Computation of transient magneto-mechanical problems in electrical machines

This paper investigates numerical results relating to several aspects on noise and vibrations of electrical machinery. This is based upon the coupling between the magnetic field and the mechanical deformation in the stator. The coupling is typically considered by using reluctance forces. Since the deformations occurring are small compared to the machine´s dimensions, there is no feedback to the magnetic system in numerical models. However, stator deformations are caused not only by reluctance forces, but also by magnetostriction effect of the stator iron. Magnetostriction is one of the main causes of noise in electromagnetic systems particularly when the flux density is above 1.5 T. In this paper, we show computational results of a transient numerical model developed earlier. This model incorporates the magnetostriction effect in addition to other electromechanical forces and related material interactions. Implementation results presented here for a 2-hp, surface mounted, permanent magnet motor. The results indicate that magnetostrictive forces are significant and must be accounted for in the electromagnetic system´s design stage