Improvement of Steady State Performance for Rotating Vector-Based Direct Torque Control

Matrix converter (MC) rotating vector (RV) has the natural advantage for common-mode voltage (CMV) minimization. However, the application of RV in direct torque control (DTC) strategy for motor drive system is limited, mainly due to the extensive torque ripple and current distortion. To improve the steady state torque and current performance of the traditional RV-based DTC, a novel RV- based DTC method is proposed in this paper. According to the analysis of the angle offset between stator flux and the candidate voltage vector, the vector plane is divided into 12 sectors, and virtual vector synthesized by two adjacent rotating vectors is employed to fill in the blank sectors. Based on this, a 12 sector- switching table combined with a novel mapping table of rotating vectors are established to fulfill the proposed RV-DTC method. Experiments are carried out to verify the proposed method. The results show that compared with the traditional RV-DTC, steady state torque and current performances are evidently improved with the proposed RV-DTC at approximate switching frequency, while zero CMV is reserved.