Principle and Maintenance of Electric Vehicle Instrument

Commonly used electric vehicle instrument function description

Power indicator indicates that the power of the vehicle has been turned on

Battery voltage Use light-emitting diode or voltmeter to indicate battery voltage

Undervoltage indication indicates whether the battery is below the normal use value

Overcurrent indication indicates that the current running current of the motor exceeds the maximum allowable continuous supply

Motor current Display the current of the motor running

Driving speed Current vehicle speed (km/h)

Lamp indicator indicates whether the headlights, left and right turn signals, and brake lights are working

Cumulative mileage Indicates the cumulative mileage of electric vehicles

This mileage The number of kilometers traveled this time

Driving time The time (hours, minutes, seconds) of this power-on driving

Current temperature The ambient temperature currently in use

1. Pointer instrument

      1. Structure and principle

    This type of instrument includes: the cumulative mileage displayed by a 6-digit digital code dial meter, the vehicle speed indicator indicator (km/h) speed, battery voltage indicator indicator battery voltage (volt), headlight indicator, left and right turn signal indicator And other content.

        The cumulative mileage digital meter is 6 "decimal" gear counters, and the vehicle speed indicator is a damped tachometer. They share a speed input signal for conversion and realize their respective indicating functions through mechanical transmission.

The voltage pointer meter is an ordinary 50 volt DC voltmeter head.

        2. Fault detection and repair

        The integration of pointer type instruments is relatively low, the wiring of the circuit is relatively simple, and the instrument circuit does not depend on the controller circuit and can work independently.

        The faults of mechanical instruments are mainly lead or instrument head faults. When disassembling and assembling the instrument, it is necessary to pay special attention to the positive and negative poles of the power supply not to be mistaken. The flasher is to provide the turning bulb gap voltage so that the turning bulb can flash. The pin marked B of the flasher shell means positive (Battery) and L means negative (Light), and you can not connect it wrongly.

2. LCD instrument

        1. Structure and principle

        The switching signal of the dedicated Hall sensor is transmitted to the single-chip microcomputer on the liquid crystal display instrument assembly. The number of wheel rotations per unit time can be counted to calculate the driving speed of the whole vehicle. The driving speed and the driving time can be multiplied by Calculate the accumulated mileage of the vehicle.

        Some brushless motor controllers use a single-chip microcomputer as the decoding chip, which can directly calculate the motor speed and accumulated mileage and send them to the liquid crystal display instrument. There is no single-chip microcomputer in this liquid crystal display instrument assembly.

        Liquid crystal display instruments are best at the digital and accurate display of various data (such as speed, battery voltage, mileage, riding time, ambient temperature, etc.), so that the operator can see the precise value at a glance, but this kind of instrument The disadvantage is that the ability to resist sunlight and ultraviolet radiation is poor, and the environment temperature requirements for use are high, so the liquid crystal display instrument cannot be exposed to the sun for a long time, and can only be used at an ambient temperature of -10--40°C. Long-term use in a high temperature or low temperature environment will cause irreversible damage to the LCD screen, so that the display value of the LCD screen will be blurred until it cannot be displayed.

        2. Fault detection and maintenance

        The circuit of this kind of instrument is complicated, and the failure rate is relatively high. Some liquid crystal instrument circuits can work independently without relying on the controller circuit, and some liquid crystal instruments must rely on the digital signal of the microcontroller in the controller to work. As the software of the display driver and the model of the single-chip microcomputer are involved, once this kind of instrument fails, the instrument assembly can only be replaced. In an emergency, the lead wires of the handlebar and brake handle can be directly supplied to the controller.

Three, LED instrument

        1. Structure and principle

        The circuit of the LED indicator is an electronic circuit, which is separated from the circuit of the vehicle lamp.

        The LED simulation indicates the high, medium and low battery voltage and whether the battery is undervoltage. Its accuracy is relatively high, the price is cheap, and it is currently widely used in electric vehicle meters.

       2. Fault detection and repair

        The signal acquisition and signal processing of the light-emitting diode instrument use digital digital logic chips, and the circuit does not depend on the controller circuit and can work independently. In some electric vehicles, the signals of the handlebar and brake handle are transferred through the dashboard and then output to the controller. In an emergency, the lead wires of the handlebar and brake handle can be directly supplied to the controller.