Development of a Controls Approach for Fuel Cell-Powered All-Electric Aero Engines based on an FHA

Abstract

Given the development of climate change in the past decades and its anticipated effects, the aviation industry is undergoing a growing momentum towards developing a future generation of electrified propulsion systems. Hence, sustainable key technologies, such as fuel cells, batteries and electric motors, must be integrated into the powertrain of commercial aircraft. While these technologies are already being applied in other transportation sectors, the feasibility of their integration still ought to be investigated for aviation. Various challenges in terms of weight and efficiency must be overcome to introduce these technologies into aircraft propulsion systems. However, significant influence is owed to the controls of these powertrains to ensure effective power output, handling quality, reliability and safety of the aircraft. From the control’s perspective the integration of fuel cell-based powertrains presents several challenges for three reasons. Firstly, more media of control are being introduced, such as hydrogen and high voltage. Secondly, the different media display highly-nonlinear interactions with each other and cannot be treated separately. Thirdly, these individual components entail numerous additional challenges with regards to durability and lifetime. Specific in-flight health monitoring is therefore crucial to the application of these technologies in aviation. An electrically powered aero engine topology using a low-temperature polymer electrolyte membrane fuel cell (LT-PEMFC) is being considered in this work. The specific control tasks that result from both performance and safety requirements are being analysed and compared to those of conventional gas turbine aero engines using functional structures. An analysis of the degrees of freedom present in both conventional and electrically powered aero engines is being performed - indicating a growth in complexity, which can arise with the electrification of aero engines. The comparison showed an almost 100% increase in the number of control variables required for the electric propulsion system. The results of this work shed light on the challenges imposed on powertrain controls by the fuel cell technology of today, in general, and the LT-PEMFC, in particular, to comply with the demanding performance and safety requirements of aviation. Based on control tasks derived for the fuel cell powered aero engines, a potential controls approach was developed addressing the challenges identified for integrating an LT-PEMFC into a passenger aircraft. This way, the introduction of sustainable electrified aero engines can be enabled.