Development of a predictive model for Regenerative Braking System

The basic problem that this project addresses is the recovery of the kinetic energy lost during braking in a conventional vehicle. With Regenerative Braking Systems (RBS) it is possible to slow a vehicle down by converting its kinetic energy into electric energy, which can be either used immediately or stored until needed. This contrasts with conventional braking systems, where the excess kinetic energy is converted into heat by friction and wasted into the environment. In hybrid electric vehicles, the regenerative braking action is performed using the electric motor as a generator. In this way the energy from the wheels is converted from kinetic into electric and the magnetic friction between the rotor and the stator windings provides the braking effect. The aim of this study is to design a model of an electric system that allows converting the kinetic energy and storing it into a high voltage battery. The powertrain configurations investigated in this project are the mild and full hybrids, in which the internal combustion engine is coupled with an electric motor, able to provide a start/stop and a power assist functions in addition to the regenerative braking actions. The final result of the study is represented by a tool that has been implemented into Matlab^® in order to predict the time variation of the electric quantities in a vehicle performing the New European Driving Cycle. This model also offers a predictive tool for dimensioning the main components of the system, according to the target electric parameters. Finally, the improvements that such a system could give in terms of efficiency, fuel consumption and emissions reduction have been analyzed. With respect to the existing models, this approach requires few main input parameters to characterize the RBS, resulting in a higher flexibility and a wider range of application.