New 492V/3A charger circuit diagram principle

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Overview:
Introduction The early chargers used single-phase mains rectification and then BUCK circuit buck output form, so when charging the 492V battery pack, two charger units are required to work in series. The structure input of the charger is to be isolated by a transformer, so the volume is large; the failure rate is high in the series; in actual production, the assembly is also inconvenient. In this case, we designed the new charger mentioned in this article.

1 Circuit Schematic The whole system consists of an input unit, a DC conversion unit, a control unit and an output unit. The input unit is a three-phase zero-free mains power; the DC conversion unit uses a double-tube BUCK-BOOST. The circuit can adapt to a wide range of changes from 304 to 456V. The control unit adopts a power supply dedicated current type PWM chip UC3843, which controls the on/off of the switch tube and adjusts the output voltage by detecting the output voltage and current signals; the output unit is composed of a power diode and a filter capacitor. A schematic diagram of its system block is shown in Figure 1.

Figure 2 is a schematic diagram of the main circuit of the charger. The three-phase mains output is smooth DC after uncontrolled rectification and filtering. The BUCK-BOOST circuit of the DC/DC conversion part adopts an unsimplified double-tube circuit. Compared with the single-tube topology, the first one is to withstand the tube. The voltage is reduced by half, and the second is to make the circuit design of short circuit protection and overcurrent protection easier. R1 and R2 are sampling resistors that can be selected based on the peak current across the inductor to ensure that the voltage across it is less than 1V. S1 and S2 select 800V/27A MOS FET, D1 and D2 select 1200V/15A soft recovery power rectifier diode. The inductance L is determined according to the output power of the system.

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