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    Resonant Converters

    T17.5 - Optimal Design of a 3-Cell Matrix Transformer for 1-MHz GaN LLC Converter Supporting 400-V/800-V Data Center Systems

    Wednesday, March 25, 2026
    2:50 PM - 3:10 PM CT
    Location: 214A
    This article presents a gallium nitride (GaN) based 1-MHz 12V/480W LLC converter employing a 3-cell matrix transformer optimized for the emerging 800-V/400-V datacenter bus. While matrix transformer with 4-cell arrays have been thoroughly investigated, flux cancellation and winding layout for odd-numbered cell arrays remain unaddressed. To fill this gap, two distinct flux path and winding patterns are proposed and compared; the preferred one achieves optimal flux balance and shrinks the print circuit board (PCB) footprint by 40 %. A core loss model for the proposed magnetic core is developed for further winding optimization. To achieve compatibility with both 400-V and 800-V architectures, a stacked bridge structure with two selectable switching modes is employed on the primary side. Finally, a 1 MHz GaN-based prototype is built and tested.