A hybrid direct torque control scheme for asymmetric six-phase PMSM drives

In this paper, a novel hybrid DTC scheme is proposed for asymmetric six-phase PMSM drives, which can achieve faster dynamic response of classical ST-DTC scheme and good steady-state performance of classical SVM-DTC scheme. The key is that a completely novel control strategy for torque and stator flux is designed. Different torque control methods are adopted under dynamic mode and steady-state mode without adding complexity of control algorithm. And a mode switching method is design to guarantee the smooth transition between the two modes. In addition, the proposed scheme can suppress current harmonics induced from inherent property of asymmetric six-phase motor effectively. Comparative experiments are carried out on a laboratory prototype to verify the effectiveness of the proposed scheme. The proposed hybrid DTC scheme applies equally to three-phase and other multiphase PMSM drives.