Simulation And Performance Analysis Of Electric Power Steering System

Electric Power steering system has turned from simple machinery system,mechanical hydraulic pressure power system ,electronic controlled hydraulic pressure power system to electric power steering system ,which is energy- conservation even more and better performance .Electric Power steering system adds sensor device ,electron controlled device and turning assisting power device based on the traditional machinery steering system. Electric power steering system is the inevitable developing direction of automobile power steering ,which is much superior to other power steering systems .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 this paper ,the characteristics of EPS ,operational principles, and structures are discussed and both the current domestic and abroad research situation and the development prospects are addressed, In this paper the author analyzes the characteristics of EPS power system, including three EPS typical power curves, and the relationship between its assistance and the steering wheel torque and the expression of the corresponding function of the steering system was expressed; the determination of the largest power.In this paper the PID control strategy of EPS system, the armature current control method and the armature voltage control method are defined. Three control modes of electric power steering are suggested: power control mode, back control mode , damping control mode, as well as to join the steering wheel control of the compensation to reduce jitter.Under the basis of mathematical model of the mechanical steering without power system, EPS system and the EPS system of PID control, using MATLAB/ simulink to simulate and analyse dynamic parameters, electrical power, ground shocking to the impact of the system ,using PID control strategy for the model control, allowing the system to meet the good dynamic characteristics.Establishing the suitable evaluation indicators of the EPS system ,which is used to guide development, control strategy and basic parameters of control of the EPS. Joining the two freedom angles input model to analyse the main performance evaluation targets of the electric power steering system: road sense , sensitivity of steering and stability of manipulation. Deducing the expression of the sensitivity of steering and the road sense, inspecting the EPS system parameters (including power transmission ratio, motor moment of inertia, torque sensor stiffness, power gain, etc.) to impact these two indicators ,on the basis of these rules the author establish the stability of manipulation criteria.