FUEL CELL BASED-ON POWERTRAIN TO HYBRIDIZE SMALL UNMANNED AERIAL VEHICLES

The proposed investigation aims at increasing the endurance of a small unmanned aerial vehicle (UAV) where the power request for propulsion can be satisfied by means of a battery and a fuel cell. The hybrid configuration allows the required power to be obtained at take-off and the fuel cell to support the battery in order to maintain the state of charge (SOC) in the other phases of flight. This operating mode avoids deep discharging, when the battery SOC falls down a suitable threshold, and overcharging, which exposes to risk of explosion in case of lithium batteries. The cost of adding different capacity batteries was evaluated in terms of the increase of mass and consequently decrease of endurance. The power split was conveniently defined at take-off to prevent from excessive hydrogen consumption and to maximize the endurance with respect to the non-hybrid configuration in which the only fuel cell is used.