Fuel Cell System Optimization Using Bypass Converters

The reduction of CO₂ emissions, and therefore the increase of ecoefficiency, is one of the most important challenges for the aircraft industry. An approach could be the more electric aircraft concept. Within this concept, the traditional auxiliary power unit could be replaced by a multifunctional fuel cell system. For integration into the ±270 V_dc grid, it is necessary to convert the load-dependent fuel cell output voltage using a direct current-to-direct current converter. The converter usually is designed for the maximum available fuel cell power. This paper deals with an adaption of the fuel cell output voltage to achieve downsizing of the converter. The proposed converter structure with an additional bypass has weight-saving effects and improves overall system efficiency.