Electric Aircraft Propulsion Concepts with Axial Flux PM Machines, Integrated Condition Sensing, and HIL Enabled WBG Power Electronic Drives

NASA Kentucky SPACE Grant Proposal for Graduate Fellowship for 2020/2021 University of Kentucky, Electrical and Computer Engineering Dept., SPARK Laboratory PI: Dan M. Ionel, Ph.D., FIEEE, ECE Professor Co-I: Aaron Cramer, Ph.D., ECE Associate Professor Co-I: James Lumpp, Ph.D., ECE Professor GF: Damien Lawhorn, Ph.D. Candidate, NASA GF 2018-2020 and NASA Glenn Research Center 2018-2020 summer intern Electric Aircraft Propulsion Concepts with Axial Flux PM Machines, Integrated Condition Sensing, and HIL Enabled WBG Power Electronic Drives Abstract – Ver. 2020 0506 Over the last two and a half years, the PhD student was a NASA Kentucky graduate fellow, and, under the advising of UK faculty and NASA Glenn experts, made substantial progress on research spanning from the optimal design of power and propulsion systems for electric and turboelectric aircrafts, down to subsystem and component level contributions. The current proposal benefits of previous results, including the systematic derivation of electric aircraft propulsion specifications, such as specific torque, electromechanical conversion efficiency, and constant power speed range, and focuses on novel concepts for the design and demonstration of axial flux permanent magnet machines, which have been identified as a potential viable solution, particularly in coreless configurations. Such machines offer, in principle, advantages for operation under normal and fault conditions, but pose major challenges, which include the inability to operate through state-of-the-art flux weakening control at high-speed and constant power. The proposed research will provide a much- needed solution to this problem by conceptualizing, formulizing and demonstrating a novel current, rather than flux, weakening method for expanding the constant power speed range of low inductance machines. Further improvements, in terms of employing an innovative printed circuit board (PCB), in lieu of traditional-type copper wire stator windings, will be theoretically and experimentally studied. To maximize the fault tolerance and compactness of electromechanical and electronic components, integrated condition monitoring circuitry will be directly mounted on the electric machine stator PCB, as opposed to the traditional discrete-component far-distance implementations, and a wide band gap device (WBG) power electronic inverter implemented directly on yet another PCB with a form factor similar to the electric machine stator. Demonstration and validation, considering realistic system-level dynamics will be performed in the lab on a hardware-in-the-loop (HIL) system and a software framework representing the subsystems of an electric airplane, which is to be prototyped.