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High Efficiency Robust Isolated Converters for Space Missions

Cook, Thomas (2023) High Efficiency Robust Isolated Converters for Space Missions. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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This research explores the use of cascaded power electronic architectures, wide-bandgap semiconductors, and radiation hardened electronics to achieve an isolated, high-efficiency, and high-power density power electronic converter for space power applications. The cascaded converter architecture enables the use of traditional, proven radiation hardened (rad-hard) topologies and devices to be augmented with more modern topologies that are better suited for high switching frequencies and high-efficiency soft-switching techniques. For wider adoption by industry, the converter hardware was designed to conform to several standard design practices including the physical size, flight manufacturing practices, and part deratings.

The topology was first proven out in the form of a cascaded Buck-LLC, with a 22V-36V input range capable of outputting up to 200W of power at 12V. Gallium Nitride High Electron Mobility Transistors (GaN HEMTs) and zero-voltage switching (ZVS) of the LLC stage are used to efficiently generate the isolated output of the converter, while the front-end converter adapts to changes in input voltages and load changes.

Next, an emphasis was made on the magnetics design of the LLC transformer to increase efficiency. After testing the Buck-LLC converter, it was found that the transformer was one of the highest loss components due to the high winding current at maximum power output. Due to this loss, a planar design was introduced that uses a planar litz routing configuration as well as the concept of paired windings to reduce winding loss and conducted electromagnetic interference (EMI).

Finally, this work presents a control system design that adapts to changes in component values over temperature, lifetime, and radiation. By adapting the switching frequency and dead time, the converter is able to maintain high efficiency ZVS operation. In total, these systems provide the basis for the next generation of high efficiency and robust power converters for space applications with power ranges from 100W to 1kW, with the potential for even higher power outputs in future work.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Cook, Thomastvc8@pitt.edutvc80000-0002-1892-0783
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairGrainger, Brandonbmg10@pitt.edubmg10
Committee MemberOhodnicki, PaulPRO8@pitt.eduPRO8
Committee MemberGeorge,
Committee MemberKim, Hong Koohkk@pitt.eduhkk
Committee MemberKwasinski,
Date: 13 June 2023
Date Type: Publication
Defense Date: 8 February 2023
Approval Date: 13 June 2023
Submission Date: 4 January 2023
Access Restriction: 2 year -- Restrict access to University of Pittsburgh for a period of 2 years.
Number of Pages: 176
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Electrical and Computer Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Isolated, power, converter, Buck, LLC, Gallium Nitride, High Electron Mobility Transistor, radiation-hardened, Commercial-Off-The-Shelf, synchronous buck converter, Small Satellite, CubeSat, deep, space
Date Deposited: 13 Jun 2023 12:58
Last Modified: 13 Jun 2023 12:58

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