Combining DMDF and Hybrid Powertrains: A Look on the Effects of Different Battery Modelling Approaches 2022-01-0658

Fleet electrification has been demonstrated as a feasible solution to decarbonize the heavy-duty transportation sector. The combination of hybridization and advanced combustion concepts may provide further advantages by also introducing reductions on criteria pollutants such as nitrogen oxides and soot. In this scenario, the interplay among the different energy paths must be understood and quantified to extract the full potential of the powertrain. One of the key devices in such powertrains is the battery, which involves different aspects regarding operation, safety, and degradation. Despite this complexity, most of the models still rely on resistance-capacity models to describe the battery operation. These models may lead to unpractical results since the current flow is governed by limiters rather than physical laws. Additionally, phenomena related with battery degradation, which decreases the nominal capacity and enhances the heat generation are also not considered in this approach. In this sense, this work investigates the potential of powertrain hybridization coupled with the dual-mode dual-fuel combustion concept while considering the use of electrochemical models for battery modelling. To do this, a commercial truck model was built in GT-Drive and validated with respect to experimental driving cycle results. Next, electric components such as battery and electric motors were included in the powertrain. The former is modelled by means of GT-Autolion, which allows detailed modelling of the electrochemical reactions and current flow by means of Butler-Volmer, Tafel and Fick’s equations. This allows to consider the limitations of power requests and the battery aging on the final energy consumption of the powertrain. The results have demonstrated an increased demand on the energy request of the combustion engine as the battery ages, as well as limitations on the maximum current transfer in the battery. Finally, the battery aging can reach limiting conditions where the driving cycle profile cannot be fulfilled, concluding that the realistic modelling of this device must be sought during the powertrain design phase.