In the objective of fuel cell power increase in order to satisfy energetic requirements for embedded applications, a solution consists in increasing the size of fuel cell stack assemblies. As possible consequence, fluidic or thermal disparity problems may occur in the fuel cell core and lead to the appearance of faults. The fuel cell, which is a low voltage-high current electrical source, needs to be connected to the on-board electrical network thanks to a static converter. This latter can be used in order to perform a corrective action in the aim of reducing disparities in the stack and also correcting resulting faults. In this perspective, the converter should permanently get information about fuel cell state of health. Hence, a fault detection and identification method for PEMFC has been explored. This method which is simple and requires only few sensors is based on 3 voltage measurements judiciously selected and localized over the stack. Using “spatial” information which corresponds to the position of the sensors, allows to identify some characteristic faults. The principle of the localized fault detection leads to consider the segmentation concept for the fuel cell, which in our case is electrically split into three parts and allows an independent control of each segment by the power converter. Electrical action can be “all or nothing” or moderated ones. The latter offers more degree of freedom, and is less constraining from an electrical point of view. In order to execute the action, study of multiple power converter topologies have been done. Among the candidate topologies, current structures are preferred, as well as the necessity of a galvanic isolation required by the segmentation concept. The resonant isolated boost is the adopted structure; as it meets at best the whole criteria. Thus the global converter assembly is composed of three single structures which offer modularity, independent action on each segment, and continuity of service thanks to degraded modes. The detection method is hence implemented in the converter control strategy. This Ph.D. thesis ends with the complete sizing of a power converter pre-prototype together with technological choices for the active, passive and associated cooling components.
