Estimating PEMFC ohmic internal impedance based on indirect measurements

Abstract

Abstract In this study, the ohmic internal impedance of a proton exchange membrane fuel cell (PEMFC) is explored. A double Kalman filter (DKF) method is proposed to estimate the internal ohmic impedance based on the monitor output current density and voltage when the fuel cell is operated in the ohmic polarization region. First, the working current density is set between 0.4 and 1 A cm−2 by carrying out an initial experiment to obtain the PEMFC polarization curve. The PEMFC is assumed to be an equivalent circuit when the output current density is set in this range. Second, an experiment is also performed within the custom‐built platform based on the DKF algorithm. Monitoring data are obtained by Hall sensors in the direct current (DC) converter, and the stack ohmic resistance is calculated by the designed PEMFC internal resistance algorithm. Finally, verification is accomplished by comparing the simulated voltage based on the ohmic resistance with the experimentally measured output voltage using MATLAB/Simulink. The feasibility of this method to estimate the ohmic resistance is demonstrated. The ohmic internal resistance of the PEMFC is obtained in real time by the designed algorithm. Furthermore, the results indicate that moisture in the proton exchange membrane (PEM) can be reflected by the internal ohmic resistance of the PEMFC. The moisture can be adjusted based on this estimated impedance.

Keywords

• double Kalman filter
• equivalent circuit
• ohmic impedance
• proton exchange fuel cell