Evaluating the efficiency of a fuel-cell hybrid powertrain

In the scope of project MAHEPA the basic hybrid drive train concepts were developed. The fuel cell hybrid drive train of the Hy4 has been designed for higher performance and improved reliability. In order to compare the new MAHEPA drive train with already tested hybrid systems and future hybrid systems, not only the power to weight ratio, emissions and costs are of interest, but also the efficiency of a drive train.

Fig. 1: The Hy4 drive train of the first generation

Depending on the load distribution between the battery and fuel cell system and also the maximum system performance, the efficiency can vary greatly in different flight phases.  An initial calculation of the drive-train efficiency of the new Hy4 drive train, based on MAHEPA component data and measurement data from old fuel cell system, was carried out. In addition, the advantages of the MAHEPA drive train were compared with the first generation of the Hy4 drive train. Therefore, the optimized MAHEPA drive train in particular offers increased system reliability.

Fig. 2: MAHEPA drive train schematics