Parameter Identification of Electrical Equivalent Circuits including Mass Transfer Parameters for the Selection of the Operating Frequencies of Pulsed PEM Water Electrolysis

Abstract

This paper proposes a parameter identification method for a PEM electrolyzer electrical equivalent circuit for pulse electrolysis. Since general water electrolysis mainly uses DC currents, identifying equivalent circuit parameters using electrical characteristics mostly ignores the operation frequency and unnecessarily adheres to the secondary RC model. However, looking at the Nyquist plot of the PEM electrolyzer, it can be confirmed that identifying the operational frequency is necessary, and the secondary RC model correction is essential. Therefore, the proposed method confirms the necessity of reconstructing an electrical equivalent circuit with a primary RC model by analyzing the transient cell voltage using step current inputs and calculating an appropriate operating frequency by identifying the parameters of the reconstructed equivalent circuit. To verify the proposed parameter identification method, a simulation was constructed from the raw test data of a 400 W commercial PEM electrolyzer. In addition, the hydrogen production amount was compared to DC using a pulse electrolysis experiment at the operating frequency obtained by the proposed method.