Cogging force reduction for the linear flux-switching permanent magnet machines based on a twisted stator

The linear flux switching permanent magnet (LFSPM) machine, with both the PMs and armature windings located on the short mover and the long iron-core only stator, is suitable for urban rail transit applications. However, this kind of machine exhibits relatively large cogging force. A cogging force reduction method based on a twisted-stator structure is investigated in this paper and the twisted angle is analyzed with emphasize on its influence on the flux-linkage magnitude and the cogging force reduction by finite-element analysis (FEA). Besides, flux-linkage and the cogging force of two modular LFSPM (MLFSPM) machines with and without structure optimization are compared, respectively.