Clamping bleeder circuit and vehicle-mounted auxiliary power supply

Abstract

The utility model provides a clamping bleeder circuit and a vehicle-mounted auxiliary power supply, and belongs to the technical field of electronic circuits. The clamp bleeder circuit comprises a trigger circuit which is connected in parallel to the output end of a vehicle-mounted auxiliary power supply and outputs a trigger signal when the voltage value of the power supply is greater than a preset voltage; and the bleeder circuit is electrically connected to the output end of the trigger circuit, and when the trigger circuit outputs a trigger signal, the two ends of the bleeder circuit are connected to the output end of the vehicle-mounted auxiliary power supply. Through the clamping bleeder circuit provided by the utility model, the output load at the rear stage of the vehicle-mounted auxiliary power supply can be protected, and the abnormity caused by overvoltage damage or overvoltage can be avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of electronic circuits, and in particular relates to a clamping discharge circuit and a vehicle-mounted auxiliary power supply. Background Art

[0002] With the popularity of new energy vehicles, power electronics technology is increasingly used in automotive electronics, and the circuit structure of new energy electric drive products is becoming more and more complex. In order to meet different functional requirements, there are more and more on-board auxiliary power supplies in the on-board power supply, and the output end of the on-board auxiliary power supply will supply power to the secondary side of the driver chip.

[0003] However, for the lower bridge chip that shares a winding output, some electrodes of the switch tube in the driver chip are connected through the busbar copper bus. At this time, when the vehicle auxiliary power supply outputs current, due to the parasitic inductance of the copper bus, an induced voltage will be generated at both ends of the parasitic inductance during the switching process of the switch tube. The generated induced voltage is equivalent to an excitation source, which will charge and discharge the power supply end of the driver chip and affect the output of the power supply end. And when the excitation source fluctuates greatly, it will also affect the life of the switch tube in the driver chip. Utility Model Content

[0004] The utility model aims to provide a clamping discharge circuit and a vehicle-mounted auxiliary power supply, which can protect the output load of the rear stage of the vehicle-mounted auxiliary power supply and avoid damage due to overvoltage or abnormality caused by overvoltage.

[0005] To achieve the above object, the utility model provides a clamping discharge circuit, wherein the clamping discharge circuit at least includes:

[0006] A trigger circuit is connected in parallel to an output terminal of the vehicle-mounted auxiliary power supply, and when a voltage value of the output terminal of the vehicle-mounted auxiliary power supply is greater than a preset voltage, the trigger circuit outputs a trigger signal; and

[0007] The discharge circuit is electrically connected to the output end of the trigger circuit. When the trigger circuit outputs a trigger signal, the discharge circuit is connected to the output end of the vehicle auxiliary power supply.

[0008] In one embodiment of the present invention, the trigger circuit includes:

[0009] A voltage regulator tube, wherein an anode of the voltage regulator tube is electrically connected to a ground terminal; and

[0010] A first current limiting resistor, one end of the first current limiting resistor is electrically connected to the cathode of the voltage regulator tube, and the other end of the first current limiting resistor is electrically connected to the positive output end of the vehicle-mounted auxiliary power supply.

[0011] In one embodiment of the present invention, the trigger circuit includes:

[0012] A control tube, wherein a control end of the control tube is electrically connected to an output end of the trigger circuit, and a first end of the control tube is electrically connected to a positive output end of the vehicle auxiliary power supply; and

[0013] A discharge resistor, one end of the discharge resistor is electrically connected to the second end of the control tube, and the other end of the discharge resistor is electrically connected to the ground end.

[0014] In one embodiment of the utility model, the trigger circuit further includes a second current limiting resistor, one end of the second current limiting resistor is electrically connected to the output end of the trigger circuit, and the other end of the second current limiting resistor is electrically connected to the control end of the control tube.

[0015] In an embodiment of the present utility model, the clamping and discharging circuit further includes a voltage stabilizing capacitor, and the voltage stabilizing capacitor is connected in parallel to the output end of the vehicle auxiliary power supply.

[0016] In one embodiment of the present invention, the trigger circuit includes:

[0017] A voltage regulator tube, wherein the cathode of the voltage regulator tube is electrically connected to the positive output terminal of the vehicle-mounted auxiliary power supply; and

[0018] A first current limiting resistor, one end of the first current limiting resistor is electrically connected to the anode of the voltage regulator tube, and the other end of the first current limiting resistor is electrically connected to the ground end.

[0019] In one embodiment of the present invention, the trigger circuit includes:

[0020] A control tube, wherein a control end of the control tube is electrically connected to an output end of the trigger circuit, and a second end of the control tube is electrically connected to a ground end; and

[0021] A discharge resistor, one end of the discharge resistor is electrically connected to the first end of the control tube, and the other end of the discharge resistor is electrically connected to the positive output end of the vehicle auxiliary power supply.

[0022] In one embodiment of the present invention, the trigger circuit includes:

[0023] A voltage regulator tube, wherein an anode of the voltage regulator tube is electrically connected to a ground terminal; and

[0024] A first current limiting resistor, one end of the first current limiting resistor is electrically connected to the cathode of the voltage regulator tube, and the other end of the first current limiting resistor is electrically connected to the positive output end of the vehicle-mounted auxiliary power supply.

[0025] In one embodiment of the present invention, the trigger circuit includes:

[0026] a first voltage-dividing resistor, one end of which is electrically connected to the positive output end of the vehicle-mounted auxiliary power supply; and

[0027] A second voltage-dividing resistor, one end of the second voltage-dividing resistor is electrically connected to the other end of the first voltage-dividing resistor, the other end of the second voltage-dividing resistor is electrically connected to the ground end, and the control end of the voltage-regulating diode is electrically connected to the common end of the first voltage-dividing resistor and the second voltage-dividing resistor.

[0028] The utility model also provides a vehicle-mounted auxiliary power supply, which is implemented by a flyback converter, and the clamping discharge circuit as described above is connected in parallel to an output load at the output end of the vehicle-mounted auxiliary power supply.

[0029] In summary, the utility model provides a clamping discharge circuit and a vehicle-mounted auxiliary power supply, and the clamping discharge circuit can effectively limit the output voltage amplitude of the output terminal of the vehicle-mounted auxiliary power supply, protect the output load of the subsequent stage, and avoid damage due to overvoltage or abnormality caused by overvoltage. The failure rate of the product is effectively reduced and the reliability of the product is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 1 is a circuit diagram of a vehicle-mounted auxiliary power supply in one embodiment of the present application.

[0032] Figure 2 This is an output voltage fluctuation diagram of the vehicle auxiliary power supply in one embodiment of the present application.

[0033] Figure 3 is a circuit diagram of a clamping discharge circuit in an embodiment of the present application.

[0034] Figure 4 is a circuit diagram of a clamping discharge circuit in another embodiment of the present application.

[0035] Figure 5 is a circuit diagram of a clamping discharge circuit in yet another embodiment of the present application. DETAILED DESCRIPTION

[0036] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly and comprehensively understood.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0038] In the description of the present invention, it should be understood that the directions or positional relationships indicated by the terms "center", "upper", "lower", "front", "back", "left", "right", etc. are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. The degrees indicated by "high" and "low" are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have high and low, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0039] It should be noted that the control tube used in the embodiment of the utility model can not only use triodes, but also thin film transistors or field effect tubes or other devices with the same characteristics. In the embodiment of the utility model, in order to distinguish the connection relationship of the control tube, one of the poles is called the first end, the other pole is called the second end, and the base is called the control end. In addition, the control tube can be divided into NPN type and PNP type according to the characteristics of the control tube. In this application, when the NPN type control tube is used, the collector of the NPN type control tube is defined as the first end, the emitter of the NPN type control tube is defined as the second end, and when the base inputs a high level, the first end and the second end are turned on. On the contrary, when the PNP type control tube is used, in the initial stage, the emitter of the PNP type control tube is defined as the first end, the collector of the PNP type control tube is defined as the second end, and when the base inputs a low level, the first end and the second end are turned on.

[0040] In vehicle-mounted equipment, a high-voltage power supply system and a low-voltage power supply system are usually provided. The high-voltage power supply system is usually implemented using a high-voltage battery, for example, a high-voltage battery with an output of 200V to 750V, which can power the key electrical components of the vehicle. The low-voltage power supply system is implemented using a low-voltage battery, such as a lead-acid battery, a lithium battery, etc., which can power high-safety loads such as vehicle braking and steering. For new energy electric-driven vehicles, in order to meet the different functional requirements of the vehicle, more and more on-board auxiliary power supplies are provided in the on-board power supply, and the on-board auxiliary power supply can realize voltage conversion. The on-board auxiliary power supply is implemented using a flyback converter.

[0041] See also Figure 1 As shown, in one embodiment of the utility model, the vehicle-mounted auxiliary power supply includes an input power supply Vin, a switch tube S, a transformer T, a diode D, a capacitor C1 and a filter inductor Lu. Among them, the switch tube S is connected in series with the input power supply Vin to the loop of the primary coil of the transformer T, and the switch tube S can be controlled by pulse width modulation (PWM), and a high-frequency square wave signal is generated at both ends of the transformer T by closing and conducting. The transformer T transmits the generated square wave signal to the secondary coil in the form of magnetic field induction. The anode of the diode D is electrically connected to the output end of the secondary coil of the transformer T, and the cathode of the diode D is electrically connected to the ground terminal GND through the capacitor C1, and the capacitor C1 is connected in parallel with the output load Ro. Through the rectification and filtering effect of the diode D and the capacitor C1, a relatively stable DC output is obtained on both sides of the output load Ro. Among them, the output load Ro is the load such as the driver chip in this application. There is also a filter inductor Lu connected in parallel with the output load Ro to realize the filtering function.

[0042] See also Figure 1 and Figure 2 As shown, in one embodiment of the utility model, when the output load Ro is a lower bridge driver chip that shares a winding output, one of the electrodes of the multiple control tubes in the lower bridge driver chip is connected together through a busbar copper bar. When the switch tube S in the vehicle-mounted auxiliary power supply is closed and turned off, due to the presence of parasitic inductance L1 in the copper bar, an induced voltage positively correlated with the switching speed and the parasitic inductance will be generated at both ends of the parasitic inductance L1, which is equivalent to an excitation source. The excitation source will charge and discharge the capacitor C1, causing voltage fluctuations at both ends of the output load Ro, that is, causing the output voltage Vo of the vehicle-mounted auxiliary power supply to fluctuate. If the energy generated by the excitation source is large, there will be a voltage ripple with power frequency components and high-frequency components on the power supply side of the driver chip. The ripple fluctuation is too large, which may affect the working state and life of the switch tube S.

[0043] See also Figures 1 to 5As shown, the present application provides a clamping discharge circuit, which is connected in parallel to the output load Ro, that is, the clamping discharge circuit is connected to the output end of the vehicle auxiliary power supply. When the output voltage Vo of the vehicle auxiliary power supply exceeds the preset voltage, the clamping discharge circuit can discharge the energy, thereby reducing the output voltage Vo, and stabilizing the output voltage Vo of the vehicle auxiliary power supply within a preset range.

[0044] See also Figures 1 to 5 As shown, in one embodiment of the utility model, the clamping discharge circuit includes a trigger circuit 100 and a discharge circuit 200. The trigger circuit 100 is connected to the output end of the vehicle auxiliary power supply, that is, the trigger circuit 100 is connected in parallel to the output load Ro. When the output voltage Vo of the output end of the vehicle auxiliary power supply rises and is greater than the preset voltage, the trigger circuit 100 will output a trigger signal. The discharge circuit 200 is electrically connected to the output end of the trigger circuit 100. When the trigger circuit 100 outputs the trigger signal, the discharge circuit 200 is turned on, so that the discharge circuit 200 is connected in parallel to the output load Ro, that is, the discharge circuit 200 is connected to the output end of the vehicle auxiliary power supply.

[0045] See also Figure 1 and Figure 3 As shown, in one embodiment of the utility model, the trigger circuit 100 includes a voltage regulator tube D10 and a first current limiting resistor R10, and the voltage regulator tube D10 and the first current limiting resistor R10 are connected in series, and the series circuit of the voltage regulator tube D10 and the first current limiting resistor R10 is connected in parallel to the output load Ro. Specifically, the anode of the voltage regulator tube D10 is electrically connected to the ground terminal GND, and the cathode of the voltage regulator tube D10 is electrically connected to the positive output terminal of the output load Ro through the first current limiting resistor R10. That is, the cathode of the voltage regulator tube D10 is electrically connected to one end of the first current limiting resistor R10, and the other end of the first current limiting resistor R10 is electrically connected to the positive output terminal of the output load Ro. In this embodiment, the cathode of the voltage regulator tube D10 triggers the output terminal of the trigger circuit.

[0046] See also Figure 1 and Figure 3As shown, in one embodiment of the utility model, the on-voltage of the trigger circuit 100 is a preset voltage, and the preset voltage is also the voltage across the output load Ro. The on-voltage of the trigger circuit 100 is positively correlated with the on-voltage of the Zener diode D10. When setting the trigger circuit, the model of the Zener diode D10 can be adjusted according to the preset voltage required across the output load Ro. And when the voltage across the output load Ro is less than the preset voltage, the voltage across the Zener diode D10 is less than the on-voltage of the Zener diode D10. At this time, the voltage across the output load Ro is applied to the Zener diode D10, but the Zener diode D10 is not turned on, that is, the trigger circuit 100 is not turned on. When the voltage across the output load Ro is equal to the preset voltage, the voltage across the Zener diode D10 is equal to the on-voltage of the Zener diode D10. At this time, the voltage across the output load Ro is applied to the two ends of the voltage regulator tube D10, and the voltage regulator tube D10 is in the on state, but there is still no voltage across the first current limiting resistor R10, that is, there is no voltage difference between the emitter and the base of the control tube Q10, and the trigger circuit 100 is still in the off state. When the voltage across the output load Ro is greater than the preset voltage, the voltage across the output load Ro is applied to the two ends of the voltage regulator tube D10 and the first current limiting resistor R10, the voltage regulator tube D10 is turned on, and there is a voltage across the first current limiting resistor R10, the trigger circuit 100 is turned on, and the trigger circuit 100 outputs a trigger signal. At this time, the cathode of the voltage regulator tube D10 has an output voltage and an output current.

[0047] See also Figure 3 As shown, in one embodiment of the present utility model, the discharge circuit 200 includes a control tube Q10 and a discharge resistor R12, the control end of the control tube Q10 is electrically connected to the output end of the trigger circuit 100, the two output ends of the control tube Q10 are connected in series to the discharge resistor R12, and the series circuit of the control tube Q10 and the discharge resistor R12 is connected in parallel to the output load Ro. Specifically, the control end of the control tube Q10 is electrically connected to the common end of the voltage-stabilizing tube D10 and the first current-limiting resistor R10, the first end of the control tube Q10 is electrically connected to the positive output end of the output load Ro, and the second end of the control tube Q10 is electrically connected to the ground terminal GND through the discharge resistor R12. That is, the second end of the control tube Q10 is electrically connected to one end of the discharge resistor R12, and the other end of the discharge resistor R12 is electrically connected to the ground terminal GND.

[0048] See also Figure 3As shown, in one embodiment of the utility model, the control tube Q10 is implemented by using a PNP type triode. At this time, the base of the control tube Q10 is electrically connected to the output end of the trigger circuit 100, the emitter of the control tube Q10 is electrically connected to the positive output end of the output load Ro, and the collector of the control tube Q10 is electrically connected to the ground terminal GND through the discharge resistor R12. In other embodiments, the control tube Q10 can also be implemented using a MOSFET, and is a PMOS.

[0049] See also Figure 3 As shown, in one embodiment of the utility model, a second current limiting resistor R11 is further provided on the control end of the control tube Q10, one end of the second current limiting resistor R11 is electrically connected to the output end of the trigger circuit 100, and the other end of the second current limiting resistor R11 is electrically connected to the control end of the control tube Q10. The second current limiting resistor R11 can limit the current flowing into the control tube Q10.

[0050] See also Figure 3 As shown, in one embodiment of the present invention, a voltage stabilizing capacitor C10 is further provided in the clamping discharge circuit, and the voltage stabilizing capacitor C10 is connected in parallel to the trigger circuit 100 and the discharge circuit 200. That is, one end of the voltage stabilizing capacitor C10 is electrically connected to the positive output end of the output load Ro, and the other end of the voltage stabilizing capacitor C10 is electrically connected to the ground end GND.

[0051] See also Figure 3 As shown, in one embodiment of the present invention, when the trigger circuit 100 outputs a trigger signal, the discharge circuit 200 is turned on. At this time, the on-voltage of the trigger circuit 100 is obtained by the following formula:

[0052] V Clamp =U D10 +U Qeb +i b *R11;

[0053] Among them, V Clamp is the on-state voltage of the trigger circuit, U D10 is the conduction voltage of the Zener diode, U Qeb is the bias voltage between the emitter and base of the control tube, i b To control the current of the tube base, R11 is the resistance of the second current limiting resistor.

[0054] See also Figure 3As shown, in one embodiment of the utility model, when the output voltage Vo of the vehicle-mounted auxiliary power supply is slightly over-voltage, the control tube Q10 operates in the amplification area, and the voltage drop between the collector and the emitter of the control tube Q10 is greater than the saturation voltage drop of the control tube Q10. At this time, the current in the discharge circuit 200 is small, the current flowing through the discharge resistor R12 is small, and the energy discharged through the discharge resistor R12 is small. When the output voltage Vo of the vehicle-mounted auxiliary power supply is further increased, so that the control tube Q10 operates in the saturation area, the voltage drop between the collector and the emitter of the control tube Q10 is equal to the saturation voltage drop of the control tube Q10. At this time, the discharge resistor R12 is directly connected in parallel to the output load Ro, the current flowing through the discharge resistor R12 is large, and the energy discharged through the discharge resistor R12 is large.

[0055] See also Figure 4 As shown, in another embodiment of the utility model, the trigger circuit 100 includes a voltage regulator tube D10 and a first current limiting resistor R10 connected in series, and the series circuit of the voltage regulator tube D10 and the first current limiting resistor R10 is connected in parallel to the output load Ro. Specifically, the anode of the voltage regulator tube D10 is electrically connected to the ground terminal GND, and the cathode of the voltage regulator tube D10 is electrically connected to the positive output terminal of the output load Ro through the first current limiting resistor R10. That is, the cathode of the voltage regulator tube D10 is electrically connected to one end of the first current limiting resistor R10, and the other end of the first current limiting resistor R10 is electrically connected to the positive output terminal of the output load Ro. In this embodiment, the anode of the voltage regulator tube D10 triggers the output terminal of the trigger circuit.

[0056] See also Figure 4As shown, in one embodiment of the utility model, the on-voltage of the trigger circuit 100 is a preset voltage, and the preset voltage is the voltage across the limited output load Ro. The on-voltage of the trigger circuit 100 is positively correlated with the on-voltage of the Zener diode D10. When setting the trigger circuit, the model of the Zener diode D10 can be adjusted according to the preset voltage required across the output load Ro. And when the voltage across the output load Ro is less than the preset voltage, the voltage across the Zener diode D10 is less than the on-voltage of the Zener diode D10. At this time, the voltage across the output load Ro is applied to the Zener diode D10, but the Zener diode D10 is not turned on, that is, the trigger circuit 100 is not turned on. When the voltage across the output load Ro is equal to the preset voltage, the voltage across the Zener diode D10 is equal to the on-voltage of the Zener diode D10. At this time, the voltage across the output load Ro is applied to the two ends of the voltage regulator tube D10, and the voltage regulator tube D10 is in the on state, but there is still no voltage across the first current limiting resistor R10, that is, there is no voltage difference between the base and emitter of the control tube Q10, and the trigger circuit 100 is still in the off state. When the voltage across the output load Ro is greater than the preset voltage, the voltage across the output load Ro is applied to the two ends of the voltage regulator tube D10 and the first current limiting resistor R10, the voltage regulator tube D10 is turned on, and there is a voltage across the first current limiting resistor R10, the trigger circuit 100 is turned on, and the trigger circuit 100 outputs a trigger signal. At this time, the anode of the voltage regulator tube D10 has an output voltage and an output current.

[0057] See also Figure 4 As shown, in another embodiment of the utility model, the discharge circuit 200 includes a control tube Q10 and a discharge resistor R12, the control end of the control tube Q10 is electrically connected to the output end of the trigger circuit 100, the two output ends of the control tube Q10 are connected in series to the discharge resistor R12, and the series circuit of the control tube Q10 and the discharge resistor R12 is connected in parallel to the output load Ro. Specifically, the control end of the control tube Q10 is electrically connected to the common end of the voltage-stabilizing tube D10 and the first current-limiting resistor R10, the first end of the control tube Q10 is electrically connected to the positive output end of the output load Ro through the discharge resistor R12, and the second end of the control tube Q10 is electrically connected to the ground end GND. That is, the first end of the control tube Q10 is electrically connected to one end of the discharge resistor R12, and the other end of the discharge resistor R12 is electrically connected to the positive output end of the output load Ro.

[0058] See also Figure 1 and Figure 4As shown, in another embodiment of the utility model, the control tube Q10 is implemented by using an NPN type triode. At this time, the base of the control tube Q10 is electrically connected to the output end of the trigger circuit 100, the collector of the control tube Q10 is electrically connected to the positive output end of the output load Ro through the discharge resistor R12, and the emitter of the control tube Q10 is electrically connected to the ground terminal GND. In other embodiments, the control tube Q10 can also be implemented using a MOSFET, and is an NMOS.

[0059] See also Figure 4 As shown, in another embodiment of the present invention, a second current limiting resistor R11 is further provided on the control end of the control tube Q10, one end of the second current limiting resistor R11 is electrically connected to the output end of the trigger circuit 100, and the other end of the second current limiting resistor R11 is electrically connected to the control end of the control tube Q10. The second current limiting resistor R11 can limit the current flowing into the control tube Q10.

[0060] See also Figure 4 As shown, in another embodiment of the present invention, a voltage stabilizing capacitor C10 is further provided in the clamping discharge circuit, and the voltage stabilizing capacitor C10 is connected in parallel to the trigger circuit 100 and the discharge circuit 200. That is, one end of the voltage stabilizing capacitor C10 is electrically connected to the positive output end of the output load Ro, and the other end of the voltage stabilizing capacitor C10 is electrically connected to the ground end GND.

[0061] See also Figure 4 As shown, in another embodiment of the present invention, when the trigger circuit 100 outputs a trigger signal, the discharge circuit 200 is turned on. At this time, the on-voltage of the trigger circuit 100 is obtained by the following formula:

[0062] V Clamp =U D10 +U Qbe +i b *R11;

[0063] Among them, V Clamp is the on-state voltage of the trigger circuit, U D10 is the conduction voltage of the Zener diode, U Qbe To control the bias voltage between the base and emitter of the tube, i b To control the current of the tube base, R11 is the resistance of the second current limiting resistor.

[0064] See also Figure 4As shown, in another embodiment of the utility model, when the output voltage Vo of the vehicle auxiliary power supply is slightly over-voltage, the control tube Q10 operates in the amplification area, and the voltage drop between the collector and the emitter of the control tube Q10 is greater than the saturation voltage drop of the control tube Q10. At this time, the current in the discharge circuit 200 is small, the current flowing through the discharge resistor R12 is small, and the energy discharged through the discharge resistor R12 is small. When the output voltage Vo of the vehicle auxiliary power supply is further increased, so that the control tube Q10 operates in the saturation area, the voltage drop between the collector and the emitter of the control tube Q10 is equal to the saturation voltage drop of the control tube Q10. At this time, the discharge resistor R12 is directly connected in parallel to the output load Ro, the current flowing through the discharge resistor R12 is large, and the energy discharged through the discharge resistor R12 is large.

[0065] See also Figure 3 and Figure 4 and Figure 5 As shown, in the present invention, since the on-voltage of the trigger circuit 100 is equal to the sum of the on-voltage of the voltage regulator tube D10, the bias voltage of the control tube Q10 and the voltage across the second current limiting resistor R11, and the bias voltage of the control tube Q10 and the voltage across the second current limiting resistor R11 are smaller than the on-voltage of the voltage regulator tube D10, most of the on-voltage of the trigger circuit 100 is applied to the two ends of the voltage regulator tube D10. In some embodiments, if the on-voltage of the trigger circuit 100 is set to be larger, the model requirement of the voltage regulator tube is higher. Therefore, a voltage regulator tube with a control end can be used, and a control signal can be provided to the control end of the voltage regulator tube through a voltage divider circuit, which can reduce the requirement for the voltage regulator tube to have a high on-voltage.

[0066] See also Figure 5As shown, in another embodiment of the utility model, the trigger circuit 100 includes a first voltage-dividing resistor R13, a second voltage-dividing resistor R14, a voltage-stabilizing tube U10 and a first current-limiting resistor R10. Among them, the first voltage-dividing resistor R13 and the second voltage-dividing resistor R14 are connected in series to form a voltage-dividing circuit, and the series voltage-dividing circuit of the first voltage-dividing resistor R13 and the second voltage-dividing resistor R14 is connected in parallel to the output load Ro. That is, one end of the first voltage-dividing resistor R13 is electrically connected to the positive output end of the output load Ro, one end of the second voltage-dividing resistor R14 is electrically connected to the other end of the first voltage-dividing resistor R13, and the other end of the second voltage-dividing resistor R14 is electrically connected to the ground end GND. The control end of the voltage-stabilizing tube U10 is electrically connected to the common end of the first voltage-dividing resistor R13 and the second voltage-dividing resistor R14, the anode of the voltage-stabilizing tube U10 is electrically connected to the ground end GND, and the cathode of the voltage-stabilizing tube D10 is electrically connected to the positive output end of the output load Ro through the first current-limiting resistor R10. That is, the cathode of the voltage regulator tube D10 is electrically connected to one end of the first current limiting resistor R10, and the other end of the first current limiting resistor R10 is electrically connected to the positive output end of the output load Ro. In this embodiment, the cathode of the voltage regulator tube U10 is connected to the output end of the generating circuit.

[0067] See also Figure 5 As shown, in another embodiment of the utility model, the discharge circuit 200 includes a control tube Q10 and a discharge resistor R12, the control end of the control tube Q10 is electrically connected to the output end of the trigger circuit 100, the two output ends of the control tube Q10 are connected in series to the discharge resistor R12, and the series circuit of the control tube Q10 and the discharge resistor R12 is connected in parallel to the output load Ro. Specifically, the control end of the control tube Q10 is electrically connected to the common end of the voltage regulator tube U10 and the first current limiting resistor R10, the first end of the control tube Q10 is electrically connected to the positive output end of the output load Ro, and the second end of the control tube Q10 is electrically connected to the ground terminal GND through the discharge resistor R12. That is, the second end of the control tube Q10 is electrically connected to one end of the discharge resistor R12, and the other end of the discharge resistor R12 is electrically connected to the ground terminal GND.

[0068] See also Figure 1 and Figure 5 As shown, in another embodiment of the utility model, the control tube Q10 is implemented by using a PNP type triode. At this time, the base of the control tube Q10 is electrically connected to the output end of the trigger circuit 100, the emitter of the control tube Q10 is electrically connected to the positive output end of the output load Ro, and the collector of the control tube Q10 is electrically connected to the ground terminal GND through the discharge resistor R12. In other embodiments, the control tube Q10 can also be implemented using a MOSFET, and is a PMOS.

[0069] See also Figure 5As shown, in another embodiment of the present invention, a second current limiting resistor R11 is further provided on the control end of the control tube Q10, one end of the second current limiting resistor R11 is electrically connected to the output end of the trigger circuit 100, and the other end of the second current limiting resistor R11 is electrically connected to the control end of the control tube Q10. The second current limiting resistor R11 can limit the current flowing into the control tube Q10.

[0070] See also Figure 5 As shown, in another embodiment of the present invention, a voltage stabilizing capacitor C10 is further provided in the clamping and discharging circuit, and the voltage stabilizing capacitor C10 is connected in parallel to the trigger circuit 100 and the discharging circuit 200. That is, one end of the voltage stabilizing capacitor C10 is electrically connected to the positive output end of the output load Ro, and the other end of the voltage stabilizing capacitor C10 is electrically connected to the ground end GND.

[0071] See also Figure 5 As shown, in another embodiment of the utility model, the trigger voltage of the voltage regulator U10 can be adjusted by using the first voltage-dividing resistor R13 and the second voltage-dividing resistor R14. In this embodiment, the on-voltage of the trigger circuit 100 is a preset voltage, which is also the voltage across the output load Ro. In this embodiment, the on-voltage of the trigger circuit 100 is obtained by the following formula:

[0072] V Clamp =V ref *(R13+R14) / R14;

[0073] Among them, V Clamp is the on-state voltage of the trigger circuit, V ref is the trigger voltage of the Zener diode, that is, the voltage required by the control end of the Zener diode when the Zener diode is turned on, R13 is the resistance value of the first voltage-dividing resistor, and R14 is the resistance value of the second voltage-dividing resistor.

[0074] See also Figure 5As shown, in another embodiment of the utility model, when the voltage across the output load Ro is less than the preset voltage, the voltage at the control end of the voltage regulator U10 is less than or equal to the trigger voltage, and the voltage regulator U10 is not turned on, that is, the trigger circuit 100 is not turned on. When the voltage across the output load Ro is greater than the preset voltage, the voltage at the control end of the voltage regulator U10 is greater than the trigger voltage, the voltage regulator U10 is turned on, that is, the trigger circuit 100 is turned on, and the trigger circuit 100 outputs a trigger signal. At this time, the cathode of the voltage regulator U10 has an output voltage and an output current. And when the output voltage Vo of the vehicle auxiliary power supply is slightly overvoltage, the control tube Q10 works in the amplification area, and the voltage drop between the collector and the emitter of the control tube Q10 is greater than the saturation voltage drop of the control tube Q10. At this time, the current in the discharge circuit 200 is small, the current flowing through the discharge resistor R12 is small, and the energy discharged through the discharge resistor R12 is small. When the output voltage Vo of the vehicle auxiliary power supply further increases, so that the control tube Q10 works in the saturation region, the voltage drop between the collector and the emitter of the control tube Q10 is equal to the saturation voltage drop of the control tube Q10. At this time, the bleeder resistor R12 is directly connected in parallel to the output load Ro, the current flowing through the bleeder resistor R12 is large, and the energy discharged through the bleeder resistor R12 is large.

[0075] See also Figures 3 to 5 As shown, in the present application, the discharge resistor R12 can be selected in series and parallel according to the energy and heat generated by the voltage source of the subsequent parasitic inductance, and the discharge resistor R12 can be set between several ohms and hundreds of ohms. The voltage divider resistor and the current limiting resistor can be set between thousands of ohms and tens of thousands of ohms.

[0076] It should be noted that in the present application, multiple resistors can be connected in series, in parallel, or in series and in parallel to realize the function of a single resistor, and multiple capacitors can be connected in series, in parallel, or in series and in parallel to realize the function of a single capacitor according to actual needs, so as to reduce the specification requirements of the device. In the present application, the clamping discharge circuit can be used not only for clamping discharge of positive voltage output, but also for clamping discharge of negative voltage output. It is only necessary to electrically connect one end of the clamping discharge circuit connected to the positive output terminal of the output load to the ground terminal, and to electrically connect one end of the clamping discharge circuit connected to the ground terminal to the negative output terminal of the output load.

[0077] In summary, the utility model provides a clamping discharge circuit and a vehicle-mounted auxiliary power supply, wherein a trigger circuit and a discharge circuit are arranged in the clamping discharge circuit, wherein the trigger circuit is connected in parallel to the output end of the vehicle-mounted auxiliary power supply, and when the voltage value of the output end of the vehicle-mounted auxiliary power supply is greater than a preset voltage, the trigger circuit outputs a trigger signal; the discharge circuit is electrically connected to the output end of the trigger circuit, and when the trigger circuit outputs a trigger signal, the discharge circuit is connected to the output end of the vehicle-mounted auxiliary power supply. Thus, when the voltage value of the output end of the vehicle-mounted auxiliary power supply is greater than a preset voltage, the excess energy at the output end of the vehicle-mounted auxiliary power supply can be released through the discharge circuit, thereby reducing the voltage at the output end of the vehicle-mounted auxiliary power supply, so that the voltage at the output end of the vehicle-mounted auxiliary power supply is stabilized within the preset voltage. Through the clamping discharge circuit and the vehicle-mounted auxiliary power supply provided by the utility model, the output load of the vehicle-mounted auxiliary power supply can be protected to avoid damage due to overvoltage or abnormalities caused by overvoltage. The failure rate of the product is effectively reduced and the reliability of the product is improved.

[0078] The embodiments of the utility model disclosed above are only used to help illustrate the utility model. The embodiments do not describe all the details in detail, nor do they limit the utility model to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the utility model, so that technicians in the relevant technical field can well understand and use the utility model. The utility model is limited only by the claims and their full scope and equivalents.

Claims

1. A clamping discharge circuit, characterized in that: At least: A trigger circuit is connected in parallel to the output end of the vehicle-mounted auxiliary power supply, and when the voltage value of the output end of the vehicle-mounted auxiliary power supply is greater than a preset voltage, the trigger circuit outputs a trigger signal; as well as The discharge circuit is electrically connected to the output end of the trigger circuit. When the trigger circuit outputs a trigger signal, the discharge circuit is connected to the output end of the vehicle auxiliary power supply.

2. A clamping discharge circuit according to claim 1, characterized in that: The trigger circuit comprises: A voltage regulator tube, wherein an anode of the voltage regulator tube is electrically connected to a ground terminal; and A first current limiting resistor, one end of the first current limiting resistor is electrically connected to the cathode of the voltage regulator tube, and the other end of the first current limiting resistor is electrically connected to the positive output end of the vehicle auxiliary power supply.

3. The clamping discharge circuit according to claim 1, characterized in that: The trigger circuit comprises: A control tube, wherein a control end of the control tube is electrically connected to an output end of the trigger circuit, and a first end of the control tube is electrically connected to a positive output end of the vehicle auxiliary power supply; and A discharge resistor, one end of the discharge resistor is electrically connected to the second end of the control tube, and the other end of the discharge resistor is electrically connected to the ground end.

4. A clamping discharge circuit according to claim 3, characterized in that: The trigger circuit also includes a second current limiting resistor, one end of the second current limiting resistor is electrically connected to the output end of the trigger circuit, and the other end of the second current limiting resistor is electrically connected to the control end of the control tube.

5. The clamping discharge circuit according to claim 1, characterized in that: The clamping discharge circuit also includes a voltage stabilizing capacitor, which is connected in parallel to the output end of the vehicle auxiliary power supply.

6. The clamping discharge circuit according to claim 1, characterized in that: The trigger circuit comprises: A voltage regulator tube, wherein the cathode of the voltage regulator tube is electrically connected to the positive output terminal of the vehicle-mounted auxiliary power supply; and A first current limiting resistor, one end of the first current limiting resistor is electrically connected to the anode of the voltage regulator tube, and the other end of the first current limiting resistor is electrically connected to the ground end.

7. The clamping discharge circuit according to claim 1, characterized in that: The trigger circuit comprises: A control tube, wherein a control end of the control tube is electrically connected to an output end of the trigger circuit, and a second end of the control tube is electrically connected to a ground end; and A discharge resistor, one end of the discharge resistor is electrically connected to the first end of the control tube, and the other end of the discharge resistor is electrically connected to the positive output end of the vehicle auxiliary power supply.

8. The clamping discharge circuit according to claim 2, characterized in that: The trigger circuit comprises: A voltage regulator tube, wherein an anode of the voltage regulator tube is electrically connected to a ground terminal; and A first current limiting resistor, one end of the first current limiting resistor is electrically connected to the cathode of the voltage regulator tube, and the other end of the first current limiting resistor is electrically connected to the positive output end of the vehicle-mounted auxiliary power supply.

9. The clamping discharge circuit according to claim 8, characterized in that: The trigger circuit comprises: a first voltage-dividing resistor, one end of which is electrically connected to the positive output end of the vehicle-mounted auxiliary power supply; and A second voltage-dividing resistor, one end of the second voltage-dividing resistor is electrically connected to the other end of the first voltage-dividing resistor, the other end of the second voltage-dividing resistor is electrically connected to the ground end, and the control end of the voltage-regulating diode is electrically connected to the common end of the first voltage-dividing resistor and the second voltage-dividing resistor.

10. A vehicle-mounted auxiliary power supply, characterized in that: The on-vehicle auxiliary power supply is implemented by a flyback converter, and the clamping discharge circuit as claimed in claim 1 is connected in parallel to the output load at the output end of the on-vehicle auxiliary power supply.

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