Time-Domain Analysis of Magnetically Shielded Wire Coils Using Homogenized Finite-Element Method

A magnetically shielded wire (MSW) is effective for the reduction of the eddy-current loss due to the proximity effect. When using the finite-element method (FEM), it is challenging to analyze the electric apparatus, including MSWs, because its radius is much smaller than the overall machine size. This problem can be circumvented by modeling a multiturn MS coil (MSC) as uniform material with the macroscopic complex permeability defined in the frequency domain. This article presents an extension of this homogenization method to the time domain. The inverse Laplace transform is effectively performed by expanding the complex permeability into partial fractions. It is shown that the proposed method is accurate even when the magnetic saturation of the magnetic core is in effect.