Efficiency upgrade of hybrid fuel cell vehicles' energy management strategies by online systemic management of fuel cell

This paper puts forward an approach for boosting the efficiency of energy management strategies (EMSs) in fuel cell hybrid electric vehicles (FCHEVs) using an online systemic management of the fuel cell system (FCS). Unlike other similar works which solely determine the requested current from the FCS, this work capitalizes on simultaneous regulation of current and temperature, which have different dynamic behavior. In this regard, firstly, an online systemic management scheme is developed to guarantee the supply of the requested power from the stack with the highest efficiency. This scheme is based on an updatable 3D map which relates the requested power from the stack to its optimal temperature and current. Secondly, two different EMSs are used to distribute the power between the FCS and battery. The EMSs' constraints are constantly updated by the online model to embrace the stack performance drifts owing to degradation and operating conditions variation. Finally, the effect of integrating the developed online systemic management into the EMSs' design is experimentally scrutinized under two standard driving cycles and indicated that up to 3.7% efficiency enhancement can be reached by employing such a systemic approach. Moreover, FCS health adaptation unawareness can increase the hydrogen consumption up to 6.6%.