Prof. Kazuhiro Muramatsu
Kazuhiro Muramatsu is a Professor of Department of Electrical and Electronic Engineering at Saga University, Japan since 2008. He was educated at Okayama University and received B.E., M.E., and Ph.D. degrees in 1988, 1990, and 1993, respectively. He was with ALPS Electric Co., Ltd. from 1990 to 1994. He moved to Okayama University from 1994 and worked as an Assistant Professor until 2001. He was a Visiting Researcher at University of Bath, U.K. in 1999 and Grenoble Institute of Technology, France in 2000. He moved to Saga University as an Associate Professor in 2001. His major research topics are the finite element methods for 3-D magnetic and coupled field analyses and their applications on electrical machines and magnetic devices. He has been a member of the ICS Board since 2016 and the chair of IEEJ Investigating R&D Committee of Innovative Technology Development Using Electromagnetic Field Analysis since 2022. He served as a Chinese High-end Foreign Expert.
Presentation: High frequency electromagnetic field analysis of inductor for power electronics
In inductors excited by the inverter using Gallium Nitride power devices, the ringing phenomenon, which is the oscillation in the current waveform, increases the noise and loss. The ringing occurs due to the multi-resonances at the switching. To clarify the mechanism of the multi-resonances, the high frequency (HF) behaviors of ring core inductors with solid and laminated iron cores in frequency domain are measured and simulated by using the electromagnetic field finite element analysis (FEA) taking account of the stray capacitance and the frequency dependance of magnetic permeability. First, the measured HF response of the inductor with solid iron core is represented by FEA taking account of the stray capacitance of winding, and the mechanism of the multiple resonance phenomena is explained by a distributed-element circuit model. Next, the measured HF response of the inductor with laminated iron core is represented by FEA taking account of not only the stray capacitance but also the frequency dependance of magnetic permeability of the steel plate. It is also suggested that the original permeability without the skin effect decreases with frequency.