Short circuit protection circuit and short circuit protection system

Abstract

The present application discloses a short-circuit protection circuit and a short-circuit protection system. The overcurrent protection unit of the short-circuit protection circuit includes a first controllable switch, a second controllable switch, a first resistor, and a second resistor. The control end of the first controllable switch is connected to the second end of the first resistor, the first end of the second controllable switch, and the second voltage end. The first end of the first controllable switch is connected to the control end of the second controllable switch and the first end of the second resistor. The second end of the first controllable switch is connected to the first end of the first resistor, the first voltage end, and the first output end. The second end of the second controllable switch is connected to the second end of the second resistor and the second output end. The short-circuit protection circuit of the present application can prevent the power supply unit with a short circuit from absorbing the current of the first output end and the second output end, thereby ensuring the normal operation of the load and improving the reliability of the system.

Description

Technical Field

[0001] The present application relates to the technical field of short circuit protection, and in particular to a short circuit protection circuit and a short circuit protection system. Background Art

[0002] In some high-power DC power scenarios, when a single DC power module cannot provide enough power, multiple modules need to be connected in parallel, and generally 1 to 2 more modules are configured for redundancy. However, when a DC power module in the system short-circuits, the short-circuited DC power module will draw voltage from the output bus, so that the voltage output to the load will be pulled down, greatly reducing the reliability of the system.

[0003] Therefore, it is necessary to provide a short circuit protection circuit and a short circuit protection system to solve the above technical problems. Summary of the invention

[0004] The present application mainly provides a short circuit protection circuit and a short circuit protection system. The short circuit protection circuit of the present application can improve the reliability of the system.

[0005] In order to solve the above technical problems, the first technical solution adopted in the present application is to provide a short-circuit protection circuit, which includes: a power supply unit, including a first voltage terminal and a second voltage terminal, for providing a working voltage; a first output terminal and a second output terminal, for connecting to a load; an overcurrent protection unit, connected to the first voltage terminal and the second voltage terminal of the power supply unit, for conducting the circuit between the power supply unit and the first output terminal and the second output terminal respectively when the power supply unit works normally, or disconnecting the circuit between the power supply unit and the first output terminal, or disconnecting the circuit between the power supply unit and the second output terminal when the power supply unit is short-circuited; the overcurrent protection unit includes a first controllable switch, a second controllable switch, a first resistor, and a second resistor, the control end of the first controllable switch is connected to the second end of the first resistor, the first end of the second controllable switch and the second voltage terminal, the first end of the first controllable switch is connected to the control end of the second controllable switch and the first end of the second resistor, the second end of the first controllable switch is connected to the first end of the first resistor, the first voltage terminal and the first output terminal, and the second end of the second controllable switch is connected to the second end of the second resistor and the second output terminal.

[0006] In order to solve the above technical problems, the second technical solution adopted in the present application is to provide a short-circuit protection system, which includes at least two short-circuit protection circuits connected in parallel, and each short-circuit protection circuit includes: a power supply unit, including a first voltage terminal and a second voltage terminal, for providing a working voltage; a first output terminal and a second output terminal, for connecting to a load; an overcurrent protection unit, connected to the first voltage terminal and the second voltage terminal of the power supply unit, for conducting the circuit between the power supply unit and the first output terminal and the second output terminal respectively when the power supply unit works normally, or disconnecting the circuit between the power supply unit and the first output terminal, or disconnecting the circuit between the power supply unit and the second output terminal when the power supply unit is short-circuited; the overcurrent protection unit includes a first controllable switch, a second controllable switch, a first resistor, and a second resistor, the control end of the first controllable switch is connected to the second end of the first resistor, the first end of the second controllable switch and the second voltage terminal, the first end of the first controllable switch is connected to the control end of the second controllable switch and the first end of the second resistor, the second end of the first controllable switch is connected to the first end of the first resistor, the first voltage terminal and the first output terminal, and the second end of the second controllable switch is connected to the second end of the second resistor and the second output terminal.

[0007] The beneficial effect of the present application is as follows: Different from the prior art, the overcurrent protection unit in the short-circuit protection circuit of the present application includes a first controllable switch, a second controllable switch, a first resistor, and a second resistor, the control end of the first controllable switch is connected to the second end of the first resistor, the first end of the second controllable switch and the second voltage end, the first end of the first controllable switch is connected to the control end of the second controllable switch and the first end of the second resistor, the second end of the first controllable switch is connected to the first end of the first resistor, the first voltage end and the first output end, and the second end of the second controllable switch is connected to the second end of the second resistor and the second output end. The overcurrent protection unit can disconnect the circuit between the power supply unit and the first output end, or disconnect the circuit between the power supply unit and the second output end in time when the power supply unit is short-circuited, and the short-circuited power supply unit will not absorb the current of the first output end and the second output end, thereby ensuring that the voltage between the first output end and the second output end connected to the load is normal, thereby improving the reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a structural schematic diagram of the short-circuit protection circuit provided by the present application;

[0009] Figure 2 is a circuit diagram of a first implementation mode of a short-circuit protection circuit provided by the present application;

[0010] Figure 3 is a circuit diagram of a second embodiment of a short-circuit protection circuit provided by the present application;

[0011] Figure 4 It is a structural schematic diagram of the short-circuit protection system provided by this application. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical scheme and technical effect of the present application more specific and clear, the present application is further described in detail below. It should be understood that the specific implementation regulations described here are only used to explain the present application and are not used to limit the present application.

[0013] In some high-power DC power consumption scenarios, when a single DC power module cannot meet the power demand, multiple modules need to be connected in parallel, and parallel connection generally configures 1 to 2 more modules for redundancy. However, when the DC power module in the system is short-circuited, the voltage output to the load will be pulled down, resulting in a significant reduction in system reliability. In order to solve this technical problem, the present application sets a first controllable switch, a second controllable switch, a first resistor, and a second resistor in the overcurrent protection unit. When the power supply unit is short-circuited, the overcurrent protection unit promptly disconnects the circuit between the power supply unit and the first output terminal, or disconnects the circuit between the power supply unit and the second output terminal, thereby ensuring that the voltage between the first output terminal and the second output terminal connected to the load is normal. Below, the present application is described in detail in conjunction with the accompanying drawings.

[0014] See also Figure 1 , is a schematic diagram of the structure of the short-circuit protection circuit provided by the present application. Figure 1 As shown, the short-circuit protection circuit includes a power supply unit 11 , an overcurrent protection unit 12 , a first output terminal 13 , and a second output terminal 14 . Among them, the first output terminal 13 and the second output terminal 14 are used to connect with the load 15 or the back-end circuit, and output the voltage required for the load 15 or the back-end circuit to work; the power supply unit 11 includes a first voltage terminal 111 and a second voltage terminal 112, and the power supply unit 11 provides the overcurrent protection unit 12 and the load 15 or the back-end circuit with the working voltage required by the first voltage terminal 111 and the second voltage terminal 112; the overcurrent protection unit 12 is connected to the first voltage terminal 111 and the second voltage terminal 112 of the power supply unit 11, and is used to conduct the circuit between the power supply unit 11 and the first output terminal 13 and the second output terminal 14 respectively when the power supply unit 11 is working normally, or disconnect the circuit between the power supply unit 11 and the first output terminal 13, or disconnect the circuit between the power supply unit 11 and the second output terminal 14 when the power supply unit 11 is short-circuited, so that the short-circuited power supply unit 11 will not absorb the current of the first output terminal 13 and the second output terminal 14, and can ensure that the voltage between the first output terminal 13 and the second output terminal 14 connected to the load 15 is normal.

[0015] Specifically, the overcurrent protection unit 12 includes a first controllable switch 121, a second controllable switch 122, a first resistor 123, and a second resistor 124. The control end a of the first controllable switch 121 is connected to the second end of the first resistor 123, the first end e of the second controllable switch 122, and the second voltage end 112. The first end b of the first controllable switch 121 is connected to the control end g of the second controllable switch 122 and the first end of the second resistor 124. The second end c of the first controllable switch 121 is connected to the first end of the first resistor 123, the first voltage end 111, and the first output end 13. The second end f of the second controllable switch 122 is connected to the second end of the second resistor 124 and the second output end 14.

[0016] In this embodiment, the voltage between the first output terminal 13 and the second output terminal 14 is a DC voltage, and the first output terminal 13 and the second output terminal 14 are connected to the positive terminal and the negative terminal of the load 15 respectively.

[0017] When the power supply unit 11 works normally, the overcurrent protection unit 12 turns on the circuit between the power supply unit 11 and the first output terminal 13 and the second output terminal 14, and outputs the working voltage required by the load 15 through the first output terminal 13 and the second output terminal 14. Specifically, when the power supply unit 11 works normally, the voltage across the first resistor 123 is the turn-on voltage of the first controllable switch 121, that is, the first controllable switch 121 is in the on state at this time, and the voltage across the second resistor 124 is the turn-on voltage of the second controllable switch 122, that is, the second controllable switch 122 is in the on state at this time; when the power supply unit 11 is short-circuited, the overcurrent protection unit 12 turns on the circuit between the power supply unit 11 and the first output terminal 13 and the second output terminal 14, and ... 12 disconnects the circuit between the power supply unit 11 and the first output terminal 13, or disconnects the circuit between the power supply unit 11 and the second output terminal 14. Specifically, when the power supply unit 11 is short-circuited, the voltage across the first resistor 123 is approximately zero volt, that is, the voltage across the first resistor 123 is lower than the turn-on voltage of the first controllable switch 121, and the first controllable switch 121 is in the off state. The voltage across the second resistor 124 is approximately zero volt, that is, the second controllable switch 122 is also in the off state. At this time, the short-circuited power supply unit 11 will not absorb the current of the first output terminal 13 and the second output terminal 14, and the voltage across the load 15 will not be pulled down.

[0018] In this embodiment, by setting the first controllable switch 121, the second controllable switch 122 and the first resistor 123 and the second resistor 124 in the overcurrent protection unit 12, it can effectively ensure that the voltage across the load 15 will not be collapsed when the power supply unit 11 is short-circuited, thereby improving the reliability of the system.

[0019] See also Figure 2 , is a circuit diagram of the first embodiment of the short-circuit protection circuit provided by the present application. Figure 2As shown, the short-circuit protection circuit includes a power supply unit 201, an overcurrent protection unit 202, a first output terminal DCVOUT+ and a second output terminal DCVOUT-. The power supply unit 201 includes a current source I, a transformer T, a first diode D1 and a second diode D2. The transformer T includes a primary coil T0 and a secondary coil. The primary coil T0 of the transformer T is connected to the current source I. The secondary coil of the transformer T includes a first secondary coil T1 and a second secondary coil T2. The anode of the first diode D1 is connected to the opposite-name end of the first secondary coil T1. The cathode of the first diode D1 is connected to the cathode of the second diode D2 and is connected to the first voltage terminal M. The anode of the second diode D2 is connected to the same-name end of the second secondary coil T2. The second voltage terminal H is connected to the same-name end of the first secondary coil T1 and the opposite-name end of the second secondary coil T2. Specifically, when the first diode D1 is turned on and the second diode D2 is reversely cut off, the like-name end of the first secondary coil T1 is connected to the second voltage terminal H, and the unlike-name end of the first secondary coil T1 is connected to the first voltage terminal M, and the working voltage is provided to the load or the back-end circuit through the first voltage terminal M and the second voltage terminal H; when the first diode D1 is reversely cut off and the second diode D2 is turned on, the like-name end of the second secondary coil T2 is connected to the first voltage terminal M, and the unlike-name end of the second secondary coil T2 is connected to the second voltage terminal H, and the working voltage is provided to the load or the back-end circuit through the first voltage terminal M and the second voltage terminal H.

[0020] The overcurrent protection unit 202 includes a first controllable switch Q1, a second controllable switch Q2, a fuse F1, and first to fourth resistors R1, R2, R3, and R4. The control end of the first controllable switch Q1 is connected to the second end of the first resistor R1 and the first end of the fourth resistor R4, the second end of the first controllable switch Q1 is connected to the first end of the first resistor R1, the first voltage end M, and the first output end DCVOUT+, the first end of the first controllable switch Q1 is connected to the first end of the third resistor R3, the control end of the second controllable switch Q2 is connected to the second end of the third resistor R3 and the first end of the second resistor R2, the first end of the second controllable switch Q2 is connected to the second end of the fourth resistor R4 and the second voltage end H, the second end of the second controllable switch Q2 is connected to the second end of the second resistor R2 and the first end of the fuse F1, and the second end of the fuse F1 is connected to the second output end DCVOUT-.

[0021] In this embodiment, the first controllable switch Q1 is a P-channel field effect transistor, and the control terminal, the first terminal and the second terminal of the first controllable switch Q1 correspond to the gate, the drain and the source of the P-channel field effect transistor respectively; the second controllable switch Q2 is an N-channel field effect transistor, and the control terminal, the first terminal and the second terminal of the second controllable switch Q2 correspond to the gate, the drain and the source of the N-channel field effect transistor respectively. In other embodiments, the first controllable switch and the second controllable switch may also be other types of transistors, which are not specifically limited here.

[0022] In this embodiment, the overcurrent protection unit 202 further includes a first filter capacitor C1, a first end of the first filter capacitor C1 is connected to a first end of the first resistor R1 and a first voltage terminal M of the power supply unit 201, and a second end of the first filter capacitor C1 is connected to a first end of the second controllable switch Q2, a second end of the fourth resistor R4 and a second voltage terminal H of the power supply unit 201. Specifically, the first filter capacitor C1 is an electrolytic capacitor, and the electrolytic capacitor can filter the voltage signal output by the first output terminal M and the second output terminal N.

[0023] When the first diode D1 is turned on and the second diode D2 is reversely cut off, or the first diode D1 is reversely cut off and the second diode D2 is turned on, that is, at this time, the power supply unit 201 works normally, the voltage across the first resistor R1 is the turn-on voltage of the first controllable switch Q1, and the voltage across the second resistor R2 is the turn-on voltage of the second controllable switch Q2, that is, the first controllable switch Q1 and the second controllable switch Q2 are both in the on state. At this time, the second resistor R2 in the overcurrent protection unit 202 is connected in series with the third resistor R3, the first resistor R1 is connected in series with the fourth resistor R4, and the first controllable switch Q1, the second controllable switch Q2 and the fuse F1 are all in the on state. The first voltage terminal M and the second voltage terminal H output the voltage signal of the power supply unit 201 to the overcurrent protection unit 202, the first filter capacitor C1 filters the voltage signal, and the overcurrent protection unit 202 transmits the filtered voltage signal to the first output terminal DCVOUT+ and the second output terminal DCVOUT-, and the load or back-end circuit connected to the first output terminal DCVOUT+ and the second output terminal DCVOUT- works normally.

[0024] When the power supply unit 201 is short-circuited, the first diode D1 and the second diode D2 are broken down, the voltage across the first resistor R1 is close to zero volts, which is lower than the turn-on voltage of the first controllable switch Q1, and the first controllable switch Q1 is disconnected, and the voltage across the second resistor R2 is close to zero volts, which is lower than the turn-on voltage of the second controllable switch Q2, and the second controllable switch Q2 is disconnected, so that the short-circuited power supply unit 201 will not absorb the current from the first output terminal DCVOUT+ and the second output terminal DCVOUT-, and the voltage across the load connected to the first output terminal DCVOUT+ and the second output terminal DCVOUT- will not be pulled down.

[0025] Furthermore, even if the first controllable switch Q1 and / or the second controllable switch Q2 is not disconnected in time due to a fault, when the current passing through the fuse F1 in the overcurrent protection unit 202 reaches a predetermined value, the fuse F1 will also blow to disconnect the circuit between the short-circuited power supply unit 201 and the load, so as to ensure the normal operation of the load. By setting the fuse F1, the reliability of the system can be further improved.

[0026] In this embodiment, the first end of the fuse F1 is connected to the second end of the second controllable switch Q2, and the second end of the fuse F1 is connected to the second output end DCVOUT-. In other embodiments, the first end of the fuse F1 can be connected to the second end of the first controllable switch Q1, and the second end of the fuse F1 is connected to the first output end DCVOUT+.

[0027] In this embodiment, by providing the first controllable switch Q1, the second controllable switch Q2 and the fuse F1 in the overcurrent protection unit 202, it can be effectively ensured that the voltage across the load will not be collapsed when the power supply unit 201 is short-circuited, thereby improving the reliability of the system.

[0028] See also Figure 3 , is a circuit diagram of the second embodiment of the short-circuit protection circuit provided by the present application. Figure 3 As shown, the short circuit protection circuit includes a power supply unit 301, an overcurrent protection unit 302, a first output terminal DCVOUT+ and a second output terminal DCVOUT-. The difference from the previous embodiment is that in the previous embodiment, the overcurrent protection unit includes first to fourth resistors and a first filter capacitor, and the overcurrent protection unit in this embodiment includes first to fifth resistors and a first filter capacitor and a second filter capacitor.

[0029] Specifically, in this embodiment, the overcurrent protection unit also includes a fifth resistor R5 and a second filter capacitor C2, the first end of the fifth resistor R5 is connected to the second end of the fourth resistor R4, the second end of the fifth resistor R5 is connected to the first end of the second controllable switch Q2, the second end of the first filter capacitor C1 and the second voltage terminal H; the first end of the second filter capacitor C2 is connected to the second end of the fuse F1 and the second output terminal DCVOUT-, and the second end of the second filter capacitor C2 is connected to the second end of the first controllable switch Q1 and the first output terminal DCVOUT+.

[0030] In this embodiment, the fifth resistor R5 is connected in series on the branch where the first resistor R1 and the fourth resistor R4 are located to increase the withstand voltage capability; the first filter capacitor C1 is an electrolytic capacitor, which first performs a filtering process on the voltage signal, and then the second filter capacitor C2 performs a second filtering process, thereby achieving a better filtering effect and obtaining a voltage signal with better performance. The second filter capacitor C2 in this embodiment is a ceramic capacitor, and in other embodiments, it can also be other types of filter capacitors, which are not specifically limited here.

[0031] As can be seen from the above, the overcurrent protection unit in the short-circuit protection circuit of the present application includes a first controllable switch, a second controllable switch, a first resistor, and a second resistor. The control end of the first controllable switch is connected to the second end of the first resistor, the first end of the second controllable switch and the second voltage end. The first end of the first controllable switch is connected to the control end of the second controllable switch and the first end of the second resistor. The second end of the first controllable switch is connected to the first end of the first resistor, the first voltage end and the first output end. The second end of the second controllable switch is connected to the second end of the second resistor and the second output end. The overcurrent protection unit can disconnect the circuit between the power supply unit and the first output end, or disconnect the circuit between the power supply unit and the second output end in time when the power supply unit is short-circuited. The short-circuited power supply unit will not absorb the current of the first output end and the second output end, thereby ensuring that the voltage between the first output end and the second output end connected to the load is normal, thereby improving the reliability of the system.

[0032] See also Figure 4 , is a structural schematic diagram of an embodiment of a short-circuit protection system provided by the present application. The short-circuit protection system includes at least two of the above-mentioned short-circuit protection circuits connected in parallel, and each short-circuit protection circuit includes: a power supply unit, including a first voltage terminal and a second voltage terminal, for providing a working voltage; a first output terminal and a second output terminal, for connecting to a load; an overcurrent protection unit, connected to the first voltage terminal and the second voltage terminal of the power supply unit, for conducting the circuit between the power supply unit and the first output terminal and the second output terminal respectively when the power supply unit is working normally, or disconnecting the circuit between the power supply unit and the first output terminal, or disconnecting the circuit between the power supply unit and the second output terminal when the power supply unit is short-circuited; the overcurrent protection unit includes a first controllable switch, a second controllable switch, a first resistor, and a second resistor, the control terminal of the first controllable switch is connected to the second end of the first resistor, the first end of the second controllable switch and the second voltage terminal, the first end of the first controllable switch is connected to the control terminal of the second controllable switch and the first end of the second resistor, the second end of the first controllable switch is connected to the first end of the first resistor, the first voltage terminal and the first output terminal, and the second end of the second controllable switch is connected to the second end of the second resistor and the second output terminal.

[0033] In this embodiment, the short-circuit protection system includes a first short-circuit protection circuit, a second short-circuit protection circuit, and an Nth short-circuit protection circuit connected in parallel, and the N short-circuit protection circuits include redundant multi-configuration short-circuit protection circuits, for example, the Nth short-circuit protection circuit is a redundant multi-configuration short-circuit protection circuit, when a power supply unit of a short-circuit protection circuit in the other N-1 short-circuit protection circuits is short-circuited, assuming that the power supply unit of the second short-circuit protection circuit is short-circuited, then the first controllable switch and the second controllable switch in the overcurrent protection unit of the second short-circuit protection circuit are disconnected or the fuse is disconnected, so that the second short-circuit protection circuit will not output a voltage signal to the load, and the second short-circuit protection circuit will not pull down the voltage across the load, thereby ensuring the normal operation of the load. The overcurrent protection unit in each short-circuit protection circuit is the overcurrent protection unit in any of the above-mentioned embodiments.

[0034] In a specific embodiment, the short circuit protection system includes a first short circuit protection circuit to a fifth short circuit protection circuit connected in parallel, wherein the fifth short circuit protection circuit is a redundant multi-configuration short circuit protection circuit, and the system output bus + and the system output bus - are used to connect the two ends of the load. When the power supply units are all working normally, the load is provided with a working voltage through the first short circuit protection circuit to the fourth short circuit protection circuit; when a power supply unit of the first short circuit protection circuit to the fourth short circuit protection circuit is short-circuited, such as when the power supply unit of the fourth short circuit protection circuit is short-circuited, at this time, the first controllable switch and the second controllable switch of the overcurrent protection unit in the fourth short circuit protection circuit are disconnected, or the fuse is blown to disconnect the circuit between the power supply unit of the fourth short circuit protection circuit and the load, that is, at this time, the fourth short circuit protection circuit will not output voltage to the load, and at the same time, the fourth short circuit protection circuit will not pull down the voltage at both ends of the load, and the multi-configuration fifth short circuit protection circuit will output voltage to the load, that is, at this time, the load is provided with a working voltage through the first, second, third and fifth short circuit protection circuits. The voltage of the load will not be collapsed due to the short circuit of the fourth short-circuit protection circuit, thereby ensuring the normal operation of the load and improving the reliability of the system.

[0035] The beneficial effect of the present application is as follows: Different from the prior art, the overcurrent protection unit in the short-circuit protection circuit of the present application includes a first controllable switch, a second controllable switch, a first resistor, and a second resistor, the control end of the first controllable switch is connected to the second end of the first resistor, the first end of the second controllable switch and the second voltage end, the first end of the first controllable switch is connected to the control end of the second controllable switch and the first end of the second resistor, the second end of the first controllable switch is connected to the first end of the first resistor, the first voltage end and the first output end, and the second end of the second controllable switch is connected to the second end of the second resistor and the second output end. The overcurrent protection unit can disconnect the circuit between the power supply unit and the first output end, or disconnect the circuit between the power supply unit and the second output end in time when the power supply unit is short-circuited, and the short-circuited power supply unit will not absorb the current of the first output end and the second output end, thereby ensuring that the voltage between the first output end and the second output end connected to the load is normal, thereby improving the reliability of the system.

[0036] The above description is only an implementation method of the present application, and does not limit the patent protection scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A short circuit protection circuit, It is characterized in that The short circuit protection circuit comprises: A power supply unit, comprising a first voltage terminal and a second voltage terminal, for providing an operating voltage; The power supply unit further includes a current source, a transformer, a first diode and a second diode, the transformer includes a primary coil and a secondary coil, the primary coil of the transformer is connected to the current source, the secondary coil of the transformer includes a first secondary coil and a second secondary coil, an anode of the first diode is connected to an opposite-name end of the first secondary coil, a cathode of the first diode is connected to a cathode of the second diode and is connected to the first voltage end, an anode of the second diode is connected to a same-name end of the second secondary coil, and the second voltage end is connected to the same-name end of the first secondary coil and an opposite-name end of the second secondary coil; The first output terminal and the second output terminal are used to connect to a load; an overcurrent protection unit, connected to the first voltage terminal and the second voltage terminal of the power supply unit, and used to conduct the circuit between the power supply unit and the first output terminal and the second output terminal respectively when the power supply unit is working normally, or disconnect the circuit between the power supply unit and the first output terminal, or disconnect the circuit between the power supply unit and the second output terminal when the power supply unit is short-circuited; The overcurrent protection unit includes a first controllable switch, a second controllable switch, a first resistor, and a second resistor, wherein the control end of the first controllable switch is connected to the second end of the first resistor, the first end of the second controllable switch, and the second voltage end, the first end of the first controllable switch is connected to the control end of the second controllable switch and the first end of the second resistor, the second end of the first controllable switch is connected to the first end of the first resistor, the first voltage end, and the first output end, and the second end of the second controllable switch is connected to the second end of the second resistor and the second output end; The first controllable switch is a P-channel field effect transistor, and the control end, the first end and the second end of the first controllable switch correspond to the gate, the drain and the source of the P-channel field effect transistor respectively; the second controllable switch is an N-channel field effect transistor, and the control end, the first end and the second end of the second controllable switch correspond to the gate, the drain and the source of the N-channel field effect transistor respectively.

2. The short circuit protection circuit according to claim 1, It is characterized in that The overcurrent protection unit further includes a fuse, a first end of the fuse is connected to the second end of the second resistor and the second end of the second controllable switch, and a second end of the fuse is connected to the second output end.

3. The short circuit protection circuit according to claim 2, It is characterized in that The overcurrent protection unit also includes a third resistor and a fourth resistor, wherein a first end of the third resistor is connected to the first end of the first controllable switch, a second end of the third resistor is connected to the first end of the second resistor and the control end of the second controllable switch, a first end of the fourth resistor is connected to the second end of the first resistor and the control end of the first controllable switch, and a second end of the fourth resistor is connected to the first end of the second controllable switch and the second voltage end.

4. The short circuit protection circuit according to claim 3, It is characterized in that The overcurrent protection unit further includes a fifth resistor, a first end of the fifth resistor is connected to the second end of the fourth resistor, and a second end of the fifth resistor is connected to the first end of the second controllable switch and the second voltage end.

5. The short circuit protection circuit according to claim 3 or 4, It is characterized in that The overcurrent protection unit also includes a first filter capacitor, a first end of the first filter capacitor is connected to the first end of the first resistor and the first voltage end of the power supply unit, and a second end of the first filter capacitor is connected to the first end of the second controllable switch and the second voltage end of the power supply unit.

6. The short circuit protection circuit according to claim 5, It is characterized in that The overcurrent protection unit also includes a second filter capacitor, a first end of the second filter capacitor is connected to the second end of the fuse and the second output end, and a second end of the second filter capacitor is connected to the second end of the first controllable switch and the first output end.

7. The short circuit protection circuit according to claim 6, It is characterized in that The first filter capacitor is an electrolytic capacitor, and the second filter capacitor is a ceramic capacitor.

8. A short circuit protection system, It is characterized in that The short-circuit protection system comprises at least two short-circuit protection circuits connected in parallel, each of the short-circuit protection circuits comprising: A power supply unit, comprising a first voltage terminal and a second voltage terminal, for providing an operating voltage; The power supply unit further includes a current source, a transformer, a first diode and a second diode, the transformer includes a primary coil and a secondary coil, the primary coil of the transformer is connected to the current source, the secondary coil of the transformer includes a first secondary coil and a second secondary coil, an anode of the first diode is connected to an opposite-name end of the first secondary coil, a cathode of the first diode is connected to a cathode of the second diode and is connected to the first voltage end, an anode of the second diode is connected to a same-name end of the second secondary coil, and the second voltage end is connected to the same-name end of the first secondary coil and an opposite-name end of the second secondary coil; The first output terminal and the second output terminal are used to connect to a load; an overcurrent protection unit, connected to the first voltage terminal and the second voltage terminal of the power supply unit, and used to conduct the circuit between the power supply unit and the first output terminal and the second output terminal respectively when the power supply unit is working normally, or disconnect the circuit between the power supply unit and the first output terminal, or disconnect the circuit between the power supply unit and the second output terminal when the power supply unit is short-circuited; The overcurrent protection unit includes a first controllable switch, a second controllable switch, a first resistor, and a second resistor, wherein the control end of the first controllable switch is connected to the second end of the first resistor, the first end of the second controllable switch, and the second voltage end, the first end of the first controllable switch is connected to the control end of the second controllable switch and the first end of the second resistor, the second end of the first controllable switch is connected to the first end of the first resistor, the first voltage end, and the first output end, and the second end of the second controllable switch is connected to the second end of the second resistor and the second output end; The first controllable switch is a P-channel field effect transistor, and the control end, the first end and the second end of the first controllable switch correspond to the gate, the drain and the source of the P-channel field effect transistor respectively; the second controllable switch is an N-channel field effect transistor, and the control end, the first end and the second end of the second controllable switch correspond to the gate, the drain and the source of the N-channel field effect transistor respectively.

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