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Title:Improving data center power delivery efficiency and power density with differential power processing and multilevel power converters
Author(s):Candan, Enver
Director of Research:Pilawa-Podgurski, Robert C.N.
Doctoral Committee Chair(s):Pilawa-Podgurski, Robert C.N.
Doctoral Committee Member(s):Krein, Philip T.; Domínguez-García, Alejandro; Banerjee, Arijit; Shenoy, Pradeep S.
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Data center power delivery
series-stacked power delivery, differential power processing
flying capacitor multilevel converters
single-phase ac to dc conversion
power factor correction
Abstract:Existing data center power delivery architectures consist of many cascaded power conversion stages. The system-level power delivery efficiency decreases each time the requisite power is processed through the individual stages, and the total power converter footprint increases by each cascaded conversion stage. Innovative approaches are investigated in this dissertation for dc-dc step-down conversion and single-phase ac-dc conversion to improve power delivery efficiency and power density in data centers. This dissertation proposes a series-stacked architecture that provides inherently higher efficiency between a dc bus and dc loads through architectural changes, reporting above 99% power delivery efficiencies. The proposed series-stacked architecture increases power delivery efficiency by connecting the dc loads in series to allow the bulk of the requisite power to be delivered without being processed and by reducing overall power conversion using differential power processing. The series-stacked architecture exhibits voltage regulation and hot-swapping while delivering power to rapidly changing computational loads. This dissertation experimentally demonstrates series-stacked power delivery using real-life computational loads in a custom designed four-server rack. In order to provide a complete grid-to-12 V power delivery for data center applications, this dissertation also proposes a buck-type power factor correction converter that yields high power density between a single-phase grid and the dc bus, achieving 79 W/in3 power density. The proposed buck-type power factor correction converter improves power density by eliminating the high-voltage step-down dc-dc conversion stage, which is typically cascaded to boost-type power factor correction converters in conventional data center power delivery architectures, and by leveraging recent developments in flying capacitor multilevel converters using wide-bandgap transistors. The buck-type flying capacitor multilevel power factor correction converter presents a unique operation condition where the flying capacitor voltages are required to follow the input voltage at 50/60 Hz. This dissertation experimentally explores the applicability of such an operation by using a digitally controlled six-level flying capacitor multilevel converter prototype.
Issue Date:2019-03-08
Rights Information:Copyright 2019 Enver Candan
Date Available in IDEALS:2019-08-23
Date Deposited:2019-05

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