Hybrid Electric Propulsion Systems

Abstract

The growing level of environmental implications of aviation and a significant increase in air traffic have been driving technological advancements in the aerospace industry. The rising developments in battery technology allowed the automotive industry to build hybrid and fully electric cars. However, the limited power-to-weight ratio components impede the development of fully electric aircrafts. In this regard, Hybrid Electric Propulsion Systems (HEPS) are more viable. With HEPS, the aero-engine is combined with an electric system. This brings several technological challenges, such as the increased complexity in the performance and sizing methodology of the propulsion system and the necessary offset of the weight increment. Because of these issues, the different state of the art HEPS concepts largely depend on the development of new technologies, as well as maintaining efficient power management during the different phases of the flight envelope. The power management system adjusts the supplied power ratio between the energy sources during operation, as power can come from fuel and/or electrical energy. The objective of this study is to analyse the power management of HEPS, focusing on passenger transport aircraft. The application of HEPS in the mid/long-term is heavily dependent on the technology maturity level of electric components. To examine the performance of HEPS, a simulation model is developed after determining the power requirements of a flight mission. The effects of different power management control strategies are analysed by combining different take-off and climb power splits. The power management control strategy with a take-off and climb power split of approximately 25% and 14% respectively, while scaling down the engine to 90%, is the most optimal and feasible strategy. This will reduce the fuel burn by 7.5% and total energy consumption by 2%.