A Novel Modulation Strategy for Asymmetrical Six-Phase Series-Winding PMSM Based on Predictive Controller

Series-winding (SW) permanent magnet synchronous motors (PMSMs) are of increasing interest and great potential for low-voltage traction in electric vehicles because of their both higher DC voltage utilization and fewer inverter legs. A few studies attempt to promote this topology from three-phase to multi-phase frame. However, the SW topology for asymmetrical multi-phase system has yet to be understood, given the fact that all existing voltage modulation strategies are not applicable. The study presents a feasible, simple carrier-based modulation strategy for this special SW-PMSM with an asymmetrical winding system. A predictive current controller is introduced in the process of modulation since the multi-phase system involves several current control loops. An asymmetrical six-phase PMSM prototype is fabricated for verification. Experimental results show that the novel strategy performs much better than its space-vector-based counterparts. Also, it is capable of suppressing the current distortion within the nonlinear modulation range. Voltage utilization and achievable rotational speed become higher.