Effect of distributed airgap in the stator for acoustic noise reduction in switched reluctance motors

This paper presents a distributed airgap in the stator of switched reluctance machines (SRMs) to reduce the vibration and the acoustic noise levels. Distributed airgap is placed in stator tooth or yoke to analyze its effectiveness on the electromagnetic and mechanical performances. According to the observations, it has been found that when the distributed airgap is placed in the stator teeth, the generated radial force is significantly reduced. In addition, the technique reduces the stator surface deformation considerably by playing a role of spring. When the distributed airgap is placed in the stator yoke, radial force does not change significantly however it reduces the stator yoke deformation by behaving as a spring. The detailed comparison of two proposed methods is performed by electromagnetic and mechanical/acoustical finite element tools.