Research Of Eps Based On Flux-weakening Control For PMSM

Electric power steering system (EPS) has become the mainstream of automotive steering system with its performance advantages of saving energy, environmental friendly, safety, the market potential is tremendous. With the rapid increasing performance and lower price of permanent magnet, the permanent magnet synchronous motor (PMSM) is becoming the main choice of EPS power motor with its performance advantages of small size, high efficiency, smooth operation and mature control technology.In view of the problem of heavy steering wheel during tight cornering in this paper, the speed regulation principle of the permanent magnet synchronous motor used in electric power steering is analyzed, the conclusion is that the limited range of speed regulation is the main cause, the control strategy of the basis of the steering wheel angular velocity, exerting id= 0 control in torque loop while low speed, exerting field weakening control in speed loop while high speed is proposed, and achieved more satisfactory results.Firstly, the motor stator current optimal trajectory is analyzed combining voltage and current limits limit circle and the principle flux-weakening control is clarified. Compared the several common flux-weak control strategy and chose the voltage negative feedback method as the flux-weak control strategy of this paper based on the actual situation.Then focused on the analysis of the voltage negative feedback method and added to the EPS system simulation model; in view of the flux-weakening control strategy is proposed in this paper, designed optimally the original laboratory EPS controller hardware and software, focusing on the design of CAN communication module, fault diagnosis module hardware structure and flux-weakening control module and switching condition module software program.Finally, by experimental calibration method to determine the key parameters of the switching conditions, combined with the hardware in the loop test and vehicle test, The simulation and experimental result verify the proposed program.