Cogging Torque Suppression of Permanent Magnet Homopolar Inductor Machine Based on Tooth Combination Method

The permanent magnet homopolar inductor machines (PMHIMs) have received attention in the field of flywheel energy storage system (FESS) due to their merits of simple structure and rotor flywheel integration. However, the presence of the permanent magnetic field results in parasitic cogging torque, which increases the torque ripple of the PMHIM and thus affects the performance of the FESS. Addressing this issue, the cogging torque suppression of PMHIM based on tooth combination method is proposed and investigated in this paper. Firstly, the mathematical model of the cogging torque of PMHIM are established based on the relationship between PMHIM and surface-mounted permanent magnet synchronous motor. Then, the methods of basic-cogging-torque-unit (BCTU) and repeated-cogging-torque-unit (RCTU) to suppress the cogging torque are proposed. The principles of parameter selection of the BCTU and the RCTU methods are explained based on the principle of minimal impact on electromagnetic performance. Finally, the theoretical analyses are validated by simulations and experiments.