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Electro-Thermal Effects of Power Transistors on Converter Performance

Kozak, Joseph P. (2016) Electro-Thermal Effects of Power Transistors on Converter Performance. Master's Thesis, University of Pittsburgh. (Unpublished)

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In this work, a comparative study of the electrical and thermal performance of a silicon carbide (SiC) MOSFET and a silicon (Si) IGBT power transistor, operating in a DC/DC boost converter, is presented. Behavioral models of Powerex Inc. switching transistors were developed in Synopsys SaberRD and used to predict the converter electrical efficiency; ANSYS Icepak modeling software was used for thermal simulations to identify potential hot spots. This work provides an overall, electro-thermal analysis of both transistor types with respect to switching frequency in the boost converter circuit. Optimal switching frequencies for each device at a given current are observed, and thermal performance of the SiC MOSFET is quantified with comparable or greater electrical efficiency to the Si IGBT. Our SiC MOSFET temperature measurements further validated published mathematical expressions, which help, in this study, to identify the best operating frequency with respect to electrical and thermal performance.

Performance analysis and design considerations from the DC/DC converter were then applied to design a 2kW, high power density, gallium nitride (GaN) based, modular multilevel converter (M2C). Half-bridge submodules for a single-phase, low voltage, high power density inverter (450 VDC, 2 kW, < 40in3 volume) were designed, constructed, and analyzed. This power density is predicted through the utilization of the EPC2014C gallium nitride (GaN) transistor into the half-bridge submodules of the M2C. These submodules are configured in series and parallel, with a switching frequency of 24 kHz, to achieve the voltage and current requirements. Each arm of the M2C was designed onto a double-sided, 6-layer, printed circuit board (PCB). The design and fabrications for these power boards are discussed as well.

The design, fabrication, and analysis of all three power conversion circuits presented here also include similar analysis for their gate drive circuits.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Kozak, Joseph P. jpkozak@gmail.comJPK540000-0002-4308-6815
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Thesis AdvisorStanchina, William wes25@pitt.eduWES25
Committee MemberKwasinski,
Committee MemberReed, Gregorygfr3@pitt.eduGFR3
Date: 14 June 2016
Date Type: Publication
Defense Date: 17 March 2016
Approval Date: 14 June 2016
Submission Date: 24 March 2016
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 103
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Electrical Engineering
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: Electro-Thermal, GaN, Power Converters, SiC, Wide Bandgap Semiconductors
Date Deposited: 14 Jun 2016 18:22
Last Modified: 15 Nov 2016 14:32


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