Ridged surface for reducing eddy-current losses in ferromagnetic shielding

Because of the increasing demand for electric power, devices operating at higher and higher currents have been developed and are being produced. These machines are placed in a closed metal enclosure that provide also shielding of the electromagnetic field. Two novel methods to reduce Joule-heat losses in shielding are described. These methods are based on making the surface of the ferromagnetic shielding material corrugated or ridged, thus increasing the conductive area for the eddy currents. The results were obtained from 1D and 2D finite element models of the new and conventional types of shielding, considering also the non-linear magnetization curve of the material used. It can be seen that the ridging can be a beneficial alternative of coating with high-conductivity material, e.g., copper, in reduction of eddy current losses.