High-Performance Speed Sensorless Direct Torque Control of PMSM

A high-performance speed sensorless direct torque control (DTC) system of permanent magnet synchronous motor (PMSM) is presented in this paper. The stator flux linkage, speed, rotor position and load torque of PMSM are observed using a fourth-order Extended Kalman Filter (EKF) and a second-order Kalman Filter (KF) and the observed load torque is used for feed-forward compensation of reference torque. Simulation results clearly demonstrate the performance of speed can be improved when load torque is changed and the validity of the proposed control strategy.