Dynamic Programming Study of a Hybrid Electric Powertrain System for a Transit Bus

Abstract

Great research efforts are invested in the quest for solutions that will increase the fuel economy of ICE-powered vehicles. The main objective of the study presented in this paper has been to analyze the ultimate fuel economy improvement potential of a transit bus by implementing a hybrid electric powertrain system utilizing an ultracapacitors-based accumulator. A simulation model of the vehicle has been calibrated by analyzing data obtained during an experiment conducted in real-world traffic conditions on a Belgrade transit bus. Apart from serving as the input for the powertrain parameters identification procedures, the acquired data also served as the basis for defining the driving cycle that will be used in numerical simulation studies. A Dynamic Programming optimization procedure has been applied on the hybrid powertrain system model in order to assess the ultimate fuel economy improvement potential. The optimization procedure has been executed for various hybrid powertrain parameters and component sizes, allowing the optimal choice of design decisions, in particular the energy accumulator size. Initial study shows that considerable fuel consumption reduction in excess of 30% can be achieved.