The proposed technique focuses on the aligned and synchronous operation for the fundamental and harmonic air-gap magnetic fields of multiphase induction machine (IM) under non-sinusoidal power supply. The M-axis and T-axis components of third harmonic air-gap flux are formulated under arbitrary synchronous rotating coordinate system, and then the deviation for the air-gap flux in terms of amplitude and space angle caused by the deviated harmonic currents are analyzed. The essence in regard to how the