Etude et conception D'un convertisseur CA/CC Dévolteur/Survolteur à Facteur de Puissance Unitaire à Bas Voltage Et à Haut Courant

Abstract

In this thesis we presents a detailed theoretical analysis and simulation results of a new method to get a non deformed input current therefore a unity power factor UPF with a cascaded buck-boost converter of low voltage and high current. Using the proposed configuration, a not deformed current and in phase with the manes voltage is accomplished, while using a new and simple to implement control strategy "variable hysterics command". Comparison between the rectified input voltage and output voltage is used to select the instantaneous operating mode of the converter. Off-line references are calculated then compared to measured currents to generate the gating signals of the appropriate switches. Low order harmonics in the input current are eliminated and the input power actor is improved to be over 0.99. Full theoretical analysis, simulation results for a 240 W application are presented for a wide range voltage. These results demonstrate the superiority of the new control strategy.