Stator flux estimation for direct torque controlled surface mounted permanent magnet synchronous motor drives over wide speed region

A novel stator flux estimation scheme for direct torque controlled (DTC) surface mounted permanent magnet synchronous motor (PMSM) drives is proposed in the paper, which achieves better low speed performance. The proposed scheme estimates stator flux from stator currents and rotor position. Both traditional voltage integration estimator and novel stator estimator are implemented in a direct torque controlled PMSM system with SVM technique. The simulation and experimental results show that the proposed stator flux estimator improves low speed performance of the system. In the full speed region the torque ripple and current distortion keeps low.