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Title:A series-stacked power delivery architecture with isolated converters for energy efficient data centers
Author(s):Candan, Enver
Advisor(s):Pilawa-Podgurski, Robert C.
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Data center power delivery
Server power supply unit
Series stacking
Differential power processing
Dual active bridge converter
Bidirectional hysteresis control
Abstract:While the Internet is spreading far and wide, the data centers located at the heart of maintaining uninterrupted access to this service continue to grow rapidly. The energy efficiency of data centers has become crucial in our energy limited world and therefore both power distribution and conversion methods for future data centers need to be reconsidered. In this thesis, alternative methods to achieve more power efficient DC power distribution and voltage regulation for future data centers are investigated. The conventional way of delivering DC power to a server rack in data centers generally contains a central converter that regulates a DC bus, which is typically at 380V rectified grid voltage. This 380V bus voltage is in turn fed to each server rack and one DC-DC converter per server then converts the DC bus voltage to a lower voltage, which is typically 12V. Since each DC-DC converter has to perform a large voltage step down, relatively high power losses are common. In order to avoid large voltage step down and the corresponding power losses of each server’s DC-DC converter, the concept of electrical series stacking of servers in a rack is proposed in this work. The concept of series stacking and active load balancing using differential power processing (DPP) ensures that only the power difference between servers needs to be processed. Therefore the amount of processed power, as well as the power lost during the conversion, is reduced in comparison to the conventional system, where each server’s DC-DC converter has to process all the power needed by the server. This results in a significant reduction in power conversion losses. The concept of series stacking and active voltage balancing by DPP is experimental validated. A DC power distribution system for a four-server rack is created. A control algorithm is developed for server to virtual bus differential power processing and the proposed solution is also supported with experimental results. This thesis presents an experimental demonstration of a series stacked server power delivery architecture with active voltage balancing for future data centers.
Issue Date:2014-09-16
Rights Information:Copyright 2014 Enver Candan
Date Available in IDEALS:2014-09-16
Date Deposited:2014-08

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