An improved Direct Torque Control method of PMSM based on backstepping control

Direct Torque Control (DTC) of Permanent Magnet Synchronous Motor (PMSM) has quick response and simple structure, but it has the disadvantages of large torque ripples and inconstant switching frequency. An improved DTC method of PMSM based on backstepping control is proposed in this paper. For direct torque control, speed, torque and flux linkage are selected as virtual state variables and then a backstepping controller is designed to produce reference stator voltage components. Then according to those voltage components, space vector modulation (SVM) is used to produce switching states of inverters. Simulation results show that the performance of the proposed DTC system has been dramatically improved. Compared to the traditional DTC, the proposed DTC based on backstepping control could effectively decrease flux and torque ripples, make inverters have constant switching frequency. Compared to the DTC based on PI control, the backstepping DTC has fewer adjusted parameters and has good dynamic performance and good robustness.