Effects of end-shields on the stator mode frequencies of electric machines

The end-shields that are directly bolted or welded to the stator-ends increase the stiffness of the stator geometry and thus increase the natural mode frequencies of a machine. The paper proposes a stiffness-modulation function to include the stiffness-effect caused by the end-shields. An analytical model is developed based on the proposed function to predict the mode frequencies of stator geometry. Experiments on a 4-phase, 8/6 switched reluctance motor (SRM) show that the obtained results match with the mode frequencies calculated by the developed analytical model.