Resistivity and core size dependencies of eddy current loss for Fe-Si compressed cores

In this study, resistivity and core size dependencies of eddy current loss were investigated for Fe-Si compressed powder cores. Over the resistivity of about 0.01 Omega m eddy current loss is independent on core height, however when the resistivity is lower than about 0.01 Omega m it increases with decrease of the resistivity. And eddy current loss increases as the core height is high. It is supposed that over about 0.01 Omega m eddy current generates only inside each particle, so eddy current loss does not depend on the core height, while under about 0.01 Omega m as, eddy current flows through particles, eddy current loss depends largely on core height. Furthermore eddy current loss is proportional to the 1.70th-1.95th power of frequency, and the exponent changes with resistivity. It is suggested that under the situation of intra-particle eddy current, domain wall motions relate to the eddy current loss.