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

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.