Power managements of a hybrid electric propulsion system for UAVs

Power managements of a UAV's hybrid electric propulsion systems are described. Three electric propulsion systems with different power sources, i.e. solar cells, fuel cells, and batteries are considered. Each power source is modeled in Matlab/Simulink and integrated into the power system. For fuel cells and batteries, the simulation process is verified via comparison between the simulation results and available flight test results of UAVs. Two types of power control logics are investigated: passive and active. The passive power management simulation shows that the behavior of each power source and its integrated system is adequate for the overall flight envelope. In addition, the active power management simulation demonstrates that active power management yields more efficient power distribution and better system safety than passive power management does. Also, a power simulation of a hybrid electric power system allows for estimation of the output behavior of the power source. Therefore, it can be a valuable tool for development of a power control logic that ensures efficient power distribution.