Comprehensive Performance Improvement of a Double‐Air‐Gap Flux‐Modulated Permanent Magnet Motor Utilizing Air‐Gap Harmonic Group Analysis Methodology

ABSTRACT In this paper, a new method of air‐gap harmonic group is proposed for analyzing the performances of the flux‐modulated permanent magnet (FMPM) motor. A double‐air‐gap FMPM (DA‐FMPM) motor is chosen for research. First, through the analysis on the relationship of air‐gap harmonics with torque, core loss, and power factor, the selection method of the air‐gap harmonic groups considering deviation from total performances is proposed. Then, based on the analysis of the harmonics in the inner and outer air gaps, air‐gap harmonic groups corresponding to the three performances are constructed. Then, the decoupled air‐gap harmonic groups and the corresponding performances are compared and evaluated with the variation of the key parameters, which further verifies the soundness for harmonic group construction. Moreover, the hierarchical optimization for harmonic groups is carried out to achieve the comprehensive improvement of torque, core loss, and power factor of the DA‐FMPM motor. Finally, the electromagnetic performances of the DA‐FMPM motor before and after optimization are compared. To some extent, the comprehensive improvement of motor performance verifies the effectiveness and feasibility of the air‐gap harmonic group analysis methodology to be a new approach to analyzing the harmonic performances of the motor, providing a new exploration helping to the motor design.