A simulation environment for assessing power management strategies in hybrid motorcycles

Reduction of the environmental impact of transportation systems is a world wide priority. Hybrid propulsion vehicles have proved to have a strong potential to this regard. Differently from cars, and even if they are considered the ideal solution for urban mobility, motorbikes and mopeds have not seen a wide application of hybrid propulsion yet, mostly due to the more strict constraints on available space and driving feeling. In this paper, we consider the problem of providing a commercial 125cc motorbike with a hybrid propulsion system, by adding an electric engine to its standard internal combustion engine. The aim for the prototype is to use the electrical machine (directly keyed on the drive shaft) to obtain a torque boost during accelerations, while reducing the emissions. Two different control algorithms are proposed, based on a standard heuristic and on torque-split optimal-control strategies, respectively. A Simulink virtual environment has been realized starting from a commercial tool, VI-BikeRealTime, to test the algorithms. The hybrid engine has been implemented in the tool from scratch, as well as a simple battery model, derived directly from data-sheet characteristics by using polynomial interpolation. The simulation system is completed by a virtual rider and a tool for build test circuits. Results of the simulations on a realistic track are included.