WO2020215279A1

WO2020215279A1 - Over-voltage protection control circuit and related device

Info

Publication number: WO2020215279A1
Application number: PCT/CN2019/084320
Authority: WO
Inventors: 罗乐; 赵德琦; 吴壬华
Original assignee: 深圳欣锐科技股份有限公司
Priority date: 2019-04-25
Filing date: 2019-04-25
Publication date: 2020-10-29
Also published as: CN111316545A

Abstract

The present application discloses an over-voltage protection control circuit, characterized in that the over-voltage protection circuit comprises a detection circuit, an input circuit, a transformer, and an output circuit, the transformer comprising a primary winding, a first secondary winding, a second secondary winding, and an iron core, the output circuit comprising a first winding output circuit and a second winding output circuit; the first secondary winding is connected to the first winding output circuit, the second secondary winding is connected to the second winding output circuit, the primary winding is connected to the input circuit, and the first winding output circuit and the second winding output circuit are connected in parallel. The over-voltage protection control circuit provided in the present application has the advantages of improving the safety and reliability of a circuit.

Description

Overvoltage protection control circuit and related equipment

Technical field

This application relates to the field of switching power supplies, in particular to an overvoltage protection control circuit and related equipment.

Background technique

With the rapid development of science and technology, switching power supplies have gradually been applied to all walks of life, and the application of switching power supplies in new energy vehicles has become more and more extensive.

At present, the circuits in some switching power supplies are active clamp forward and flyback circuits, but if the active clamp forward and flyback circuits are working, if the external high voltage input exceeds the specifications or other abnormalities cause the voltage on the main switch to exceed specifications, It is easy to make the entire circuit unable to work normally, resulting in no output of the entire circuit, and even a short circuit at the input terminal, causing large-scale damage to the circuit, and ultimately causing the vehicle to catch fire or lose power on the road and cause a car accident.

There is still no circuit in the prior art that can monitor and control the overvoltage condition of the main switch tube of the active clamp forward and flyback circuit.

Summary of the invention

This application provides an overvoltage protection control circuit and related equipment, which are used to monitor and control the overvoltage condition of the main switch tube of the active clamp forward and flyback circuit, improve the reliability of the switching power supply circuit, and improve the safety of the switching power supply circuit Sex.

The first aspect of the present application provides an overvoltage protection control circuit. The circuit includes a detection circuit, an input circuit, a transformer, and an output circuit. The transformer includes a primary winding, a first secondary winding, and a second secondary winding. Side winding and iron core, the output circuit includes a first winding output circuit and a second winding output circuit;

The first secondary winding is connected to the first winding output circuit, the second secondary winding is connected to the second winding output circuit, the primary winding is connected to the input circuit, and the first The winding output circuit is connected in parallel with the second winding output circuit.

With reference to the first aspect of the present application, in a possible implementation of the first aspect of the present application, the input circuit includes: a first transistor, a second transistor, a first capacitor, and a first diode; and an external input high voltage The power supply is connected to one end of the first capacitor and one end of the primary winding, the other end of the first capacitor is connected to the drain of the first transistor, and the source of the first transistor is connected to the first transistor. The drains of the two transistors are connected to the other end of the primary winding, and the source of the second transistor is grounded; the first diode is connected in parallel with the first transistor, wherein the first diode The anode of the first diode is connected to the source of the first transistor, and the cathode of the first diode is connected to the drain of the first transistor.

In a possible implementation manner, the detection circuit includes: a control device, a first resistor, a second resistor, a third resistor, an optocoupler, a second capacitor, and a controllable precision voltage regulator source; One end is connected to an external input power source, the other end of the third resistor is connected to the positive electrode of the optocoupler, the negative electrode of the optocoupler is connected to the cathode of the controllable precision voltage regulator, and the controllable precision voltage regulator The anode of the source is grounded, the reference electrode of the controllable precision stabilized voltage source is connected to one end of the second capacitor, one end of the first resistor, and one end of the second resistor, and the other end of the second capacitor It is connected to the other end of the second resistor and then grounded.

In a possible implementation manner, the first winding output circuit includes: a second diode and a third capacitor; the cathode of the second diode is connected to one end of the first secondary winding, so The anode of the second diode is connected to one end of the third capacitor, the other end of the third capacitor is connected to the second output port, and one end of the third capacitor is connected to the other end of the first secondary winding. One end is connected, and the other end of the third capacitor is connected to the first output port.

In a possible implementation manner, the second winding output circuit includes: a third diode and a third capacitor; the cathode of the third diode is connected to the other end of the second secondary winding, The anode of the third diode is connected to one end of the third capacitor, one end of the third capacitor is connected to the second output port, and the other end of the third capacitor is connected to the second secondary side. One end of the winding is connected, and the other end of the third capacitor is connected to the first output port.

In a possible implementation manner, the parallel connection of the first winding output circuit and the second winding output circuit includes: connecting the other end of the first secondary winding to one end of the first secondary winding.

In a possible implementation manner, the primary winding, the first secondary winding and the second secondary winding are wound on the iron core.

In a possible implementation manner, the first transistor and the second transistor are both insulated gate field effect transistors.

A second aspect of the present application provides a switching power supply device, characterized in that the switching power supply device includes the overvoltage protection control circuit as described in the first aspect.

A third aspect of the present application provides an in-vehicle device, which is characterized in that the in-vehicle device includes the switching power supply device as described in the second aspect.

In the overvoltage protection control circuit provided by the present application, by adding a detection circuit, the first resistor and the second resistor reduce the voltage on the first capacitor to a certain value and then transmit it as a detection signal to the detection circuit for monitoring. Filtering ensures that the detection signal is not interfered by noise and improves the detection accuracy of the detection circuit. The detection circuit detects the detection signal and executes the detection action, drives the optocoupler, and the optocoupler transmits the overvoltage signal to the control device for processing, and the control device receives the overvoltage signal Then close the input and output circuit or limit the input and output circuit, realize the overvoltage protection control of the circuit, improve the safety of the circuit, improve the reliability of the circuit, and improve the customer experience.

Description of the drawings

In order to more clearly describe the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative work, other drawings can be obtained based on these drawings.

FIG. 1 is a schematic diagram of a circuit structure of an overvoltage protection control circuit provided by an embodiment of the present application;

1A is a schematic diagram of a first state of an overvoltage protection control circuit provided by an embodiment of the present application;

FIG. 1B is a schematic diagram of a second state of an overvoltage protection control circuit provided by an embodiment of the present application;

1C is a schematic diagram of a third state of an overvoltage protection control circuit provided by an embodiment of the present application;

2 is a circuit block diagram of an overvoltage protection control circuit provided by an embodiment of the present application;

3 is a schematic structural diagram of an input circuit of an overvoltage protection control circuit provided by an embodiment of the present application;

4 is a schematic structural diagram of a detection circuit of an overvoltage protection control circuit provided by an embodiment of the present application;

FIG. 5 is a schematic structural diagram of a first winding output circuit of an overvoltage protection control circuit provided by an embodiment of the present application;

FIG. 6 is a schematic structural diagram of a second winding output circuit of an overvoltage protection control circuit provided by an embodiment of the present application.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of them. Based on the implementation manners in this application, all other implementation manners obtained by those of ordinary skill in the art without creative work fall within the protection scope of this application.

The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific sequence. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes unlisted steps or units, or optionally also includes Other steps or units inherent to these processes, methods, products or equipment.

The reference to "embodiments" in this application means that a specific feature, structure or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art clearly and implicitly understand that the embodiments described in this application can be combined with other embodiments.

During the working process of the active clamp forward and flyback circuit, it is easy to cause the transistor in the input circuit to be damaged due to overvoltage due to problems such as over-spec high-voltage input or defective components, causing the entire circuit to fail to work or more serious results. This application is implemented The overvoltage protection control circuit provided in the example monitors the voltage of the input circuit through the detection circuit to ensure that the voltage of the input circuit is stable, thereby improving the safety and reliability of the entire circuit.

In order to better describe the embodiments of the present application, the embodiments of the present application will be described in detail below with reference to the drawings.

Please refer to FIG. 1, which is a schematic diagram of a circuit structure of an overvoltage protection control circuit provided by an embodiment of the present application. The overvoltage protection control circuit includes a detection circuit 101, an input circuit 102, a transformer 103 and an output circuit 104.

Optionally, the detection circuit 101 includes a control device U3, a first resistor R1, a second resistor R2, a third resistor R3, an optocoupler U2, a second capacitor C2, and a controllable precision voltage regulator source U1, wherein the third resistor R3 One end of the third resistor R3 is connected to the first input port A, the other end of the third resistor R3 is connected to the positive electrode of the optocoupler U2, and the negative electrode of the optocoupler U2 is connected to the cathode of the controllable precision voltage regulator source U1. The anode is grounded, the reference electrode of the controllable precision voltage stabilizing source U1 is connected to one end of the second capacitor C2, one end of the first resistor R1, and one end of the second resistor R2. The other end of the second capacitor C2 is connected to the other end of the second resistor R2. One end is connected, the other end of the second resistor R2 is grounded, and the first input port A is connected to an external input power source.

Optionally, the input circuit 102 includes a first transistor Q1, a second transistor Q2, a first capacitor C1, and a first diode D1; one end of the first capacitor C1 is connected to the second input port D, and the other of the first capacitor C1 One end is connected to the drain of the first transistor Q1 and the cathode of the first diode D1. The source of the first transistor Q1 is connected to the drain of the second transistor Q2 and the anode of the first diode D1. The anode of the tube D1 is also connected to the drain of the second transistor Q2, the source of the second transistor Q2 is grounded, one end of the first capacitor C1 is connected to one end of the primary winding, and the drain of the second transistor Q2 is connected to the primary winding. The other end is connected, where the second input port D is connected to an external input high-voltage power supply.

Optionally, the output circuit 104 includes: a first winding output circuit and a second winding output circuit, where the first winding output circuit includes: a second diode D2 and a third capacitor C3; the cathode of the second diode D2 Connected to one end of the first secondary winding, the anode of the second diode D2 is connected to one end of the third capacitor C3, the other end of the third capacitor C3 is connected to the second output port F, the other end of the first secondary winding, and The first output port E is connected.

Optionally, the second winding output circuit includes: a third diode D3 and a third capacitor C3; the cathode of the third diode D3 is connected to the other end of the second secondary winding, and the anode of the third diode D3 It is connected to one end of the third capacitor C3, one end of the third capacitor C3 is connected to the second output port F, and the other end of the third capacitor C3 is connected to the other end of the second secondary winding and the first output port E.

Optionally, the first winding output circuit is connected in parallel with the second winding output circuit, and the other end of the first secondary winding is connected to one end of the second secondary winding.

Optionally, the transformer 103 includes: a primary winding, an iron core, a first secondary winding, and a second secondary winding, wherein the primary winding, the first secondary winding, and the second secondary winding are wound on the same iron core on.

Optionally, the first transistor Q1 and the second transistor Q2 are insulated gate field effect transistors.

The working process of the overvoltage protection control circuit provided in the embodiment of the application includes four states in one cycle, which are specifically as follows:

The first state is shown in Figure 1A. When the first transistor Q1 is turned off and the second transistor Q2 is turned on: the current is input from the external high-voltage power source and flows to the primary winding of the transformer, and the current enters the grounding point through the second transistor Q2. A current loop, the voltage polarity on the primary winding is up positive and down negative. At the same time, the first secondary winding induces a positive and down negative voltage, and the current flows from the cathode of the second diode to the anode. When the second diode is reverse biased and does not conduct, it cannot form a current loop. The second secondary winding induces a positive and negative voltage at the top and bottom, and the current flows from the anode of the third diode to the cathode. When turned on, the current flows from the upper end of the second secondary winding through the third capacitor C3 and then through the third diode back to the lower end of the second secondary winding to form a current loop.

The second state is shown in Figure 1B. When the first transistor Q1 and the second transistor Q2 are both turned off, due to the inductance characteristics, the current direction of the primary winding remains unchanged, and the primary winding generates a reflected voltage, and the polarity of the reflected voltage is down Positive and negative, the reflected voltage makes the current flow from the lower end of the primary winding through the first diode D1, and then back to the primary winding after passing through the first capacitor C1, forming a current loop to charge the first capacitor C1, the first capacitor The voltage on C1 is positive and negative at the bottom. At the same time, the voltage direction and current direction of the secondary winding remain unchanged. The voltage of the first secondary winding is positive and negative at the bottom. The second diode D2 is reverse biased and does not conduct. A current loop cannot be formed. The voltage of the second secondary winding is positive and negative. The current flows from the upper end of the second secondary winding through the third capacitor C3, and then through the third diode D3 back to the lower end of the second secondary winding , Forming a loop.

The third state is shown in Figure 1C. When the first transistor Q1 is turned on and the second transistor Q2 is turned off, the voltage of the first capacitor C1 after being charged is positive and negative, and the current flows from the lower end of the first capacitor C1 through the first capacitor. The transistor Q1 passes through the primary winding to the upper end of the first capacitor C1 to form a current loop. At the same time, the energy generated by the discharge of the first capacitor C1 is induced to the secondary winding, and the first secondary winding induces positive and negative The voltage and current flow from the lower end of the first secondary winding, pass through the third capacitor C3, and then return to the upper end of the first secondary winding through the second diode D2, forming a current loop, and the second secondary winding induces the lower positive When the negative voltage is applied, the third diode D3 is reversely biased and does not conduct, and a current loop cannot be formed.

In the fourth state, the circuit state is updated to the first state, and the circuit operation process from the first state to the third state is repeated.

Please refer to FIG. 2, which is a circuit block diagram of an overvoltage protection control circuit provided by an embodiment of the present application. The overvoltage protection control circuit includes a detection circuit 101, an input circuit 102, a transformer 103, and an output circuit 104. The transformer 103 includes: a primary winding 105, a magnetic core, a first secondary winding 106, and a second secondary winding 107. The output circuit 104 includes: a first winding output circuit 108 and a second winding output circuit 109;

Optionally, the output circuit 104 is connected to the transformer 103, the input circuit 102 is connected to the transformer 103, and the first winding output circuit 108 is connected in parallel to the second winding output circuit 109, wherein the input circuit 102 is connected to the primary winding 105, The winding output circuit 108 is connected to the first secondary winding 106, and the second winding output circuit 109 is connected to the second secondary winding 107.

The input circuit 104 is used to generate a first electrical signal according to the input voltage through the input circuit 104; the primary winding 105 is used to convert the first electrical signal into a first magnetic flux; the first secondary side The winding 106 is used to receive the first magnetic flux and generate a second magnetic flux according to the first magnetic flux, and at the same time, the second magnetic flux generates a first induced electromotive force on the secondary side through the first secondary winding 106; the second secondary winding 107 is used to receive the first magnetic flux and generate a third magnetic flux according to the first magnetic flux, and meanwhile, the third magnetic flux generates a secondary induced electromotive force through the second secondary winding 107; the first winding outputs The circuit 108 is used to convert the first induced electromotive force of the secondary side into a voltage signal and output; the second winding output circuit 109 is used to convert the second induced electromotive force of the secondary side into a voltage signal and output.

It can be seen that in this application, two secondary windings are connected in parallel to form two working branches. The two working branches perform the conversion of induced electromotive force at the same time, which improves the conversion efficiency. The sum of the voltage signals of the two working branches is the whole The final output result of the circuit has a large output power and a wide range of applications.

Please refer to FIG. 3, which is a schematic structural diagram of an input circuit of an overvoltage protection control circuit provided by an embodiment of the present application.

Optionally, the input circuit includes a first transistor Q1, a second transistor Q2, a first capacitor C1, and a first diode D1; one end of the first capacitor C1 is connected to the second input port D, and the other end of the first capacitor C1 Connected to the drain of the first transistor Q1, the other end of the first capacitor C1 is connected to the cathode of the first diode D1, the source of the first transistor Q1 is connected to the drain of the second transistor Q2, and the The source is connected to the anode of the first diode D1, the anode of the first diode D1 is connected to the drain of the second transistor Q2, the source of the second transistor Q2 is grounded, and one end of the first capacitor C1 is connected to the primary winding The drain of the second transistor Q2 is connected to the other end of the primary winding, and the second input port D is connected to the external input high-voltage power supply.

Please refer to FIG. 4, which is a schematic structural diagram of a detection circuit of an overvoltage protection control circuit provided by an embodiment of the present application.

Optionally, the detection circuit includes a control device U3, a first resistor R1, a second resistor R2, a third resistor R3, an optocoupler U2, a second capacitor C2, and a controllable precision voltage stabilizer source U1, wherein the third resistor R3 One end is connected to the first input port A, the other end of the third resistor R3 is connected to the positive electrode of the optocoupler U2, the negative electrode of the optocoupler U2 is connected to the cathode of the controllable precision voltage regulator source U1, and the anode of the controllable precision voltage regulator source U1 Grounded, the reference electrode of the controllable precision voltage stabilization source U1 is connected to one end of the second capacitor C2, the reference electrode of the controllable precision voltage stabilization source U1 is connected to one end of the first resistor R1, and the reference electrode of the controllable precision voltage stabilization source U1 It is connected to one end of the second resistor R2, the other end of the second capacitor C2 is connected to the other end of the second resistor R2, and the other end of the second resistor R2 is grounded. The first input port A is connected to an external input power source.

Optionally, the first transistor Q1 and the second transistor Q2 are turned on in turn. When the second transistor Q2 is turned on, the current is transferred to the first secondary winding and the second secondary winding through the primary winding, and the current is rectified and filtered. Supply power to the first winding output circuit and the second winding output circuit. When the second transistor Q2 is disconnected, the reflected high voltage generated by the primary winding charges the first capacitor C1 through the first diode D1, and the primary winding generates The reflected high voltage is suppressed to a certain value to ensure that the reflected high voltage does not exceed the voltage value of the second transistor Q2. When the first capacitor C1 is charged, the first transistor Q1 is turned on, and the current of the first capacitor C1 passes through the first The transistor Q1 is transferred to the primary winding, and the current is transferred to the first secondary winding and the second secondary winding through the primary winding;

Further, the detection circuit is used to ensure that the value of the reflected high voltage does not exceed the voltage value borne by the second transistor Q2, wherein the first resistor R1 and the second resistor R2 reduce the voltage of the first capacitor C1 to a certain value and send it as a detection signal To the controllable precision voltage regulator source U1 for detection, the second capacitor C2 filters the clutter contained in the detection signal. The first resistor R1 and the second resistor R2 jointly determine the voltage threshold. For example, the voltage on the first capacitor C1 is higher than the preset The voltage is reduced by the first resistor R1 and the second resistor R2, and then filtered by the second capacitor C1 to obtain the detection signal. The detection signal is sent to the controllable precision voltage regulator source U1, and the controllable precision voltage regulator source U1 receives the detection After the signal, the optocoupler U2 is driven, and the second transistor Q2 overvoltage signal is output to the control circuit U3 through the optocoupler U2. The control circuit U3 receives the second transistor Q2 overvoltage signal and executes actions to close the input circuit, transformer, and output circuit or limit The power output of the input circuit, transformer, and input circuit, where the control circuit includes but is not limited to: a single-chip microcomputer or a digital signal processing chip.

Please refer to FIG. 5. FIG. 5 is a schematic structural diagram of a first winding output circuit of an overvoltage protection control circuit provided by an embodiment of the present application.

Optionally, the first winding output circuit includes: a second diode D2 and a third capacitor C3; the cathode of the second diode D2 is connected to one end of the first secondary winding, and the anode of the second diode D2 is connected to One end of the third capacitor C3 is connected, the other end of the third capacitor C3 is connected to the second output port F, the other end of the third capacitor C3 is connected to the other end of the first secondary winding, and the other end of the third capacitor C3 is connected to the second output port F. An output port E is connected.

Please refer to FIG. 6, which is a schematic structural diagram of a second winding output circuit of an overvoltage protection control circuit provided by an embodiment of the present application.

Optionally, the second winding output circuit includes: a third diode D3 and a third capacitor C3; the cathode of the third diode D3 is connected to the other end of the second secondary winding, and the anode of the third diode D3 It is connected to one end of the third capacitor C3, one end of the third capacitor C3 is connected to the second output port F, the other end of the third capacitor C3 is connected to the other end of the second secondary winding, and the other end of the third capacitor C3 is connected to the second output port F. An output port E is connected.

An embodiment of the application also provides a switching power supply device, including the above-mentioned overvoltage protection control circuit.

An embodiment of the present application also provides an in-vehicle device, including the above-mentioned switching power supply device.

It should be noted that for the foregoing application embodiments, for the sake of simple description, they are all expressed as a series of action combinations, but those skilled in the art should know that this application is not limited by the described sequence of actions. Because according to this application, some steps can be performed in other order or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by this application.

In the above-mentioned embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in an embodiment, reference may be made to related descriptions of other embodiments.

In the several embodiments provided in this application, it should be understood that the disclosed device may be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the above-mentioned units is only a logical function division, and there may be other divisions in actual implementation, for example, multiple units or components can be combined or integrated. To another system, or some features can be ignored, or not implemented. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical or other forms.

The units described above as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

In addition, the functional units in each embodiment of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or software functional unit.

The embodiments of the application are described in detail above, and specific examples are used in this article to illustrate the principles and implementation of the application. The descriptions of the above embodiments are only used to help understand the application and its core ideas; at the same time, for the field According to the ideas of the application, the general technical personnel of, will have changes in the specific implementation and application scope. In summary, the content of this specification should not be construed as a limitation of the application.

Claims

An overvoltage protection control circuit, characterized in that the overvoltage protection circuit includes a detection circuit, an input circuit, a transformer, and an output circuit, wherein the transformer includes a primary winding, a first secondary winding, and a second secondary winding. Winding and iron core; the output circuit includes a first winding output circuit and a second winding output circuit;

The first secondary winding is connected to the first winding output circuit, the second secondary winding is connected to the second winding output circuit, the primary winding is connected to the input circuit, and the first The winding output circuit is connected in parallel with the second winding output circuit.
The circuit according to claim 1, wherein the input circuit comprises a first transistor, a second transistor, a first capacitor and a first diode;

The external input high-voltage power supply is connected to one end of the first capacitor and one end of the primary winding, the other end of the first capacitor is connected to the drain of the first transistor, and the source of the first transistor Is connected to the drain of the second transistor and the other end of the primary winding, and the source of the second transistor is grounded; the first diode is connected in parallel with the first transistor, wherein the The anode of a diode is connected to the source of the first transistor, and the cathode of the first diode is connected to the drain of the first transistor.
The circuit according to claim 1, wherein the detection circuit comprises: a control device, a first resistor, a second resistor, a third resistor, an optocoupler, a second capacitor, and a controllable precision voltage regulator source;

One end of the third resistor is connected to an external input power source, the other end of the third resistor is connected to the positive electrode of the optocoupler, and the negative electrode of the optocoupler is connected to the cathode of the controllable precision stabilized voltage source. The anode of the controllable precision stabilized voltage source is grounded, and the reference electrode of the controllable precision stabilized source is connected to one end of the second capacitor, one end of the first resistor, and one end of the second resistor. The other end of the second capacitor is connected to the other end of the second resistor and then grounded.
The circuit according to claim 1, wherein the first winding output circuit comprises: a second diode and a third capacitor;

The cathode of the second diode is connected to one end of the first secondary winding, the anode of the second diode is connected to one end of the third capacitor, and one end of the third capacitor is connected to the second The output port is connected, the other end of the third capacitor is connected to the other end of the first secondary winding, and the other end of the third capacitor is connected to the first output port.
The circuit according to claim 1, wherein the second winding output circuit comprises: a third diode and a third capacitor;

The cathode of the third diode is connected to the other end of the second secondary winding, the anode of the third diode is connected to one end of the third capacitor, and one end of the third capacitor is connected to the The second output port is connected, the other end of the third capacitor is connected to one end of the second secondary winding, and the other end of the third capacitor is connected to the first output port.
The circuit according to claim 1, wherein the parallel connection of the first winding output circuit and the second winding output circuit comprises:

The other end of the first secondary winding is connected to one end of the second secondary winding.
The circuit according to claim 1, wherein the primary winding, the first secondary winding and the second secondary winding are wound on the iron core.
The circuit according to claim 1, wherein the first transistor and the second transistor are both insulated gate field effect transistors.
A switching power supply device, wherein the switching power supply device includes the overvoltage protection control circuit according to any one of claims 1-8.
An in-vehicle device, characterized in that the in-vehicle device includes the switching power supply device according to claim 9.