Research and Implementation of Step High Voltage Constant Current Closed-Loop Pre-Charging Technology

In the past, the mode of contactor and current limiting resistor is generally used for high voltage pre-charging of electric vehicle, which is simple in structure and easy to realize. Besides, the integration degree of this mode is low. It needs to cooperate with external independent voltage sensor to realize over-voltage monitoring and current sensor to realize over-current protection, so its volume is large, its cost is high and its informatization degree is low. In this paper, the capacitive load pre-charging technology in the high voltage power supply system of electric vehicle is studied specially. The step type constant current charging circuit and proportional-integral-derivative (PID) control method are designed by using the constant current source technology of metal-oxide-semiconductor field-effect transistor (MOSFET), and the practical engineering application is carried out. The practice shows that this method can better realize the pre-charging control of the high voltage system of the electric vehicle, and provide a strong support for the modularization, integration and information design of the high voltage system.