Date of Award

Spring 1-1-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Khurram Afridi

Second Advisor

Dragan Makismovic

Third Advisor

Robert Erickson

Fourth Advisor

Hanh-Phuc Le

Fifth Advisor

Zoya Popovic

Abstract

Telecommunication systems and datacenters require compact isolated power converters that maintain high efficiencies across wide operating ranges. This thesis introduces high-efficiency high-power-density isolated dc-dc converters suitable for such applications. These converters are based on the impedance control network (ICN) resonant converter architecture, which enables high performance by achieving soft-switching across wide variations in operating conditions. First, an ICN-based telecom bus converter is developed. The design of this ICN converter is optimized using an enhanced augmented state-space analysis approach. A 1-MHz 550-W prototype of this ICN converter achieves a peak efficiency of 97.6%, maintains >95.3% full-power efficiency across 2:1 ranges of input voltage and output voltage, and >93.6% efficiency across a 10:1 range of output power. Next, an approach to reduce the size of this ICN converter is developed, in which the three inductors of the converter are combined into a single integrated magnetic structure utilizing two coupled windings. The integrated magnetic structure is designed and optimized using 3D finite element analysis. This results in a very high performance 550-W quarter-brick ICN converter prototype, which maintains efficiencies comparable to those described above, while achieving a much higher power density of 462 W/in3. The ICN converter architecture is then applied to a large step-down conversion application – a single-stage isolated 48V-to-1.8V point-of-load (PoL) converter for datacenters. Three generations of this PoL ICN converter are developed, progressively achieving higher efficiencies and reduced size through innovations in the design of magnetically integrated matching networks and transformers, and through the utilization of transformer and rectifier architectures suitable for providing large voltage step-down. The final 1-MHz 90-W PoL ICN converter prototype provides up to 33:1 voltage step-down while achieving a peak efficiency of 92.6% and a power density of 314 W/in3. This thesis also describes an improved approach to optimizing the design of high-efficiency high-gain matching networks, with applications in large-conversion-ratio resonant converters and in wireless power transfer (WPT) systems. Finally, a high-frequency inverter architecture building upon the concepts of the ICN is developed, which compensates for coupling variations in WPT systems while maintaining high power transfer and high efficiency.

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