噴霧粉を用いたFe-Si-Al系圧粉磁芯の低コアロス化

概要

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Magnetic powder cores are widely used for smoothing and boost choke coils of switching regulators as well as DC-DC converters. However , in general powder cores have a disadvantage of large core loss compared to sintered soft ferrite cores , and lower core loss powder cores are strongly required. In this study effects of particle size and microstructure on core loss of powder cores with Fe-Si-Al water-atomized and modified water-atomized powders were investigated. We concluded as follows.(1) Both eddy current loss and hysteresis loss are small for modified water-atomized powder cores compared with water-atomized cores. (2) Eddy current loss decreases with being particle size small. (3) Modified water-atomized powder cores have low eddy current loss through higher resistivity than that of water atomized powder cores. (4) Crystal grains are large for modified water atomized powder cores , thus hysteresis loss is small. It is guessed that aluminum oxides included in water atomized powder prevent grain growth through images with electron probe micro analyzer.
電気製鋼研究会の論文