A Simple Modulation Scheme With Zero Common-Mode Voltage and Improved Efficiency for Direct Matrix Converter-Fed PMSM Drives

For the direct matrix converter (DMC) applied to permanent-magnet synchronous motor (PMSM) drives, a novel modulation scheme is proposed in this article, which could reduce the control complexity and improve the efficiency while achieving zero common-mode voltage (CMV). Only three counterclockwise or clockwise rotating vectors are adopted to operate the DMC. The proposed scheme has the inherent ability to generate sinusoidal input currents without explicit control in the modulation. The duty cycle expressions for the three vectors are quite simple without any trigonometric operations. The switching pattern is fixed, saving the need for sector and sequence determination. Therefore, compared with the conventional modulation scheme which also uses only rotating vectors, the proposed scheme could reduce the execution time by over 80%. In addition, it achieves higher efficiency benefiting from the reduced switching actions. Its validity is verified by experimental results on a 2.4-kW DMC-fed PMSM drive prototype.