ORCID

0009-0002-0445-1506

Keywords

Dual Active Bridge (DAB), Stacked Secondary Phasing (SSP), High-Voltage, DC Power Delivery, Gallium Nitride (GaN) Converters, Optimal Phase-Shift Control, AI Data Center Power Systems

Abstract

The rapid electrification of hyperscale AI data centers is accelerating a shift from legacy 48 V distribution ladders to ±400 V high-voltage DC backbones, concentrating residual loss and dynamic stress on a single isolated bidirectional interface. This work presents a high-density Dual Active Bridge with Stacked Secondary Phasing (DAB-SSP) architecture as a scalable GaN-based solution for 48 V–800 V rack-level power conversion. By stacking 400 V secondaries, the topology leverages 650 V GaN devices while satisfying 800 V system requirements, reducing clearance and creepage distances, minimizing magnetic path lengths, and embedding leakage inductance necessary for wide-range zero-voltage switching.

A rigorous time-domain modeling framework is developed for single and dual phase-shift operation, yielding closed-form solutions for power transfer, RMS current stress, and soft-switching boundaries. An optimal control formulation based on Pontryagin’s Minimum Principle minimizes conduction loss while maintaining power transfer, providing a globally optimal phase schedule and revealing fundamental efficiency trade-offs. These analytical results are paired with a physics-based design methodology that links modulation strategy, magnetic geometry, and device characteristics.

The models are validated in GaN-based hardware demonstrating peak efficiencies exceeding 98 % with wide-range ZVS and stable transient response. Experimental thermal and calorimetric data confirm close agreement with the theoretical loss framework. The resulting converter provides a compact, efficient, and bidirectional interface for AI data center backbones, enabling peak shaving, renewable energy absorption, and fast ride-through without intermediate stages. This work establishes the DAB-SSP as a building block for future high-voltage, high-density power delivery systems

Completion Date

2025

Semester

Fall

Committee Chair

Issa Batarseh

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Department of Electrical and Computer Engineering

Format

PDF

Identifier

DP0029793

Document Type

Thesis

Campus Location

Orlando (Main) Campus

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