PhD Thesis Defense: Yue Wu
"Design and Comparison of Air-core Miniaturized Magnetics"
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Abstract: As magnetics have always taken up a large portion of the total volume of power electronic devices, miniaturization of the magnetics is important. Past works have studied how magnetic components can be miniaturized. In this thesis, we will follow the path of using air-core magnetics at high frequency and explore how to design good miniaturized magnetic components under certain constraints. We studied toroid, solenoid, staple and spiral air-core inductor geometries; concentric, end-to-end, interleaved, side-by-side, and stacked transformer topologies. For inductors in a buck converter at 30 MHz, solenoid inductors outperform toroid and staple inductors for a wide range of parameters. Solenoid inductors can also outperform spiral inductors with enough height. For transformers in an isolated DC-DC converter, the concentric solenoid is the best topology under 1 mm^2 area when height is greater than 0.7 mm. An isolated DC-DC converter with concentric toroid transformer is designed to achieve high efficiency, good thermals, and low EMI. Preliminary EMI tests have been performed and an additional EMI test is proposed. This work presents a method for designing good magnetic components under constraints.
Thesis Committee: Charles Sullivan (chair); Jason Stauth; William Scheideler; David Perreault (MIT)
