A FEM formulation to treat 3D eddy currents in laminations

A method is presented to compute the eddy current losses in laminated nonsa turated iron cores based on the finite element method. In the first step, a three-dimensional model of the core treated as a bulk of anisotropic mater ial with low conductivity in the direction normal to the lamination is anal yzed. Each laminate is taken into account in the second step by writing the field components in it as fundamental solutions of the diffusion equation so that the averages of the tangential electric and magnetic field componen ts over the thickness of the sheet equal the averages obtained in the first step.