A multi-stage overvoltage protection circuit for low-voltage power units on vehicles

Abstract

The present invention relates to the field of protection circuit technology, and discloses a multi-level overvoltage protection circuit for a low-voltage electric unit on a vehicle, including a normal power voltage detection module P1, a normal power voltage hardware overvoltage protection module P2 and a controlled power voltage detection module P3. The low-voltage continuous power supply interface KL30 of the vehicle high-voltage power supply system is connected to the normal power voltage detection module P1, the normal power voltage detection module P1 is connected to the normal power voltage hardware overvoltage protection module P2, and the normal power voltage hardware overvoltage protection module P2 is also connected to the controlled power voltage detection module P3 and supplies power to the subsequent power equipment. By superimposing a small number of discrete devices on the MOS back-to-back anti-reverse topology, a multi-level overvoltage protection function is realized, including a normal power voltage detection module, a normal power voltage hardware overvoltage protection module, and a controlled power voltage detection module, including a normal power voltage hardware overvoltage protection module, and having a protection function of an adjustable overvoltage threshold at a hardware-level speed.

Description

Technical Field

[0001] The present invention relates to the technical field of protection circuits, and in particular to an overvoltage multi-stage protection circuit for a vehicle-mounted low-voltage power unit. Background Art

[0002] With the tremendous development of my country's new energy vehicle industry, the proportion of internal electrical equipment has gradually increased, and low-voltage electrical equipment is often used as the logic processing unit of the car. Therefore, the comprehensiveness and reliability of the hardware protection of the power supply inlet circuit of the low-voltage electrical equipment is one of the important factors affecting whether the car can maintain a safe operating state; In the product design process of existing on-board low-voltage electrical equipment, the overvoltage protection function faces many challenges. From the perspective of low power consumption and hardware cost, the overvoltage protection function design is currently relatively simple. This simple design makes it difficult to fully guarantee the safety of the product in actual applications. Usually, the low-voltage overvoltage protection function mainly relies on software implementation, that is, the software is used to detect whether there is an overvoltage situation. However, software-level protection has obvious limitations. The software detects overvoltage relatively slowly and may not be able to respond in time when overvoltage occurs, thereby affecting the protection effect on the electrical unit. In addition, there are certain problems with the reliability of the software. It is easily affected by factors such as program failures and electromagnetic interference, and cannot provide overvoltage protection stably. At the same time, if the low-voltage overvoltage protection function is to be fully considered, it is often necessary to add an integrated circuit module with overvoltage protection function. Although this can improve the protection effect, it will inevitably lead to a significant increase in hardware costs. Summary of the invention

[0003] The object of the present invention is to provide a multi-stage overvoltage protection circuit for a vehicle-mounted low-voltage power unit, which can effectively solve the problems in the background technology.

[0004] To achieve the above object, the technical solution adopted by the present invention is: A multi-stage overvoltage protection circuit for a low-voltage power unit on a vehicle, comprising a normal power voltage detection module P1, a normal power voltage hardware overvoltage protection module P2 and a controlled power voltage detection module P3, wherein a low-voltage continuous power supply interface KL30 of a high-voltage power supply system on a vehicle is connected to the normal power voltage detection module P1, the normal power voltage detection module P1 is connected to the normal power voltage hardware overvoltage protection module P2, and the normal power voltage hardware overvoltage protection module P2 is also connected to the controlled power voltage detection module P3 and supplies power to subsequent power equipment; The constant voltage detection module P1 also includes a PMOS transistor Q1, an NMOS transistor Q2, a resistor R1, a resistor R2, resistors R3, R4 and a capacitor C1; The normal voltage hardware overvoltage protection module P2 also includes a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a PNP transistor Q4, an NMOS transistor Q5, a diode D1, and a diode D2; The controlled voltage detection module P3 further includes a resistor R10, a resistor R11 and a capacitor C2.

[0005] As a further preferred embodiment of the present invention, the low-voltage continuous power supply interface KL30 of the vehicle-mounted high-voltage power supply system is connected to the source of the PMOS tube Q1 and one end of the resistor R1, the low-voltage ground interface KL31 of the vehicle-mounted high-voltage power supply system is connected to one end of the resistor R2, the other end of the resistor R1 is connected to the source of the PMOS tube Q1, the other end of the resistor R2 is connected to the drain of the NMOS tube Q2, one end of the resistor R3 is connected to the gate of the PMOS tube Q1, and the other end of the resistor R3 is connected to R4, one end of R4 is also connected to the low-voltage analog ground interface AGND of the vehicle-mounted high-voltage power supply system, and a capacitor C1 is also connected between the resistor R3 and the low-voltage analog ground interface AGND of the vehicle-mounted high-voltage power supply system.

[0006] As a further preferred solution of the present invention, the low-voltage continuous power supply interface KL30 of the vehicle-mounted high-voltage power supply system is also connected to the source of the PMOS tube Q3.

[0007] As a further preferred embodiment of the present invention, one end of the resistor R5 is connected to the drain of the PMOS tube Q3, and the other end is connected to the base of the PNP transistor Q4, one end of the resistor R6 is connected to the emitter of the PNP transistor Q4, one end of the resistor R7 is connected to the collector of the PNP transistor Q4, and the other end is connected to the low-voltage analog ground interface AGND of the vehicle-mounted high-voltage power supply system, one end of the resistor R8 is connected to the vehicle-mounted high-voltage power supply system wake-up electrical interface KL15, and the other end is connected to the anode of the diode D1 and the drain of the NMOS tube Q5, one end of the resistor R9 is connected to the low-voltage analog ground interface AGND of the vehicle-mounted high-voltage power supply system, and the other end is connected to the source of the NMOS tube Q5, the anode of the diode D1 is connected to the vehicle-mounted high-voltage power supply system wake-up electrical interface KL15, and the cathode is connected to the resistor R8, and the diode D2 is connected to one end of the NMOS tube Q5.

[0008] As a further preferred solution of the present invention, the source of the PMOS tube Q6 is connected to the low-voltage continuous power supply interface KL30 of the vehicle-mounted high-voltage power supply system, and the drain is connected to the subsequent power consumption unit.

[0009] As a further preferred embodiment of the present invention, one end of the resistor R10 is connected to the post-stage power consumption unit, and the other end is connected to the resistor R11 and the gate of the PMOS tube Q6. One end of the resistor R11 is connected to one end of the low-voltage analog ground interface AGND of the vehicle-mounted high-voltage power supply system. The capacitor C2 is connected between the resistor R10 and the low-voltage analog ground interface AGND of the vehicle-mounted high-voltage power supply system.

[0010] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, a small number of discrete devices are superimposed on the MOS back-to-back anti-reverse topology to achieve a multi-level overvoltage protection function, including a normal power voltage detection module, a normal power voltage hardware overvoltage protection module, and a controlled power voltage detection module, including a normal power voltage hardware overvoltage protection module, which has a hardware-level speed adjustable overvoltage threshold protection function, greatly improving the comprehensiveness and reliability of the hardware protection of the automotive low-voltage power unit.

[0011] 2. In the present invention, a small number of simple discrete devices are used to add overvoltage multi-level protection logic to the original architecture, which will not destroy the original back-to-back MO anti-reverse and on-off control circuit topology, and a more comprehensive protection function is obtained with extremely low hardware cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the circuit of the present invention. DETAILED DESCRIPTION

[0013] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0014] like Figure 1 As shown, a multi-stage overvoltage protection circuit for a low-voltage electric unit on a vehicle provided by the present invention includes a normal power voltage detection module P1, a normal power voltage hardware overvoltage protection module P2 and a controlled power voltage detection module P3, a low-voltage continuous power supply interface KL30 of the on-board high-voltage power supply system is connected to the normal power voltage detection module P1, the normal power voltage detection module P1 is connected to the normal power voltage hardware overvoltage protection module P2, the normal power voltage hardware overvoltage protection module P2 is also connected to the controlled power voltage detection module P3 and supplies power to the subsequent power equipment; The constant voltage detection module P1 also includes a PMOS tube Q1, an NMOS tube Q2, a resistor R1, a resistor R2, resistors R3, R4 and a capacitor C1; The normal voltage hardware overvoltage protection module P2 also includes a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a PNP transistor Q4, an NMOS transistor Q5, a diode D1, and a diode D2; The controlled voltage detection module P3 further includes a resistor R10, a resistor R11 and a capacitor C2.

[0015] The low-voltage continuous power supply interface KL30 of the on-board high-voltage power supply system is connected to the source of the PMOS tube Q1 and one end of the resistor R1, the low-voltage ground interface KL31 of the on-board high-voltage power supply system is connected to one end of the resistor R2, the other end of the resistor R1 is connected to the source of the PMOS tube Q1, the other end of the resistor R2 is connected to the drain of the NMOS tube Q2, one end of the resistor R3 is connected to the gate of the PMOS tube Q1, the other end of the resistor R3 is connected to R4, one end of R4 is also connected to the low-voltage analog ground interface AGND of the on-board high-voltage power supply system, and a capacitor C1 is also connected between the resistor R3 and the low-voltage analog ground interface AGND of the on-board high-voltage power supply system. The low-voltage continuous power supply interface KL30 of the on-board high-voltage power supply system is also connected to the source of the PMOS tube Q3, one end of the resistor R5 is connected to the drain of the PMOS tube Q3, and the other end is connected to the base of the PNP transistor Q4, one end of the resistor R6 is connected to the emitter of the PNP transistor Q4, and one end of the resistor R7 is connected to the PNP transistor Q4 The collector of the vehicle high-voltage power supply system is connected to the low-voltage analog ground interface AGND of the vehicle high-voltage power supply system. One end of the resistor R8 is connected to the wake-up electrical interface KL15 of the vehicle high-voltage power supply system, and the other end is connected to the anode of the diode D1 and the drain of the NMOS tube Q5. One end of the resistor R9 is connected to the low-voltage analog ground interface AGND of the vehicle high-voltage power supply system, and the other end is connected to the source of the NMOS tube Q5. The anode of the diode D1 is connected to the wake-up electrical interface KL15 of the vehicle high-voltage power supply system, and the cathode is connected to the resistor R8. The diode D2 is connected to one end of the NMOS tube Q5. The source of the PMOS tube Q6 is connected to the low-voltage continuous power supply interface KL30 of the vehicle high-voltage power supply system, and the drain is connected to the subsequent power unit. One end of the resistor R10 is connected to the subsequent power unit, and the other end is connected to the gate of the resistor R11 and the PMOS tube Q6. One end of the resistor R11 is connected to one end of the low-voltage analog ground interface AGND of the vehicle high-voltage power supply system. The capacitor C2 is connected between the resistor R10 and the low-voltage analog ground interface AGND of the vehicle high-voltage power supply system.

[0016] It should be noted that the present invention is a multi-level overvoltage protection circuit for a low-voltage power unit on a vehicle, and the specific principle is as follows: When the vehicle-mounted high-voltage power system wake-up electrical interface KL15 is at a high level, the NMOS tube Q5 is turned on, and the drain potential of the NMOS tube Q5 is grounded. Further, the source and gate potential difference of the PMOS tube Q3 and the PMOS tube Q6 reaches the conduction voltage threshold, and the PMOS tube Q3 and the PMOS tube Q6 are turned on. When the low-voltage continuous power supply interface KL30 of the vehicle-mounted high-voltage power system does not exceed the normal operating voltage range, the emitter and base potential difference of the PNP transistor Q4 does not reach the conduction threshold (the typical threshold value is -0.7V), the PNP transistor Q4 is not turned on, and the hardware overvoltage protection action will not be triggered. The subsequent power consumption unit obtains power input normally. The subsequent power consumption unit includes an MCU (Microcontroller Unit), MCU outputs a normal power voltage monitoring enable signal (DO_KL30_MON1_EN) to the normal power voltage detection module P1, and the normal power voltage detection module P1 outputs a normal power voltage monitoring signal (Ain_KL30_MON1) to the MCU to monitor the normal power voltage value in real time. When the voltage of the low-voltage continuous power supply interface KL30 port of the on-board high-voltage power supply system reaches the overvoltage threshold expected by the program, the MCU will output a low-voltage power supply enable signal (DO_KL30_SWITH_EN) as a low level, and the NMOS tube Q5 enters the off state from the on state, and the drain potential of the NMOS tube Q5 is no longer grounded. Further, the source and gate potential difference of the PMOS tube Q3 and the PMOS tube Q6 begins to be lower than the on-voltage threshold, and the PMOS tube Q3 and the PMOS tube Q6 enter the off state from the on state, and the power supply of the low-voltage continuous power supply interface KL30 of the on-board high-voltage power supply system is shut down, completing the overvoltage protection from the normal power voltage monitoring; The controlled voltage detection module P3 outputs the controlled voltage monitoring (Ain_KL30_MON2) to the MCU to monitor the controlled voltage value in real time. When the voltage of the low-voltage continuous power supply interface KL30 of the vehicle-mounted high-voltage power supply system reaches the overvoltage threshold set by the program, the MCU will output the low-voltage power supply enable signal (DO_KL30_SWITH_EN) as a low level, and the NMOS tube Q5 enters the off state from the on state, and the drain potential of the NMOS tube Q5 is no longer grounded. Further, the source and gate potential difference of the PMOS tube Q3 and the PMOS tube Q6 begins to be lower than the on-voltage threshold, and the PMOS tube Q3 and the PMOS tube Q6 enter the off state from the on state, and the KL30 power supply is shut down, completing the overvoltage protection from the controlled voltage monitoring; When the voltage of the low-voltage continuous power supply interface KL30 of the vehicle high-voltage power supply system exceeds the normal operating voltage range, the potential difference between the emitter and base of the PNP transistor Q4 reaches the conduction threshold (the typical threshold value is -0.7V), and the PNP transistor Q4 is turned on, which will not trigger the hardware overvoltage protection action. The subsequent power consumption unit will disconnect the power supply input, completing the hardware-level overvoltage protection from the normal power voltage hardware self-monitoring; When the voltage at the KL30 port of the low-voltage continuous power supply interface of the vehicle-mounted high-voltage power supply system is within the normal operating range, the circuit is normally turned on under the monitoring of multi-level overvoltage protection to provide the energy required for normal operation of the subsequent power consumption units.

[0017] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A multi-level overvoltage protection circuit for a low-voltage power unit on a vehicle, characterized in that: It includes a normal power voltage detection module P1, a normal power voltage hardware overvoltage protection module P2 and a controlled power voltage detection module P3. The low-voltage continuous power supply interface KL30 of the vehicle-mounted high-voltage power supply system is connected to the normal power voltage detection module P1. The normal power voltage detection module P1 is connected to the normal power voltage hardware overvoltage protection module P2. The normal power voltage hardware overvoltage protection module P2 is also connected to the controlled power voltage detection module P3 and supplies power to the subsequent electrical equipment. The constant voltage detection module P1 also includes a PMOS transistor Q1, an NMOS transistor Q2, a resistor R1, a resistor R2, resistors R3, R4 and a capacitor C1; The normal voltage hardware overvoltage protection module P2 also includes a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a PNP transistor Q4, an NMOS transistor Q5, a diode D1, and a diode D2; The controlled voltage detection module P3 further includes a resistor R10, a resistor R11 and a capacitor C2.

2. The vehicle-mounted low-voltage power unit overvoltage multi-stage protection circuit according to claim 1 is characterized in that: The low-voltage continuous power supply interface KL30 of the vehicle-mounted high-voltage power supply system is connected to the source of the PMOS tube Q1 and one end of the resistor R1, and the low-voltage ground interface KL31 of the vehicle-mounted high-voltage power supply system is connected to one end of the resistor R2, and the other end of the resistor R1 is connected to the source of the PMOS tube Q1, and the other end of the resistor R2 is connected to the drain of the NMOS tube Q2. One end of the resistor R3 is connected to the gate of the PMOS tube Q1, and the other end of the resistor R3 is connected to R4. One end of R4 is also connected to the low-voltage analog ground interface AGND of the vehicle-mounted high-voltage power supply system, and a capacitor C1 is also connected between the resistor R3 and the low-voltage analog ground interface AGND of the vehicle-mounted high-voltage power supply system.

3. The vehicle-mounted low-voltage power unit overvoltage multi-stage protection circuit according to claim 1 is characterized in that: The low-voltage continuous power supply interface KL30 of the vehicle-mounted high-voltage power supply system is also connected to the source of the PMOS tube Q3.

4. The vehicle-mounted low-voltage power unit overvoltage multi-stage protection circuit according to claim 3 is characterized in that: One end of the resistor R5 is connected to the drain of the PMOS tube Q3, and the other end is connected to the base of the PNP transistor Q4. One end of the resistor R6 is connected to the emitter of the PNP transistor Q4. One end of the resistor R7 is connected to the collector of the PNP transistor Q4, and the other end is connected to the low-voltage analog ground interface AGND of the vehicle-mounted high-voltage power supply system. One end of the resistor R8 is connected to the vehicle-mounted high-voltage power supply system wake-up electrical interface KL15, and the other end is connected to the anode of the diode D1 and the drain of the NMOS tube Q5. One end of the resistor R9 is connected to the low-voltage analog ground interface AGND of the vehicle-mounted high-voltage power supply system, and the other end is connected to the source of the NMOS tube Q5. The anode of the diode D1 is connected to the vehicle-mounted high-voltage power supply system wake-up electrical interface KL15, and the cathode is connected to the resistor R8. The diode D2 is connected to one end of the NMOS tube Q5.

5. The vehicle-mounted low-voltage power unit overvoltage multi-stage protection circuit according to claim 4 is characterized in that: The source of the PMOS tube Q6 is connected to the low-voltage continuous power supply interface KL30 of the vehicle-mounted high-voltage power supply system, and the drain is connected to the subsequent power consumption unit.

6. The vehicle-mounted low-voltage power unit overvoltage multi-stage protection circuit according to claim 5 is characterized in that: One end of the resistor R10 is connected to the subsequent power unit, and the other end is connected to the resistor R11 and the gate of the PMOS tube Q6. One end of the resistor R11 is connected to one end of the low-voltage analog ground interface AGND of the vehicle-mounted high-voltage power supply system. The capacitor C2 is connected between the resistor R10 and the low-voltage analog ground interface AGND of the vehicle-mounted high-voltage power supply system.

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