Short circuit protection circuit and device for an auxiliary power supply

Abstract

The application discloses a short-circuit protection circuit of an auxiliary power supply, which comprises a voltage detection module, a control receiving end, a voltage feedback end and a short-circuit protection module. The voltage detection module is used for detecting voltage variation of a primary side of a transformer. The control receiving end is used for receiving a control signal of an inverter chip. The voltage feedback end is used for outputting a feedback voltage to the inverter chip according to high / low level output by the control receiving end. When the feedback voltage exceeds a set threshold value, the inverter chip outputs the control signal to stop the auxiliary power supply from working. The input end of the short-circuit protection module is electrically connected with the voltage detection module, and the output end is electrically connected between the control receiving end and the voltage feedback end, and is used for turning on / off the electrical connection between the control receiving end and the voltage feedback end according to voltage variation output by the voltage detection module. The design can effectively avoid circuit burning caused by short circuit of the auxiliary power supply.

Description

Technical Field

[0001] This application relates to the technical field of photovoltaic inverters, and more particularly to a short-circuit protection circuit for an auxiliary power supply and an inverter. Background Technology

[0002] The auxiliary power supply circuit in the inverter provides the necessary electrically isolated, multi-channel regulated DC power supply for the core control and drive system. Its core functions include: efficiently converting the high-voltage DC bus voltage (or input source) into low-voltage power for control circuits such as sensing and protection logic; simultaneously generating mutually isolated drive power supplies to ensure that the gate drive signals of power devices are synchronized with the high-potential floating nodes of the main circuit, meeting the floating potential requirements of the upper transistor drive in half / full-bridge topologies. This circuit has cold-start capability, enabling it to establish the initial operating voltage of the system when the main converter is not operating, and maintaining monitoring and communication functions in standby or fault states. It is a key supporting unit for ensuring the reliable operation of the inverter.

[0003] In designs with a wide range of auxiliary power supply input voltage, the large fluctuations in the input voltage make it difficult to determine the short-circuit protection point. When the values ​​of the current sensing resistor and RC filter are set to their limits, large and small fluctuations may occur. Without short-circuit protection, a short circuit at the auxiliary power supply output could lead to overheating and damage to electronic components, potentially causing a fire and endangering personal safety and property.

[0004] Therefore, those skilled in the art urgently need to address the aforementioned issues. Utility Model Content

[0005] To address the technical deficiencies mentioned in the background section, this application provides a short-circuit protection circuit for an auxiliary power supply, which can effectively prevent circuit burnout due to a short circuit in the auxiliary power supply.

[0006] The present invention adopts the following technical solution: Firstly, a short-circuit protection circuit for an auxiliary power supply includes: A voltage detection module, the input terminal of which is electrically connected to the primary side of the transformer, is used to detect voltage changes on the primary side of the transformer; A control receiver, which is electrically connected to the inverter chip, is used to receive control signals from the inverter chip. The voltage feedback terminal has its input terminal electrically connected to the control receiver and its output terminal electrically connected to the control chip. It is used to output a feedback voltage to the inverter chip according to the high / low level output by the control receiver. When the feedback voltage exceeds a set threshold, the inverter chip outputs a control signal to stop the auxiliary power supply from working. A short-circuit protection module is provided, wherein the input terminal of the short-circuit protection module is electrically connected to the voltage detection module, and the output terminal is electrically connected between the control receiving terminal and the voltage feedback terminal, and is used to connect / disconnect the electrical connection between the control receiving terminal and the voltage feedback terminal according to the voltage change output by the voltage detection module.

[0007] Optionally, the short-circuit protection module includes: The first voltage divider unit has a first terminal electrically connected to the voltage detection module and a second terminal grounded. A switching unit, wherein the control terminal of the switching unit is electrically connected to the second terminal of the voltage divider unit, and is used to control the on / off connection between the control receiving terminal and the voltage feedback terminal according to the voltage output by the voltage divider unit; The second voltage divider unit has its first end electrically connected between the control receiving end and the voltage feedback end, and its second end grounded.

[0008] Optionally, the switching unit includes: The first NPN transistor has its base electrically connected to the first voltage divider unit, and its collector connected between the control receiving terminal and the voltage feedback terminal. The first PNP transistor has its base electrically connected to the collector of the first NPN transistor, the collector electrically connected to the control receiving terminal, and the emitter electrically connected to the voltage feedback terminal. The second NPN transistor has its base electrically connected to the second terminal of the second voltage divider unit, its collector connected between the base of the first PNP transistor and the collector of the first NPN transistor, and its emitter grounded.

[0009] Optionally, the first voltage divider unit includes: A first resistor, the first end of which is electrically connected to the output terminal of the voltage detection module, and the second end of which is grounded; The second resistor has its first end electrically connected to the second end of the first resistor, and its second end grounded.

[0010] Optionally, the second voltage divider unit includes: The third resistor has its first end electrically connected between the first PNP transistor and the voltage feedback terminal, and its second end grounded. The fourth resistor has its first end electrically connected to the second end of the third resistor, and its second end is grounded.

[0011] Optionally, the short-circuit protection circuit further includes: A first current-limiting resistor is electrically connected between the control receiving terminal and the collector of the first PNP transistor. The second current-limiting resistor is electrically connected between the collector of the first NPN transistor and the base of the first PNP transistor.

[0012] Optionally, a fifth resistor is electrically connected between the first current-limiting resistor and the second current-limiting resistor.

[0013] Optionally, the short-circuit protection circuit further includes: A first capacitor, wherein a first terminal of the first capacitor is electrically connected to a second terminal of the first resistor, and the second terminal of the first capacitor is grounded; The second capacitor has its first terminal electrically connected to the second terminal of the first current-limiting resistor, and its second terminal grounded. The third capacitor has its first terminal connected between the third resistor and the fourth resistor, and its second terminal grounded.

[0014] Optionally, the voltage detection module includes several current-sensing resistors connected in parallel. The first end of each current-sensing resistor is electrically connected to the primary side of the transformer, and the other end is grounded.

[0015] Secondly, a short-circuit protection device for an auxiliary power supply includes the short-circuit protection circuit for the auxiliary power supply as described above; The short-circuit protection circuit of the auxiliary power supply is etched onto the circuit board.

[0016] In summary, the beneficial effects of this utility model are as follows: The auxiliary power supply voltage is detected by a voltage detection module and then sent to the short-circuit protection module. The short-circuit protection module determines whether the voltage exceeds its set threshold, thereby enabling conduction between its control receiver and voltage feedback terminal. At this time, the voltage at the voltage feedback terminal will increase. When the feedback voltage exceeds the set threshold, the inverter chip outputs a control signal to stop the auxiliary power supply from working, thus protecting the auxiliary power supply from short circuits, preventing the entire circuit from burning out, and providing safety. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1This is a schematic diagram of the architecture of an embodiment of the present utility model; Figure 2 This is a circuit diagram of an embodiment of the present invention. Attached image description: 100. Voltage detection module; 200. Control the receiving end; 300, Voltage feedback terminal; 400. Short-circuit protection module; 410. First voltage divider unit; 420. Switching unit; 430. Second voltage divider unit; Q1, First NPN transistor; Q2, First PNP transistor; Q3, Second NPN transistor; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, first current-limiting resistor; R6, second current-limiting resistor; R7, fifth resistor; R8, current-sensing resistor; C1, the first capacitor; C2, the second capacitor; C3, the third capacitor. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] like Figure 1 As shown, this application embodiment provides a short-circuit protection circuit for an auxiliary power supply, including a voltage detection module 100, a control receiving terminal 200, a voltage feedback terminal 300, and a short-circuit protection module 400. The input terminal of the voltage detection module 100 is electrically connected to the primary side of the transformer and is used to detect voltage changes on the primary side of the transformer. The control receiver 200 is electrically connected to the inverter chip and is used to receive control signals from the inverter chip. The input terminal of the voltage feedback terminal 300 is electrically connected to the control receiver 200, and the output terminal is electrically connected to the control chip. It is used to output a feedback voltage to the inverter chip according to the high / low level output by the control receiver 200. When the feedback voltage exceeds a set threshold, the inverter chip outputs a control signal to stop the auxiliary power supply from working. The input terminal of the short-circuit protection module 400 is electrically connected to the voltage detection module 100, and the output terminal is electrically connected between the control receiver 200 and the voltage feedback terminal 300. It is used to connect / disconnect the electrical connection between the control receiver 200 and the voltage feedback terminal 300 according to the voltage change output by the voltage detection module 100.

[0022] In this embodiment, the voltage detection module 100 is directly connected to the primary side of the transformer, monitoring the dynamic changes of the primary side voltage in real time and providing a basic voltage signal for short-circuit detection; the control receiver 200 serves as the signal output interface of the inverter chip, ensuring the real-time transmission of control signals; the voltage feedback terminal 300 receives the PWM duty cycle signal from the control receiver 200, causing the voltage at the voltage feedback terminal 300 to rise and output the feedback voltage to the inverter chip. When the feedback voltage exceeds a preset threshold, a protection mechanism is triggered, forcing the inverter chip to stop the auxiliary power supply, thereby avoiding the risk of overheating caused by continuous short circuits; the short-circuit protection module... Block 400 dynamically adjusts the connection state between the control receiver 200 and the voltage feedback terminal 300 based on the output signal of the voltage detection module 100. When the control receiver 200 and the voltage feedback terminal 300 are conducting, the voltage feedback terminal 300 will output a high voltage. When the high voltage exceeds a certain threshold, the inverter chip will limit the output of the PWM duty cycle. When the voltage feedback terminal 300 increases to the point that the PWM duty cycle decreases to 0, the entire auxiliary power supply will stop working. When an abnormal voltage is detected, the signal path is quickly cut off, forming a closed-loop protection circuit, thereby preventing the auxiliary power supply from continuing to work and avoiding burning out the entire circuit. When the inverter chip stops working, the control receiver 200 will remain at a low level, essentially setting it to 0. With the inverter chip and auxiliary power supply both ceasing operation, the voltage detection module 100 will also be at a low level, resulting in zero current flowing through it. At this point, the short-circuit protection circuit will not activate. When the inverter chip restarts, the auxiliary power supply resumes operation. However, due to the persistent output short circuit, the increased current flowing through the voltage detection module 100 causes its voltage to rise. When the voltage of the voltage detection module 100 reaches 1V, the short-circuit protection circuit will activate again, ensuring the auxiliary power supply stops working promptly in the event of a short circuit, preventing circuit burnout.

[0023] Instead of relying on the traditional method of detecting voltage changes at the feedback pin to determine the short circuit status of the auxiliary power supply for protection, a short circuit protection module 400 is used to raise the voltage at the voltage feedback terminal 300 to regulate the duty cycle of the PWM wave, making short circuit detection more accurate and the response faster.

[0024] Optional, such as Figure 2As shown, the short-circuit protection module 400 includes a first voltage divider unit 410, a switching unit 420, and a second voltage divider unit 430. The first end of the voltage divider unit is electrically connected to the voltage detection module 100, and the second end is grounded. The control terminal of the switching unit 420 is electrically connected to the second end of the voltage divider unit, and is used to control the connection / disconnection between the control receiving terminal 200 and the voltage feedback terminal 300 according to the voltage output by the voltage divider unit. The first end of the second voltage divider unit 430 is electrically connected between the control receiving terminal 200 and the voltage feedback terminal 300, and the second end is grounded.

[0025] In this embodiment, the first voltage divider unit 410 divides the primary-side voltage signal output by the voltage detection module 100, converting the high-voltage signal into a reference voltage suitable for the operation of the switching unit 420. This solves the problem of false triggering that may occur if the high-voltage signal directly drives the switching device. The switching unit 420 controls the main signal path based on the divided reference voltage. When the switching unit 420 is turned on, the control receiver 200 and the voltage feedback terminal 300 are turned on. Since the control receiver 200 receives the signal from the inverter chip, the voltage at the voltage feedback terminal 300 will rise. When it exceeds a certain threshold, the inverter chip receives the voltage from the voltage feedback terminal 300. The inverter chip then controls the output PWM duty cycle signal, causing the entire auxiliary power supply to stop working. Thus, the inverter chip cannot operate, and the entire auxiliary power supply can be shut down.

[0026] Optional, such as Figure 2 As shown, the switching unit 420 includes a first NPN transistor Q1, a first PNP transistor Q2, and a second NPN transistor Q3. The base of the first NPN transistor Q1 is electrically connected to the first voltage divider unit 410, and its collector is connected between the control receiving terminal 200 and the voltage feedback terminal 300. The base of the first PNP transistor Q2 is electrically connected to the collector of the first NPN transistor Q1, and its collector is electrically connected to the control receiving terminal 200. Its emitter is electrically connected to the voltage feedback terminal 300. The base of the second NPN transistor Q3 is electrically connected to the second terminal of the second voltage divider unit 430, and its collector is connected between the base of the first PNP transistor Q2 and the collector of the first NPN transistor Q1. The emitter is grounded.

[0027] In this embodiment, the first NPN transistor Q1 controls its collector potential based on the voltage change output by the first voltage divider unit 410. When the detected voltage exceeds a set value (>0.7V), it conducts, causing the base potential of the first PNP transistor Q2 to decrease and conduct, forming a direct connection between the control receiver 200 and the voltage feedback terminal 300. Simultaneously, the second NPN transistor Q3 performs a secondary judgment based on the voltage division result of the second voltage divider unit 430. When its base voltage reaches the conduction threshold (<-0.7V), it pulls the base potential of the first PNP transistor Q2 down to ground potential, forcibly cutting off the control signal transmission path. Through two-stage voltage division detection and three-stage switch linkage, a rapid response to changes in the primary side voltage is achieved. The negative feedback mechanism introduced by the second NPN transistor Q3 avoids false triggering that may occur with a single detection path. The conduction voltage threshold of the second NPN transistor Q3 is >0.7V, ensuring accurate triggering of protection actions only under actual short-circuit conditions.

[0028] Optional, such as Figure 2 As shown, the first voltage divider unit 410 includes a first resistor R1 and a second resistor R2. The first end of the first resistor R1 is electrically connected to the output end of the voltage detection module 100, and the second end of the first resistor R1 is grounded. The first end of the second resistor R2 is electrically connected to the second end of the first resistor R1, and the second end of the second resistor R2 is grounded.

[0029] In the embodiments of this application, the first resistor R1 is directly connected between the output terminal of the voltage detection module 100 and ground, forming a primary voltage divider network that converts the high-voltage signal into a processable low-voltage signal. The second resistor R2 is connected in series with the second terminal of the first resistor R1 and then grounded, forming a secondary voltage divider network. Through the superposition effect of the two-stage voltage dividers, the linear voltage divider characteristics can still be maintained even when the input voltage fluctuates over a wide range. The dual voltage divider structure, through precise matching of resistor values, can effectively suppress the impact of input voltage fluctuations on detection accuracy, ensuring that the voltage change signal output by the voltage detection module 100 maintains a strict proportional relationship with the actual voltage on the primary side of the transformer, thereby providing a stable and reliable detection reference for the subsequent short-circuit protection module 400.

[0030] Optional, such as Figure 2 As shown, the second voltage divider unit 430 includes a third resistor R3 and a fourth resistor R4. The first end of the third resistor R3 is electrically connected between the first PNP transistor Q2 and the voltage feedback terminal 300, and the second end of the third resistor R3 is grounded. The first end of the fourth resistor R4 is electrically connected to the second end of the third resistor R3, and the second end of the fourth resistor R4 is grounded.

[0031] In this embodiment, the second voltage divider unit 430 forms a voltage divider network through a series-grounded structure of a third resistor R3 and a fourth resistor R4 to adjust the threshold voltage of the feedback voltage. The first end of the third resistor R3 is connected between the first PNP transistor Q2 and the voltage feedback terminal 300, allowing the voltage divider network to directly act on the feedback loop. By adjusting the resistance ratio of the third resistor R3 and the fourth resistor R4, the feedback voltage is divided to the ground terminal, thereby precisely setting the threshold voltage for triggering short-circuit protection. The first end of the fourth resistor R4 is connected to the second end of the third resistor R3, further refining the voltage division ratio and ensuring that the divided feedback voltage can be stably compared with the preset threshold voltage when the input voltage fluctuates. This voltage divider structure, through the series-grounded connection of two resistors, achieves adjustable voltage threshold voltage, avoiding the problems of insufficient sensitivity or poor anti-interference capability caused by single-resistor voltage division. Therefore, even with a large input voltage range, it can accurately determine the short-circuit state and trigger protection action.

[0032] Optional, such as Figure 2 As shown, the short-circuit protection circuit also includes a first current-limiting resistor R5 and a second current-limiting resistor R6. The first current-limiting resistor R5 is electrically connected between the control receiving terminal 200 and the collector of the first PNP transistor Q2; the second current-limiting resistor R6 is electrically connected between the collector of the first NPN transistor Q1 and the base of the first PNP transistor Q2.

[0033] In the embodiments of this application, a first current-limiting resistor R5 and a second current-limiting resistor R6 are used to provide dual current-limiting protection for the current path between the control receiver 200 and the switching unit 420. The first current-limiting resistor R5 is directly connected in series between the control receiver 200 and the collector of the first PNP transistor Q2, which can effectively limit the peak current of the control signal transmission path and prevent the surge current generated during a short circuit from impacting the inverter chip. The second current-limiting resistor R6 is connected between the collector of the first NPN transistor Q1 and the base of the first PNP transistor Q2. By limiting the base drive current, it precisely controls the conduction speed of the PNP transistor, ensuring the fast response capability of the switching unit 420 and avoiding heat loss of the transistor due to overdrive current. The synergistic effect of the two current-limiting resistors realizes stable transmission of high and low level signals. The energy distribution during short-circuit protection triggering is optimized through a graded current-limiting mechanism, ensuring that the control loop can be reliably cut off when an abnormal voltage is detected.

[0034] Optional, such as Figure 2 As shown, a fifth resistor R7 is also electrically connected between the first current-limiting resistor R5 and the second current-limiting resistor R6.

[0035] In this embodiment, a composite current-limiting network is formed by adding a fifth resistor R7 between the two current-limiting resistors. The introduction of this fifth resistor R7 alters the current distribution relationship between the original first current-limiting resistor R5 and the second current-limiting resistor R6. By adjusting the equivalent resistance value of the resistor network, the shunt ratio of the base drive current of the switching unit 420 can be precisely controlled. When the voltage detection module 100 detects an abnormal voltage, the synergistic effect of the fifth resistor R7 and the current-limiting resistors optimizes the conduction threshold of the switching transistor, ensuring accurate triggering of protection actions even during primary-side voltage fluctuations. This enhances the circuit's adaptability to input voltage fluctuations, and the matching design of the resistor values ​​effectively suppresses large and small wave phenomena, avoiding protection delays or false triggering caused by inaccurate current path control.

[0036] Optional, such as Figure 2 As shown, the short-circuit protection circuit further includes a first capacitor C1, a second capacitor C2, and a third capacitor C3. The first terminal of the first capacitor C1 is electrically connected to the second terminal of the first resistor R1, and the second terminal of the first capacitor C1 is grounded. The first terminal of the second capacitor C2 is electrically connected to the second terminal of the first current-limiting resistor R5, and the second terminal of the second capacitor C2 is grounded. The first terminal of the third capacitor C3 is connected between the third resistor R3 and the fourth resistor R4, and the second terminal of the third capacitor C3 is grounded.

[0037] In this embodiment, the first capacitor C1 is connected between the second terminal of the first voltage divider unit 410 and ground to filter out voltage fluctuations at the output of the voltage detection module 100, preventing false triggering caused by changes in the primary side voltage. The second capacitor C2 is connected in parallel between the output of the first current-limiting resistor R5 and ground to suppress high-frequency noise in the signal path between the control receiver 200 and the voltage feedback terminal 300, ensuring the purity of the control signal. The third capacitor C3 is connected across the two resistors of the second voltage divider unit 430 to further stabilize the voltage division ratio of the feedback voltage, preventing misjudgment by the inverter chip due to transient voltage changes at the voltage division point. The three sets of capacitors suppress interference in the detection, control, and feedback stages, respectively, solving the problem of protection threshold drift caused by the expansion of the input voltage range, and ensuring the accuracy and timeliness of short-circuit protection action. Optional, such as Figure 2 As shown, the voltage detection module 100 includes several current-sensing resistors R8 connected in parallel. The first end of the current-sensing resistor R8 is electrically connected to the primary side of the transformer, and the other end is grounded.

[0038] In this embodiment, a distributed current sensing network is formed on the primary side of the transformer by connecting multiple current sensing resistors R8 in parallel. The parallel structure allows each current sensing resistor R8 to share the current sensing task, effectively reducing the power loss of a single resistor. Simultaneously, precise control of the total parallel resistance enables more sensitive capture of minute changes in the primary side voltage. One end of the current sensing resistor group R8 is directly connected to the primary side of the transformer, while the other end is grounded to form a closed loop. This topology ensures the integrity of the voltage sampling signal and improves the redundancy of the detection system through multi-point parallel connection. When any current sensing resistor R8 experiences an open-circuit fault, the remaining parallel resistors can still maintain their sensing function, ensuring the reliability of short-circuit protection triggering. This design is specifically designed for operating conditions with large-range input voltage fluctuations, optimizing the robustness of the current sensing circuit to provide a stable and accurate voltage change signal reference for subsequent protection circuits.

[0039] A second aspect of this application discloses a short-circuit protection device for an auxiliary power supply. This device includes a short-circuit protection circuit for the auxiliary power supply as described above, and a circuit board, with the short-circuit protection circuit etched onto the circuit board. By providing the aforementioned short-circuit protection device, a signal can be promptly sent to the inverter chip when a short circuit occurs in the auxiliary power supply, thereby stopping the operation of the auxiliary power supply and preventing short-circuit burnout in the embodiments of this application.

[0040] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this application 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. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0041] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A short-circuit protection circuit for an auxiliary power supply, characterized in that, include: A voltage detection module (100) is provided, the input terminal of which is electrically connected to the primary side of the transformer and is used to detect voltage changes on the primary side of the transformer. A control receiver (200) is electrically connected to the inverter chip and is used to receive control signals from the inverter chip. A voltage feedback terminal (300) is provided, with its input terminal electrically connected to a control receiver terminal (200) and its output terminal electrically connected to a control chip. The voltage feedback terminal (300) is used to output a feedback voltage to the inverter chip based on the high / low level output by the control receiver terminal (200). When the feedback voltage exceeds a set threshold, the inverter chip outputs a control signal to stop the auxiliary power supply from working. A short-circuit protection module (400) is provided, with its input terminal electrically connected to the voltage detection module (100) and its output terminal electrically connected between the control receiver (200) and the voltage feedback terminal (300). The short-circuit protection module (400) is used to connect / disconnect the electrical connection between the control receiver (200) and the voltage feedback terminal (300) based on the voltage change output by the voltage detection module (100).

2. The short-circuit protection circuit for an auxiliary power supply as described in claim 1, characterized in that, The short-circuit protection module (400) includes: The first voltage divider unit (410) has its first end electrically connected to the voltage detection module (100) and its second end grounded. A switching unit (420) is provided, wherein the control terminal of the switching unit (420) is electrically connected to the second terminal of the voltage divider unit, and is used to control the on / off connection between the control receiving terminal (200) and the voltage feedback terminal (300) according to the voltage output by the voltage divider unit; The second voltage divider unit (430) has its first end electrically connected between the control receiving end (200) and the voltage feedback end (300), and its second end grounded.

3. The short-circuit protection circuit for an auxiliary power supply as described in claim 2, characterized in that, The switching unit (420) includes: The base of the first NPN transistor (Q1) is electrically connected to the first voltage divider unit (410), and the collector is connected between the control receiving terminal (200) and the voltage feedback terminal (300). The first PNP transistor (Q2) has its base electrically connected to the collector of the first NPN transistor (Q1), the collector electrically connected to the control receiving terminal (200), and the emitter electrically connected to the voltage feedback terminal (300). The base of the second NPN transistor (Q3) is electrically connected to the second terminal of the second voltage divider unit (430), and the collector is connected between the base of the first PNP transistor (Q2) and the collector of the first NPN transistor (Q1). The emitter is grounded.

4. The short-circuit protection circuit for an auxiliary power supply as described in claim 3, characterized in that, The first voltage divider unit (410) includes: The first resistor (R1) has its first end electrically connected to the output terminal of the voltage detection module (100), and its second end grounded. The second resistor (R2) has its first end electrically connected to the second end of the first resistor (R1), and its second end is grounded.

5. The short-circuit protection circuit for an auxiliary power supply as described in claim 4, characterized in that, The second voltage divider unit (430) includes: The third resistor (R3) has its first end electrically connected between the first PNP transistor (Q2) and the voltage feedback terminal (300), and its second end grounded. The fourth resistor (R4) has its first end electrically connected to the second end of the third resistor (R3), and its second end is grounded.

6. The short-circuit protection circuit for an auxiliary power supply as described in claim 5, characterized in that, The short-circuit protection circuit also includes: The first current-limiting resistor (R5) is electrically connected between the control receiver (200) and the collector of the first PNP transistor (Q2); The second current-limiting resistor (R6) is electrically connected between the collector of the first NPN transistor (Q1) and the base of the first PNP transistor (Q2).

7. The short-circuit protection circuit for an auxiliary power supply as described in claim 6, characterized in that, A fifth resistor (R7) is also electrically connected between the first current-limiting resistor (R5) and the second current-limiting resistor (R6).

8. The short-circuit protection circuit for an auxiliary power supply as described in claim 6, characterized in that, The short-circuit protection circuit also includes: The first capacitor (C1) has its first terminal electrically connected to the second terminal of the first resistor (R1), and its second terminal is grounded. The second capacitor (C2) has its first terminal electrically connected to the second terminal of the first current-limiting resistor (R5), and its second terminal grounded. The third capacitor (C3) has its first terminal connected between the third resistor (R3) and the fourth resistor (R4), and its second terminal grounded.

9. The short-circuit protection circuit for an auxiliary power supply as described in claim 1, characterized in that, The voltage detection module (100) includes several current-sensing resistors (R8) connected in parallel. The first end of the current-sensing resistor (R8) is electrically connected to the primary side of the transformer, and the other end is grounded.

10. A short-circuit protection device for an auxiliary power supply, characterized in that, Includes a short-circuit protection circuit for the auxiliary power supply as described in any one of claims 1-9; The short-circuit protection circuit of the auxiliary power supply is etched onto the circuit board.

Images