The charger manufacturer tells you whether the electric car charger can be repaired

Fault: a brand electric car charger, model DZM602000, the green light is not on when the power is switched on, the red light is not on when the battery of the electric car is switched on, unable to charge.

Maintenance: According to the fault phenomenon, it is preliminarily judged that the high voltage loop stops vibration, resulting in no output of secondary low voltage. For the convenience of analysis, draw the schematic diagram of the charger (as shown in the figure below) for reference.

Measure the operating voltage of the power-up base point: Drive pin 1 of the high-voltage part IC1 is 2.9V, normal; The low-voltage part is isolated by SCR, and the output voltage cannot be measured, but the voltage at both ends of the measured capacitor C8 is 0V. After measuring the voltage at both ends of the auxiliary power filter capacitor C6, it can be seen that the high voltage circuit does not begin to vibrate. Then what causes the high voltage to stop vibrating? Thus, the external 15V power supply is connected to both ends of the C6. At this point, the external 15V voltage is limited by the resistor RX(222) and the voltage of Z1 is stabilized to obtain 5V. When one pin of PD532 is powered on, 7 pins should output high levels. The green light is supposed to be on, but it's not.

At this time, key point voltage is measured: pin 8 of comparator AS358 is 15V, normal; The voltage at the first pin of PD532 is 0V abnormal. It is judged that Z1 is short circuit, but the welding end of Z1 is well measured. Then, measure PD532 pin 1 ground short circuit, confirm PD532 damage. PD532 is electric car charger dedicated MCU, Taobao can not buy. So, with the idea of giving it a try, we took the following emergency measures to fix it.

First, weld off the No. 8 pin of PD532(suspended), connect the positive terminal of Z1 to the No. 7 pin of PD532, and then connect the 15V power supply after welding, start and debug. At this time, the green light of LED1 immediately lights up, and it is normal to measure the voltage at both ends of C8 around 70V (no load). The voltage at both ends of C6 is 15V, indicating that the high voltage circuit is in good condition. The reason is that PD532 is damaged, so the information of the low voltage circuit cannot be fed back to the high voltage. As a result, the high voltage stops oscillating. After the test electric vehicle is charged and the battery is connected, the IC4 thyristor is triggered to switch on by the remaining battery voltage. At this time, the upper potential of the current detection resistor R5 increases and pin 3 of the voltage comparator AS358 becomes high. Comparator A internal rotation, pin 1 output high level, Q1 on, fan normal operation. But LED2(red light) is still off. It is estimated that because PD532 is broken, it can not automatically control the switch of red light and green light, and can not realize the function of battery charging saturation and stop. However, as an emergency treatment, only the LED2 should be welded off, the current limiting resistance should be connected in series, and the cooling fan should be connected in parallel (as shown in the dotted line in the attached figure), so that the LED2 and the fan can be switched on and off synchronously, so that the red light indicates that they are charging. However, the green light of LED1 can only be on all the time, which will not affect the charging. After the above treatment, the emergency charging is normal, but the automatic function is lost.

Warm tips: Remember manual control, avoid overcharging, damage to the battery.