The Impact of Multi-Stack Fuel Cell Configurations on Electrical Architecture for a Zero Emission Regional Aircraft

Abstract

All-electric aircraft can eliminate greenhouse gas emissions during aircraft mission, but the low predicted energy storage density of batteries (=0.5 kWh/kg), and their life cycle, limits aircraft payload and range for regional aircraft. Proton Exchange Membrane Fuel Cells (PEMFCs) using hydrogen are explored as an alternative power source. As the effort on designing high power density and highly efficient fuel cell systems continues, a trade off study on the effect of fuel cell configurations and the electrical conversion strategy on system efficiency, total weight, failure cases, and reduction of power due to failures, will inform future designs. Introducing viable fuel cell stacks and electrical configurations motivates such a trade off study, as well as concentrated design effort into these components. Currently available fuel cell stacks are designed at lower power (in the range of 150kW) to what is required for regional aircraft propulsion (in the range of 4MW). Hence to achieve the total required power, the fuel cell stacks are connected in parallel and series to create multi-stack configurations and provide higher power. In this study, multi-stack fuel cell configurations and the selected DC/DC converters are assessed. Each configuration is evaluated based on power converter design and redundancy, design for high voltage, degradation of fuel cell stacks, total system efficiency, and controllability of fuel cell stacks.

The Impact of Electric Machine and Propeller Coupling Design on Electrified Aircraft Noise and Performance

“…E-HEART is part of a digital-twin model being developed. The low fidelity FC model in E-HEART has been explained in [21] and [22].…”

Integrated Mission Performance Analysis of Novel Propulsion Systems: Analysis of a Fuel Cell Regional Aircraft Retrofit

“…Converter and FC configuration selection The selection of the fuel cell configurations and the DC-DC converter is based on the study conducted in [17] out of which a configuration with higher reliability has been selected. Designing a protection system for four fuel cell stacks in series with lower current in comparison with four stacks in series and parallel is recommended.…”

“…The four DC-DC converters that are used for voltage control can potentially be removed from the selected architecture (Fig. 5) with a slight benefit (max 2% increase) on total system efficiency and also reducing total weight from four converters as discussed in [17]. In this paper, the more reliable architecture with four converters was selected, but in future work, the effect of the converter removal on the aircraft and mission performance can be explored.…”

“…This can be the topic of a comparative study between oversized systems that improve operability and performance in a wide range of condition and reduced system designs that reduce system mass but decrease energy efficiency and impose operational constraints at less extreme conditions. • The presented mission scenarios, and other scenarios, will be repeated using different component designs from [17] and [28] to compare and identify which design offers the lowest energy consumption and most beneficial weight/efficiency trade-off across a wide range of mission requirements and conditions while operating within safe limits. • In the uncertainty analysis of the technology factors, it was demonstrated that the passenger capability and flight energy per passenger are highly affected by the technology factors and were compared against the energy per pax of the conventional 50-pax, 70-pax and hydrogen GT retrofit.…”