Henry Quach

While the vast majority of UAVs are powered by lithium-type batteries (LiPo, Li- ion, LiCo, etc.), the choice of such batteries ultimately limits flight time because of their characteristically low energy density. In fact, the most advanced commercially available heavy-lift UAVs provide less than one hour of flight time.1 More energy-dense, gas-powered drones exist, but their performance hinges on multiple independent combustion engines and a system of pulleys to replace the brushless motors.2 To meet the 3 hour flight time demanded by our proposed heavy-lift UAV for the Shell Ocean Discovery XPRIZE, we propose a hybrid gas- electric system that provides DC power by using a 3-phase, full-wave bridge rectifier to convert the AC power supplied by a generator. The generator is coupled to combustion engine, whose shaft speed is determined by servo- controlled throttle and choke valves, thereby being able to produce instantaneous power to meet demand as needed. Here, we present a compact generator assembly that can be controlled with a simple electromechanical architecture. We implemented this hybrid power generation scheme with a benchtop model and demonstrate that it can meet the consumption needs of the heavy-lift UAV.

NOTE: This page is not mean to suggest ANY instructions or provide guidance towards implementing this yourself - these are just snippets of the project our team completed for class. That being said, please use proper ESD equipment and grounding for all projects using rectifiers and non-trivial quantities of current. Once our engine was started, we physically disconnected the ESC as to not destroy it. High power electronics work should always be well-supervised no matter the type - we had a safety checklist that we checked during every run to reduce the possibility that we would be harmed. Safety is the most important thing in all projects - please do be careful.