الفهرس 
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Abstract
In recent decades, the electrical vehicles are opened to the exploitation of renewable energy sources such as solar energy, wind energy, fuel cells, The search for non-polluting energy is also updated, particularly for applications such as ground transportation (electrical vehicles), portable devices (computers, stereos, phones ...) and the power supply for the isolated housing. The world of industry is currently moving towards solutions around solar energy and fuel cells and these in different sectors (electronics, mobile phones, vehicles, aircraft, stationary production of electricity, heating ...) and the investment in the development of these technologies which generate a low emission of polluting gases. In the automotive sector, this research is mainly devoted to the production of electric or hybrid vehicle. However, nowadays, these vehicles still suffer from insufficient autonomy. If the fuel cells are embarked as a source of energy; it is possible to consider a good compromise between local pollution very low or almost zero, and operation close to the so-called classic cars. For applications based on the fuel cell, the type of the fuel cell most commonly used is proton exchange membrane (PEMFC). Indeed, this type of fuel cell operates at low temperature and does not generate polluting products but only generates water. Hydrogen as a fuel can be supplied in specific reservoirs or obtained by reforming other fuels, such as natural gas, methanol or others. The work presented in this thesis was conducted in GREEN (group for Research in Electronics and Electrical Engineering of Nancy) which is a part of ENSEM (Ecole Nationale Supérieure d’Electricité et de Mécanique), which is a part of INPL (Institut National Polytechnique de Lorraine) - Nancy University. It covers the study of high-ratio voltage converter which used as an interface between low voltage sources (solar cells or fuel cells) with a number of constraints and a medium voltage DC bus. In this thesis, the nonlinear source used is a fuel cell of type PEMFC. The main problem related to the use of a fuel cell for the medium power applications is that the output voltage of the fuel cells decreases and becomes low when they supply strong currents. In addition, the voltage delivered falls rapidly with the current. These two characteristics mean that in most applications, it is necessary to shape the energy out of the fuel cell using a static converter in order to connect it to a stabilized DC bus.