Numerical Analysis of 3D Eddy Current Fields in Laminated Media Under Various Frequencies

A homogenization method for analyzing eddy current fields and resultant loss in laminated ferromagnetic media is presented, where the equivalent conductivity tensor proposed in a previous paper is applied. In order to compute fields at various frequencies, the formulas for the effective skin depths along different directions in the anisotropic solid core are derived, which are accompanied with a new scheme for finite element mesh generation. The proposed method is numerically investigated in a small iron core model over a very wide frequency range. The calculation results are compared with those from the direct method involving the actual description of the laminations and those from the traditional homogenization method. It is shown that the proposed method yields basically the same results as the direct method with much lower computational cost both in linear and nonlinear cases, whereas in some cases the traditional method results in large errors even at low frequencies.