Investigation of cogging torque reduction for a 6/10 hybrid axial field flux‐switching permanent magnet machine by harmonic field current injection

Abstract

Hybrid axial field flux-switching permanent magnet (HAFFSPM) machine exhibits a high-cogging torque due to its doubly salient structure and flux focusing effect. In consideration of the armature and field windings are both equipped in the HAFFSPM machine, a cogging torque reduction method by the harmonic field current injection is proposed in this study. Initially, the mathematical model of the HAFFSPM machine is analysed. Moreover, the theoretical principle of the proposed method is investigated based on the analytical model of the machine. The amplitude and phase angle of the injected current are calculated according to the harmonic component of the cogging torque. The feasibility of the proposed method is analysed and validated by both the finite-element analysis method and experiments on the prototype. Finally, the comparison between the proposed method and several topology optimisation methods of the HAFFSPM machine is given to indicate the priority of the harmonic field current injection method on cogging torque reduction.