Short-circuit protection circuit, power conversion device and charging equipment

Abstract

The utility model relates to the technical field of charging pile systems, in particular to a short-circuit protection circuit, a power conversion device and charging equipment. The short-circuit protection circuit comprises an auxiliary rectification module, a current detection module, a relay module and a control module. The auxiliary rectification module is used for shunting the AC input current of the AC-DC conversion circuit when the non-isolated AC-DC conversion circuit is short-circuited. The current detection module is used for sampling the DC output current of the AC-DC conversion circuit. The relay module is used for connecting or disconnecting the AC input current of the AC-DC conversion circuit. And the control module is used for comparing the direct current output current with a preset current threshold value, and stopping driving the AC-DC conversion circuit and disconnecting the alternating current input current of the AC-DC conversion circuit during short circuit. According to the application, the short-circuit protection module is arranged, so that the current is quickly shunted when the short circuit occurs, the input current is cut off, and the AC-DC conversion circuit driving is stopped, and the system safety and reliability are effectively improved.

Description

Technical Field

[0001] This application relates to the field of charging pile system technology, and in particular to short-circuit protection circuits, power conversion devices, and charging equipment. Background Technology

[0002] With the increasing driving range and number of electric vehicles, electric vehicle batteries have become an indispensable resource. Furthermore, in supercharging systems, the cascading of photovoltaic (PV) and energy storage on the DC bus is a future trend. This necessitates bidirectional capability for AC-DC (alternating current to direct current) power conversion modules. As module power increases, new demands arise for power density, efficiency, and reliability. A highly reliable, efficient, and high-power-density power conversion topology is an inevitable requirement for the industry. Currently, the solution combining AC-DC and DC-DC converters, cascading PV and energy storage on the intermediate bus, is a simple, efficient, and low-cost approach. However, this solution carries the risk of short circuits after the high-voltage bus is extended. Since non-isolated AC-DC topologies lack output short-circuit capability, this architecture suffers from lower safety and reliability. Utility Model Content

[0003] One objective of this application is to provide a short-circuit protection circuit, a power conversion device, and a charging device to solve the technical problem of low safety and reliability of non-isolated AC-DC conversion circuits due to short-circuit risks.

[0004] In a first aspect, embodiments of this application provide a short-circuit protection circuit for use in short-circuit protection of non-isolated AC-DC converter circuits, the short-circuit protection circuit comprising:

[0005] An auxiliary rectifier module, connected in parallel with the non-isolated AC-DC converter circuit, is used to shunt the AC input current of the non-isolated AC-DC converter circuit when the non-isolated AC-DC converter circuit is short-circuited.

[0006] A current detection module is electrically connected to the non-isolated AC-DC converter circuit and is used to detect the DC output current of the non-isolated AC-DC converter circuit.

[0007] A relay module, electrically connected to the non-isolated AC-DC converter circuit, and the relay module, electrically connected to the auxiliary rectifier module, are used to connect or disconnect the AC input current of the non-isolated AC-DC converter circuit; and

[0008] The control module is electrically connected to the non-isolated AC-DC converter circuit, the relay module, and the current detection module, respectively. It is used to drive the non-isolated AC-DC converter circuit and control the relay module, and to stop driving the non-isolated AC-DC converter circuit when the DC output current exceeds a preset current threshold, and to control the relay module to disconnect the AC input current of the non-isolated AC-DC converter circuit.

[0009] Optionally, the AC side of the non-isolated AC-DC converter circuit includes three AC buses, and the DC side of the non-isolated AC-DC converter circuit includes a positive bus and a negative bus. The relay module can be electrically connected to each AC bus of the non-isolated AC-DC converter circuit.

[0010] The auxiliary rectification module includes three auxiliary rectification units. Each auxiliary rectification unit can be electrically connected to the positive bus, the negative bus, and a corresponding AC bus of the non-isolated AC-DC converter circuit. The auxiliary rectification unit is used to shunt one phase current in the AC input current when the non-isolated AC-DC converter circuit is short-circuited.

[0011] Optionally, each of the auxiliary rectifier units includes a first diode and a second diode. In each auxiliary rectifier unit, the anode of the first diode can be connected to a corresponding AC bus, and the cathode of the first diode can be connected to the positive bus. The cathode of the second diode can be connected to a corresponding AC bus, and the anode of the second diode can be connected to the negative bus.

[0012] Optionally, the relay module includes:

[0013] Three relays, each capable of being connected to the AC mains and a corresponding AC bus in the non-isolated AC-DC converter circuit; and

[0014] A relay driving unit is provided, which is connected to each of the relays and the control module respectively. The relay driving unit is controlled by the control module and is used to drive each of the relays to connect or disconnect the AC input current of the non-isolated AC-DC conversion circuit.

[0015] Optionally, the relay drive unit includes:

[0016] Three drive subunits, each connected to a corresponding relay, wherein the drive subunit is used to drive the corresponding relay to close or open; and

[0017] A control subunit is provided, which is connected to each of the drive subunits and the control module. The control subunit is controlled by the control module and is used to drive the corresponding relay to close or open by controlling any of the drive subunits.

[0018] Optionally, each of the driving subunits includes a first resistor, a second resistor, a driving switch, and a freewheeling diode. The control subunit is connected to one end of the first resistor, the other end of the first resistor is connected to the gate of the driving switch, one end of the second resistor is connected to the gate of the driving switch, the other end of the second resistor is grounded, the source of the driving switch is grounded, and the drain of the driving switch is connected to the positive terminal of the freewheeling diode.

[0019] The relay includes a coil, an armature, a first contact, and a second contact. One end of the coil is connected to the negative terminal of the freewheeling diode and used to connect to a power supply. The other end of the coil is connected to the drain of the driving switch. One of the first contact and the second contact can be connected to the AC mains, and the other can be connected to a corresponding AC bus in the non-isolated AC-DC converter circuit. One end of the armature is connected to the first contact, and the other end of the armature is connected to the second contact. The armature can be attracted by the magnetic field generated by the coil when it is energized, so as to detach from one of the first contact and the second contact.

[0020] Optionally, each of the driving sub-units includes a Zener diode, which is disposed on one end of the coil and on the connection line of the freewheeling diode. The positive terminal of the Zener diode is connected to one end of the coil, and the negative terminal of the Zener diode is connected to the negative terminal of the freewheeling diode.

[0021] Optionally, the current detection module is a Hall sensor, a current shunt, or a fluxgate current sensor.

[0022] In a second aspect, embodiments of this application provide a power conversion device, comprising:

[0023] Non-isolated AC-DC converter circuits; and

[0024] The short-circuit protection circuit as described in any of the above claims is electrically connected to the non-isolated AC-DC converter circuit.

[0025] In a third aspect, embodiments of this application provide a charging device, including the power conversion device as described above.

[0026] The embodiments of this application can achieve the following technical effects: When a short circuit occurs in the non-isolated AC-DC converter circuit, the control module samples the DC output current through the current detection module and compares it with a preset current threshold. When the DC output current exceeds the preset current threshold, the AC input current path is disconnected, cutting off the current source. Simultaneously, the auxiliary rectifier module is connected in parallel to the non-isolated AC-DC converter circuit, diverting a portion of the AC input current when a short circuit occurs. This reduces the impact of the short-circuit current on the internal components of the non-isolated AC-DC converter circuit, achieving effective short-circuit protection and thus effectively improving the system's resistance to impact, overall safety, and reliability under short-circuit conditions. Attached Figure Description

[0027] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings do not constitute a limitation on scale.

[0028] Figure 1 This application provides one topology of a non-isolated AC-DC converter circuit.

[0029] Figure 2 Another topology of a non-isolated AC-DC converter circuit provided in the embodiments of this application;

[0030] Figure 3 A schematic block diagram of a power conversion device provided in an embodiment of this application;

[0031] Figure 4 Another principle block diagram of a power conversion device provided in an embodiment of this application;

[0032] Figure 5 A schematic diagram of a relay module for a short-circuit protection circuit provided in an embodiment of this application;

[0033] Figure 6 Another schematic diagram of a relay module for a short-circuit protection circuit provided in an embodiment of this application. Detailed Implementation

[0034] To facilitate understanding of this utility model, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as "connected" to another element, it can be directly on the other element, or one or more intermediate elements can exist between them. The terms "upper," "lower," "left," "right," "upper end," "lower end," "top," and "bottom," etc., used in this specification indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention.

[0036] Non-isolated AC-DC converter circuits are suitable for applications such as electric vehicle charging systems, distributed power systems, and integrated photovoltaic-energy storage-charging systems. Figure 1 An AC-DC converter circuit with a bidirectional interleaved Vienna rectifier topology, and Figure 2 An AC-DC converter circuit with a T-type three-level rectifier topology, etc.

[0037] In existing technologies, although non-isolated AC-DC topologies in these systems have the advantages of high efficiency and low cost, they often lack effective protection mechanisms in the event of a short circuit, which makes the switching transistors susceptible to damage during a short circuit and reduces the safety and reliability of the system.

[0038] To address the aforementioned problems, in a first aspect, embodiments of this application provide a short-circuit protection circuit for short-circuit protection of AC-DC conversion circuits.

[0039] Please see Figure 3 The short-circuit protection circuit 20 includes an auxiliary rectifier module 21, a current detection module 22, a relay module 23, and a control module 24.

[0040] The auxiliary rectifier module 21 is connected in parallel with the non-isolated AC-DC converter circuit 10 and is used to shunt the AC input current of the non-isolated AC-DC converter circuit 10 when it is short-circuited. The current detection module 22 is electrically connected to the non-isolated AC-DC converter circuit 10 and is used to detect the DC output current of the non-isolated AC-DC converter circuit 10.

[0041] Relay module 23 is electrically connected to the non-isolated AC-DC converter circuit 10 and the auxiliary rectifier module 21, and is used to connect or disconnect the AC input current of the non-isolated AC-DC converter circuit 10. Control module 24 is electrically connected to the non-isolated AC-DC converter circuit 10 and the current detection module 22, respectively, and is used to drive the non-isolated AC-DC converter circuit 10 and control the relay control module 23. When the DC output current exceeds a preset current threshold, it stops driving the non-isolated AC-DC converter circuit 10 and controls the relay module 24 to disconnect the AC input current of the non-isolated AC-DC converter circuit 10.

[0042] The working principle of the short-circuit protection circuit 20 in this embodiment is as follows: When a short circuit occurs in the non-isolated AC-DC converter circuit 10, the current detection module 22 detects the magnitude of the DC output current, and the control module 24 compares the DC output current with a preset current threshold. When the DC output current exceeds the preset current threshold, it is determined that the DC output current is overcurrent, and the non-isolated AC-DC converter circuit 10 is stopped. Simultaneously, the relay module 23 is controlled to disconnect the input path of the AC input current, cutting off the current source. At the same time, the auxiliary rectifier module 21 is connected in parallel to the non-isolated AC-DC converter circuit 10. When a short circuit occurs, it diverts a portion of the AC input current, reducing the impact of the short-circuit current on the internal components of the non-isolated AC-DC converter circuit 10, thus achieving effective short-circuit protection.

[0043] It is understood that, by configuring an auxiliary rectification module 21, a current detection module 22, a relay module 23, and a control module 24 for the non-isolated AC-DC converter circuit 10, the system can quickly shunt and cut off the input current and stop the driving of the non-isolated AC-DC converter circuit 10 when a short circuit occurs, thereby effectively improving the system's shock resistance, overall safety, and reliability under short circuit conditions.

[0044] Please see Figure 4 In some embodiments, taking the conversion of three-phase AC (phase A, phase B, phase C) to DC as an example, the AC side of the non-isolated AC-DC converter circuit 10 includes three AC buses (AC_A, AC_B, AC_C), each AC bus being used to transmit one phase of AC power. The DC side of the non-isolated AC-DC converter circuit 10 includes a positive bus BUS+ and a negative bus BUS-. The relay module 23 can be electrically connected to each AC bus of the non-isolated AC-DC converter circuit 10. The auxiliary rectifier module 21 includes three auxiliary rectifier units 211, each auxiliary rectifier unit 211 being electrically connected to the positive bus BUS+, the negative bus BUS-, and a corresponding AC bus of the non-isolated AC-DC converter circuit 10. The auxiliary rectifier unit 211 is used to shunt the corresponding phase current in the AC input current when the non-isolated AC-DC converter circuit 10 is short-circuited.

[0045] Understandably, the AC input side of the non-isolated AC-DC converter circuit 10 includes three AC buses, and the DC output side includes a positive bus BUS+ and a negative bus BUS-. In the event of a short circuit, the three auxiliary rectifier units 211 in the auxiliary rectifier module 21 are connected in parallel between each AC bus and the positive bus BUS+ and negative bus BUS- at the DC output terminal. Each auxiliary rectifier unit 211 shunts one phase current on the corresponding AC bus through its internal diode, thereby reducing the impact of the short-circuit current on the non-isolated AC-DC converter circuit 10 and achieving effective shunt protection against the short-circuit current.

[0046] In the actual deployment of auxiliary rectifier units 211, each auxiliary rectifier unit 211 can achieve electrical connection with the relay module 23 through electrical connection with the AC bus of the non-isolated AC-DC converter circuit 10, or each auxiliary rectifier unit 211 can first complete the electrical connection with the relay module 23, and then connect the common contact point of each auxiliary rectifier unit 211 and the relay module 23 to each AC bus of the non-isolated AC-DC converter circuit 10 one by one.

[0047] In some embodiments, specifically, each auxiliary rectifier unit 211 includes a first diode D1n (n = 1, 2, 3) and a second diode D2n. In each auxiliary rectifier unit 211, the anode of the first diode D1n can be connected to a corresponding AC bus, and the cathode of the first diode D1n can be connected to the positive bus BUS+. The cathode of the second diode D2n can be connected to a corresponding AC bus, and the anode of the second diode D2n can be connected to the negative bus BUS-.

[0048] Understandably, in each auxiliary rectifier unit 211, the anode of the first diode D1n is connected to the corresponding AC bus, and the cathode is connected to the DC positive bus BUS+. The cathode of the second diode D2n is connected to the corresponding AC bus, and the anode is connected to the DC negative bus BUS-. When a short circuit occurs in the non-isolated AC-DC converter circuit 10, the two diodes in each auxiliary rectifier unit 211 provide shunt paths for the positive and negative currents, respectively, guiding the impact portion of the AC input current to the positive and negative buses BUS- at the DC output terminal, thereby shunting the short-circuit current, reducing the current impact on the internal AC-DC converter circuit, and protecting the circuit components.

[0049] Please refer to the following: Figure 4 and Figure 5In some embodiments, the relay module 23 includes three relays Km (m = 1, 2, 3) and a relay drive unit 231. Each relay can be connected to the AC mains and a corresponding AC bus in the non-isolated AC-DC converter circuit. The relay drive unit 231 is connected to each relay Km and the control module 23, and is controlled by the control module 23 to drive each relay Km to connect or disconnect the AC input current of the non-isolated AC-DC converter circuit 10.

[0050] Understandably, relay module 23 includes three relays Km, which are respectively connected to the three AC buses and the AC power grid of the non-isolated AC-DC converter circuit 10. Furthermore, under the control of control module 23, relay drive unit 231 controls each relay to disconnect the input path of the AC input current, thereby quickly cutting off the AC power input in the event of a short circuit, preventing the short-circuit current from continuing to flow into the AC-DC converter circuit, and protecting the safe and stable operation of the circuit.

[0051] Please see Figure 5 In some embodiments, the relay driving unit 231 includes three driving subunits 2311 and a control subunit 2312. Each driving subunit 2311 is connected to a corresponding relay Km, and the driving subunit 2311 is used to drive the corresponding relay Km to close or open. The control subunit 2312 is connected to each driving subunit 2311 and the control module 23, and the control subunit 2312 is controlled by the control module 23, and is used to drive the corresponding relay Km to close or open by controlling any driving subunit 2311.

[0052] Understandably, the relay drive unit 231 comprises three drive subunits 2311, each controlling the closing or opening of a relay Km. In the event of a short circuit or overcurrent, the control subunit 2312 sends a command to each drive subunit 2311 to ensure that each relay Km quickly disconnects the AC input current path, thereby protecting the safety of the non-isolated AC-DC converter circuit 10. Specifically, the control subunit 2312 has the following functions: signal reception, receiving control signals sent by the control module 23; command distribution, sending a disconnect command to each drive subunit 2311 according to the corresponding control signal when a short circuit occurs, to synchronously control all relays Km to disconnect the input current; and coordinated control, ensuring that each drive subunit 2311 accurately executes the received command, coordinating the disconnection action of the relays Km to achieve the purpose of short circuit protection.

[0053] In some embodiments, the control subunit 2312 may be implemented using logic circuits, microcontrollers or other programmable chips to ensure a fast response when short-circuit protection is triggered, thereby achieving safe protection for non-isolated AC-DC circuits.

[0054] In some embodiments, each driving subunit 2311 includes a first resistor R1, a second resistor R2, a driving switch Q1, and a freewheeling diode D1. The control subunit 2312 is connected to one end of the first resistor R1, the other end of the first resistor R1 is connected to the gate of the driving switch Q1, one end of the second resistor R2 is connected to the gate of the driving switch Q1, the other end of the second resistor R2 is grounded, the source of the driving switch Q1 is grounded, and the drain of the driving switch Q1 is connected to the positive terminal of the freewheeling diode D1.

[0055] The relay Km includes a coil, an armature, a first contact a, and a second contact b. One end of the coil is connected to a power source and to the negative terminal of a freewheeling diode D1. The other end of the coil is connected to the drain of a driving switching transistor Q1. One of the first contact a and the second contact b can be connected to an AC mains, and the other can be connected to a corresponding AC bus in the non-isolated AC-DC converter circuit 10. One end of the armature is connected to the first contact a, and the other end of the armature is connected to the second contact b. The armature can be attracted by the magnetic field generated by the coil when it is energized, so as to detach from one of the first contact a and the second contact b.

[0056] Understandably, each drive subunit 2311 includes a first resistor R1, a second resistor R2, a drive switch Q1, and a freewheeling diode D1. The gate voltage of the drive switch Q1 is adjusted by controlling the first and second resistors R2 to control the turn-on or turn-off of the drive switch Q1. When the drive switch Q1 is on, the power supply current flows through the relay Km coil, generating a magnetic field that actuates the armature and closes or opens the relay contacts, thereby connecting or disconnecting the AC input current path. In one embodiment, when the drive switch Q1 is on, the power supply current flows through the relay Km coil, generating a magnetic field that attracts the armature to open the first contact a or the second contact b of the relay Km, thereby disconnecting the AC input current path and achieving short-circuit protection for the non-isolated AC-DC converter circuit 10.

[0057] Please see Figure 6 In some embodiments, each driving subunit 2311 includes a Zener diode D2, which is disposed on one end of the coil and on the connection line of the freewheeling diode D1. The positive terminal of the Zener diode D2 is connected to one end of the coil, and the negative terminal of the Zener diode D2 is connected to the negative terminal of the freewheeling diode D1.

[0058] Understandably, the Zener diode D2 accelerates the turn-off of relay Km by limiting the peak reverse voltage at the moment the relay Km coil is de-energized. Specifically, when the relay Km coil is de-energized, the coil generates a reverse induced electromotive force due to its inductive characteristics. The Zener diode D2 quickly clamps the reverse voltage to a set value, accelerating the disappearance of the coil's magnetic field. This rapid release of the reverse voltage effectively speeds up the relay's turn-off process, shortening the time it takes for the relay Km contacts to fully open from closing, thus achieving the effect of accelerated turn-off of relay Km.

[0059] In some embodiments, the current detection module 22 is a Hall sensor, a current shunt, or a fluxgate current sensor, etc. These sensor types provide different current detection methods to meet requirements for accuracy, isolation, response speed, etc., ensuring that the current detection module 22 can monitor the output current in real time and accurately and trigger protection. Exemplarily, in this embodiment, the current detection module 22 is configured on the positive bus BUS+ to detect the magnitude of the current on the positive bus+.

[0060] In some embodiments, the control module 24 is a core component for managing the non-isolated AC-DC converter circuit 10. It is responsible for providing drive signals to the non-isolated AC-DC converter circuit 10, driving the individual transistors within the circuit to control its normal power conversion process. Simultaneously, the control module 24 is connected to the current detection module 22 to sample the DC output current and compare it with a preset current threshold. When the DC output current exceeds the preset current threshold (e.g., in the case of a short circuit or overcurrent), the control module 24 immediately responds, stopping the drive of the non-isolated AC-DC converter circuit 10 and controlling the relay control module 23 to disconnect the AC input current to prevent further current surges from damaging the circuit.

[0061] In some embodiments, the control module 24 includes a first control unit and a second control unit. The first control unit may include at least one chip or integrated circuit, which includes logic units and is capable of driving each transistor in the non-isolated AC-DC converter circuit 10 to control its normal power conversion process.

[0062] Furthermore, the second control unit may include at least a portion of a chip or integrated circuit, which includes logic units capable of comparing the sampled DC output current with a preset current threshold and controlling the relay module 23 to drive the relay. The second control unit and the first control unit can transmit and interact with electrical signals. When it is confirmed that the DC output current exceeds the preset current threshold, the second control unit feeds back a signal to the first control unit, causing the first control unit to stop driving the non-isolated AC-DC converter circuit 10 and control the relay module 23 to cut off the input path of the AC input current, thereby quickly triggering a short-circuit protection action.

[0063] In other embodiments, the control module 24 may be constructed from two or more chips that can work in coordination with each other. For example, the control module 24 may also be constructed from various logic devices, such as general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), microcontrollers, ARM (Acorn RISC Machine) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of these components.

[0064] Please review Figure 3 In a second aspect, embodiments of this application provide a power conversion device that converts input electrical energy into power electronic equipment with a specific output form, typically used to meet the voltage, current or frequency requirements of different devices.

[0065] In some embodiments, the power conversion device includes a non-isolated AC-DC conversion circuit 10 and a short-circuit protection circuit 20 as described in the above embodiments, wherein the short-circuit protection circuit 20 is electrically connected to the non-isolated AC-DC conversion circuit 10.

[0066] In this embodiment, the power conversion device includes a non-isolated AC-DC conversion circuit 10 and a short-circuit protection circuit 20, mainly used to convert alternating current (AC) to direct current (DC) for load use. The non-isolated AC-DC conversion circuit 10 has the advantages of high efficiency and low cost, but it poses a risk in the event of a short circuit. Therefore, the short-circuit protection circuit 20 promptly cuts off the input current and protects circuit components by detecting current, shunting current, and controlling relays, thereby enhancing the reliability and safety of the device. This makes it suitable for applications such as electric vehicle charging, distributed power systems, and integrated photovoltaic-energy storage-charging systems.

[0067] In some embodiments, the power conversion device further includes a DC-DC conversion circuit, which is connected to the DC terminal of the non-isolated AC-DC conversion circuit 10 and the load (or energy storage device) respectively, for DC voltage conversion between the non-isolated AC-DC conversion circuit 10 and the load (or energy storage device). In one embodiment, the DC-DC conversion circuit is a bidirectional DC-DC conversion circuit.

[0068] In a third aspect, embodiments of this application provide a charging device. In some embodiments, the charging device is the charging host of a charging pile system, used to provide electrical energy for electric vehicles, battery storage devices, etc., and capable of converting AC power from the grid or other power sources into DC power or electrical energy output at a specific voltage that meets the load requirements. This device typically includes a power conversion circuit 100, a control circuit, and a safety protection circuit to ensure efficient, stable, and safe charging. In embodiments of this application, the charging device uses a non-isolated AC-DC conversion circuit 10 to achieve efficient power conversion, while a short-circuit protection circuit 20 quickly cuts off the input current in the event of a short circuit or overcurrent, protecting internal components from damage and enhancing the reliability of the device.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it; under the concept of this utility model, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this utility model as described above. For the sake of brevity, they are not provided in detail; although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A short-circuit protection circuit, applied to short-circuit protection of a non-isolated AC-DC converter circuit, characterized in that, The short-circuit protection circuit includes: An auxiliary rectifier module, connected in parallel with the non-isolated AC-DC converter circuit, is used to shunt the AC input current of the non-isolated AC-DC converter circuit when the non-isolated AC-DC converter circuit is short-circuited. The current detection module can be electrically connected to the non-isolated AC-DC converter circuit and is used to detect the DC output current of the non-isolated AC-DC converter circuit. A relay module, electrically connected to the non-isolated AC-DC converter circuit, and the relay module, electrically connected to the auxiliary rectifier module, are used to connect or disconnect the AC input current of the non-isolated AC-DC converter circuit; and The control module is electrically connected to the non-isolated AC-DC converter circuit, the relay module, and the current detection module, respectively. It is used to drive the non-isolated AC-DC converter circuit and control the relay module, and to stop driving the non-isolated AC-DC converter circuit when the DC output current exceeds a preset current threshold, and to control the relay module to disconnect the AC input current of the non-isolated AC-DC converter circuit.

2. The short-circuit protection circuit according to claim 1, characterized in that, The AC side of the non-isolated AC-DC converter circuit includes three AC buses, and the DC side of the non-isolated AC-DC converter circuit includes a positive bus and a negative bus. The relay module can be electrically connected to each AC bus of the non-isolated AC-DC converter circuit. The auxiliary rectification module includes three auxiliary rectification units. Each auxiliary rectification unit can be electrically connected to the positive bus, the negative bus, and a corresponding AC bus of the non-isolated AC-DC converter circuit. The auxiliary rectification unit is used to shunt one phase current in the AC input current when the non-isolated AC-DC converter circuit is short-circuited.

3. The short-circuit protection circuit according to claim 2, characterized in that, Each of the auxiliary rectifier units includes a first diode and a second diode. In each auxiliary rectifier unit, the anode of the first diode can be connected to a corresponding AC bus, and the cathode of the first diode can be connected to the positive bus. The cathode of the second diode can be connected to a corresponding AC bus, and the anode of the second diode can be connected to the negative bus.

4. The short-circuit protection circuit according to claim 2, characterized in that, The relay module includes: Three relays, each capable of being connected to the AC mains and a corresponding AC bus in the non-isolated AC-DC converter circuit; and A relay driving unit is provided, which is connected to each of the relays and the control module respectively. The relay driving unit is controlled by the control module and is used to drive each of the relays to connect or disconnect the AC input current of the non-isolated AC-DC converter circuit.

5. The short-circuit protection circuit according to claim 4, characterized in that, The relay drive unit includes: Three drive subunits, each connected to a corresponding relay, wherein the drive subunit is used to drive the corresponding relay to close or open; and A control subunit is provided, which is connected to each of the drive subunits and the control module. The control subunit is controlled by the control module and is used to drive the corresponding relay to close or open by controlling any of the drive subunits.

6. The short-circuit protection circuit according to claim 5, characterized in that, Each of the driving subunits includes a first resistor, a second resistor, a driving switch transistor, and a freewheeling diode. The control subunit is connected to one end of the first resistor, the other end of the first resistor is connected to the gate of the driving switch transistor, one end of the second resistor is connected to the gate of the driving switch transistor, the other end of the second resistor is grounded, the source of the driving switch transistor is grounded, and the drain of the driving switch transistor is connected to the positive terminal of the freewheeling diode. The relay includes a coil, an armature, a first contact, and a second contact. One end of the coil is connected to the negative terminal of the freewheeling diode and used to connect to a power supply. The other end of the coil is connected to the drain of the driving switch. One of the first contact and the second contact can be connected to the AC mains, and the other can be connected to a corresponding AC bus in the non-isolated AC-DC converter circuit. One end of the armature is connected to the first contact, and the other end of the armature is connected to the second contact. The armature can be attracted by the magnetic field generated by the coil when it is energized, so as to detach from one of the first contact and the second contact.

7. The short-circuit protection circuit according to claim 6, characterized in that, Each of the driving subunits includes a Zener diode, which is disposed on one end of the coil and on the connection line of the freewheeling diode. The positive terminal of the Zener diode is connected to one end of the coil, and the negative terminal of the Zener diode is connected to the negative terminal of the freewheeling diode.

8. The short-circuit protection circuit according to claim 1, characterized in that, The current detection module is a Hall sensor, a current shunt, or a fluxgate current sensor.

9. A power conversion device, characterized in that, include: Non-isolated AC-DC converter circuit; as well as The short-circuit protection circuit as described in any one of claims 1-8 is electrically connected to the non-isolated AC-DC converter circuit.

10. A charging device, characterized in that, Includes the power conversion device as described in claim 9.

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