Improved powertrain system and control strategy of an hybrid vehicle

In the last decade, the subject of hybrid vehicle (HV) has attracted a great attention of many searchers, and various works have been published about the modeling and the control of that systems with the goal of fuel consumption optimization. In this way different architectures of the hybrid vehicle have been proposed (parallel, serial, mixed and other architectures). However the optimization problem remains a current subject of several research projects. Indeed the series architecture is the simplest design one, but it doesn´t offer the better overall energy efficiency, since the heat engine transmits its energy indirectly to wheels through the electric generator, the battery and the electric machine. The parallel architecture provides a total return better than that of the serial architecture but requires relatively complex power management compared too there architectures and especially the management of the state of charge (soc) for unknown trajectories at advance. For other architectures such as mixed hybrid, although they provide additional degrees of freedom relatively to the parallel architecture, they present the inconvenient of volume size and weight of the vehicle which must be equipped with two or more electrical machines. In addition these architectures don´t present a better performance than the parallel one. Our contribution in this paper is to propose an energy model of the HV based on energy balance, and to discuss the optimality conditions in the different operating modes of a parallel hybrid vehicle. Also, is considered the choice of the power train system.