Humidification of polymer electrolyte membrane fuel cell using short circuit control for unmanned aerial vehicle applications

In the present study, a short circuit controller for use in the humidification of polymer electrolyte membrane fuel cells was developed for unmanned aerial vehicles (UAVs). Fuel cells (FCs) require an external humidifier to avoid drying up. Particularly in UAV applications, humidity control is more important because the boiling point of water decreases with increase in flight altitude. In this study, overcurrent was generated by short-circuiting an FC to humidify the electrolyte membrane and improve the electric power output. An FC controller incorporating a short circuit unit was developed, and a battery was hybridized with the FC to compensate the power when the latter was short-circuited. The performance of the FC was evaluated for the interval (period) and duration of short circuit. Using this method, the power output was improved by 16% when short circuit control was operated at the optimal condition.