Design and Implementation of the Luenberger Observer for Estimating the Voltage Response of a PEM Electrolyzer During Supply Current Variations

Equivalent electrical circuits (ECM) have proven to be effective in modeling the dynamic behavior of proton exchange membrane (PEM) electrolyzer voltage response. They are a valuable tool for studying the interactions between power electronics and PEM electrolyzers during dynamic operating conditions. Generally, the ECM takes into consideration the activation over-voltage that is present at both the anode and the cathode for the dynamic part of the model. Therefore, the monitoring of the ECM activation over-voltage is an important issue for the correct modeling of the PEM electrolyzer voltage. However, voltage sensors for this over-voltage are expensive and the reported observers of the PEM electrolyzer activation over-voltage are scarce and have not been validated over a sufficiently long time. This work aims at overcoming these drawbacks by proposing the use of a Luenberger observer to accurately estimate the activation over-voltage using an ECM. Based on this proposal, it is possible to build a device capable of emulating the electrolyzer voltage efficiently. Furthermore, a stability analysis of the observable system is provided to ensure its performance throughout the experiment period. Statistical results, based on experimental voltage data from a PEM electrolyzer QL–300, demonstrate the high accuracy and performance of the Luenberger observer under continuous changes in input currents, which demonstrates its robustness.