A Novel Zero-Sequence Current Hysteresis Control-Based Space Vector Modulation With Reduced Zero-Sequence Current Ripple for Six-Phase PMSMs

The symmetrical six-phase permanent magnet synchronous motor (S6-PMSM) connected with a single neutral point (SNP) exhibits superior fault-tolerant performance. However, this configuration inevitably introduces a zero-sequence loop (ZSL), which subsequently induces zero-sequence current (ZSC) that causes torque ripple and additional losses. Although the traditional ZSC hysteresis control-based space vector modulation (ZHC-SVM) is capable of suppressing ZSC, the hysteresis control will introduce ZSC ripple components, thereby resulting in a deteriorated suppression effect. Consequently, in this article, a novel ZHC-SVM with reduced ZSC ripple is proposed for S6-PMSM, while the linear modulation range remains invariant. In the proposed method, the zero-sequence voltage (ZSV) output characteristics under different vector selections are analyzed in depth. On this basis, two kinds of vector selection methods are proposed and integrated, significantly reducing the ZSV output of each control period, and hence mitigating the ZSC ripple. The proposed method possesses the merits of eliminating the need for parameter tuning, avoiding overmodulation at a high fundamental modulation index, and being easily implemented. Experimental results substantiate the feasibility and efficacy of the proposed method.