Magneto-vibro-acoustic Computational Techniques for Electrical Machines

Abstract

This thesis investigates the electromagnetic, magnetomechanical and vibro-acoustic interactions in an electrical machine, and proposes numerical computational tools and experimental techniques for modeling these phenomena in electrical motors. In an electrical motor, the supplied electrical energy goes through different physical domains in the form of magnetic, mechanical, acoustic and thermal energy. In this thesis, computational methods for magnetic forces, magnetostriction, mechanical deformations, vibrations, and finally the acoustic sound produced by electrical motors are successfully implemented. The study starts with the analysis of magnetic forces in ferromagnetic materials and electrical motors by crafting finite element methods for computing these forces and validating them with experiments. From there, the investigations proceed to structural mechanics zone, where the effects of magnetic forces and magnetostriction on the deformations and vibrations of electrical steel sheets and the stator core of electrical motors are studied using numerical methods and experimental justifications. The causes of vibrations in two induction motors were examined with computational and experimental methodologies. The generation of acoustic noise due to mechanical vibrations is modeled using a numerical method that is based on a combination of the finite-element and boundary-element methods. The results and findings in the thesis from numerical and experimental studies provide efficient tools for analyzing and computing various quantities pertaining to the behavior of ferromagnetic materials and electrical motors. These methods can be applied in practical facets such as the design and condition-monitoring stages of electrical motors. This thesis has succeeded in addressing different domains of energy conversions and their effects in electrical machines by developing reliable and proficient computational tools and experimental methods in the realms of magnetics, mechanics and acoustics.