Study of modeling method of lamination of reactor core

The eddy current is induced in silicon steel sheets of core block of power reactor due to the fringing flux, and this causes a local overheating. An exact and quick calculation using three-dimensional finite element method is important in order to design a reactor without such a local overheating. If each lamination of core is subdivided into a fine mesh, the number of unknown variables becomes huge and the calculation is difficult within an acceptable CPU time. Therefore, a practical modeling method of lamination of core should be investigated. In this paper, an exact and quick practical nonlinear analysis is performed by subdividing only the region near the surface of lamination into a fine mesh, and by modeling the inner part of lamination as a bulk core having anisotropic conductivity. A criterion how to determine the surface region of lamination which should be subdivided into a fine mesh is denoted. It is shown that the number of elements can be considerably reduced by classifying the analyzed region into two kinds of parts with fine mesh and coarse mesh.