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 higher dc voltage utilization and fewer inverter legs. A few studies attempt to promote this topology from a three-phase frame to a multiphase frame. However, the SW topology for the asymmetrical multiphase 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 multiphase 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.