National service hotlineThe 220v AC is filtered by T0 bidirectional filtering to suppress interference. The D1 rectifier is pulsed DC, and then filtered by C11 to form stable DC of about 300V. U1 is a TL3842 PWM integrated circuit. Pin 5 is the negative electrode of the power supply, pin 7 is the positive electrode of the power supply, pin 6 is the pulse output direct drive field effect tube Q1(K1358) and pin 3 is the large current limit. The large current of the charger can be adjusted by adjusting the resistance value of R25(2.5 ohm). Pin 2 is voltage feedback, which can adjust the output voltage of the charger. The 4-pin external oscillation resistor R1 and oscillation capacitor C1 are connected. T1 is a high-frequency pulse transformer, which has three functions.
It depresses a high voltage pulse to a low voltage pulse.
The second is to play the role of high voltage isolation, to prevent electric shock.
The third is to provide working power for uc3842. D4 is the high-frequency rectifier tube (16A60V), C10 is the low-voltage filter capacitor,D5 is the 12V voltage regulator diode, U3(TL431) is the precision reference voltage source, with U2(optical coupler 4N35) to automatically adjust the charger voltage. Adjust w2(trimmer resistance) to fine-tune the charger voltage. D10 is the power indicator. D6 is the charging indicator.
Electric car charger schematic diagram
R27 is the current sampling resistance (0.1 ohm, 5w). Changing the resistance value of W1 can adjust the inflection point current of the charger float charge (200-300 mA). At the beginning of power-up, there is about 300v voltage on C11. This voltage is applied all the way through T1 to Q1.
The second route passes R5,C8,C3, and reaches the seventh leg of U1. Force U1 to start. Pin 6 of U1 emits square wave pulses, Q1 operates, and electricity flows through R25 to the ground. At the same time, T1 secondary coil generates induced voltage, and D3,R12 provides a reliable power supply to U1. The voltage of T1 output coil is rectified and filtered by D4 and C10 to obtain a stable voltage. This voltage charges the battery along the way through D7, which prevents the battery's current from flowing back into the charger.
Electric car charger schematic diagram
The second route, through R14,D5,C9, provides 12V power supply for the LM358(dual operational amplifier, pin 1 as power ground, pin 8 as power positive) and its peripheral circuit. D9 provides reference voltage for LM358, and the partial voltage of R26 and R4 reaches the second and fifth pins of LM358. During normal charging, there is a voltage of 0.15-0.18V at the upper end of R27. This voltage is added to the third pin of LM358 by R17, and a high voltage is sent from pin 1. This voltage goes all the way through R18, forcing Q2 to turn on, D6 (red light) to light up, the second way infuses pin 6 of LM358, pin 7 outputs low voltage, forcing Q3 to turn off, D10(green light) to turn off, and the charger enters the constant current charging stage. When the battery voltage rises to about 44.2V, the charger enters the constant-voltage charging stage, the output voltage is maintained at about 44.2V, the charger enters the constant-voltage charging stage, and the current gradually decreases. When the charging current decreases to 200mA -- 300mA, the voltage at the upper end of R27 drops, the voltage of pin 3 of LM358 is lower than pin 2, pin 1 outputs low voltage, Q2 is turned off, and D6 is turned off. At the same time, pin 7 outputs a high voltage, which makes Q3 turn on and D10 turn on. The other route goes through D8, W1 to the feedback circuit, which reduces the voltage. The charger enters the trickle charging phase. The charge ends after 1-2 hours.