Abstract : The world's ever growing energetic consumption, the instability and uncertainty of the price of fossil fuels, electrical market liberalisation and a strong environmental consciousness have renewed the interest in developing renewable energies. Among these, wind energy holds an advantaged position due to its high level of technological development and its comparatively low associated cost. In this context, the aim of this PhD work is to study the optimal design of a small wind energy system for locations where network extension is difficult or too expensive to implement. An optimisation tool for a wind energy battery charger is proposed and validated. The power system is composed of a minimal set of elements. Therefore, the system's simplicity allows reduction of its maintenance and increases its reliability at minimal cost. When a higher energy output is desired with the same production means (wind turbine and electrical generator), the inclusion of a switched-mode electronic power converter is useful. Such a system is studied and verified by computer simulation. This generation system allows an optimal power transfer, increasing energy production and therefore reducing costs. An electronic power converter loss estimation method is also proposed and validated. This method is used to calculate more accurately the energy-not-supplied of a hybrid renewable energy system which is located in an isolated place.