Development of a Fuel Cell Hybrid Electric Vertical Takeoff and Landing Aircraft Power Train

This paper proposed the development of a fuel cell and battery hybrid electric vertical takeoff and landing (eVTOL) aircraft power train to address the dramatic power requirement difference during the cruise, takeoff and landing of the eVTOL aircraft. During the eVTOL aircraft cruise mode, the fuel cell would serve as the main power source due to its high energy density feature. During the eVTOL aircraft takeoff and landing mode, the power requirement could be about $7\sim 10$ times higher than the cruise mode. The Lithium-polymer (Li-po) battery has high power density feature and can provide high power surge during a short period of time. Therefore, both fuel cell and battery must provide the power simultaneously during the takeoff and landing in the proposed hybrid eVTOL power train. A GaN based DC-DC converter has been utilized to interface the fuel cell and the battery to serve as a voltage regulator and a battery charger. The proposed GaN DC-DC converter design and control strategy is described, a hardware prototype has been developed. The simulation and the experiment results of the hardware prototype are also demonstrated.