ADVANCED POWER MANAGEMENT STRATEGIES FOR COMPLEX HYBRID-ELECTRIC AIRCRAFT

Aircraft electrification for propulsion is a promising way to alleviate the negative environmental impact of conventional carbon-powered aviation. Inclusion of the electrical powertrain aims to enhance design freedom allowing for more efficient power systems and operational schemes. In this work a design space exploration is performed aiming to derive power management guidelines based on aircraft environmental performance. A 19-passenger commuter aircraft employing the series/parallel partial hybrid-electric architecture is examined. Two underwing-mounted turboprop engines are combined with a boundary layer ingestion fan mounted in the aircraft aft and powered by an electrical drive. The primary electrical energy source is a battery system. A multi-disciplinary framework is utilized, comprising modelling approaches for multi-point thermal engine design, physics-based electrical component sizing and performance, aircraft sizing, mission design, and environmental assessment. The investigation revealed that the reference designed hybrid-electric configuration with entry-into-service 2035-assumed technologies yields roughly 18% improvement in block consumption and emissions, but an 8% increase in maximum take-off weight, compared to its 2014 conventional counterpart. The design space exploration for an optimal power management scheme indicated a minimum ratio of 1:1.35 between cruise and design point hybridization power. However, even the optimally operated hybrid aircraft showcases worse environmental performance compared to the conventional design of same entry-into-service date. The investigation has revealed that the complex powertrain and hybrid architecture selected may be more suitable for larger class aircraft, with the accumulated performance benefits reaching the order of 5% for the hybrid designs explored under relaxed top-level constraints.