Low cost flux-switching brushless AC machines

A low cost 3-phase DC winding excited flux-switching (FS) brushless AC machine is developed from the FS permanent magnet (FSPM) machine. The influence of stator and rotor pole number combination on its electromagnetic performance, including flux-linkage and back-emf waveforms, electromagnetic static torque, and torque-current density characteristics, are predicted by 2-D finite element analyses and validated by experiment. In addition, the torque capability of the FS machine and FSPM machines with rare earth and ferrite magnets, respectively, are compared by the finite element analyses. It is found that whilst it is low cost, the torque capability in the FS machine may be limited by the significant magnetic saturation in the stator teeth.