Electromagnetic design and analysis of double-rotor flux-modulated permanentmagnet machines

Abstract

Two double-rotor flux-modulated permanent-magnet (DR-FMPM) machines are proposed for direct-drive applications, including the DR coaxial magnetic-geared (CMG) type and the DR PM vernier (PMV) type. The key of the DR-CMG type is to utilize two modulation rings for obtaining the desired magnetic-gearing effect, whereas the key of the DR-PMV type is to utilize the flux-modulation poles and fractional-slot concentrated-winding arrangement for achieving the magnetic-gearing effect. Thus, both proposed machines are able to directly connect their rotors with two different rotating loads. Their rotating speeds can also be independently controlled by two sets of armature windings. The proposed machines are designed and then analyzed by using the time-stepping finite element method. The corresponding results confirm the validity of the proposed machine design.