A generic equivalent circuit model for PEM electrolyzer with multi-timescale and stages under multi-mode control

The accurate and comprehensive equivalent circuit model (ECM) of Proton Exchange Membrane electrolyzer (PEME) is needed urgently in the design process of power supply for electrolytic hydrogen production such as rectifier or dc/dc converter. However, the existing ECM can only simulate the steady-state and dynamic electrical characteristics of electrolyzer in the electrolysis process under current controlled mode. In this paper, in-situ electrochemical impedance spectroscopy (EIS) is employed to measure the electrode impedance (R) and double-layer capacitance (C) of PEME. It's worth noting that for gaining the value of R and C, only the electrochemical circle fit method is used without further proceeding. Based on this method to identify parameters, a novel and generic ECM of PEME is proposed to simulate stable electrical characteristics of three different PEMEs under current controlled mode and voltage controlled mode, respectively, in the start-up, electrolysis, and turn-off stages. Specially in this model, diodes' switching characteristics are innovatively employed to simulate the start-up stage; on the other hand, an RC circuit connects with the diode parallelly to model the turn-off stage. Moreover, it can precisely characterize the dynamic and transient electrical behaviors of PEME. Finally, the validity of proposed ECM of PEME is verified based on small scale experiments.