A novel high torque-density triple-permanent-magnet-excited magnetic gear

This paper presents a novel magnetic gear, which has a higher torque transmission density than its conventional counterparts. This new topology deploys an extra set of permanent magnetic (PM) poles on the stationary ferromagnetic segments, which functions ingeniously as an extra pair of magnetic gear inside the same original volume and helps to increase the transmitted torque significantly. The magnetic flux distributions and magnetic torque are analyzed comprehensively by solving the magnetic field and mechanical motion coupled models using finite-element method (FEM). The performance of this new structure is compared with those of a traditional magnetic gear and other possible topologies using FEM. The proposed triple-PM-excited magnetic gear can transmit an addition of at least 20%of torque density (torque per unit overall volume) when compared with conventional magnetic gears with the same size.