Design optimization and comparative analysis of dual-stator flux modulation machines

This paper proposes three novel dual-stator flux-modulated permanent magnet (DSFMPM) machine concepts, which are particularly suitable for direct-drive applications with the virtue of their high torque density and low operation speed. The dual-stator configuration can help improve the use of inner cavity space, and achieve higher torque density comparing with the single-stator counterparts. Moreover, flux modulation is artfully employed to produce the gear effect, which can further benefit for the torque improvement. According to the PM location, the proposed DSFMPM machines are referred as (i) Stator-PM machine, (ii) Stator-rotor-PM machine, and (iii) Rotor-PM machine. Finite element method coupled with genetic algorithm, namely FEM-GA coupled method, is used to optimal design the proposed DSFMPM machines. Their electromagnetic performances are investigated in detail and quantitatively compared. The results show that the dual-stator topology can well improve the torque capability. Among all the proposed DSFMPM machines, the stator-PM one owns the lowest torque density because it has more short-circuit leakage flux.