Efficiency Improvement of a Cascaded Buck and Boost Converter for Fuel Cell Hybrid Vehicles with Overlapping Input and Output Voltages

Fuel cell hybrid vehicles represent an alternative to battery electric and will gain importance in the future as they do not need large capacities thus require less critical raw materials. Depending on architecture, voltage of fuel stack traction may overlap. Accordingly, it is necessary use a bidirectional DC–DC converter that connects DC bus, which supports overlapping input output voltages. Furthermore, these converters should be non-isolating terms compact design. Concerning complexity controllability, cascaded buck boost preferable subject this study. Published literature presents with high losses for voltages, introducing two methods operation mode. The method selected study, namely + boost, uses switches, whereby one switch has fixed duty cycle. However, there no appropriate investigation determine impact cycle efficiency date. improvement possible by switching frequency modulation, but current does address modulation Therefore, paper investigates non-isolated hard-switched operating up 19.8 kW. study focuses determining optimum optimisation through novel conduction mode adapted utilising load-dependent inductance inductor powder cores. Measurements experimental setup validate proposed Si-IGBT half-bridge modules. results demonstrate loss reduction 39% compared frequency. As result, achieves efficiencies 99% low device junction temperatures.