PEM fuel cell as an auxiliary power unit for range extended hybrid electric vehicles

Significant research efforts have been invested in the automotive industry on hybrid-electrified powertrains in order to reduce the passenger cars’ dependence on oil. Powertrains electrification resulted in a wide range of hybrid vehicle architectures. Fuel consumption of these powertrains strongly relies on the energy converters performance, as well as on the energy management strategy deployed on-board. This paper investigates the potential of energy consumption savings of a serial hybrid electric vehicle (SHEV) using a hydrogen proton-exchange membrane fuel cell (PEMFC) as energy converter operating as an auxiliary power unit (APU) instead of the conventional internal combustion engine (ICE). A PEMFC model is developed and the thermodynamic system efficiency is simulated. The PEMFC APU is integrated in the modelled SHEV powertrain. The hydrogen stored on board is gaseous and pressurized under 700 bars. Energy consumption simulations are performed on WLTP cycle with 4 different battery capacities using dynamic programing as global optimal energy management strategy. The results show improved efficiency with PEMFC as an auxiliary power unit (APU) compared to ICE. The auxiliary power unit consumes less than 1 kg/100 km of hydrogen on a normalized cycle. The integration of an additional power unit based on PEMFC is studied as a solution for the extension of the range of the electric vehicles.