Investigation and Suppression of Cogging Torque of Permanent Magnet Homopolar Inductor Machine

Cogging torque (CT) would cause the vibration and noise of the permanent magnet homopolar inductor machine (PMHIM), which should be suppressed. However, the unipolar air-gap flux density and the dual-segment stator and rotor cores of PMHIM make the characteristics of CT unclear, which leads to a lack of theoretical basis for suppressing the CT. Addressing this issue, the CT of PMHIM is investigated and suppressed. First, the model of CT of PMHIM with integer and fractional slot configurations is developed, and the factors affecting the CT are revealed. Then, the methods for suppressing the CT are proposed based on changing rotor parameters. The influences of different rotor parameters on electromagnetic performance, including back electromagnetic force (EMF), output torque, current, and efficiency are fully analyzed. In addition, the characteristics of the proposed method are highlighted by comparing the performance of the method proposed in this article with the global optimization method in terms of CT suppression. Finally, the theoretical analyzes are validated by experiments. The results show that the CT of PMHIM can be effectively suppressed by the proposed method in this work.