Fuel Efficiency Analysis for Simultaneous Optimization of the Velocity Trajectory and the Energy Management in Hybrid Electric Vehicles

Hybrid electric vehicles (HEV) enable higher fuel-efficiency compared to conventional vehicles. The main potential for fuel efficiency lies in the choice of torque split between the internal combustion engine and the electric motor and the gear shifting strategy. In the framework of a predictive control strategy, the vehicle velocity can be considered as another degree of freedom. To achieve minimum fuel consumption, the right choice for these three degrees of freedom over time has to be found. In this paper, a discrete dynamic programming approach is used to find a global optimal solution for fuel efficiency potential analysis, optimizing torque split, gear shifting and velocity trajectory. For illustration, the results for a parallel hybrid electric passenger car are shown.