Integration scenarios to improve fuel cell dynamics for modern aircraft application

An approach to achieve a high efficiency for energy transfer in modern aircraft could be the More Electric Aircraft concept. According to this, the replacement of the conventional auxiliary power unit by a multi functional fuel cell system reduces the emission of carbondioxide significantly and can increase the efficiency. However, requirements on the electrical system dynamics are higher than currently available fuel cell systems can provide. To improve the electrical dynamics of the fuel cell especially during high peak power demands different methods are considered. This paper compares four possible integration scenarios to improve the system dynamic. Special characteristics as the additional system weight, the stored available energy, the complexity as well as the feasibility under the required conditions are considered. For supplementing the theoretical concepts, a prototype of a super capacitor short-time energy storage was built and integrated into an existing fuel cell test bench. Therefore, a voltage balancing as well as an overvoltage protection is implemented. Measurements show the improved dynamic of the hybrid fuel cell system.