A proton exchange membrane fuel cell (PEMFC) model for use in power electronics

Abstract

Fuel cell is considered as the most environmentally green energy source. Electricity is generated by the reaction of hydrogen and oxygen with the byproduct of water. This technology has been adopted in space programs since 1968. However, due to the high cost in material and system complexity, this technology has not been widely used in public. Recently, as a result of the support from the US government and the infhence of energy crises, fuel cells are now gaining attention in the public and research programs. A number of remarkable advancements, including the creation of polymer membrane, reduction in platinum content and invention of hydrogen reformer, enable fuel cells to get closer to the general public. Still, a number of weaknesses, such as instability of output power, long startup time, slow dynamic responses and complexity in system design are impeding the progress of fuel cell development. These issues are still challenges to power electronics engineers. Novel approaches such as application of bi-directional conversion, assistance of super capacitor and integration of hybrid system etc. are proposed to solve some problems. Unfortunately, engineers have been slow in considering the relationship between fuel cell and power manipulation system. A fuel cell has a very unstable voltage which is sensitive to fuel purity, operation pressure, temperature and hydration. As a result, separate system considerations cannot lead to satisfactory results in term of overall system efficiency, stability and usability. The objective of this study is to fll this gap by presenting the operation of fuel cell system in an understandable language to electronic engineers. In addition, a proton exchange membrane fuel cell (PEMFC) model was proposed in this thesis. The model was then integrated into a PSpice simulator. By doing so, it is expected that electronic engineers can have a more in depth understanding of the fuel cell operation. The objective is to create a more reliable system with higher efficiency. Detailed simulation results based on MathCAD and PSpice are given. Suggestions and comparisons are also provided in this thesis.