A simple evaluation of magnetic fields and eddy currents in ferromagnetic straps of finite length

A simple analytical method to evaluate the electromagnetic fields in a ferromagnetic strap of finite dimensions, excited by a short coil, is presented. The method can be extended to ferromagnetic cylindrical parts of finite length, and also to nonlinear ferromagnetic materials by assuming an appropriate change of magnetic permeability with material depth. The original configuration of the finite-length strap and short excitation coil is replaced by an arrangement of many straps glued together, and magnetized by a suitable succession of excitation coils. This last configuration can be solved analytically according to the Fourier transform method. Results obtained by the proposed method are in good agreement with results obtained by a finite-element method, and also with experimental results