Development of a power converter to improve CO tolerance in proton exchange membrane fuel cells

Abstract

Hydrogen for supplying fuel cells is oftentimes produced by reforming hydrocarbon fuels like natural gas. As a byproduct of this process, carbon monoxide (CO) is produced, whose concentration can be as high as 500 ppm during start-up. The presence of such a contaminant in the fuel flow of the fuel cell has serious side effects derived from the reduction of its active area due to poisoning; which translates in reduced output voltage and power. To cope with this problem, the development of a power converter and current modulation technique is presented in this study. It is shown that the use of the proposed converter allows increasing CO tolerance of the stack, thus allowing the system to continue operation while showing minimal degradation in output voltage and power.