Decentralized Optimal Control Strategy for Parallel Hybrid Electric Vehicles

In the present article, a decentralized optimal control strategy (DOC) for hybrid electric vehicles (HEV) is introduced. In contrast to central supervisory control strategy (CS) approaches, every power instance of the drive train (motor, engine, brakes, battery etc.) is controlled by a local controller, which receives merely information from its accompanying power instance and the drivers command. It is shown, that the local controllers can be designed in such a way that the overall system efficiency converges to an internal optimum. Moreover, it is shown that the battery management can be implemented decentrally, too. Therefore, the optimal behavior is not affected by possible internal gear change or by power branch off along the energy paths. The proposed approach and the behavior of a decentral controlled parallel HEV is demonstrated by using a dynamic simulation model of a counterbalanced forklift truck.