Power systems based on proton exchange membrane fuel cell (PEMFC) technology have been the object of increasing attention in recent years as they appear very promising in both stationary and mobile applications. The output-voltage characteristic in a PEMFC is limited by the mechanical devices which are used for regulating the temperature, the humidity and their air and hydrogen flows. As a consequence, a fast load transient demand could cause a high voltage drop in a short time known as oxygen starvation phenomenon that is harmful for the FC. Therefore, batteries, ultracapacitors or other...