A Method for Solving the Time-Periodic Electromagnetic Field Problem in Ferromagnetic Shielding

Abstract

Ferromagnetic shield is an efficient solution for shielding the static and periodic electromagnetic field. Therefore, it is also a shilding solution for an electromagnetic field having a rich contain of harmonics. Using the polarization fixed point method, the nonlinear media is replaced by a linear one having the vacuum permeability and a magnetization that is iteratively corrected by the flux density. For each harmonic of the magnetization, the electromagnetic field may be obtained by solving the sinusoidal steady-state eddy-current equation in the shield. The solution process can be started by retaining a small number of harmonics and, finaly, the acuracy of the solution may be improved with adding some more. The proposed method always yields to stable results, even when the characteristic B-H is strongly nonlinear, and has a superior computational efficiency with respect to various time-stepping techniques and to the “harmonic balance method”.

Keywords

• ferromagnetic shield
• eddy-current equation
• nonlinear periodic fields
• polarization fixed point method
• fourier analysis