An Asymmetric Pole Coaxial Magnetic Gear With Unequal Halbach Arrays and Spoke Structure

In this paper, a novel asymmetric pole coaxial magnetic gear (CMG) with unequal Halbach arrays and spoke structure is proposed to improve the output torque of CMG. The inner rotor has an asymmetric N-S pole structure, the permanent magnets (PMs) on the inner rotor of the CMG are arranged in Halbach arrays with unequal magnetic poles, and PMs on the outer rotor are Spoke-type. According to the flux modulation effect, the contents of higher harmonics can be reduced and the output torque of the proposed CMG can be significantly improved compared to the conventional CMG with radial magnetization. The proposed CMG topology with 4 inner and 17 outer pole pairs is established. The proportional relationship between N pole and S pole is introduced. Then, the air gap flux density, electromagnetic torque, harmonic component of the CMG are investigated and verified by finite element analysis.