Research And Design On Electric Power Steering Control System Of Automobile

Electric power steering system is the inevitable developing direction for automobile power steering, which is much superior to hydraulic power steering system. The assist torque is provided by motor directly in EPS system, whose value is controlled by ECU. EPS can save energy, improve vehicle safety, benefit environment protection, and it is a new high-tech which follows modern vehicle development topic closely. In the foundation of the newest accomplishment of domestic and international EPS, this paper particularly researches the assist characteristic, control strategy and control system design, constructs the bench for EPS, develops electric control unit.In this paper, the key technique of EPS system, the assist characteristic and control strategy, are studied. Assist characteristic is analyzed theoretically and the feature parameters of straight-line assist characteristic curve is studied. The simulation indicates the easy straight-line assist characteristic can't generate desired static torque boost and avoid road disturbance at the same time. So it is necessary that compensation control should be used. And, based on the assist characteristic, the control strategy of EPS is described in detail and the algorithms is designed to control the motor current also.The EPS control system consists of the controller, sensors and the signal processing circuits, the electric motor and its driving circuits, communication circuit. 16-bit MCU named MC9S12DP256 is the core of controller. For the purpose to realize the control strategy, software design and code compiling are completed. Under different operation condition and different control modes, motor can be controlled precisely.At last, the debug software and hardware environment is introduced. The experiment results are analyzed which verify that the scheme above is valid and its performance is good. It provides good basis and useful reference for future study.