Walmsley, Robert
(2025)
An investigation into mass and volume reductions on Hydrogen-Electric Aircraft Propulsion Systems using biased magnetics in an interleaved DC-DC Buck Converter topology.
PhD thesis, University of Nottingham.
Abstract
Hydrogen-electric aircraft offer the potential to support reductions in CO2, NOX and noise emissions, from the aviation sector. However, integrating fuel cells and batteries into aircraft propulsion systems introduces the requirement for additional onboard power electronic converters. Power electronic converters utilise semi-conductor switching devices, and energy storage components, such as capacitors and inductors. Currently, these passive components account for approximately 50% of the converter's packaged volume. Reducing their mass or increasing power density could lead to overall aircraft mass reduction and package size reduction; providing a compelling incentive to investigate techniques for improvement.
This research includes two primary objectives. The first objective was to develop a novel hydrogen-electric aircraft simulation tool, capable of optimising propulsion system parameters for a selected measure of merit. The tool, designed for preliminary or conceptual commuter aircraft specifications, enables hybridisation of power inputs for a mission analysis and trade studies. Specifically, it assesses the impact of different power converter technologies and drag polar models on overall aircraft mass. Results indicate that a simplified drag polar model led to an overestimation of aircraft mass by approximately 6.6%, when using baseline converter technologies. Additionally, increasing the converter technology level showed diminishing returns in mass reduction, but still achieved a 1.6% decrease in aircraft mass when baseline technologies were doubled. Furthermore, in-flight battery recharging resulted in a 0.89% increase in total aircraft mass.
The second objective focused on enhancing the performance of magnetic components within an interleaved buck converter topology. A novel approach was investigated, leveraging permanent magnets to provide simultaneous DC biasing for a pair of AMCC-100 inductor cores, and placing them into an interleaved converter. Experimental testing, using the University of Nottingham's Galvano Electrochemical Impedance Spectroscopy (GEIS) test equipment, demonstrated significant improvement in current handling capabilities, before saturation, ranging from 87% to 125%, depending on magnet quantity. The complete magnetic arrangement was subsequently validated through experimental implementation in an interleaved buck converter rig, confirming the positive impact of biased magnetics on converter performance.
Overall, this study contributes to the advancement of hydrogen-electric aircraft propulsion systems, by introducing a simulation framework for investigating aircraft mass and propulsion system configuration, and demonstrating novel technique to improve the power density of power electronic converters.
| Item Type: |
Thesis (University of Nottingham only)
(PhD)
|
| Supervisors: |
Klumpner, Christian
Ahmed, Rishad
Hart, Simon
Degano, Michele |
| Keywords: |
Hydrogen-electric aircraft; Simulation tool; Propulsion
system parameters; Power converter technologies; Drag polar models; Magnetic components |
| Subjects: |
T Technology > TL Motor vehicles. Aeronautics. Astronautics |
| Faculties/Schools: |
UK Campuses > Faculty of Engineering > Department of Electrical and Electronic Engineering |
| Item ID: |
82715 |
| Depositing User: |
Walmsley, Robert
|
| Date Deposited: |
09 Dec 2025 04:40 |
| Last Modified: |
09 Dec 2025 04:40 |
| URI: |
https://eprints.nottingham.ac.uk/id/eprint/82715 |
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