Comparison of induction machine stator vibration spectra induced by reluctance forces and magnetostriction

For rotating electric machines, the reluctance forces (Maxwell stresses) acting on the stator teeth are a major cause of noise emission. Next to the reluctance forces, magnetostriction is a potential cause of additional noise from electric machines. First, a thermal stress analogy is used to introduce magnetostriction in the finite-element framework. Next, we present the computation and comparison of the stator vibration spectra caused by these two effects separately, by example of a 45-kW induction machine. Moreover, two kinds of magnetostriction characteristics of the stator yoke material are compared: a quadratic A (B) curve and a A (B) curve with zero-crossing around 1.5 Tesla.