Electrical Analog of the Eddy-Current-Limited Domain-Boundary Motion in Ferromagnetics

The observed losses in a ferromagnetic core are always greater than those calculated on the basis of a homogeneous permeability. In a magnetization process by domain-boundary displacements the permeability is certainly not homogeneous, but attains extreme values in the domain walls. As a result of this concentration of the changes in magnetic flux the dispersion curves of the initial permeability as a function of frequency show a shift of the dispersion region towards lower frequencies with increasing domain size. This is the well-known eddy-current anomaly encountered in laminated cores. An electric-circuit model was utilized to determine the eddy-current distribution and domain-boundary motion in a number of idealized cases.