Preventive control method for stable operation of proton exchange membrane fuel-cell stacks

Flooding and dry-out are major drawback issues in proton exchange membrane fuel cells (PEMFC), which necessitate adequate prevention control techniques. In a fuel-cell stack, as flooding and dry-out occur on the inlet and outlet sides, respectively, both faults can exist simultaneously. Therefore, the timely detection of these two contradictory faults is crucial for implementing timely control measures. In this study, we propose a preventive control method that detects the fault signs early for more effective prevention. The proposed method uses a curve-fitting method, which uses overpotential as the control index. As the control index can be obtained by measuring the current, voltage, and temperature, the evaluation can be performed quickly, making it easy to implement in a PEMFC system. Under a single fault, the stack output power, hydrogen consumption, and power efficiency of the proposed preventive control method and the previous study on flooding were compared. The results showed that our preventive control method could detect flooding sooner and was superior in stack output power, hydrogen consumption, and power generation compared to the fault control method. Under conditions of mixed flooding and dry-out, both flooding and dry-out were detected using the overpotential as the control index. Thus, because the proposed method initiates control measures before the fault progresses, it is possible to ensure the continued stable operation of the fuel cells.