Natural Frequencies and Vibration Behaviour of Motor Stators

In order to reduce electromagnetic acoustic noise in motors, it is essential to understand the vibration behaviour of the stators so as to prevent resonance between the electromagnetic forces and the stators. This paper presents an assessment of the effects of teeth, windings, impregnation and wedges on the natural frequencies and vibration response of stators on the basis of experiments and simulation through numerical computation of the natural frequencies and vibration response of ring- and segmented-core stators having totally impregnated formed coils. The results show that assessment of the Young's modulus of the insulating layers of the impregnated windings and the wedges is the most important, and that the insulating layers of the windings can be reasonably dealt with as having a value of about 30% of the converged equivalent Young's modulus, and the wedges as having a value of 100% of that of their material.