Numerical modelling of anisotropy and eddy current effects in ferromagnetic laminations using a co-energy formulation

The paper deals with a numerical model for the evaluation of electromagneti c fields in one steel lamination under the influence of a rotating magnetic flux, taking into account anisotropy effects. For this purpose a detailed material model, described by a differential permeability tensor, is include d in the macroscopic electromagnetic field calculations in one lamination. Here, by geometrical and physical considerations, the governing Maxwell equ ations are reduced to a system of parabolic PDEs for the components of the magnetic field vector, under appropriate boundary and initial conditions. W e present a suitable numerical approximation based upon a finite element-fi nite difference method, which properly takes into account the material char acteristics. The study leads to a more realistic numerical modelling of the electromagnetic phenomena inside electric and magnetic conducting laminati ons due to anisotropy effects. Numerical results are compared with those fr om simplified analytical formulae. Copyright (C) 2001 John Wiley & Sons, Lt d.