Modelling the evolution of voltage inconsistency in proton exchange membrane fuel cell stacks: Temperature and oxygen excess ratio dependencies

Cell-to-cell inconsistency has emerged as a predominant performance factor in commercial proton exchange membrane fuel cell (PEMFC) stacks. However, prevailing operation management studies emphasize aggregate stack output performance, while neglecting systematic analysis of inter-cell inconsistency. To address this research gap, an in-depth investigation of the voltage inconsistency evolution is conducted by modeling the variation of coefficients α and β in voltage inconsistency-voltage (C_V-V) model with respect to operating conditions. Regarding the evolution model, both coefficients α and β have been found to exhibit the quadratic polynomial relationships with temperature, while demonstrating exponential function relationships with the oxygen excess ratio (OER), respectively. Experimental data from two commercial stacks are employed to confirm model effectiveness. Verification results indicate that the temperature-dependent C_V(T) model achieves superior performance (RMSE = 0.031) in predicting voltage inconsistency under dynamic temperature variations, representing a 61.73 % improvement over C_V(50) expression (RMSE = 0.081). Furthermore, the OER-evolutionary model C_V(OER) yields an RMSE of only 0.0077 in estimating voltage inconsistency under dynamic OER conditions, corresponding a 51.88 % of error reduction compare to the C_V(2.0) expression (RMSE = 0.016). These findings offer critical insights on estimating voltage inconsistency for the real-world PEMFC systems.