A Novel Sensor-less Direct Torque Control for PMSM Based Extended Kalman Filter

An Extended Kalman Filter is established in the paper to obtain the stator flux linkages and motor speed without the mechanical sensors for Direct Toque Control of Permanent Magnet Synchronous Motor drives. In this method, the stator flux linkages on the fixed a alpha - beta coordinate, rotor speed and position are chosen as states. The input and output of the Extended Kalman Filter arc stator voltages and currents. The stator flux linkages and rotor speed are estimated by the Extended Kalman Filter. Space Vector Modulation with constant switching frequency is applied to realize Direct Toque Control in order to reduce the torque ripples. The theoretic analyses are validated by both digital simulation and experimental test.