A novel speed sensorless direct torque and flux controlled interior permanent magnet synchronous motor drive

This paper investigates a modified direct torque control (DTC) scheme based on space vector modulation (SVM) for interior permanent magnet synchronous motor (IPMSM) drives. Closed-loop control of both the torque and stator flux linkage are achieved by using two proportional-integral (PI) controllers. The reference voltage vectors are generated by a SVM unit, which replaces the switching table in the conventional DTC scheme. Whilst retaining its main advantages, the new DTC method features reduced torque and flux ripples as compared to the classical DTC. A speed estimator based on the stator flux linkage and torque angle is incorporated into the proposed DTC scheme. Simulation and experimental results confirm the effectiveness of the proposed method.