Polarization loss decomposition-based online health state estimation for proton exchange membrane fuel cells

This paper systematically investigates the steady-state polarization losses and health assessment of proton exchange membrane fuel cells. Activation and ohmic losses are quantitatively decoupled using Tafel analysis and high-frequency resistance measurements. Under conventional stoichiometry, activation-free polarization curves show high linearity (Pearson coefficient $<$ −0.99), which may lead to overestimation of ohmic resistance and underestimation of concentration loss if fitted directly. To address this, a simplified voltage model incorporating equivalent resistance for ohmic and concentration losses is proposed. Based on this model, an online health state estimation method using open-circuit voltage transients is developed to estimate electrochemical surface area and resistance in real time. Experimental results confirm the accuracy of our model, with prediction errors below 1% over the full test cycle. Furthermore, a virtual rated voltage metric is introduced to capture performance degradation trends. This framework provides a practical solution for PEMFC performance evaluation, health monitoring, and life prediction.