Analysis of the magnetic properties of a silicate-coated spherical FeSiAl-based soft magnetic composite for high-frequency power-applications

In this paper, the relationship of the frequency-dependent magnetic permeability, magnetic loss, and DC-bias of a soft magnetic composite was analyzed. The permeability is divided into a domain wall movement component at low frequencies and a spin-rotation part at high frequencies. The resonance-frequency increases when the pressure decreases and, simultaneously, the permeability also decreases following the Snoek limit. Magnetic loss is separated into hysteresis loss, eddy-current loss, and excess loss, which is found to closely relate to the density of the powder core. The DC-bias properties of the composite tend to deteriorate slightly with the density increase. This is due to a decrease in the gap between the particles, which is associated with the pinning of the domain wall movement and coercivity. It is found that DC-bias is positively correlated with hysteresis loss and excess loss with respect to coercivity and pinning of the movable domain-wall. These results provide insights into the soft magnetic performance of soft magnetic composites, particularly with respect to compact, high-DC applications with high frequency and high magnetic saturation for high-power supply.