Rotor Tooth Number Effect on the Performance of a Double Stator Flux Switching Motor with Low Cost Magnets

Flux switching (FS) machines have recently received much attention because of their high torque density and their simple rotor structure. In these machines, the armature coil and excitation system are both mounted on the stator structure, and there is no coil, magnet or cage on the rotor. One of the drawbacks of the FS machines is the employment of large amounts of expensive rare earth magnets in their stator structure. Although ferrite permanent magnets can be used instead of rare earth magnets with about one tenth of the price, but the machine torque density is reduced. To solve this problem double stator structures are suggested. In machines with this structure, as in the conventional FS machines, the number of rotor teeth has a significant effect on machine’s performance. Therefore, in this paper, the effect of rotor topology on the performance of a double stator ferrite magnet FS machine is investigated using finite element modeling and simulation under nominal operating conditions. Finally, to evaluate the accuracy of simulation results, a prototype of the best structure with maximum torque is manufactured and tested. The test results confirm the correctness of the simulation results with considerable accuracy.