Speed-Sensorless Predictive Direct Speed Control for PMSM Drives

Predictive direct speed control (PDSC) of electric motors makes the control of both electrical and mechanical systems possible over a single control law by eliminating the cascade control structure. Speed-sensorless control also reduces the cost of electric drive while increasing system reliability. In this paper, a speed-sensorless PDSC-based permanent magnet synchronous motor (PMSM) drive is proposed, which combines the advantages of speed-sensorless control and the PDSC strategy. An extended Kalman filter (EKF) is designed to estimate stator currents, speed, position, and load torque. By using estimated stator currents in the prediction models of the PDSC, a reduction in current/torque ripples is achieved. Additionally, EKF uses a PMSM model defined in the stator stationary reference frame to eliminate the adverse effect of the initial position estimation errors. The proposed drive system is tested in different operating conditions, and finally, satisfactory control performance is achieved overall.