Development of a Virtual Test Rig for Evaluating Hybridisation Potential in Non-Road Mobile Machinery

Non-Road Mobile Machinery (NRMM) accounts for about 3% of total CO₂ emissions in both the U.S. and the EU. Due to their high-power demand and long operating missions in harsh environments, NRMMs are considered a hard-to-abate sector. Therefore, a pragmatic pathway toward decarbonization must involve a combined approach that integrates a wide range of technologies. Among them, powertrain hybridisation can play a crucial role in reducing CO₂ and pollutant emissions, leveraging the experience gained from the electrification of passenger cars and commercial vehicles. Within this framework, the present thesis aims to develop a virtual test rig to assess the potential CO₂ emission reductions of a skid-steer loader. This case study is particularly challenging due to the machine’s versatility in performing diverse tasks and using multiple implements, which increase the variability of its duty cycles. A digital twin of the conventional powertrain was developed using the commercial software GT-Suite, adopting a 1D modelling approach for both the hydraulics and the vehicle dynamics. This baseline configuration was established to benchmark the performance of an electrified powertrain across a wide range of mission profiles. Subsequently, the powertrain was electrified using a parallel P1 configuration, selected for its ability to enable engine downsizing, electric boosting, and load point shifting with minimal impact on the original layout. The numerical simulations carried out on the proposed hybrid powertrain demonstrated a remarkable reduction in CO₂ emissions across a wide range of real-world operating conditions, confirming the viability of electrification in the NRMM sector. Furthermore, the thesis highlights that the developed digital twin represents a valuable tool to support the optimisation of powertrain architectures for this class of machinery.