Magnetostriction strain measurement and its application for the numerical deformation calculation of a transformer

摘要

Attempts to lower the noise of electrical machines in general and the noise of transformers in particular have gained more attention during the last years. The deformation of the magnetised ferromagnetic materials, known as magnetostriction, is a significant contributor to this noise. The aim of this work is to model such deformation by means of numerical tools. To this end, first the magnetostrictive behaviour of the material is required to apply it further for the calculations. We start with an overview of the magnetostriction strain measurement setups developed at the Electrical Energy Laboratory of Ghent University. A recently developed setup using a heterodyne laser interferometer is compared with a strain gauge setup that has been developed in the past. The results obtained by the laser setup prove to have a higher accuracy than those obtained by the strain gauge setup. In the next step, the laser measurement results are applied to the numerical magnetostrictive deformation technique. Such technique is based on finite element approach and requires a model of the magnetostrictive behaviour of the core material, which is made on the basis of the experimental results. For the computation, continuum description of magnetoelastic materials based on Chu model formulations is considered. In this method, a set of forces are introduced, which in fact induce the same strain in the material as the magnetostriction does. Applying the measurement results obtained by the laser setup in the computation method enables us to better identify the core deformation. Copyright © 2013 John Wiley & Sons, Ltd.