Fault tolerance and optimization of DC/DC converters for fuel cell electric vehicles

Over the last years, reliability and continuity of service of powertrains have become major challenge so that the fuel cell electric vehicles (CFEV) can access to to the mass automotive market. Indeed, the presence of faults in power trains can lead up to malfunctions in the vehicle and consequently reduce its performances compared with conventional vehicles. In the case of electrical faults, power trains of FCEV have to include fault tolerant topology and/or control for the different DC/DC and DC/AC converters. Within the framework of this research work, the study is focused on DC/DC converter combined with a Proton Exchange Membrane Fuel Cell (PEMFC). The DC/DC converter must respond to challenging issues in FCEV applications such as: low weight and small volume, high energy efficiency, fuel cell current ripple reduction and reliability. Basing on a thorough bibliographical study on non-isolated and isolated DC/DC converter topologies, an interleaved DC/DC boost converter has been chosen meeting the FCEV requirements. The purpose of this thesis has then consisted in sizing and controlling the chosen fault-tolerant DC/DC converter topology for FCEVs. Algorithms for degraded mode management of this converter have been developed and implemented experimentally. As such, the interaction between PEMFC and interleaved DC/DC boost converter has been investigated. A theoretical approach, simulation and experimental results have been carried out to complete this work. (author)