Design of a Hybrid Excited Permanent Magnet Machine with AC Field Winding Excitation

Flux adjustable permanent magnet (FAPM) machines are a novel type permanent magnet machines which have attracted much attention in modern industry as they are able to adjust the flux linkage flexibly and ensure a wide speed range operation. In this paper, a hybrid excited permanent magnet (HEPM) machine with AC field windings is proposed, which presents the permanent magnets (PMs) located on the rotor side and AC field windings in the stator side to realize the flux adjustability while ensuring high torque density. As the PMs magnetic field rotate with rotor, the AC currents would share the same frequency with the motor speed. Then the accurate superposition of excitation magnetic field and PMs magnetic field could be achieved for higher torque output. Furthermore, through the 2-D finite element analysis (FEA), the proposed HEPM machine are researched and the results indicate that the HEPM machine can demonstrate high torque density and good flux-weakening capability.