Working Harmonic Analysis of Coaxial Magnetic Gear and Its Application in Motor Integration

Abstract

Coaxial magnetic gear (CMG) exhibits the advantages including lubrication-free, inherent overload protection, and less maintenance cost, thus has received lots of attention in low-speed high-torque applications. However, the majority of CMG research is concentrated on the development of innovative topologies, and the investigation of the flux density harmonic characteristics is barely seen. In this paper, a new perspective of analyzing the flux density harmonic characteristics is presented for three most typical CMGs, i.e. surface-mounted CMG (SM-CMG), spoke-type CMG (ST-CMG), and triple-layer CMG (TL-CMG). On this basis, the corresponding contributions of the flux density harmonics to the average torque are comparatively studied and quantified. In addition, the three CMGs are globally optimized based on the multi-objective genetic algorithm, to allow for a more comprehensive comparison of other key performances. The results indicate that the TL-CMG has the best overall performance among these CMGs. As the CMG is usually integrated with the motor, the integration pattern of the two is analyzed. Finally, a prototype for the automated guided vehicle (AGV) robot application is built and tested, and the experimental results match well with the simulation results.