reducing operational and maintenance costs.

[0061] The solid-state switch may include an IGBT (Insulated Gate Bipolar Transistor) or a MOS tube (Metal-Oxide-Semiconductor, Metal-Oxide-Semiconductor Field Effect Transistor).

[0062] Optionally, the mechanical switch includes a circuit breaker.

[0063] The circuit breaker can interrupt overload currents under load and extinguish arcs within the power converter, eliminating the risk of arcing. Compared to contactors, this circuit breaker eliminates the risk of arcing, ensuring the safety of the power converter and the entire power conversion system.

[0064] In order to solve the problem that the space occupied by the circuit breaker and the solid-state switch increases as the power density increases, the circuit breaker and the solid-state switch can be integrated inside the power converter to reduce the overall volume.

[0065] As an optional implementation, the power converter protection device provided by the present invention, as shown in FIG2 , has one or two protection elements.

[0066] As shown in FIG. 2( a ), when the number of the protection element is one, the protection element 11 is connected in series to the positive electrode or the negative electrode of the DC power supply 21 .

[0067] When a short circuit fault occurs in the power converter, the protection element receives a shutdown signal and is disconnected, thereby disconnecting the DC power supply 21 from the power converter 22 .

[0068] As shown in FIG2(b) and FIG2(c), when the number of protection elements 11 is two, each protection element 11 is connected in series to the positive and negative poles of the DC power supply 21, or two protection elements 11 are connected in series to either pole of the DC power supply 21.

[0069] To improve the reliability of the power converter protection device and avoid the problem of only one protection element failing to shut down in time when the protection element fails, two or more protection elements can be provided. If there are two protection elements, the two protection elements can be connected in series to the positive and negative poles of the DC power supply, respectively, as shown in Figure 2(b). Of course, the two protection elements can also be connected in series to either pole of the DC power supply, such as connecting both protection elements in series to the positive pole of the DC power supply, or connecting both protection elements in series to the negative pole of the DC power supply.

[0070] Optionally, the number of mechanical switches is two, and each mechanical switch 12 is connected to the positive pole and the negative pole of the DC side of the power converter 22 respectively.

[0071] When an overload fault occurs in the power converter 22 , if both mechanical switches 12 receive a shutdown signal, both mechanical switches 12 are disconnected, thereby disconnecting the DC power source 21 from the power converter 22 .

[0072] As an optional embodiment, as shown in FIG3 , the power converter protection device provided by the present invention further includes:

[0073] Controller 31.

[0074] The protection element 11 and the mechanical switch 12 are both controlled by the controller 31 .

[0075] An input terminal of the controller 31 receives a sampling signal, and an output terminal of the controller 31 is connected to control terminals of the protection element 11 and the mechanical switch 12 .

[0076] When there are two mechanical switches, the output of the controller is connected to the control terminal of each mechanical switch. When there is one protection element, the output of the controller is connected to the control terminal of the protection element. When there are two protection elements, the output of the controller is connected to the control terminal of each protection element.

[0077] The controller can control the on / off operation of the protection element and the mechanical switch. When the power converter is overloaded, the controller outputs a control signal to the mechanical switch. This control signal is an off signal, causing the mechanical switch to turn off and disconnecting the DC power supply from the power converter. When the power converter short-circuits, the controller outputs a control signal to the protection element. This control signal is an off signal, causing the protection element to turn off and disconnecting the DC power supply from the power converter. When the power converter is operating normally, the controller can output control signals to the mechanical switch and protection element, respectively. These control signals are on signals, causing them to close and connect the DC power supply to the power converter.

[0078] As another optional embodiment, as shown in FIG4 , the power converter protection device provided by the present invention further includes:

[0079] Sampling circuit 41.

[0080] An output terminal of the sampling circuit 41 is connected to an input terminal of the controller 31 .

[0081] The controller receives a sampling signal transmitted by the sampling circuit and outputs a shutdown signal to the mechanical switch when the sampling signal indicates an overload of the power converter. When the sampling signal indicates a short circuit of the power converter, the controller outputs a shutdown signal to the protection element. The sampling signal may be a current sampling signal, or may be a current sampling signal and a voltage sampling signal. The sampling circuit may be integrated with the mechanical switch and the protection element in the power converter.

[0082] Optional sampling circuit, including:

[0083] Current sampling unit.

[0084] The current sampling unit is connected in series on the DC side of the power converter.

[0085] The current sampling unit can be positioned between the mechanical switch and the DC side of the power converter to collect the current of the power converter. When the current of the power converter collected by the current sampling unit is higher than the normal current of the power converter, it indicates that the power converter has failed. When a short-circuit fault occurs in the power converter, the current collected by the current sampling unit is higher than the current when an overload fault occurs. Therefore, the magnitude of the current collected by the current sampling unit can be used to determine whether the power converter has a short-circuit fault or an overload fault. The controller controls the mechanical switch or protective element to disconnect based on the fault type indicated by the current collected by the current sampling unit.

[0086] The current sampling unit may be a current sensor or a shunt.

[0087] Optionally, the sampling circuit also includes:

[0088] Voltage sampling unit;

[0089] The voltage sampling unit is connected in parallel on the DC side of the power converter.

[0090] The voltage sampling unit can collect the voltage of the power converter. Specifically, the voltage sampling unit can be connected in parallel to the DC side of the power converter. The voltage sampling unit can also be connected in parallel to both ends of the DC power supply. When the voltages collected by the two voltage sampling units are the same and not zero, it indicates that the DC power supply and the power converter are turned on. Under the condition that the DC power supply and the power converter are turned on, if the voltage of the power converter collected by the voltage sampling unit is zero, it indicates that a short circuit fault has occurred in the power converter. The controller can control the protection element to disconnect, thereby disconnecting the DC power supply and the power converter. Of course, when the voltage of the power converter collected by the voltage sampling unit is zero, it is also possible to determine whether a short circuit fault has occurred in the power converter in combination with the current value collected by the current sampling unit. If the current collected at this time is also higher than the normal current value, it is determined that a short circuit fault has occurred. The controller can send a shutdown signal to the protection element, which disconnects the protection element to disconnect the DC power supply and the power converter.

[0091] As another optional embodiment, the power converter protection device provided by the present invention further includes:

[0092] Slow-down circuit.

[0093] The slow-start circuit is connected in parallel across the mechanical switch.

[0094] The snubber circuit is used to conduct electricity before the mechanical switch closes.

[0095] The slow-start circuit can prevent the current shock caused by the instantaneous switching of the DC power supply. Before closing the mechanical switch, the slow-start circuit is turned on first. After the slow-start is completed, the mechanical switch is closed and the slow-start circuit is disconnected.

[0096] Optionally, as shown in FIG5 , the slow-start circuit includes:

[0097] Slow-down switch K0 and slow-down resistor R0.

[0098] The slow-start switch K0 is connected in series with the slow-start resistor R0.

[0099] When the DC power supply 21 and the power converter 22 are turned on, the protection element 11 is closed. Before the mechanical switch 12 is closed, the slow-start switch K0 can be closed first, then the mechanical switch 12 is closed, and then the slow-start switch K0 is opened to prevent the current shock caused by the instantaneous switching of the DC power supply.

[0100] The present invention further provides a power converter, as shown in FIG6 , comprising: a main circuit 6 and a power converter protection device 1 as shown in FIG1 to FIG5 .

[0101] The power converter may be an energy storage converter, and the power converter protection device may be an energy storage converter protection device.

[0102] Optionally, the main circuit includes:

[0103] Inverter circuit 61.

[0104] The DC side of the inverter circuit 61 is connected to the power converter protection device 1 .

[0105] Optionally, the main circuit further includes:

[0106] Bus capacitor 62.

[0107] The bus capacitor is connected between the positive and negative electrodes of the DC side of the inverter circuit 61 .

[0108] Optionally, the main circuit further includes:

[0109] Busbar voltage balancing resistor 63;

[0110] The busbar voltage balancing resistor 63 is connected between the positive and negative electrodes of the DC side of the inverter circuit 61 .

[0111] In an optional embodiment, the power converter provided by the present invention, as shown in Figure 7 (a), includes: a power converter protection device and a main circuit. Among them, the power converter protection device includes a solid-state switch 71 and two circuit breakers 72, a controller 73, slow-start switches K1 and K2, slow-start resistors R1 and R2, and a sampling circuit (not shown in the figure). The main circuit includes busbar equalizing resistors R3 and R4, busbar capacitors C1 and C2, and an inverter circuit, which includes 6 IGBTs, namely Q1, Q2, Q3, Q4, Q5, and Q6. Among them, the connection point of R3 and R4, the connection point of C1 and C2, and the connection point of Q1 and Q2 are connected.

[0112] In another optional embodiment, the power converter provided by the present invention is shown in FIG7( b ), which differs from the power converter shown in FIG7( a ) in that the power converter protection device includes two solid-state switches 71 .

[0113] The utility model also provides a power conversion system, comprising:

[0114] A DC power supply and a power converter are shown in FIG6 and FIG7 .

[0115] The DC power supply is connected to the DC side of the power converter.

[0116] The power converter includes the power converter protection device described above.

[0117] A DC power supply is connected to the power converter protection device.

[0118] If the power converter is an energy storage converter, the power conversion system is an energy storage system, and the DC power supply is an energy storage battery.

[0119] In FIG6 , the DC power supply is connected to the power converter protection device 1 of the power converter.

[0120] In FIG7( a ), the positive electrode of the DC power supply is connected to the solid-state switch 71 , and the negative electrode of the DC power supply is connected to the circuit breaker 72 .

[0121] In FIG7( b ), the positive and negative electrodes of the DC power supply are connected to two solid-state switches 71 respectively.

[0122] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. It should also be noted that the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, commodity, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, commodity, or device comprising the element.

[0123] Each embodiment in this specification is described in a related manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiment is generally similar to the method embodiment, so the description is relatively simple. For related parts, refer to the description of the method embodiment.

[0124] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A power converter protection device, characterized in that: include: Protection components and mechanical switches; The protection element is connected to the mechanical switch; The protection element and the control end of the mechanical switch receive corresponding control signals respectively; When the power converter is overloaded, the control signal received by the mechanical switch is a shutdown signal, thereby realizing on-load disconnection and arc extinguishing inside the power converter; When the power converter is short-circuited, the control signal received by the protection element is a shutdown signal, which disconnects the power converter from the DC power supply.

2. The power converter protection device according to claim 1, characterized in that: The number of the protection elements is 1 or 2; When the number of the protection element is 1, the protection element is connected in series to the positive electrode or the negative electrode of the DC power supply; When the number of the protection elements is 2, each protection element is connected in series to the positive electrode and the negative electrode of the DC power supply, or two protection elements are connected in series to any electrode of the DC power supply.

3. The power converter protection device according to claim 1, characterized in that: The number of the mechanical switches is 2, and each of the mechanical switches is connected to the positive pole and the negative pole of the DC side of the power converter respectively.

4. The power converter protection device according to claim 1, characterized in that: The protection element is a solid-state switch.

5. The power converter protection device according to claim 4, characterized in that: The solid-state switch includes an IGBT or a MOS tube.

6. The power converter protection device according to claim 1, characterized in that: The mechanical switch includes a circuit breaker.

7. The power converter protection device according to any one of claims 1 to 6, characterized in that: Also includes: Controller; The protection element and the mechanical switch are both controlled by the controller; The input end of the controller receives the sampling signal, and the output end of the controller is connected to the protection element and the control end of the mechanical switch.

8. The power converter protection device according to claim 7, characterized in that: Also includes: Sampling circuit; The output end of the sampling circuit is connected to the input end of the controller; The controller receives the sampling signal transmitted by the sampling circuit, and outputs a shutdown signal to the mechanical switch when the sampling signal indicates that the power converter is overloaded, and outputs a shutdown signal to the protection element when the sampling signal indicates that the power converter is short-circuited.

9. The power converter protection device according to claim 8, characterized in that: The sampling circuit comprises: A current sampling unit and a voltage sampling unit; The current sampling unit is connected in series on the DC side of the power converter; The voltage sampling unit is connected in parallel to the DC side of the power converter.

10. The power converter protection device according to claim 9, characterized in that: The current sampling unit is a current sensor or a shunt.

11. A power conversion system, characterized in that: include: DC power supplies and power converters; The power converter comprises a power converter protection device as claimed in any one of claims 1 to 10; The DC power supply is connected to the power converter protection device.

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