Output overvoltage protection self-locking circuit and switching power supply

Abstract

The invention discloses an output overvoltage protection self-locking circuit and a switching power supply. The circuit comprises a first switching module, a second switching module, a first control self-locking module and a second control self-locking module, the first control self-locking module is used for determining that the output voltage exceeds the reference voltage, controlling the first switch module to cut off the power supply input, and self-locking and maintaining the cut-off state of the first switch module to the power supply input; and the second control self-locking module is used for determining that the output voltage exceeds the reference voltage, controlling the second switch module to cut off the output loop, and self-locking and maintaining the cut-off state of the second switch module to the output loop. According to the invention, two completely independent overvoltage protection loops are adopted to form a heterogeneous redundancy design, so that the reliability is greatly improved; in addition, self-locking after overvoltage protection can be achieved, the protection function can be released only when input power supply is restarted, and it is ensured that the system can be in a safe state continuously and stably.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of power supply, and particularly relates to an output overvoltage protection self-locking circuit and a switching power supply. BACKGROUND

[0002] As a core power supply component of modern electronic devices, the reliability of the output overvoltage protection function of the switching power supply is directly related to the safe operation of the rear-end load and the entire system. At present, the overvoltage protection scheme commonly used in the industry mainly relies on an optocoupler device to monitor the output voltage in real time and transmit the feedback signal to the primary side of the main control IC to realize the protection function by adjusting or shutting down the energy transmission. Although this scheme has a simple structure and low cost, it has the following significant defects in actual application: Firstly, the execution of the protection function is deeply coupled with the control loop of the main control IC. When the system requires that the protection mechanism must be completely electrically isolated from the drive control, the existing architecture is difficult to meet the design requirements, especially in high-voltage, high-power or safety level applications with strict requirements. This non-completely isolated design has safety hazards. Secondly, the traditional scheme uses a single protection path and lacks redundancy design. Once the optocoupler device fails or the main control IC malfunctions, the overvoltage protection function will be completely lost, and the system reliability cannot be guaranteed. Thirdly, the existing technology cannot realize independent control of the protection function, and its action logic depends on the normal operation of the main control IC. In the extreme case of IC abnormality or program runaway, the protection mechanism may fail. Finally, the traditional optocoupler feedback scheme usually does not have a protection-after self-locking function. When the output overvoltage fault is not completely eliminated, the system may repeatedly restart or automatically restore the output, causing the rear-end load to be in an uncertain state for a long time, which makes it difficult to maintain continuous safety locking.

[0003] Therefore, there is an urgent need for an independent overvoltage protection scheme that can be completely isolated from the main control IC, has heterogeneous redundancy capability and can realize self-locking function, so as to improve the safety and reliability of the switching power supply system in complex application environments. SUMMARY

[0004] In order to solve the above problems, the purpose of the present application is to provide an output overvoltage protection self-locking circuit and a switching power supply which can be completely isolated from the main control IC, have heterogeneous redundancy capability and realize self-locking function.

[0005] In a first aspect, the present application provides an output overvoltage protection self-locking circuit, comprising a first switch module, a second switch module, a first control self-locking module and a second control self-locking module. The first input terminal of the first switch module is connected to the power input terminal Vin. The second input terminals of the first switch module and the second switch module are both connected to the protection circuit power supply Vcc. The first output terminal of the first switch module is connected to the first input terminal of the second switch module. The output terminal of the first control self-locking module is connected to the third input terminal of the first switch module. The output terminal of the second control self-locking module is connected to the third input terminal of the second switch module. The output terminal of the second switch module outputs the power output voltage Vo+. The first input terminals of the first control self-locking module and the second control self-locking module are both connected to the output terminal of the second switch module. The first control self-locking module is used to determine that the output voltage exceeds the reference voltage, control the first switching module to cut off the power input, and self-lock to maintain the first switching module's cut-off state of the power input; The second control self-locking module is used to determine that the output voltage exceeds the reference voltage, control the second switching module to cut off the output circuit, and self-lock to maintain the cut-off state of the output circuit by the second switching module.

[0006] Optionally, the first control self-locking module self-locks and maintains the power input cut-off state of the first switch module until the power input is restarted.

[0007] Optionally, the second control self-locking module self-locks and maintains the output circuit cut-off state of the second switching module until the input power supply is restarted.

[0008] Optionally, it also includes an output backflow prevention module, wherein the output terminal of the second switch module is connected to the input terminal of the output backflow prevention module, and the output backflow prevention module outputs a power supply output voltage Vo+.

[0009] Optionally, the first switching module includes a first relay K1, a first switching transistor Q1, a first resistor R1, and a second resistor R2. The first end of the coil of the first relay K1 is connected to the power supply Vcc of the protection circuit, and the second end of the coil of the first relay K1 is connected to the first end of the first switching transistor Q1. The contact end of the first relay K1 is connected to the positive terminal Vin+ of the power input terminal, and the normally open contact of the first relay K1 outputs the power supply output voltage Vo+. The second end of the first switching transistor Q1 and one end of the second resistor R2 are both connected to the negative terminal Vin- of the power input terminal. The control end of the first switching transistor Q1 is connected to one end of the first resistor R1, the other end of the second resistor R2, and the output end of the first switch control self-locking module, respectively. The other end of the first resistor R1 is connected to the power supply Vcc of the protection circuit.

[0010] Optionally, the second switching module includes a sixth switch Q6, a sixteenth resistor R16, and a fifteenth resistor R15. The first terminal of the sixth switch Q6 is connected to the output ground GND. The control terminal of the sixth switch Q6 is connected to one end of the sixteenth resistor R16 and one end of the fifteenth resistor R15. The second terminal of the sixth switch Q6 is connected to the other end of the sixteenth resistor R16 and the negative terminal Vin- of the power input. The other end of the fifteenth resistor R15 is connected to the protection circuit power supply Vcc.

[0011] Optionally, the first control self-locking module includes a second switch Q2, a third switch Q3, a first reference chip U1, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first capacitor C1, a second capacitor C2, and a first diode D1. The first terminal of the second switch Q2 is connected to the third input terminal of the first switch module. The second terminal of the second switch Q2 is connected to one terminal of the third resistor R3, the third terminal of the first reference chip U1, one terminal of the eighth resistor R8, one terminal of the second capacitor C2, and the negative terminal Vin- of the power input. The control terminal of the second switch Q2 is connected to the other terminal of the third resistor R3, the second terminal of the third switch Q3, and the sixth resistor R6. One end of the third switch Q3 is connected to one end of the fourth resistor R4, one end of the first capacitor C1, and connected to the protection circuit power supply Vcc. The first end of the third switch Q3 is connected to the other end of the fourth resistor R4, the other end of the first capacitor C1, and one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the second end of the first reference chip U1. The first end of the first reference chip U1 is connected to the cathode of the first diode D1, the other end of the eighth resistor R8, the other end of the second capacitor C2, one end of the seventh resistor R7, the anode of the first diode D1, and the other end of the sixth resistor R6. The other end of the seventh resistor R7 is connected to the power supply output voltage Vo+.

[0012] Optionally, the second control self-locking module includes a fourth switch Q4, a fifth switch Q5, a second reference chip U2, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a third capacitor C3, a fourth capacitor C4, and a second diode D2. The first terminal of the fifth switch Q5 is connected to one end of the fifteenth resistor R15 and one end of the sixteenth resistor R16. The second terminal of the fifth switch Q5 is connected to one end of the fourteenth resistor R14, the third terminal of the second reference chip U3, one end of the tenth resistor R10, one end of the third capacitor C3, and the negative terminal Vin- of the power input. The control terminal of the fifth switch Q5 is connected to the other end of the fourteenth resistor R14 and the second terminal of the fourth switch Q4. One end of the twelfth resistor R12 and the third end of the fourth switch Q4 are respectively connected to one end of the eleventh resistor R11, one end of the fourth capacitor C4 and the protection circuit power supply Vcc. The first end of the fourth switch Q4 is respectively connected to the other end of the eleventh resistor R11, the other end of the fourth capacitor C4 and one end of the thirteenth resistor R13. The other end of the thirteenth resistor R13 is connected to the second end of the second reference chip U2. The first end of the second reference chip U2 is respectively connected to the cathode of the second diode D2, the other end of the eighth resistor R8, the other end of the second capacitor C2 and one end of the seventh resistor R7. The anode of the first diode D2 is connected to the other end of the twelfth resistor R12. The other end of the ninth resistor R9 is connected to the power supply output voltage Vo+.

[0013] Optionally, the output anti-backflow module includes a third diode D3, the anode of the third diode D3 is connected to the output terminal of the second control self-locking module, and the cathode of the third diode D3 outputs the power supply output voltage Vo+.

[0014] Secondly, the present invention also provides a switching power supply, including the output overvoltage protection self-locking circuit described in the first aspect.

[0015] The beneficial effects of this invention are as follows: This invention establishes independent first and second control self-locking modules to control the first and second switching modules respectively. This ensures that the protection function is unaffected by the main control circuit state, guaranteeing rapid and reliable operation even in situations requiring functional isolation or where the main control IC fails. This significantly enhances the system's tolerance to local faults and overall safety. The two completely independent overvoltage protection circuits of the first and second switching modules constitute a heterogeneous redundancy protection mechanism. Both circuits achieve electrical and physical isolation in detection, control, and execution, ensuring that the failure of any single path will not lead to complete loss of protection function. This redundancy design effectively avoids the single-point-of-failure problem of traditional single protection paths, greatly enhancing the fault tolerance and reliability of the overvoltage protection function and meeting the stringent requirements of high-reliability applications. The first and second control self-locking modules enable self-locking of the state after overvoltage protection triggering. This self-locking mechanism effectively prevents cumulative equipment damage or safety accidents that may result from repeated system restarts under intermittent or incompletely resolved fault conditions, ensuring that the system remains continuously and stably in a safe state from the occurrence of a fault to manual intervention. Attached Figure Description

[0016] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments thereof.

[0017] Figure 1 This is a circuit block diagram of an output overvoltage protection self-locking circuit according to the present invention; Figure 2 This is a circuit diagram of an output overvoltage protection self-locking circuit according to the present invention.

[0018] Reference numerals: 100-First switch module, 200-First control self-locking module, 300-Second control self-locking module, 400-Second switch module, 500-Output anti-backflow module. Detailed Implementation

[0019] To make the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention. Those skilled in the art can make other modifications, substitutions, or alterations to the present invention without creative effort, and these modifications, substitutions, or alterations still fall within the protection scope of the present invention.

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe the order or sequence of specific objects. It should be understood that such data can be used interchangeably where appropriate for describing embodiments of this application herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, systems, products, or apparatus.

[0022] It should be understood that in the specification, claims, and drawings, when a step is described as continuing into another step, the step may directly continue into that other step or be continued into that other step through a third step; when an element / unit is described as "continuing" into another element / unit, the unit may be "directly connected" to that other element / unit or "connected" to that other element / unit through a third element / unit.

[0023] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions thereof will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0024] Most commercially available switching power supply products employ overvoltage protection schemes that rely on optocouplers to collect feedback signals from the output voltage and transmit these signals to the main control integrated circuit (IC). The IC then regulates or shuts down energy transfer to achieve protection. While this architecture, based on optocoupler feedback and relying on the main control IC to execute protection actions, has advantages such as simple structure and low cost in conventional applications, it also has significant limitations.

[0025] First, the protection function of this solution is highly coupled with the power transmission control of the main control IC, making complete physical and electrical isolation impossible. In applications with extremely high safety and reliability requirements (such as industrial control, medical equipment, and rail transportation), it is often necessary to design the protection function as a completely isolated system independent of the main power and control loop to prevent the protection function from failing simultaneously when the main control circuit fails, thus achieving a so-called "fail-safe" design. Existing optocoupler solutions struggle to meet this stringent isolation requirement.

[0026] Secondly, this solution typically forms a single-path protection closed loop, and its reliability depends on the normal operation of individual components such as optocouplers and main control ICs, lacking redundancy design. Once any link in this path (such as optocoupler failure, feedback loop open circuit, or main control IC failure) malfunctions, the entire overvoltage protection function is lost, and the system will be exposed to overvoltage risk, which may cause damage to the load equipment or even lead to a safety accident.

[0027] Furthermore, traditional overvoltage protection schemes often lack a self-locking function after activation, or the locking logic still relies on the main control IC. When the fault voltage disappears, the system may automatically restore power supply. However, if the root cause of the overvoltage fault is not eliminated, the system may repeatedly switch between normal and fault states, which may not only amplify the impact of the fault but also fail to guarantee that the system remains in a safe state until the fault is manually investigated.

[0028] To solve the above problems, refer to Figure 1 and Figure 2 This invention provides an output overvoltage protection self-locking circuit, including a first switch module 100, a second switch module 400, a first control self-locking module 200, and a second control self-locking module 300; The first input terminal of the first switch module 100 is connected to the power input terminal Vin. The second input terminals of the first switch module 100 and the second input terminal of the second switch module 400 are both connected to the protection circuit power supply Vcc. The first output terminal of the first switch module 100 is connected to the first input terminal of the second switch module 400. The output terminal of the first control self-locking module 200 is connected to the third input terminal of the first switch module 100. The output terminal of the second control self-locking module 300 is connected to the third input terminal of the second switch module 400. The output terminal of the second switch module 400 outputs the power output voltage Vo+. The first input terminals of the first control self-locking module 200 and the second control self-locking module 300 are both connected to the output terminal of the second switch module 400. The first control self-locking module 200 is used to determine that the output voltage exceeds the reference voltage, control the first switch module 100 to cut off the power input, and self-lock to maintain the power input cut-off state of the first switch module 100. The second control self-locking module 300 is used to determine that the output voltage exceeds the reference voltage, control the second switch module 400 to cut off the output circuit, and self-lock to maintain the cut-off state of the output circuit by the second switch module 400.

[0029] The first control self-locking module 200 self-locks and maintains the power input cut-off state of the first switch module 100 until the power input is restarted.

[0030] The second control self-locking module 300 self-locks and maintains the output circuit cut-off state of the second switch module 400 until the input power supply is restarted.

[0031] In one embodiment, an output backflow prevention module is also included, wherein the output terminal of the second switch module 400 is connected to the input terminal of the output backflow prevention module, and the output backflow prevention module outputs a power supply output voltage Vo+.

[0032] The output anti-backflow module 500 includes a third diode D3. The anode of the third diode D3 is connected to the output terminal of the second control self-locking module 300, and the cathode of the third diode D3 outputs the power supply output voltage Vo+.

[0033] In one embodiment, the first switch module 100 includes a first relay K1, a first switch Q1, a first resistor R1, and a second resistor R2. The first end of the coil of the first relay K1 is connected to the power supply Vcc of the protection circuit, and the second end of the coil of the first relay K1 is connected to the first end of the first switch Q1. The contact end of the first relay K1 is connected to the positive terminal Vin+ of the power input terminal, and the normally open contact of the first relay K1 outputs the power output voltage Vo+. The second end of the first switch Q1 and one end of the second resistor R2 are both connected to the negative terminal Vin- of the power input terminal. The control end of the first switch Q1 is connected to one end of the first resistor R1, the other end of the second resistor R2, and the output end of the first switch control self-locking module, respectively. The other end of the first resistor R1 is connected to the power supply Vcc of the protection circuit.

[0034] In this configuration, the first switch Q1 can be an NMOS transistor, in which case the first terminal of the first switch Q1 is the drain, the second terminal of the first switch Q1 is the source, and the control terminal of the first switch Q1 is the gate. The first switch Q1 can also be a switch formed by combining multiple components such as a single relay, multiple IGBTs combined with diodes, multiple gallium nitride, multiple silicon carbide MOS, or multiple NMOS transistors.

[0035] The first relay K1 is a single-pole double-throw relay. The third terminal of the first relay K1 is the relay fixed terminal 3, the fourth terminal of the first relay K1 is the relay normally closed contact 4, the fifth terminal of the first relay K1 is the relay normally open contact 5, the first terminal of the first relay K1 is the power supply terminal, and the second terminal of the first relay K1 is the ground terminal.

[0036] In one embodiment, the second switching module 400 includes a sixth switch Q6, a sixteenth resistor R16, and a fifteenth resistor R15. The first terminal of the sixth switch Q6 is connected to the output ground GND. The control terminal of the sixth switch Q6 is connected to one end of the sixteenth resistor R16 and one end of the fifteenth resistor R15. The second terminal of the sixth switch Q6 is connected to the other end of the sixteenth resistor R16 and the negative terminal Vin- of the power input. The other end of the fifteenth resistor R15 is connected to the protection circuit power supply Vcc.

[0037] The sixth switch Q6 can be an NMOS transistor. In this case, the first terminal of the sixth switch Q6 is the drain, the second terminal is the source, and the control terminal is the gate. The sixth switch Q6 can also be a switch formed by combining multiple components, such as a single relay, multiple IGBTs combined with diodes, multiple gallium nitride transistors, multiple silicon carbide MOS transistors, or multiple NMOS transistors.

[0038] In one embodiment, the first control self-locking module 200 includes a second switch Q2, a third switch Q3, a first reference chip U1, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first capacitor C1, a second capacitor C2, and a first diode D1. The first terminal of the second switch Q2 is connected to the third input terminal of the first switch module 100. The second terminal of the second switch Q2 is connected to one end of the third resistor R3, the third terminal of the first reference chip U1, one end of the eighth resistor R8, one end of the second capacitor C2, and the negative terminal Vin- of the power input. The control terminal of the second switch Q2 is connected to the other end of the third resistor R3, the second terminal of the third switch Q3, and the sixth resistor R6. One end of resistor R6 and the third end of the third switch Q3 are respectively connected to one end of the fourth resistor R4, one end of the first capacitor C1, and connected to the protection circuit power supply Vcc. The first end of the third switch Q3 is respectively connected to the other end of the fourth resistor R4, the other end of the first capacitor C1, and one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the second end of the first reference chip U1. The first end of the first reference chip U1 is respectively connected to the cathode of the first diode D1, the other end of the eighth resistor R8, the other end of the second capacitor C2, one end of the seventh resistor R7, the anode of the first diode D1, and the other end of the sixth resistor R6. The other end of the seventh resistor R7 is connected to the power supply output voltage Vo+.

[0039] The first reference chip U1 is a TL431 reference chip, and the reference voltage can be 1.25V or 2.5V. The second switch Q2 can be an NMOS transistor, in which case the first terminal of the second switch Q2 is the drain, the second terminal of the second switch Q2 is the source, and the control terminal of the second switch Q2 is the gate. The third switch Q3 can be an NPN transistor, in which case the first terminal of the third switch Q3 is the base, the second terminal of the third switch Q3 is the collector, and the third terminal of the third switch Q3 is the emitter. The second switch Q2 and the third switch Q3 can also be a combination of multiple components such as a single relay, multiple IGBTs combined with diodes, multiple gallium nitride, multiple silicon carbide MOS, or multiple NMOS transistors.

[0040] In one embodiment, the second control self-locking module 300 includes a fourth switch Q4, a fifth switch Q5, a second reference chip U2, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a third capacitor C3, a fourth capacitor C4, and a second diode D2. The first terminal of the fifth switch Q5 is connected to one terminal of the fifteenth resistor R15 and one terminal of the sixteenth resistor R16. The second terminal of the fifth switch Q5 is connected to one terminal of the fourteenth resistor R14, the third terminal of the second reference chip U3, one terminal of the tenth resistor R10, one terminal of the third capacitor C3, and the negative terminal Vin- of the power input. The control terminal of the fifth switch Q5 is connected to the other terminal of the fourteenth resistor R14 and the second terminal of the fourth switch Q4. The second terminal and one end of the twelfth resistor R12, the third terminal of the fourth switch Q4 are respectively connected to one end of the eleventh resistor R11, one end of the fourth capacitor C4 and the protection circuit power supply Vcc, the first terminal of the fourth switch Q4 is respectively connected to the other end of the eleventh resistor R11, the other end of the fourth capacitor C4 and one end of the thirteenth resistor R13, the other end of the thirteenth resistor R13 is connected to the second terminal of the second reference chip U2, the first terminal of the second reference chip U2 is respectively connected to the cathode of the second diode D2, the other end of the eighth resistor R8, the other end of the second capacitor C2 and one end of the seventh resistor R7, the anode of the first diode D2 is connected to the other end of the twelfth resistor R12, and the other end of the ninth resistor R9 is connected to the power supply output voltage Vo+.

[0041] The second reference chip U2 is a TL431 reference chip, and the reference voltage can be 1.25V or 2.5V. The fifth switch Q5 can be an NMOS transistor, with its first terminal being the drain, its second terminal being the source, and its control terminal being the gate. The fourth switch Q4 can be an NPN transistor, with its first terminal being the base, its second terminal being the collector, and its third terminal being the emitter. The fifth switch Q5 and the fourth switch Q4 can also be a combination of multiple components, such as a single relay, multiple IGBTs combined with diodes, multiple gallium nitride, multiple silicon carbide MOS, or multiple NMOS transistors.

[0042] In this embodiment, the power input is connected to the first switch module 100, which is connected to the second switch module 400. The first control self-locking module 200 is connected to the first switch module 100, and the second control self-locking module 300 is connected to the second switch module 400. The output anti-backflow module 500 is connected to the second switch module 400. The protection circuit power supply Vcc is connected to the first control self-locking module 200 and the second control self-locking module 300. When the protection circuit power supply Vcc is energized, the first switch transistor Q1 in the first switch module 100 is turned on, and the coil of the first relay K1 is energized, causing pins 3 and 5 of the relay to engage. At the same time, when the protection circuit power supply Vcc is energized, the sixth switch transistor Q6 in the second switch module 400 is turned on. At this time, after the power input terminal Vin+ is established, the system will have an output power supply output voltage Vo+.

[0043] When the output voltage exceeds the reference voltage, the system triggers output overvoltage protection. The first control self-locking module 200 detects the output overvoltage state and turns on the second terminal and pin 3 of the first reference chip U1, thus turning on the third switch Q3. This causes the second terminal and pin 3 of the third switch Q3 to be on, resulting in a high level at the gate of the second switch Q2, which turns on the DS pin of the second switch Q2, pulling the gate of the first switch Q1 low. Consequently, the coil of the first relay K1 is de-energized, and the relay pins 3 and 5 are disconnected, de-energizing the output voltage Vo+. Simultaneously, because the third switch Q3 is on, energy is continuously transferred to the first terminal of the first reference chip U1 through resistor R6 and diode D1, causing the second terminal and pin 3 of the first reference chip U1 to remain on, thus achieving the self-locking protection function.

[0044] When the system experiences output overvoltage protection, the first control self-locking module 300 detects the output overvoltage state and turns on the second terminal and the third pin of the second reference chip U2, turning on the fourth switch Q4. This causes the second terminal and the third pin of the fourth switch Q4 to conduct, resulting in a high level at the gate of the fifth switch Q5, which turns on the DS pin of the fifth switch Q5, pulling down the gate of the sixth switch Q6. The output power supply voltage Vo+ is de-energized. Simultaneously, because the fourth switch Q4 is conducting, energy is continuously transferred to the first terminal of the second reference chip U2 through resistor R12 and diode D2, causing the second terminal and the third pin of the second reference chip U2 to remain conducting, thus achieving the self-locking function of the protection.

[0045] This solution adds a first relay K1 and a sixth switch Q6 to the output circuit as overvoltage protection actuators. When the system detects an output overvoltage, it will disconnect either the first relay K1 or the sixth switch Q6, thus cutting off the output power supply. Furthermore, the control and execution circuits of the first relay K1 and the sixth switch Q6 are completely independent, achieving heterogeneous redundancy. This solution also features a self-locking function after overvoltage protection; the protection function will only be released when the input power supply restarts, ensuring the system remains in a safe state even during abnormalities until the power supply is cut off.

[0046] The above description is only for illustrating the technical solutions of the present invention and is not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can make modifications or substitutions to the specific embodiments of the present invention. Any modifications or substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention.

Claims

1. An output overvoltage protection self-locking circuit, characterized in that: It includes a first switch module, a second switch module, a first control self-locking module, and a second control self-locking module; The first input terminal of the first switch module is connected to the power input terminal Vin. The second input terminals of the first switch module and the second switch module are both connected to the protection circuit power supply Vcc. The first output terminal of the first switch module is connected to the first input terminal of the second switch module. The output terminal of the first control self-locking module is connected to the third input terminal of the first switch module. The output terminal of the second control self-locking module is connected to the third input terminal of the second switch module. The output terminal of the second switch module outputs the power output voltage Vo+. The first input terminals of the first control self-locking module and the second control self-locking module are both connected to the output terminal of the second switch module. The first control self-locking module is used to determine that the output voltage exceeds the reference voltage, control the first switching module to cut off the power input, and self-lock to maintain the first switching module's cut-off state of the power input; The second control self-locking module is used to determine that the output voltage exceeds the reference voltage, control the second switching module to cut off the output circuit, and self-lock to maintain the cut-off state of the output circuit by the second switching module.

2. The output overvoltage protection self-locking circuit according to claim 1, characterized in that: The first control self-locking module self-locks and maintains the power input cut-off state of the first switch module until the power input is restarted.

3. The output overvoltage protection self-locking circuit according to claim 1, characterized in that: The second control self-locking module self-locks and maintains the output circuit cut-off state of the second switch module until the input power supply is restarted.

4. The output overvoltage protection self-locking circuit according to claim 1, characterized in that: It also includes an output backflow prevention module, the output terminal of the second switch module is connected to the input terminal of the output backflow prevention module, and the output backflow prevention module outputs power supply voltage Vo+.

5. The output overvoltage protection self-locking circuit according to claim 1, characterized in that: The first switching module includes a first relay K1, a first switching transistor Q1, a first resistor R1, and a second resistor R2. The first end of the coil of the first relay K1 is connected to the power supply Vcc of the protection circuit, and the second end of the coil of the first relay K1 is connected to the first end of the first switching transistor Q1. The contact end of the first relay K1 is connected to the positive terminal Vin+ of the power input terminal, and the normally open contact of the first relay K1 outputs the power supply output voltage Vo+. The second end of the first switching transistor Q1 and one end of the second resistor R2 are both connected to the negative terminal Vin- of the power input terminal. The control end of the first switching transistor Q1 is connected to one end of the first resistor R1, the other end of the second resistor R2, and the output end of the first switch control self-locking module, respectively. The other end of the first resistor R1 is connected to the power supply Vcc of the protection circuit.

6. The output overvoltage protection self-locking circuit according to claim 1, characterized in that: The second switching module includes a sixth switch Q6, a sixteenth resistor R16, and a fifteenth resistor R15. The first terminal of the sixth switch Q6 is connected to the output ground GND. The control terminal of the sixth switch Q6 is connected to one end of the sixteenth resistor R16 and one end of the fifteenth resistor R15. The second terminal of the sixth switch Q6 is connected to the other end of the sixteenth resistor R16 and the negative terminal Vin- of the power input. The other end of the fifteenth resistor R15 is connected to the protection circuit power supply Vcc.

7. The output overvoltage protection self-locking circuit according to claim 1, characterized in that: The first control self-locking module includes a second switch Q2, a third switch Q3, a first reference chip U1, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first capacitor C1, a second capacitor C2, and a first diode D1. The first terminal of the second switch Q2 is connected to the third input terminal of the first switch module. The second terminal of the second switch Q2 is connected to one end of the third resistor R3, the third terminal of the first reference chip U1, one end of the eighth resistor R8, one end of the second capacitor C2, and the negative terminal Vin- of the power input. The control terminal of the second switch Q2 is connected to the other end of the third resistor R3, the second terminal of the third switch Q3, and one end of the sixth resistor R6. The third terminal of the third switch Q3 is connected to one end of the fourth resistor R4, one end of the first capacitor C1, and the power supply Vcc of the protection circuit. The first terminal of the third switch Q3 is connected to the other end of the fourth resistor R4, the other end of the first capacitor C1, and one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the second terminal of the first reference chip U1. The first terminal of the first reference chip U1 is connected to the cathode of the first diode D1, the other end of the eighth resistor R8, the other end of the second capacitor C2, one end of the seventh resistor R7, the anode of the first diode D1, and the other end of the sixth resistor R6. The other end of the seventh resistor R7 is connected to the power supply output voltage Vo+.

8. The output overvoltage protection self-locking circuit according to claim 1, characterized in that: The second control self-locking module includes a fourth switch Q4, a fifth switch Q5, a second reference chip U2, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a third capacitor C3, a fourth capacitor C4, and a second diode D2. The first terminal of the fifth switch Q5 is connected to one end of the fifteenth resistor R15 and one end of the sixteenth resistor R16. The second terminal of the fifth switch Q5 is connected to one end of the fourteenth resistor R14, the third terminal of the second reference chip U3, one end of the tenth resistor R10, one end of the third capacitor C3, and the negative terminal Vin- of the power input. The control terminal of the fifth switch Q5 is connected to the other end of the fourteenth resistor R14, the second terminal of the fourth switch Q4, and the... One end of the twelfth resistor R12 is connected to one end of the eleventh resistor R11, one end of the fourth capacitor C4, and the protection circuit power supply Vcc. The first end of the fourth switch Q4 is connected to the other end of the eleventh resistor R11, the other end of the fourth capacitor C4, and one end of the thirteenth resistor R13. The other end of the thirteenth resistor R13 is connected to the second end of the second reference chip U2. The first end of the second reference chip U2 is connected to the cathode of the second diode D2, the other end of the eighth resistor R8, the other end of the second capacitor C2, and one end of the seventh resistor R7. The anode of the first diode D2 is connected to the other end of the twelfth resistor R12. The other end of the ninth resistor R9 is connected to the power supply output voltage Vo+.

9. The output overvoltage protection self-locking circuit according to claim 4, characterized in that: The output anti-backflow module includes a third diode D3. The anode of the third diode D3 is connected to the output terminal of the second control self-locking module, and the cathode of the third diode D3 outputs the power supply output voltage Vo+.

10. A switching power supply, characterized in that, Includes the output overvoltage protection self-locking circuit as described in any one of claims 1-9.

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