High Frequency Magnetic Properties of Co-Based Amorphous Wound Cores Used for Controlling a Switched-Mode Power Supply

The magnetic properties, and especially the core losses at near-saturation, of Co-Fe-Si-B system amorphous wound cores with various squarenesses are reported. Under ac magnetization at 50 kHz, when control current is zero the core loss increased with the H
Lm
, while core losses were lower for samples with higher dc B-H loop squarenesses B
r
/B
s
. When control current is zero, it is thought that for magnetic amplifier cores, core losses must also be understood, and that a high B
r
/B
s
is useful in lowering core losses at or near core saturation.