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A double fed three-phase flux-switching linear motor with complementary magnet circuit for urban rail transit

In this paper, the general design method of a double fed flux-switching linear (DFFL) motor with complementary magnet circuit is proposed. The proposed motor can be used as urban rail transit drive motor. The key of this structure is to have DC field windings and armature windings all on the short mover, while the long stator is only made of segment iron. Also, each phase including two armature coils whose position are mutually 180 electrical degrees apart, which can offer sinusoidal back-EMF and smaller force ripple. The air gap flux density can be regulated by changing the magnitude of DC excitation current, so it can not only reduce the drive system cost but also offer controllable electromagnetic force and electromotive force (EMF). This is helpful to extend the motor speed range and improve the system efficiency at different loads and speeds. The finite element analysis (FEA) results validated the claims.