Research And Design Of Electric Steering Control System Of Passenger Car Based On DC Motor

An electric power steering system for a vehicle is a specialized mechanism for assisting a driver in changing or maintaining the driving direction of the vehicle.As a high-tech development of modern automobiles,it has broad prospects for development in the field of automotive power steering.One of the core components of an electric power steering system is a power assist motor.Currently,the research and application of the most widely used power assist motor is mainly a DC motor.This is mainly because the DC motor starts and speed regulation performance is relatively good,and is easy to control,and because the onboard power is DC power supply,DC motor can be directly driven.However,the automobile electric power steering system using DC motor as a power source has the disadvantages of small torque and obvious torque ripple.Therefore,this topic proposes an electric power steering control strategy for passenger cars based on DC motors.The dissertation firstly studies the basic working principle of DC motor,and the structure and principle of DC motor.It further studies and analyzes the control of DC motor,the principle of PWM speed regulation,and the H-bridge control.Complete the electromechanical design of the electric power steering system.The electric power steering system model was established,the physical model of the steering system and the dynamic differential equation of the steering system were established,the working principle and composition of the electric power steering system were studied,and the requirements of the electric power steering system for the motor drive circuit were given.Secondly,this paper proposes an electric steering control strategy for passenger cars based on DC motors.The difference in road feeling and lightness requirements is based on steering conditions under different vehicle speeds and steering wheel torques.This paper proposes a hybrid power assist control.The strategy divides the composite boost curve into two intervals.Three components of compensation control,motor damping compensation control and motor friction compensation control have been added to the conventional electric power steering control system;a damping control strategy was introduced,and a positive control algorithm was set in the control strategy;closed-loop torque control This article uses a torque two-point regulator to achieve.Finally,the paper completes the design and simulation of the electric power steering control system,which mainly includes hardware design and software design.The simulation results show that the direct torque method has excellent dynamic response characteristics,and the DC motor speed control system can complete the torque response in only a few milliseconds.In addition,the corresponding motor speed drop is also more limited,and within a 0.03 s can be tracked again on a given speed.The direct torque control method can effectively control the pulsation of the electromagnetic torque,and can greatly improve the dynamic and steady state driving performance of the motor.By comparison with the straight-type boost curve,it can be seen that the composite boost curve can effectively alleviate the contradiction between road intensity and lightness,and it also tends to demand the ideal assist characteristic curve.The compound boost curve satisfies low-speed steering.Lightweight,good road feeling at high speed.