Doctoral Dissertations
Date of Award
8-2022
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Electrical Engineering
Major Professor
Fei (Fred) Wang
Committee Members
Leon Tolbert, Hua Bai, Zheyu Zhang
Abstract
The electrified aircraft propulsion (EAP) system using electric motors to replace conventional engines to propel aircraft can increase propulsive efficiency, reduce CO2 emission, and lower noise levels. High power lightweight solid-state circuit breakers (SSCBs) and motor drives are key enablers for the EAP.
This dissertation first identifies the challenges of developing high power and lightweight SSCBs by implementing a 500 kW rated prototype. The main challenges found include the instability of multiple paralleled switches and the high peak-to-average clamping voltage ratio of high-power TVS diodes. The instability is caused by the differential mode oscillation among paralleled MOSFETs. A model is proposed to consider the influences of the switching trajectory and nonlinear device parameters on stability. Then, a method is proposed to manipulate the switching trajectory to avoid the unstable region where the conventional switching trajectory normally goes through to improve stability. On the other hand, the foldback characteristic of the high-power TVS diode is investigated by an improved characterization method. Moreover, at cryogenic temperature, the peak-to-average clamping ratio would decrease due to the carrier freeze-out, making the high-power TVS diode promising in cryogenic applications. Other than turning off high fault current, the current limiting during faults is also a desired function of the SSCB to enable longer sustained fault current withstand time. Using switches alone to limit the current suffers from short withstand time. A control strategy is proposed to utilize the TVS diode to consume the major part of the energy for a much longer current limiting withstand time.
The design tool can speed up the design and optimization of motor drives. An automated and comprehensive design tool for motor drives is introduced. To improve the accuracy and speed of the design tool, 2 models are discussed. First, a data-driven modeling approach is proposed to improve the leakage inductance model accuracy of common mode chokes by using the artificial neural network. Second, an improved single Fourier analysis approach is proposed to consider conditions with non-integral carrier ratios for harmonic analysis of voltage source inverters by using a made-up fundamental frequency for coefficient calculation.
Recommended Citation
Dong, Zhou, "High power lightweight solid-state circuit breaker development and motor drive design for electrified aircraft propulsion. " PhD diss., University of Tennessee, 2022.
https://trace.tennessee.edu/utk_graddiss/11573