Analysis & Optimization of Electric Propulsion Systems for Aircraft Applications
MS Student Anubhav Bose with Advisor Prof. Kiruba Haran
Development of all-electric aircraft poses new challenges for electrified propulsion systems (EPS). The limited weight and volume availability on most aircraft, coupled with the extreme power demands across the mission profile put significant demands on propulsion system performance. The emergence of electrified vertical take-off and landing (e-VTOL) aircraft using distributed electric propulsion (DEP) systems consisting of tens of electric machines for thrust, also necessitate novel approaches for power transmission inside the aircraft. Solving these challenges requires a holistic and integrated approach to EPS design, with co-optimization of electric machines, drives, energy storage systems and even the dc transmission cables. This research focuses on qualitatively analyzing tradeoffs in subsystem performance with variations in the fundamental powertrain parameters, such as the dc network voltage, to arrive at a solution that maximizes both gravimetric and volumetric power density of the EPS and to meet the demands of the aircraft mission. Initial results of the study can be seen in Figure 2. It also analyses the impact to electrical safety (such as the heightened risk of partial discharge) and attempts to balance it with the system power densities. Other areas of investigation include large diameter and aspect-ratio electric machines, which promise higher efficiencies and torque densities, hybrid energy storage systems that blend hydrogen fuel cells and lithium-ion batteries to accommodate varying power demands across the aircraft mission profile, and power electronic converters operating at medium voltage direct current levels. The aim is to create a framework and approach to aircraft EPS design that takes into account the mission profile, propulsion architecture and trends in subsystem power densities, and leads to a lightweight aircraft powertrain.