Modeling of nonlinear material with linear inhomogeneous medium for loss prediction of transformer cores

Abstract

A method for the approximate prediction of the power loss of a nonlinear ferromagnetic laminated iron core is presented. The calculation is made in two subsequent steps. In the first step, the approximate magnetization of the material is predicted assuming a bulk nonlinear material with anisotropic electric conductivity. In the second step the nonlinear materials of the ferromagnetic sheets are replaced with linear ones whose permeability is spatially inhomogeneous. The actual permeability distributions are determined based on the nonlinear B-H curve of the material and the magnetic field values obtained from the first calculation. In this paper the applicability of the method is demonstrated through calculations made by FEM studying a benchmark arrangement.