Analysis of a Fuel-Cell/Battery /Supercapacitor Hybrid Propulsion System for a UAV Using a Hardware-in-the-Loop Flight Simulator

Fuel-cell based hybrid propulsion systems are being considered as a means to increase the endurance and range of small electric powered unmanned aerial vehicles. However fuel cell durability is limited by the rapid load changes requested by the autopilot. In a fuel-cell/battery /supercapacitor triple hybrid the battery provides boost power whilst the supercapacitor increases fuel cell life through load levelling. This paper presents the analysis of a fuel-cell/battery /supercapacitor hybrid propulsion system using a high fidelity hardware-in-the-loop simulator. The hardware-in-the-loop simulator allows accurate application of the expected dynamic electrical loads experienced in flight on the hardware components without the risks associated with flight testing. The triple hybrid system demonstrates load smoothing by the supercapacitor to the fuel cell under simulated operating conditions, with this buffering increasing fourfold under gusty flight conditions.