Cylindrical Rotor Design for Acoustic Noise and Windage Loss Reduction in Switched Reluctance Motor for HEV Applications

A switched reluctance motor (SRM) is one of the candidates of rare-earth-free motors for hybrid electric vehicles (HEVs). An SRM has been developed with same interior permanent magnet synchronous motor (IPMSM) dimensions having competitive maximum torque, operating area, and maximum efficiency. However, this SRM has a windage loss of 1.3 kW due to the salient poles of the SRM driven at the maximum rotational speed. In addition, considerable acoustic noise is caused by the salient poles. In this paper, a simple design of a cylindrical outer shape rotor is proposed, and a comparison with the conventional SRM rotor is carried out. It is found that the efficiency is improved due to the windage loss reduction. It is also found that the acoustic noise is significantly reduced in the proposed rotor design.