Electromagnetic computations with Preisach hysteresis model

Abstract

This paper presents a novel algorithm for the computation of transient electromagnetic fields in nonlinear magnetic media with hysteresis. We deal with an axisymmetric transient eddy current problem where the constitutive relation between H and B is given by a hysteresis operator, i.e., the values of the magnetic induction B depend not only on the present values of the magnetic field H but also on its past history. First, we introduce the mathematical model of the problem and, by applying some abstract result, we show the well posedness of a weak formulation written in terms of the magnetic field. For the numerical solution, we consider the Preisach model as hysteresis operator, a finite element discretization by piecewise linear functions, and the backward Euler time discretization. By taking into account the monotonicity property of the Preisach model, we propose a fixed point algorithm to deal with hysteresis effects which is numerically validated: we report a numerical test in order to assess the order of convergence and we compare the results with experimental data. For the later, we consider a physical application: the numerical computation of eddy current and hysteresis losses in laminated media as those used in transformers or electric machines.