Adaptive Control Strategy for Aligned and Synchronous Operation of Harmonic Air-Gap Magnetic Field for Multi- Phase Induction Machine

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 harmonic currents influence the harmonic air-gap flux is revealed through the analysis of error equations. Furthermore, the adaptive law for the harmonic currents online regulation is developed utilizing the flux error. The voltage model of air-gap flux model is employed as the adjustable model to establish the Model Reference Adaptive System (MRAS). The parametric robustness is improved significantly for the precise control of harmonic air-gap magnetic field. Comprehensive experimental verifications are performed to validate the effectiveness of the proposed method.