FEM analysis of eddy current losses in nonlinear laminated iron cores

A finite element method is presented to compute three-dimensional eddy current distributions in nonlinear laminated iron cores. In a first step, the core is assumed to have an anisotropic conductivity of zero value in the direction perpendicular to the laminations. In a second step, the eddy currents within the sheets are computed by solving the nonlinear field problem individually in each layer. The boundary conditions for these essentially two-dimensional analyses are taken from the three dimensional field distribution determined in the first step. Numerical examples prove the validity of the method.