Research on DC Motor Driver in Automobile Electric Power Steering System

摘要

Aiming at the problems of unstable working voltage control of DC motor driver module, low frequency of speed regulating switch, conduction and cut-off delay of FET, a design method of DC motor driver for automotive electric power steering system is proposed. The relationship formula between armature voltage and motor output torque are determined by the mathematical modeling method of equivalent circuit and armature voltage control method, and the corresponding armature voltage and current values under different torque output are calculated. The switching frequency of the system is obtained by the relationship between the current value and the rotating speed. The test results show that the driver designed according to the research scheme can work stably in the current environment of 30a with the cooperation of radiator, and the output voltage of DC drive module is stable under the condition of high, medium and low PWM duty cycle, the power loss is small, the direction change control is fast, the drive current is large, the switching frequency can be adjusted in a large range, and it can match different types of medium and high power DC Motor, fully meet the requirements of the system.