Granular Power Conversion with Distributed Switching Cells and Magnetics Integration

Abstract

Power electronics is the backbone of future energy systems including data centers, electric vehicles, and grid-scale energy storage. These high-impact applications demand increased efficiency, density, and reliability in power conversion. To leverage the advances in semiconductor devices and the scaling laws of passive components, a promising trend is to adopt granular power architecture with magnetics integration for minimized power conversion stress and maximized component utilization. In pursuit of this vision, this thesis first develops a systematic approach to all-in-one magnetics integration through matrix coupling. The benefits of matrix coupling in size reduction, ripple compression, and transient acceleration are quantified. A matrix coupled SEPIC prototype is designed and built. It can support load current up to 185 A at 5-to-1-V voltage conversion with over 470 W/in3 power density. Compared to commercial discrete inductors, the matrix coupled inductor has a 5.6 times smaller size and 8.5 times faster transient speed with similar current ripples and ratings. Next, a multistack switched-capacitor point-of-load (MSC-PoL) architecture is presented to power high current computing systems with high efficiency and ultra-compact size. Benefiting from granular architecture, coupled magnetics, and soft-charging technique, the MSC-PoL architecture can reduce current ripple, boost transient speed, reduce charge sharing loss, and enable the self-balancing of granular switching cells. A 48-to-1-V/450-A voltage regulator containing two MSC-PoL modules is fabricated and tested. The prototype is enclosed into a 1/16-brick/0.31-in3/6-mm-thick package with 724 W/in3 power density, enabling ultra-compact power-supply-in-package (PwrSiP) voltage regulation for extreme efficiency, density, and control/communication bandwidth. Finally, a multiport ac-coupled differential power processing (MAC-DPP) architecture is introduced to support large-scale energy systems with ultra-high system efficiency (>99%). The proposed MAC-DPP architecture associates all granular switching ports through a series coupled multi-winding transformer, featuring reduced component count, smaller magnetic volume, and fewer differential power conversion stages compared to other DPP solutions. A stochastic loss model is developed to explore DPP performance scaling limits. A 10-port 450 W MAC-DPP prototype with over 700 W/in3 power density is built and tested on a 50-HDD storage server. It achieves 99.77% system efficiency, completing the first demonstration of a DPP-powered data storage server with full reading, writing, and hot-swapping capabilities. The exploration of software, hardware, and power architecture co-design yields valuable insights for designing next-generation power architectures in data centers. The matrix coupling theory, the MSC-PoL architecture, and the systematic DPP analysis advance the fundamentals of granular power electronics and pave the way toward high-performance power conversion systems for a wider range of applications.