Sensorless direct torque control for permanent magnet synchronous motor based on fuzzy logic

Fast dynamic response is an outstanding feature of the direct torque controlled (DTC) permanent magnet synchronous motor (PMSM) systems. However, the two-value hysteresis controllers and the 60/spl deg/ region based position signal employed to select the proper space voltage vector in the conventional DTC system result in large torque and flux linkage ripples. Another main,advantage of the DTC is that the requirement for the continuous rotor position information is eliminated. However, the speed feedback signal is unavoidable in closed loop speed control system. In this paper, a fuzzy controller is designed to solve the contradiction between the dynamic and steady state performance of the PMSM DTC system; and furthermore, a simple sensorless method is introduced to this fuzzy DTC system to improve the reliability, reduce the cost and make it a real sensorless DTC system. The proposed strategies are verified by the simulation and experimental results.