A Linear Instrument for In Situ Stack-Level Fuel Cell Characterization Using Periodical EIS Perturbations

This article proposes a perturbation generation technique to enable electrochemical impedance spectroscopy (EIS) for high-power fuel cell stack (FCS) using linear power metal–oxide–semiconductor field-effect transistors (MOSFETs). A periodical sequence is designed to reduce the maximum temperature rise of the linear power MOSFET (LPM). As a result, the LPM only needs a small heat sink to keep the device within its thermal limit while producing full-range EIS ac perturbations to a whole FCS. This leads to a low-cost and compact EIS solution for stack-level fuel cell characterization. The effectiveness of the approach is validated with experiments on a commercial FCS testbed. It enables the implementation of a device that delivers comparable EIS results to traditional equipment while being approximately five times smaller.