Electric vehicle maintenance method

Wuxi electric vehicle manufacturer reminds the maintenance method: first use a multimeter to check whether the high-voltage DC filter capacitor has deteriorated, whether the capacity has decreased, and whether it can be charged and discharged normally. If there are no above problems, measure the current limiting resistance of the electrode of the switching power tube and the over-current protection of the source electrode, and measure whether the resistance changes value, deteriorates or opens welding and poor contact. If there is no problem, check - whether the iron core of the high-frequency transformer is intact. In addition Z, it is also possible to reduce the output filter capacitor capacity, or open welding or virtual connection; The output current limiting resistance of the power supply is changed or falsely connected; Virtual connection of power output line, etc.

We should not let go of these difficulties. We should carefully check them and ensure that there is no loss.

The cooling fan does not work: this fault is mainly caused by the damage of the triode (generally 8550 or 8050) controlling the fan, or the damage of the fan itself or the blockage of the fan blade by sundries. However, some chargers apply for intelligent heat dissipation. For chargers that use this way of heat dissipation, the probability of thermistor damage is very high.

Maintenance method: first use a multimeter to measure whether the triode controlling the fan is damaged. If the tube is not damaged, it may be the fan itself. Pull the fan off the circuit board and connect a 12V DC (pay attention to the positive and negative poles) to see whether it rotates and whether there is foreign matter stuck. If the fan rotates when the wire of the fan is swung, it indicates that there is a broken wire or poor contact of the connector in the wire. If it still does not turn, the fan will break down. For chargers with intelligent heat dissipation, in addition to the above inspection, check whether the thermistor is in poor contact or damaged, open welding, etc. However, it should be noted that the thermistor has a negative temperature coefficient, which should be noted during replacement.

Maintenance method: because the charger has an overvoltage protection circuit, the overvoltage protection circuit will act first if the output voltage is too high. Therefore, in case of such fault, we can disconnect the overvoltage protection circuit to make the overvoltage protection circuit inoperative, and then measure the main voltage of the power supply at the moment of startup. If the measured value is more than 1V higher than the normal value, it indicates that the reason for the high output voltage is indeed in the control loop.

At this time, check whether the sampling resistance changes value or is damaged, and whether the precision reference voltage source (TL431) or optocoupler (PC817) of the electric vehicle manufacturer has poor performance, deterioration or damage. Among them, the precision reference voltage source (TL431) is very easy to be damaged. We can judge the precision voltage stabilizing amplifier by the following methods: connect the reference end (Ref) of TL431 with its cathode (cathode), connect the resistance of 1ok Ω in series, and connect 5 ∨ voltage. If the voltage between anode and cathode is 2.5V, and the waiting time is still 2.5 ∨, it is a good tube, otherwise it is a bad tube.