Direct torque control of permanent magnet synchronous motors based on extended Kalman filter observer of flux linkage

This paper proposed that extended Kalman filter (EKF) observer was applied to the direct torque control (DTC) of permanent magnet synchronous motor (PMSM). The EKF observed the stator voltage and current to estimate rotor speed, rotor position, stator flux linkage and torque. Based on the estimation, the sensorless speed control system of PMSM was built. Simultaneously, by improving conventional EKF estimated equation of state, this method raised the accuracy of velocity estimation. The EKF observer provides a good optimal state estimation of PMSM which is a system of nonlinear, parameter variations and disturbance. Stability properties of PMSM control system based on EKF was proved. The simulation results show that this method can estimate the state variables accurately, improve the performance of the direct torque control of PMSM.