Fabrication and Evaluation of Composite Magnetic Core Using Iron-Based Amorphous Alloy Powder With Different Particle Size Distributions

The authors proposed the iron-based metal composite bulk magnetic core for high efficient and lightweight MHz switching DC-DC converter using SiC/GaN power devices. Although the iron-based metal composite bulk magnetic core exhibited a lower core loss than that of Ni-Zn ferrite in MHz frequency band, its relative permeability was low around 10. In this paper, in order to increase the permeability of such composite magnetic core with low core loss, we investigated an effect of mixing amorphous alloy powder having different particle size distributions. This method estimated increasing volume fraction of amorphous alloy powder and decreasing the demagnetization field of the composite magnetic core. From the experimental results, the composite magnetic core with an optimal mixing ratio of 2.4 μm and 12.8 μm median diameter Fe-based amorphous alloy (Fe-AMO) powders exhibited a relative permeability of 20.5 which was 2.4 times higher than that of composite magnetic core using 2.4 μm median diameter Fe-AMO powders. And its core loss was 555 kW/m
³
at 1 MHz in frequency and under 20 mT in maximum flux density.