Model-Supported Design of a Range-Extended Electric Vehicle with a Hydrogen-Fueled Internal Combustion Engine

Hybrid electric vehicles are a suitable solution for the transition from fossil fuels-based transportation to electric mobility. They have the benefits of zero-emissions operation when only the electric engine is used preventing the typical range anxiety of full-electric vehicles. Also, they can have a low battery pack capacity and weight thanks to the continuous recharge from the internal combustion engine that becomes the only responsible for exhaust emissions. A practical solution to limit the combustion engine emissions is represented by the range extender configuration, where the engine works at a fixed operating point with the highest efficiency serving uniquely as a battery charger. In the face of the current world situation and future changes, research for alternative energy sources is crucial. Hydrogen can be used as an alternative fuel for common internal combustion engines; moreover, it has the great advantage of high efficiency (about 44%). The present work investigates by experiments the combustion behavior of a small spark-ignition engine fed with hydrogen and then uses modeling to propose different configurations of a range-extended electric vehicle (REEV) to satisfy the present requirements for emissions limitations and power demand. The analysis of the combustion cycle is performed for different loads and lambda values. The experimental measurements are used in a multi-domain model of an electric vehicle built in Simulink. The behavior of the vehicle running the homologation cycle WLTC is analyzed for the optimal combustion engine operating condition and different activation thresholds of the range extender to provide the best trade-off between exhaust emissions, weight, and driving range. The hydrogen-fueled REEV can grant a high driving range and recharge flexibility with NOx exhaust emissions inside the Euro 6 standards.