Model-based development of alternative propulsions for HD off-highway applications

Legislative tendencies for on-highway heavy-duty vehicles show a further tightening of NOx emissions limits for the EU and USA and will be most probably followed by the Non-Road Mobile Machinery (NRMM) sector in the future. The stricter regulations and the upcoming trend for low- and zero-emission construction sides the drivers for alternative propulsion systems in this sector. Multiple propulsion systems including alternative fuels like Hydrogen combustion are currently being developed and some are already on the market.This study provides a review on the state of the art of alternative propulsion systems including the NRMM specific requirements for off-highway heavy duty applications. In addition to that a model based approach to evaluate different powertrain solutions, depending on machine type and load cycle is presented.The model based approach is shown by the examples of a medium sized excavator and wheel loader. The internal combustion engine will be included in a powertrain system model in GT-Suite commercial simulation software which contains the respective component models like battery and electrical engines. The control strategy for engine, motors and battery is coupled to the powertrain model with a MATLAB/Simulink system environment. This study focuses on the modelling methodology of the powertrain components and describes their integration into the model.The simulation study results in a comparison between diesel and multiple hybrid architectures in representative off-highway working cycles. The influence of the engine characteristics, possible advantages of a single-operating point engine concept calibration, recuperation potentials and the general potentials of the hybridization are discussed.The experiences within this study are showing that a differentiated view by using model based development is essential to evaluate different complex powertrain structures, to define suited operating strategies and to use the potentials which can be offered by the alternative powertrains.Based on the results an outlook is given on a further CO2 reduction potentials using hydrogen as an alternative fuel in a combustion engine or for fuel cell technology.