This paper describes the process of electrical energy management and optimization in a multi-source system such as a Hybrid Electric Vehicle (HEV), running on a known mission profile. The purpose of the committed study is to minimize the consumption of the fuel used by one of the sources, to respect the different constraints related to the operating system and to meet the demand of the electrical motor powertrain. Lots of studies were led on a non-linear modeling of the problem giving suboptimal solution with important computation time. In this paper, a new combinatorial modeling is proposed to avoid such drawback. A computational study shows the benefits obtained using an exact combinatorial approach.