Control Strategy of Flooding Avoidance With Active Humidifier System for High Performance Automotive Fuel Cell Systems

A dynamic proton exchange membrane fuel cell (PEMFC) system model for automotive applications is developed, integrating fuel cell stack, compressor, humidifier, and bypass valve to study membrane humidity regulation. Results indicate that the bypass ratio is a key determinant of fuel cell humidity. Lower ratios enhance membrane hydration but increase flooding risk, while higher ratios reduce flooding at the expense of under‐hydration and higher internal resistance. Optimized bypass management ensures balanced hydration and performance. Two dynamic control strategies are proposed to maintain 100% membrane hydration and prevent flooding: one based on cathode water mass and the other on membrane water content. Both approaches successfully adjust the humidifier bypass ratio during load transients, keeping the cathode relative humidity close to 100% while avoiding flooding. The water mass‐based approach better limits liquid accumulation and flooding, whereas the water content‐based approach prioritizes membrane hydration. Selection of the strategy should depend on the operational goal, either maximizing membrane durability or minimizing flooding risk.