Hybrid cars, optimization and control

The paper presents new optimization results for the design and control of a hybrid vehicle. The powertrain consists of a combustion engine and an electrical drive, combined with a continuously variable transmission gear. For simulation and analysis, the optimal control of the powertrain is calculated directly by using of the optimal control theory. The objective is minimum fuel consumption. From the results, both an optimal design of the components and an operation strategy for online driving can be derived. Especially the optimal rating of the electric motor and the effects of bounded rating on operation and fuel consumption are discussed. In this regard, the effect of a flat minimum appears there exist a range of varying solutions for minimum fuel consumption.