With the aim at reducing the fuel consumption and carbon dioxides emissions from the automotive transport, the electric hybridization of automotive internal combustion engines has been largely developed. However, the knowledge of the influence of thermal transfers seems to be a key point when trying to minimize the fuel consumption, in particular after a cold start. Thus, the aim of this thesis is to study the heat transfers occurring in the various parts of the powertrain (internal combustion engine, electric motor, battery). A bibliographical survey is first presented, describing the various hybrid architectures, the heat transfers and their respective models, and the various operating strategies. The development of a zero-dimensional model of an hybrid powertrain taking into account the various heat transfers is then presented. Main heat transfers models used are justified in terms of accuracy and calculation speed. After that, owing to the simulator, the impact of heat transfers is studied, in particular on instantaneous and cumulative consumption during various driving cycles. The impact of heat transfers as a function of the hybridization level is also studied. Finally, some sensitivity and prospective studies are undertaken at the end of the thesis, showing some means to reduce the fuel consumption.
