Comparative Study of Consequent-Pole and Hybrid-Pole Permanent Magnet Machines

This paper presents a novel consequent-pole permanent magnet (PM) (CPM) machine featuring N-S-iron sequences. In order to enhance the output torque and efficiency, the flux barriers are employed to improve the magnetic symmetry and reduce the saturation of the stator yoke. The tangential magnetized PMs are embedded in the flux barriers to form the hybrid-pole PM (HPM) machine, which further improves the output torque and efficiency. The rotor of the proposed CPM and HPM machines, as well as its conventional counterpart which employing N-iron sequences, are optimized by finite element analysis. Furthermore, the electromagnetic performances of the proposed machines, including the open-circuit airgap flux density, back EMF, average torque, torque ripple, efficiency, flux-weakening capability, unbalanced magnetic force, and unipolar leakage flux, are compared with the conventional CPM machine. It is demonstrated that the proposed HPM machine can obtain almost equivalent torque, efficiency, and better flux-weakening capability when compared to the conventional one. Moreover, the proposed HPM machine has no unipolar leakage flux in the end region, and thus the magnetization of the mechanical components can be effectively reduced. Finally, a 9-slot/8-pole HPMmachine is prototyped andmeasured to validate the analyses.