Direct Torque Control for Three-Phase Open-End Winding Permanent Magnet Synchronous Motor Based on Zero-Sequence Current Suppression

Abstract

Three-phase open-end winding permanent magnet synchronous motor (OEW-PMSM) with common dc bus, which has advantages of good controllability, high driving power and strong fault-tolerant ability, is becoming more and more popular. Direct torque control (DTC) has simple structure and rapid dynamic response, which is a competitive control strategy. However, DTC of this drive system is difficult to implement for that the zero-sequence current suppression should be also taken into consideration besides the control of electromagnetic torque and stator flux amplitude. To address this problem, a novel DTC strategy based on zero-sequence current suppression is proposed in this paper. Different from the conventional DTC, one more hysteresis controller is introduced to suppress the zero-sequence current. In addition, the optimal switching table has been modified based on the synthesized virtual voltage vectors. Simulation research on this strategy has been done, and the results show that the electromagnetic torque, stator flux amplitude and zero-sequence current can be controlled at the same time.