Novel DC-Saturation-Relieving Hybrid Reluctance Machine With Skewed Permanent Magnets for Electric Vehicle Propulsion

Reluctance machines with dc excitation coils have become a promising solution for electric vehicle propulsion system because of its robust rotor structure and good field-weakening ability. However, these machines usually suffer from relatively low torque density and efficiency. To solve this problem, this article proposes a novel hybrid reluctance machine with improved torque density and efficiency. The key novelty is to introduce skewed permanent magnets (PMs) in slot openings. The tangential component of skewed PMs can be used to relieve the dc saturation in the stator iron core, so that the $B-H$ working range can be extended and relatively high dc excitation can be applied in the proposed machine. Besides, the radial component of skewed PM provides extra torque component under flux modulation effect. Therefore, the proposed skewed PMs can achieve torque boost and core utilization improvement simultaneously. In this article, the dc-saturation-relieving effect of the proposed design is thoroughly investigated and verified by finite element analysis.