Electromagnetic Field Analysis on High-Frequency Response of Inductor Considering Frequency Dependence of Magnetic Permeability

In inductors for power electronics, the driving source frequency increases to MHz range by applying new semiconductors (GaN/SiC). To represent the high frequency (HF) response of the inductor with the iron core of laminated electrical steel sheets using the electromagnetic field finite element analysis (FEA), not only the stray capacitance of the winding but also the frequency dependence of magnetic permeability of the steel plate is considered in this paper. The original complex permeability without the influence of the skin effect of the steel plate is determined so that the HF response of the inductor obtained from FEA matches the measurement. It is shown that the HF response can be represented by taking into account the frequency dependence of magnetic permeability. It is also suggested that the real part of complex permeability decreases with frequency, and its imaginary part has a peak at 10 kHz.