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High Density Power Conversion Electronics Enabled by GaN-Based Modular Topologies

Barchowsky, Ansel (2017) High Density Power Conversion Electronics Enabled by GaN-Based Modular Topologies. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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This dissertation explores the use of modular multilevel converter (MMC) architectures, coupled with wide-bandgap semiconductors, to achieve high power-density in power electronics converters. At the converter level, the capabilities of the modular multilevel converter are investigated for their use in low voltage, low power, DC-DC and DC-AC applications. This investigation shows that the use of modular multilevel architectures enables low voltage Gallium Nitride high electron mobility transistors (GaN HEMTs) to be used in applications for which their voltage thresholds are not typically suited. This results in lightweight, compact, conversion systems.

GaN HEMTs have been shown to provide a low loss, low volume alternative to Silicon transistors for power conversion, but require several enabling technologies to make them ideally suited to high-density converters. This work therefore presents two enabling technologies for GaN-based conversion circuits. First, a technique is developed that optimizes the gate resistance for driving GaN HEMTs in order to ensure safe, rapid device turn on. Next, the development of planar magnetic transformers is discussed, with a focus on high-frequency converter operation. For each of these technologies mathematical analysis, circuit simulation, and hardware development are performed and compared to ensure proper functionality.

Taking advantage of those two enabling technologies, two converter architectures based on the MMC structure are developed. First, a DC-AC MMC is presented, taking advantage of GaN HEMTs and minimal filtering requirements to achieve high power density in low voltage systems. Next, that topology is extended and a novel DC-DC converter based on two coupled DC-AC MMCs is presented. Both systems are described mathematically, simulated, and developed as hardware prototypes to prove functionality. While both converter systems are relevant for applications in DC microgrids, the DC-AC converter will be specifically investigated for its application as a variable speed drive in naval power systems. Likewise, the DC-DC MMC will be shown to provide new solutions for high voltage spacecraft power systems.

Based on the work presented in this dissertation, engineers will be presented with alternatives to traditional methods of achieving high density in power conversion systems. By coupling the low filtering requirements and low losses of the modular multilevel converter with low voltage, highly efficient GaN HEMTs, the presented converter systems achieve high power density and efficiency with minimal filtering requirements. The result of this work is two novel converter systems that will enable further research into lightweight, low volume, power conversion.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Barchowsky, Anselanb105@pitt.eduanb105
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairReed, Gregorygfr3@pitt.edugfr3
Committee MemberGrainger, Brandonbmg3@pitt.edubmg3
Committee MemberMao, Zhi-Hongzhm4@pitt.eduzhm4
Committee MemberOhodnicki, Paulpaul.ohodnicki@netl.doe.govpro6
Committee MemberStanchina, Williamwes25@pitt.eduwes25
Date: 14 June 2017
Date Type: Publication
Defense Date: 31 March 2017
Approval Date: 14 June 2017
Submission Date: 5 April 2017
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 156
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Electrical Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Power conversion electronics, wide bandgap, gallium nitride, HEMT, HFET, planar magnetics, modular multilevel converter, naval, spacecraft, power density, efficiency
Date Deposited: 14 Jun 2017 17:52
Last Modified: 14 Jun 2017 17:52


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