A new, systematic approach to determine the global energy optimum of a hybrid vehicle

Abstract

Hybridization is one of the key technologies to reduce the fuel consumption of a vehicle with internal combustion engine (ICE) significantly. Using at least one electric motor (EM), the kinetic energy of the vehicle can be recuperated and the ICE can operate more efficiently. The control strategy (CS) coordinates the torque of the ICE and the EM. If the driving cycle is known, the coordination of the drive units can be adjusted for every point in time, therefore the fuel consumption based on the entire cycle is minimal. Dynamic programming, for example, can be used, but computation time is long and it offers only a few degrees of freedom to evaluate the potential of hybrid drives. For this reason, a new method to identify the global energy optimum in a particularly systematic and transparent way was developed at the Institute of Automotive Engineering. It is therefore a globally optimal control strategy. At the same time, the approach is efficient in terms of computation time and inherently SOC neutral, therefore allowing a very good comparability of results.