Influence of rotor pole number on optimal parameters in e-core axial field flux-switching permanent magnet machine

E-core axial field flux-switching permanent magnet (AFFSPM) machines are a novel brushless AC machine. It exhibits some advantages, such as short axial size, high torque density and fault tolerant capability. In the paper, the 6/10, 6/11, 6/13, and 6/14 stator/rotor pole E-core machines are optimized for attainting the maximum output torque, respectively. The influence of rotor pole number on design parameters, including rotor pole width, split radio, side tooth and middle tooth width of E-core stator, and stator yoke length, are investigated by 3-D finite element method (FEM). Moreover, the E-core AFFSPM machines are compared and analyzed in terms of the open-circuit flux linkage, back-EMF, electromagnetic torque and inductance. It is shown that 14-rotor pole machine can largely reduce the asymmetry of back-EMF and the cogging torque, and 13-rotor pole machine can increase the electromagnetic torque and reduce torque ripple. The ratio of mutual- to self-inductance of the 14-rotor pole machine is ~35% smaller than that of 13-rotor pole machine.