Comparative analysis of spoke‐type, consequent‐pole and hybrid‐pole permanent magnet machines

In recent years, consequent‐pole permanent magnet (CPM) machines draw much attention due to their high utilisation ratio of permanent magnet (PM) material. However, they have some disadvantages, such as the even‐order harmonics of airgap flux density, which may cause asymmetric phase back‐EMF and the increase of torque ripple. In this study, a novel hybrid‐pole PM (HPM) machine is proposed, in which the rotor combines consequent‐pole and spoke‐type PM rotors. The working principle of the proposed HPM machine is analysed based on the equivalent magnetic circuit, and validated by the finite‐element method. Then, the electromagnetic performance of the HPM machine is compared with those of the existing CPM and spoke‐type PM machines. It is shown that the HPM machine obtains similar average torque, PM utilisation ratio, torque ripple and efficiency to the spoke‐type PM machine, whilst it has a higher PM utilisation ratio and much lower torque ripple than the conventional CPM machines. Finally, these analyses are validated by the tested results of a 9‐slot/6‐pole HPM machine.