Computation of core losses in electrical sheets used in electrical machines

Abstract

One of the most important quantities for magnetic materials is energy loss, usually expressed in terms of loss per mass unit and one cycle. From an engineering point of view, it would be desirable to have an accurate and simple model of energy losses in electrical sheets. This study presents a new approach to describing core losses in electrical sheets. The proposed approach allowed one obtaining a new formula for total losses in the material, in which only basic material coefficients such as material conductivity and magnetic permeability expressed in the form of a magnetic hysteresis loop are needed. The expressions used so far are semi-empirical, whereas the proposed model clearly indicates how the material parameters affect the losses. This stays in contrary to the approach in which the hysteresis losses are obtained from measurements by extrapolation of the ratio of losses and frequency when the frequency tends to zero. The obtained expression for total losses in the material was compared with the commonly used expression proposed by Bertotti, and comparable approximation errors of prediction were obtained. The comparisons were made on the example of non-oriented electrical sheets.