Hybrid PEM Fuel Cell Systems

PEM fuel cell drivetrains in heavy duty applications are mostly implemented using multiple fuel cell systems and as battery hybrid systems. The complex architecture of those hybrid system results in various degrees of freedom in the operating strategy. Those have a major influence on aspects such as dynamics, efficiency and lifetime of the entire system. In order to be able to analyze and evaluate the capability of an efficiency optimized operating strategies, the ZBT fuel cell model is integrated into a fuel cell system and a full vehicle simulation. The dimensioning and also the load profiles are inspired by the Hyundai XCIENT Fuel Cell with 20 t total permitted mass. Starting from a rudimentary and purely functional operating strategy, an efficiency optimized operating strategy is presented. A mere optimization of the fuel cell system operation is not sufficient, since the losses in the battery system must also be considered. The numerous effects of the operating strategy are described.