Power Loss Properties of Fe-Si-Al Powder cores

摘要

Powder cores are remarkable as reactor for switching regulators. But power loss (Pcv) of powder cores is worse than Ferrites. To improve the power loss we measured and analyzed power loss of Fe-Si-Al powder cores. Power loss was separated into hysteresis loss (Ph), eddy current loss (Pe) and residual loss (Pr). The residual loss was obtained from the intersection of Y-axis and the plot of (Pcv-Ph) versus reciprocal of the resistivity of powder cores. The following results were obtained. The eddy current loss and the residual loss were remarkably reduced by powders annealed in air atmosphere. The reason seems to be purpose of the increase of resistivity for cores and particles. It is because of the oxide layers were formed on the surface of particles when powders were annealed in air atmosphere. It was found that the powder's resistivity is related to the eddy current loss and the residual loss.