Magnetic properties of Compressed amorphous powder cores and their application to DC-DC converters.

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Fe-based amorphous powder particles with excellent soft-magnetic properties were fabricated by our new atomization process "spinning water atomization process(SWAP)", which has both a high quenching rate and mass- production potential. In addition, these amorphous particles were insulated by glass fine powder and pressed into toroidal, E- and pot-shaped cores by hot-pressing techniques at relatively high temperature conditions below crystallization temperature. The cores fablicated had superior magnetic properties compared with commercial Sendust powder core. The coercive force was half and the flux density B_m at 300 Oe was 30% higher. The initial permeability up to 1 MHz was about 90-110, and the core loss at 100 kHz for B_m=0.1 T was 660 kW/m^3. The former was comparable to that of Sendust and the latter was 20% lower. The amorphous cores obtained were applied to DC-DC converters working at 100 kHz. The conversion efficiency examined at out put power up to 300 W was higher than that of converters utilizing a typical commercial Sendust core and a single gapped ferrite core. Furthermore, the magnetic properties of gapped pot-shped core for inductive charger were also studied. For the cores with a gap of above 1.5mm, the loss of amorphous powder core exhibited lower than that of ferrite.