DC-DC Current Perturbation Based EIS Measurement for PEM Stack

Electrochemical Impedance Spectroscopy is effective in monitoring the internal operation states of Proton Exchange Membrane stack. Impedance data can be used for feedback control and advance fault diagnosis to improve the durability and reliability of stack. In this paper, an online impedance measurement system based on DC-DC current perturbation was designed. As two modules of this system, a DC-DC converter with wide frequency perturbation ability, and a signal condition circuit which can acquire perturbation current and response voltage accurately were also designed. Furthermore, the effectiveness of the designs was verified by simulation and experiment. Results show that the measurement system is highly accurate (maximum error <6%) and can be easily implemented with low cost. Overall, the system offers great potential to accomplish online monitoring and fault diagnosis of the proton exchange membrane fuel cells or electrolysis cells.