Design of Conical Rotor Flux-Switching Permanent Magnet Machine with Improved Flux-Weakening Capability for Traction Applications

The purpose of this paper is to propose a novel flux-switching permanent magnet machine (FSPM) with a conical rotor. The conical rotor has two degree-of-freedom movement, including axial and radial movements. The axial movement is realized by controlling the axial force generated by the d-axis current. During the positive axial movements, the air gap length is reduced and leads to higher air gap flux density to increase the torque production capability. During the negative axial movements, the air gap flux density is reduced due to the increase of air gap length, which creates an opportunity for the improved flux-weakening compared with normal FSPM machines. In this paper, the design parameters of the conical FSPM are provided. The axial force and torque production capability are investigated by analytical equations and 3-D finite element analysis (FEA). Flux-weakening is also evaluated at various axial positions and d-axis currents.