Investigation of an improved hybrid-excitation flux switching brushless machine for HEV/EV applications

Hybrid-excited flux-switching (HEFS) machine was proposed by reducing the permanent magnet (PM) length of an original flux-switching permanent magnet (FSPM) machine and introducing a set of field windings into the saved space. In this paper, the open-circuit performance of an original 3-phase 12-stator-slot/10-rotor-pole HEFS machine is analyzed by 2D finite element analysis (FEA), and further validated by experimental measurement. Then an improved topology is proposed to enhance the flux-regulation capability. The improved topology shares identical motor structure with the original one, but has different field current directions in some field slots. Based on FEA, the open-circuit electromagnetic performances of the two HEFS machines are compared with more attention paid to field regulations. It is found that the improved HEFS machine exhibits distinct field excitation functions and significantly better flux-regulation capability than the original one.