Hybrid Vehicle Simulation Addressing Real Driving Emissions Challenges

Abstract

The upcoming Real Driving Emissions (RDE) legislation requirements impose new challenges for future powertrains. In parallel, hybridization increases the importance for the engine and exhaust system thermal management. In this new technological and legislative environment, the application of model-based methodologies could support the tough optimization problem of exhaust system design and control. The purpose of the present study is to present a practical simulation approach for the complete vehicle-powertrain-aftertreatment chain, focusing on Hybrid Electric Vehicle applications. The methodology is supported by a complete vehicle simulation platform (velodyn), with emphasis on the prediction of engine-out and tailpipe emissions via appropriate engine and aftertreatment modeling. The exhaust aftertreatment devices simulation is based on well-established and validated mathematical models of the physico-chemical phenomena using the software axisuite®. The engine-out emissions prediction is based on a semi-empirical approach with sufficient degrees of freedom to describe the effect of the engine thermal state on baseline engine emissions. The models are coupled in order to allow a closed-loop simulation of the complete powertrain and apply various aftertreatment control strategies depending on the driving scenaria. Next, the impact of hybridization on emissions is discussed and studied on the basis of complete vehicle simulation, addressing the exhaust system thermal management with the support of advanced 3D thermal loss calculations. It is demonstrated that the presented methodologies could substantially support the design and optimization of integrated engine and aftertreatment controls to comply with Real Driving Emissions requirements.