Research on Characteristic Airgap Harmonics of a Double Rotor Flux-Modulated PM Motor Based on Harmonic Dimensionality Reduction

In this paper, a method of dimension reduction analysis of airgap harmonics is proposed and investigated for a double-rotor flux-modulated permanent magnet (DR-FMPM) motor. By analyzing the relationships among the torque, core loss and power factor of DR-FMPM motor, the characteristic harmonics related to the three performances are determined, and number of harmonics is reduced. To investigate the influence of characteristic harmonics on motor performances, the ratios of torque to core loss and torque to power factor are defined. And the corresponding characteristic harmonic coefficients are also defined. Afterwards, the sensitivity degrees of design parameters to characteristic harmonics are calculated to pick out highly sensitive parameters. Then, the effects of the design parameters on the harmonics, as well as the motor performance are carried out in detail. In addition, the performances of DR-FMPM motor are also evaluated. Finally, a prototype motor of the DR-FMPM motor is constructed and tested. Theoretical analysis and experimental results verify the proposed method and the DR-FMPM motor to a large extent.