Energy Management for Fuel Cell Powered Hybrid-Electric Aircraft

Many researchers have proposed hybridization of fuel cell powerplants for unmanned aerial vehicles with the goal of improving the aircraft performance. The mechanisms of this performance improvement are not well understood. This work poses the problem of deriving energy management strategies for fuel cell powered, hybrid fuel cell powered and internal combustion powered aircraft as an optimal control problem. Dynamic programming and sequential quadratic programming are used with reduced order dynamic models to solve for optimal energy management strategies and optimal flight paths for these aircraft. Results show that hybridization and flight path management does not improve the endurance of fuel cell powered aircraft for a fixed airframe design, as it can for internal combustion powered aircraft. During the aircraft design process, hybridization does allow the aircraft power constraints to be decoupled from the aircraft energy requirements, with beneficial results in an integrated aircraft design process.