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Electric vehicle technology has been adopting fuel cells (FCs) for hybrid applications over the past few years. Therefore, the development of advanced power electronic systems for the integration of fuel cells with on-board energy management is fundamental for achieving high-performance systems. An FC for vehicular applications is usually a low-voltage current-source like device that produces electricity and heat directly from input hydrogen and oxygen. Most often, it is required that the FCs be stacked for high-voltage dc-link in order to supply the input power for the drivetrain and electric motor drive system. The FC has a nonlinear nature, and it must be controlled to operate in the high-efficiency operating range. Hybrid electric vehicles have physical constraints such as volume and weight under limited cost and expected lifetime. There is a need for high-voltage input/output ratio of dc-dc boost converters to be connected between the FC to the motor drive dc-link. In addition, it is necessary to have low input ripple at the dc-dc boost converter in order to maximize the FC lifetime, and the traditional dc-dc boost converter topologies have poor performance on these specifications. This paper proposes a new dc-dc converter family of topologies aimed at improving the application to electric vehicle power control. This family is defined as floating-interleaving boost converters (FIBCs). The paper will thoroughly show analysis and experimental verification of FIBC's, and they will be compared with conventional boost converter characteristics. The paper supports how performance figures related to the passive components, i.e., the inductor and capacitor, will have better volume and weight, extremely low input current ripple, and improved efficiency and transfer ratio. The analysis presented in this paper shows how to choose the most suitable topology in order to achieve the desired specifications. The selected topology is fully validated experimentally using advan- ed nonlinear sliding mode control, which has the additional feature of operating even in faulty conditions.
Date of Publication: Oct. 2012