Abstract:Electric power steering (EPS) system driven by permanent magnet synchronous motor (PMSM) has become the future trend of development. In order to adapt the characteristics of AC motor, dynamical-returnability characteristics based on fuzzy rules were designed. The extended Kalman filter (EKF) was introduced to estimate the stator flux and location, and the direct torque control (DTC) was adopted to control PMSM, so as to accelerate the response rate and precision. Referring to the national standard, simulation of this system was carried out on steering portability and return performance, the results show that the effect of the proposed system is significant under PMSM assisting, the steering wheel average operating torque is reduced by 45%, and the wheel self-turning time shortens 50%. Finally the bench test was experimented and shows that the whole system dynamic operates well and can fully complete the power control target.