Analysis of optimal stator concentric winding patterns design

Most small induction motors in current use employ concentric windings which have equal numbers of turns per coil. An optimal choice of turns can achieve better distribution of MMF in the gap while keeping the turns in each slot essentially the same. In this paper, the air gap magnetic motive force (MMF) harmonics of electrical machine created by the stator concentric windings with sinusoidal current injection are investigated. The air gap MMF is modeled ideally by a linear winding function, which simplifies the MMF expression significantly by neglecting the slot effects and saturation for uniform air-gap machines. By evaluating the harmonic property of the synthesized three phase air gap MMF waveform, optimal winding patterns can be developed for conventional choices of phase belts.