Design considerations of switched reluctance motors: vibration and control issues

The vibration produced in a switched reluctance motor (SRM) may be viewed from the manner radial component of the electromagnetic force and stator structure interact. Machine dimensions such as effective airgap length can alter the distribution of the radial attraction forces acting on the stator structure. In addition, design of the machine affects frequency characteristics of the stator. Furthermore, some design modifications of the machine geometry can provide more room for improvement in control of vibration during turn-off process. Therefore, in order to effectively mitigate the vibration in SRM drives, effects of motor dimensions on its vibratory behavior must be investigated. This paper examines the impact of various design parameters on the structural behavior of the stator body. Investigation of natural frequencies and the maximum deformation of the stator indicates that stator back iron and stator pole length are determining parameters in frequency response of the stator. Furthermore, using the finite element method, the impact of machine geometry on the profile of the radial attraction forces has been studied. The information obtained from this analysis is essential in development of a proper control strategy for mitigating vibration in SRM drives.