Development of a controller for voltage stabilisation in fuel cells using an electric field modifier (EFM) electrode

Abstract

The present work expands on the idea of the electric field modifier (EFM) as a control electrode in the membrane of a fuel cell (FC). Through electrochemical impedance spectroscopy (EIS) measurements it is shown experimentally that an EFM-electrode made of a gold mesh can be integrated into a fuel cell, without disrupting its function. Using the measured impedance spectra and a distribution of relaxation times (DRT)-approach a suitable equivalent circuit (EQC)-model is derived for the measured cell with the integrated EFM. Further measurements show that the EFM can mainly be regarded as a double layer (dl)-capacitor inside of the membrane. This capacitor, in conjunction with a specially designed H∞ -controller are used in a simulation to stabilise the cell voltage, while a square wave current is drawn from the cell, to represent a direct connection of the FC with an inverter. The system is shown to have excellent disturbance rejection.