Research On Torque Ripple Reduction Method Of Electric Power Steering Motor

Electric power steering system is energy saving and safe, The steering motor is themain component of electric power steering system. Permanent magnet synchronousmotor (PMSM) has been widely used with the characteristic of high torque at low speed.Torque ripple is a major factor limiting motor performance, study of permanent magnetsynchronous motor control and torque ripple reduction has a very positive meaning.This paper mainly researches the mathematical modeling of permanent magnetsynchronous motors, torque ripple reduction control methods, and hardware andsoftware system design and implementation.First, permanent magnet synchronous motor vector control and coordinatetransformation method are introduced. The model of motor can be simplified anddecoupled through coordinate transformation. Then, permanent magnet synchronousmotor model is established based on the rotating coordinate system. Permanent magnetsynchronous motor torque ripple causes and characteristics are analyzed, permanentmagnet synchronous motor state space model is established for the simulation.According to the periodic characteristic of the torque ripple, iterative learningcontrol method is proposed to reduce torque ripple. The implementation of iterativelearning control in time domain is introduced, the convergence condition is proved.Mathematical model of the motor and vector control simulation system are built inMatlab/simulink. Simulation analysis of speed closed loop, torque control and torqueclosed loop indicate that the torque output changes with ILC and compared that withoutILC, verifying the effectiveness of the algorithm.Finally, according to the simulation results the permanent magnet synchronousmotor control system is established. Introduce implementation of the system fromhardware and software design，and applicate the hardware and software developed inthe auctual system. With the existing experimental environment, closed-loop speedcontrol method is used, the results show that the iterative learning control can effectively reduce speed ripple and improve system performance.