Reduction of torque ripple of VSI-fed PMSM machine by direct torque control method

An improved scheme of direct torque control (DTC) based on space vector modulation (SVM) is introduced. Based on surface-mounted permanent magnet synchronous motor (PMSM) mathematical model, a deadbeat control method of the stator flux and electromagnetic torque is discussed in this paper, which can compensate the torque error and flux error exactly in one sampling period by calculating the real-time reference voltage vector in two phase stationary reference frame. Both of stator flux and torque ripples can be greatly reduced in comparison with the traditional DTC. And the control scheme can not only retain the advantages of classical control scheme, but also keep a constant switching frequency. The validity and feasibility of the adopted control scheme have been tested through experiment prototype.