Analysis and Experiments on a Lab-Fabricated Inductor of Improved Composite Material Core in a High Frequency Synchronous Buck Converter

This paper presents the development and use of a magnetic composite material of low relative permeability (barium ferrite (BaFe)) in an inductor core of a GaN-based DC-DC Synchronous Buck Converter (SBC). The details of the core development from the commercially available BaFe powder are provided. Experimental and analytical investigations have been conducted to validate its performance. The estimation of parameters is presented as a part of the material performance validation exercise duly. The external characteristics (F <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$B-H$</tex> loop) of the material are obtained from the internal characteristics <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(M-H)$</tex> through appropriate conversion. The <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$B-H$</tex> characteristic is then used in finite element (FE)-based simulation. The inductor is tested for large ripple values over much smaller average current, while the converter output is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$12 V, 15W$</tex> (nominal), at 500 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$kHz$</tex>. The analytical and experimental results are found to be in good agreement.