Investigation of Phase Angle Displacements in Six-Phase PMSM with Concentrated Windings for Reduced MMF Harmonics

Multiphase concentrated wound (CW) permanent magnet synchronous machines (PMSMs) have high content of space harmonics in the magneto-motive force (MMF) waveforms. These harmonics result in distorted voltage waveforms and cause additional losses thereby deteriorating the machine's performance. However, the magnitude of space harmonics in multi-phase machines is lesser when compared to three-phase CW PMSM. In order to eliminate and/or reduce space harmonics even further in the MMF waveforms, this paper investigates non-conventional phase angle displacements for a six-phase 36-slot/34-pole CW PMSM. The six-phase CW PMSM considered has two independent three-phase windings. Conventional six-phase CW PMSM have phase angle displacements of 60° (symmetrical configuration) or 30° (asymmetrical configuration) between the two-phase sets. Based on star of slots method, a number of possible phase shifts between the two sets of three phase windings are investigated for reduced MMF harmonics, improved demagnetization and other performance characteristics for the 36-slot/34-pole PMSM and are compared along with conventional phase displacement angles of 60° and 30°.