A High Torque Density Claw-Pole Permanent-Magnets Vernier Machine

Permanent magnets vernier (PMV) machine is gaining more and more attention due to its high torque density contributed by multi-orders working harmonics, especially low-pole-pair numbers harmonics. Spoke-array PM machine seems to be a good way to increase the machine working harmonics. But the flux barrier effect is revealed and it explains why the advantages of the spoke-array PMV (SAPMV) machine are not fully used. Thus, its low-pole-pair numbers harmonics could be further enhanced. In this article, a novel structure-claw-pole PMV (CPPMV) machine-is first proposed and its working principle is investigated. Then, the CPPMV machine is compared with the surface-mounted PMV machine, the SAPMV machine, and the SAPMV machine with alternate flux bridges in terms of their electromagnetic performances using equivalent circuit analysis and FEM. The result shows that claw-pole structure can enhance the magnetic flux modulation effects, which increases the machine torque density. At last, a CPPMV machine prototype is manufactured and tested. Experimental results indicate that it reaches a torque density of 30.5 kNm/ \text{m}^{3} and a power factor of 0.84 underrated conditions.