Influence of Modular‐Stator Design on the Space Harmonic Characteristics of Six‐Phase Permanent‐Magnet Synchronous Machine

ABSTRACT Due to the inherent fault‐tolerant capability, the multi‐phase permanent‐magnet synchronous machine (PMSM) is suitable for applications with high reliability requirements. Modular‐stator design is beneficial for fault isolation and will further enhance the reliability of multi‐phase PMSM. Fractional‐slot concentrated winding (FSCW) is widely applied in multi‐phase PMSM. However, it will cause higher space harmonics and losses than those of the conventional distributed winding. The influence of modular‐stator design on the space harmonic characteristics of six‐phase PMSM is investigated in this paper. Five modular‐stator six‐phase PMSM schemes with different magnetic barrier locations are developed. Based on the analysis of the equivalent magnetic circuit, the variation of magnetic field distribution is studied, and the suppression ability of the non‐working space harmonics of the armature magnetic field is demonstrated. By analysing the alternating frequency of flux density in different positions, the correlation between loss types and magnetic field harmonics is investigated. An optimal scheme of low‐space‐harmonic modular‐stator six‐phase PMSM (LSHMS‐SPPMSM) is designed. Compared with the PMSM with a non‐modular stator, its core loss and permanent‐magnet (PM) eddy current loss of the six‐phase modular‐stator PMSM are significantly reduced and the electromagnetic torque is increased. Finally, a prototype is built, and experiments are carried out to verify the analysis results.