Hybrid Energy Storage Systems for UAV Applications

Energy storage constraints limit the range and endurance of electric based unmanned aerial vehicles (UAVs). Solving the energy storage problem allows the adoption of UAVs on a much wider scale. A solution to the problem would ideally retain the significant performance and efficiency benefits of the electric based propulsion system. The contents of this study focused on solving the energy storage problem through research, experiment, and simulation based testing of the application of hybrid energy storage systems (HESS) to existing UAV designs. A review of literature was done exploring existing and future applications of electric based aircraft propulsion systems. Research was conducted on current energy storage technology limitations and potential hybrid energy storage design solutions. The solution allows bridging the gap to full adoption of electric propulsion. After extensive research, a passively controlled hybrid battery and supercapacitor configuration was chosen for experimental and simulation based evaluations. The experiment and simulation tested for key battery performance improvements using the HESS and its applicability to UAV designs. Results showed a significant reduction to the peak amperage and peak temperature of the battery under identical load profiles. The experimentally tested passive HESS did not show a reduction in energy consumption, but the active HESS simulation results did. The simulation results showed a theoretical gain of 8.8% for state of charge (SOC) for the battery. Equating the SOC to range improvement, a 10% increase in range was possible for the UAV tested