Comprehensive electrical modeling and hybridization strategies for multi-stack PEM fuel cells under dynamic loads

Proton Exchange Membrane Fuel Cells (PEMFCs) are highly promising for sustainable power generation. However, their direct application to dynamic industrial loads is severely limited by slow transient responses, poor voltage profiles at high current densities, and a critical vulnerability to fuel starvation. Furthermore, in practical multi-stack applications, individual fuel cells rarely exhibit identical electrical behaviors due to manufacturing tolerances and asymmetric degradation over time. This paper presents a comprehensive electrical modeling and simulation study of a hybrid multi-stack PEMFC system designed to overcome these physical and electrochemical constraints. Five asymmetric PEM stacks, characterized by varying charge transfer coefficients and internal resistances, were mathematically modeled and evaluated. To optimize power generation and prevent degradation, an advanced hybrid architecture is proposed, integrating Maximum Power Point Tracking (MPPT), DC-DC Buck-Boost converters, and a secondary battery storage system. A State of Charge-based Energy Management System was developed to govern the discrete ON/OFF activation of the stacks according to power thresholds, effectively isolating the fragile fuel cells from harmful load transients. The proposed topology was rigorously validated using TRNSYS simulations under three demanding industrial load profiles: intermittent medium-power hand tools, sporadic high-power welding equipment, and continuous compressors with operational gaps. The simulation results demonstrate that the hybrid control strategy successfully absorbs high-frequency load spikes, extracts maximum power from heterogeneous stacks, maintains optimal battery energy reserves, and mitigates primary operational stressors (such as high-frequency current cycling and transient fuel starvation), thereby fostering operating conditions highly favorable to long-term component durability.