Transient behavior experiments for hybrid fuel cell-battery systems

This study presents the transient behavior of a PEM fuel cell-battery system by experiments. The dynamic characterizations of this hybrid fuel cell-battery system with a single dc/dc boost converter were investigated by experiments under a step-up power load. It was found that the pure fuel cell power system transient response to a steady level after a period time exhibits a current overshoot. This was followed by a voltage undershoot behavior because of a step increase in power due to the inherent time delay experienced by the redistribution of membrane water content with a response time order of 8~29 seconds. The redistribution of membrane water content caused a rapid drop in cell voltage with a time delay of 22.40 seconds, calculated by δ²/D_w, which is in agreement with the experimental results. Finally, some experimental results are presented for verifying the effectiveness of the proposed fuel cell-battery systems with a single dc/dc boost converter that could improve the overshoot and undershoot responses on fuel cell.