Abnormal operation protection method and protection circuit for low-speed electric vehicle control system

Abstract

The invention discloses a low-speed electric vehicle control system abnormal operation protection method and a protection circuit thereof, if a relay is disconnected, a low-speed electric vehicle loses power; power of the low-speed electric vehicle comes from a motor, a power-down brake is installed on a motor shaft, the power-down brake is attracted after power down, the motor shaft is locked, and parking braking force is formed by the low-speed electric vehicle. In a normal mode, the MCU and the PWM output high and low level overturning signals through software sequentially executed by the MCU instead of an MCU peripheral, and the relay driving circuit and the power-down brake driving circuit are driven normally; in the abnormal mode, when the MCU works abnormally, if the MCU.PWM outputs a high-low level overturning signal abnormally, the relay driving circuit loses driving and is released, so that the vehicle loses power and slows down, and the power-down brake driving circuit is powered down, so that the brake acts, and the vehicle is parked. According to the invention, the problem of abnormal operation of the MCU can be effectively solved and prevented, and the overall prevention and control cost can be reduced.

Description

Technical Field

[0001] The present invention relates to a low-speed electric vehicle control system, and in particular to a low-speed electric vehicle control system abnormal operation protection method used in the low-speed electric vehicle control system. Background Art

[0002] Low-speed electric vehicles (such as electric wheelchairs, electric scooters, golf carts, golf carts, and electric tricycles) generally refer to vehicles or auxiliary tools used for the purpose of transportation. The control system of low-speed electric vehicles usually requires the use of MCU microcontroller chips or MCU single-chip microcomputer chips for integrated control of their control systems. MCU chips are key components of the electric control system of low-speed electric vehicles. Once the MCU enters abnormal operation, it is easy to directly cause the electric control system of the low-speed electric vehicle to enter a shutdown mode, which is easy to cause safety hazards to the low-speed electric vehicle. The existing protection mode to prevent abnormal operation of the MCU generally adopts a watchdog or a multi-chip redundant design to protect against abnormal operation such as MCU freeze. However, this also brings about the problem of increased overall control costs of the low-speed electric vehicle control system. Summary of the Invention

[0003] The present invention aims to solve the problem that the key component MCU of the existing low-speed electric vehicle control system enters abnormal operation, which may cause safety risks such as driving, and to solve the current situation of high control costs for preventing abnormal operation of the MCU. It provides a low-speed electric vehicle control system abnormal operation protection method that can effectively solve the problem of preventing the MCU from entering abnormal operation and reduce the overall prevention and control costs.

[0004] The specific technical solution adopted by the present invention to solve the above technical problems is: a method for protecting a low-speed electric vehicle control system from abnormal operation, comprising the following abnormal operation protection steps: A1. The DC bus circuit of the low-speed electric vehicle control system is connected to the battery via a relay. If the relay is disconnected, the low-speed electric vehicle will lose power. The low-speed electric vehicle's power comes from the motor, which has a power-off brake installed on its shaft. When power is lost, the power-off brake engages, locking the motor shaft and applying parking force to the low-speed electric vehicle. A2. In normal mode, the MCU chip's PWM port outputs the MCU.PWM signal. This signal is generated by software, not by the MCU chip's peripheral circuits. The relay drive circuit and power-off brake drive circuit operate normally. A3. In abnormal mode, when the MCU chip enters abnormal operation, if the PWM port of the MCU chip abnormally outputs high and low level flipping signals, the relay drive circuit loses drive and releases, causing the vehicle to lose power and slow down. The power-off brake drive circuit loses power, causing the brake to apply and the vehicle to enter parking.

[0005] The combination of software and hardware enables the system to enter protective shutdown mode after the MCU enters abnormal operation, reducing safety risks. It can not only effectively solve the problem of preventing the MCU from entering abnormal operation, but also reduce the overall prevention and control costs.

[0006] Preferably, in step A2, the PWM port output signal of the MCU chip is converted via the first capacitor, the first diode, the second capacitor, the first resistor, and the second resistor to form a driving voltage for the first MOS transistor. This voltage is insufficient to drive the first MOS transistor, causing the first MOS transistor to be cut off, and the relay drive circuit and the power-off brake drive circuit can be normally driven by the DRV1 and DRV2 function ports of the MCU chip. This improves the effectiveness of the simple protection that the relay drive circuit and the power-off brake drive circuit can be normally driven by the DRV1 and DRV2 function ports of the MCU chip in normal mode.

[0007] Preferably, in step A3, when the MCU chip enters abnormal operation, if the PWM port of the MCU chip abnormally outputs a high-low level flipping signal, the MCU chip's DR1 function port and the fifth resistor, and the MCU chip's DR2 function port and the sixth resistor, respectively, conduct the first MOS transistor via the second diode, causing the relay drive circuit to lose drive and release, causing the vehicle to lose power and decelerate, and the power-off brake drive circuit to lose power, causing the brake to actuate and the vehicle to enter parking. This improves the simplicity and effectiveness of the protection mechanism in abnormal mode, in which the relay drive circuit loses drive and releases, causing the vehicle to lose power and decelerate, and the power-off brake drive circuit loses power, causing the brake to actuate and the vehicle to enter parking.

[0008] Another object of the present invention is to provide an abnormal operation protection circuit for a low-speed electric vehicle control system, comprising an MCU chip, a first capacitor connected in series to a PWM port of the MCU chip, the other end of the first capacitor connected in series to a first diode, the first diode connected in series to a first resistor and then electrically connected to the gate of a first MOS tube, the source of the first MOS tube is electrically connected to the circuit power ground, the drain of the first MOS tube is connected in series to a third resistor and then electrically connected to the positive electrode of the circuit power supply, the gate of the first MOS tube is connected in series to a second resistor and then electrically connected to the positive electrode of the circuit power supply; the drain of the first MOS tube is connected in series to the cathode of a second diode, the anode of the second diode is connected in series to a fifth resistor and then electrically connected to the DRV1 function port of the MCU chip, the anode of the second diode is electrically connected to the drive control end of the relay drive circuit, the drive output control end of the relay drive circuit is electrically connected to the DC bus relay coil; the anode of the second diode is connected in series to a sixth resistor and then electrically connected to the DRV2 function port of the MCU chip, the anode of the second diode is electrically connected to the drive control end of the power-off brake drive circuit, the drive output control end of the power-off brake drive circuit is electrically connected to the power-off brake. The operation protection circuit is simple and effective. When the MCU enters abnormal operation, the system enters the protection shutdown mode to reduce safety risks. It can not only effectively solve the problem of preventing the MCU from entering abnormal operation, but also reduce the overall prevention and control costs.

[0009] Preferably, the drain of the first MOS transistor is connected in series with a fourth resistor and then electrically connected to the INT function port of the MCU chip. The INT function port can trigger the abnormal interrupt protection of the MCU. In the interrupt service routine, the software can handle the abnormal event and perform corresponding protection processing.

[0010] Preferably, the second diode is formed by connecting two diodes in parallel, with the cathodes of the two diodes connected in parallel and the anodes of the two diodes connected in parallel. This improves the effectiveness of using the second diodes to conduct the first MOS transistors, thereby increasing the simplicity and effectiveness of releasing the relay drive circuit when it loses drive, causing the vehicle to lose power and slow down, and increasing the simplicity and effectiveness of applying the brake when the power-off brake drive circuit loses power, causing the vehicle to enter a parking position.

[0011] Preferably, the first diode is formed by connecting two diodes in parallel, with the cathodes and anodes of the two diodes electrically connected in anti-parallel, wherein the anode of one of the parallel diodes is electrically connected to the first resistor, and a second capacitor is connected in parallel with the circuit power ground, wherein the cathode of one of the parallel diodes is electrically connected to the circuit power ground. This improves the efficiency of controlling the first MOS transistor to be cut off in normal mode, and improves the efficiency of the relay drive circuit and the power-off brake drive circuit being normally driven by the MCU.DRV1 and MCU.DRV2 functional ports of the MCU chip.

[0012] The beneficial effects of the present invention are: the combination of software and hardware enables the system to enter a protection shutdown mode after the MCU enters abnormal operation, thereby reducing safety risks; it can effectively solve the problem of preventing the MCU from entering abnormal operation and reduce the overall prevention and control costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a circuit structure diagram of the abnormal operation protection method of the low-speed electric vehicle control system of the present invention. DETAILED DESCRIPTION

[0014] Example 1: Figure 1 In the embodiment shown, a method for protecting a low-speed electric vehicle control system from abnormal operation includes the following abnormal operation protection steps: A1. The DC bus circuit of the low-speed electric vehicle control system is connected to the battery via a relay. If the relay is disconnected, the low-speed electric vehicle will lose power. The low-speed electric vehicle's power comes from the motor, which has a power-off brake installed on its shaft. When power is lost, the power-off brake engages, locking the motor shaft and applying parking force to the low-speed electric vehicle. A2. In normal mode, the MCU chip's PWM port outputs the MCU.PWM signal. This signal is generated by software, not by the MCU chip's peripheral circuits. The relay drive circuit and power-off brake drive circuit operate normally. A3. In abnormal mode, when the MCU chip enters abnormal operation, if the PWM port of the MCU chip abnormally outputs high and low level flipping signals, the relay drive circuit loses drive and releases, causing the vehicle to lose power and slow down. The power-off brake drive circuit loses power, causing the brake to apply and the vehicle to enter parking.

[0015] In the above step A2, the PWM port output signal of the MCU chip forms a driving voltage for the first MOS tube through the first capacitor, the first diode, the second capacitor, the first resistor and the second resistor. This voltage is insufficient to drive the first MOS tube, and the first MOS tube is cut off. The relay drive circuit and the power-off brake drive circuit can be driven normally by the MCU.DRV1 function port and the MCU.DRV2 function port of the MCU chip.

[0016] In the above step A3, when the MCU chip enters abnormal operation, if the PWM port of the MCU chip abnormally outputs a high or low level flip signal, the DR1 function port of the MCU chip and the fifth resistor, as well as the DR2 function port of the MCU chip and the sixth resistor respectively turn on the first MOS tube through the second diode, the relay drive circuit loses drive and is released, causing the vehicle to lose power and slow down, and the power-off brake drive circuit loses power, causing the brake to operate and the vehicle to enter parking.

[0017] Example 2 Figure 1 In the embodiment shown, a low-speed electric vehicle control system abnormal operation protection circuit includes an MCU chip, a PWM port of the MCU chip is connected in series with a first capacitor, the other end of the first capacitor is connected in series with a first diode D1, the first diode D1 is connected in series with a first resistor R1 and then electrically connected to the gate of a first MOS transistor Q1, the source of the first MOS transistor Q1 is electrically connected to the circuit power ground GND, the drain of the first MOS transistor Q1 is connected in series with a third resistor R3 and then electrically connected to the positive electrode +5V of the circuit power supply, the gate of the first MOS transistor Q1 is connected in series with a second resistor R2 and then electrically connected to the positive electrode of the circuit power supply; the first MOS transistor Q The drain of diode D1 is connected in series with the cathode of diode D2. The anode of diode D2 is connected in series with resistor R5 and then electrically connected to the DRV1 function port of the MCU chip. The anode of diode D2 is connected in series with resistor R6 and then electrically connected to the DRV2 function port of the MCU chip. The anode of diode D2 is connected in series with resistor R6 and then electrically connected to the DRV2 function port of the MCU chip. The anode of diode D2 is connected in series with resistor R6 and then electrically connected to the DRV2 function port of the MCU chip. The anode of diode D2 is connected in series with resistor R4 and then electrically connected to the INT function port of the MCU chip. The INT function port can trigger the MCU's abnormal interrupt protection. In the interrupt service routine, software can handle abnormal events and perform corresponding protection operations. The second diode D2 is composed of two diodes connected in parallel, with the cathodes of the two diodes connected in parallel and the anodes of the two diodes connected in parallel. The first diode D1 is formed by connecting two diodes in parallel, with the cathodes and anodes of the two diodes electrically connected in antiparallel. The anode of one of the parallel diodes is electrically connected to the first resistor. A second capacitor C2 is connected in parallel with the circuit power ground, with the cathode of one of the parallel diodes electrically connected to the circuit power ground GND. The positive electrode of the circuit power supply is +5V.

Claims

1. A method for protecting a low-speed electric vehicle control system from abnormal operation, characterized in that The abnormal operation protection steps include the following: A1. The DC bus circuit of the low-speed electric vehicle control system is connected to the battery via a relay. If the relay is disconnected, the low-speed electric vehicle will lose power. The low-speed electric vehicle's power comes from the motor, which has a power-off brake installed on its shaft. When power is lost, the power-off brake engages, locking the motor shaft and applying parking force to the low-speed electric vehicle. A2. In normal mode, the MCU chip's PWM port outputs the MCU.PWM signal. This signal is generated by software, not by the MCU chip's peripheral circuits. The relay drive circuit and power-off brake drive circuit operate normally. A3. In abnormal mode, when the MCU chip enters abnormal operation, if the MCU.PWM port of the MCU chip abnormally outputs high and low level flipping signals, the relay drive circuit loses drive and releases, causing the vehicle to lose power and slow down. The power-off brake drive circuit loses power, causing the brake to apply and the vehicle to enter parking.

2. The abnormal operation protection method for a low-speed electric vehicle control system according to claim 1, characterized in that: In the above step A2, the PWM port output signal of the MCU chip forms a driving voltage for the first MOS tube through the first capacitor, the first diode, the second capacitor, the first resistor and the second resistor. This voltage is insufficient to drive the first MOS tube, and the first MOS tube is cut off. The relay drive circuit and the power-off brake drive circuit can be driven normally by the MCU.DRV1 function port and the MCU.DRV2 function port of the MCU chip.

3. The abnormal operation protection method for a low-speed electric vehicle control system according to claim 1, characterized in that: In the above step A3, when the MCU chip enters abnormal operation, if the MCU.PWM port of the MCU chip abnormally outputs a high or low level flip signal, the MCU.DRV1 function port of the MCU chip and the fifth resistor, as well as the MCU.DRV2 function port of the MCU chip and the sixth resistor respectively turn on the first MOS tube through the second diode, the relay drive circuit loses drive and is released, causing the vehicle to lose power and slow down, and the power-off brake drive circuit loses power, causing the brake to operate and the vehicle to enter parking.

4. A low-speed electric vehicle control system abnormal operation protection circuit, including an MCU chip, characterized by: The PWM port of the MCU chip is connected in series with the first capacitor, the other end of the first capacitor is connected in series with the first diode, the first diode is connected in series with the first resistor and then electrically connected to the gate of the first MOS tube, the source of the first MOS tube is electrically connected to the circuit power ground, the drain of the first MOS tube is connected in series with the third resistor and then electrically connected to the positive electrode of the circuit power supply, the gate of the first MOS tube is connected in series with the second resistor and then electrically connected to the positive electrode of the circuit power supply; the drain of the first MOS tube is connected in series with the cathode of the second diode, the anode of the second diode is connected in series with the fifth resistor and then electrically connected to the DRV1 function port of the MCU chip, the anode of the second diode is electrically connected to the drive control end of the relay drive circuit, and the drive output control end of the relay drive circuit is electrically connected to the DC bus relay coil; the anode of the second diode is connected in series with the sixth resistor and then electrically connected to the DRV2 function port of the MCU chip, the anode of the second diode is electrically connected to the drive control end of the power-off brake drive circuit, and the drive output control end of the power-off brake drive circuit is electrically connected to the power-off brake.

5. The abnormal operation protection circuit of the low-speed electric vehicle control system according to claim 4, characterized in that: The drain of the first MOS tube is connected in series with a fourth resistor and then electrically connected to the INT function port of the MCU chip.

6. The abnormal operation protection method for a low-speed electric vehicle control system according to claim 1, characterized in that: The second diode is formed by connecting two diodes in parallel, and the cathodes of the two diodes are connected in parallel, and the anodes are connected in parallel.

7. The abnormal operation protection circuit of the low-speed electric vehicle control system according to claim 4, characterized in that: The first diode is formed by connecting two diodes in parallel, and the cathodes and anodes of the two diodes are electrically connected in reverse parallel to each other, wherein the anode of one of the parallel diodes is electrically connected to the first resistor, and the second capacitor is connected in parallel with the circuit power ground, wherein the cathode of one of the parallel diodes is electrically connected to the circuit power ground.

Images