An Enhanced Rotating Vector-Based Direct Torque Control for Matrix Converter-Fed PMSM Drives Using Virtual Pulsating Vectors

Matrix converter (MC) rotating vectors (RVs) have the natural advantage for common-mode voltage (CMV) minimization, but it is rather complicated to establish the switching table with RVs in a direct torque control (DTC) strategy for motor drive systems. Moreover, the conventional RV-based MC-DTC has limited practical application, as it suffers from increased torque ripple and current distortion. A novel MC-DTC method using RVs is proposed in this paper, which breaks down the compromise between minimization of CMV and performance of torque and current. Two RVs that rotate in opposite directions are employed to synthesize a virtual vector. These virtual vectors are pulsating in a fixed line and are evenly distributed in the vector plane. Therefore, the switching table with virtual pulsating vectors can be established conveniently. The proposed method can not only eliminate common-mode voltage, but also improve the torque and current steady state performances evidently compared with the existing rotating vector-based method. Experiments are carried out and the advantage of the proposed method is verified.