Design and implementation of high gain soft switched dc dc converters

Abstract

The DC-DC step-up converters are widely used in computer newlineperipherals and industrial applications such as computer periphery power newlinesupplies, car auxiliary power supplies, servo-motor drives and medical newlineequipment. In recent years the DC-DC conversion technique has been greatly newlinedeveloped. The main objective of this thesis is to achieve high efficiency, newlinehigh power density and cheap topology with increase in the output voltage. newlineTo increase the power density and to reduce the size and weight of the newlineconverter, voltage boost converters with high voltage conversion ratio newlineoperating at high switching frequencies are used. Voltage boost methods are newlineused in buck, boost, buck-boost and Cuk DC-DC converters. These newlineconverters experience high switching losses, reduced reliability and newlineElectromagnetic Interference (EMI) problems. To overcome the above newlinementioned difficulties, Quasi-Resonant Converters (QRCs) with increase in newlinethe output voltage are used. The efficiency of these converters can be newlineimproved by having either Zero Voltage Switching (ZVS) or Zero Current newlineSwitching (ZCS) in the converter operation. newline The voltage (or) current is forced to pass through zero crossing by newlineusing an LC resonant circuit to achieve ZVS (or) ZCS in the converter circuit. newlineThere are many ways to achieve the ZVS (or) ZCS in the converter circuit at newlinehigh frequency by rearranging the components of the converter circuit. The so called soft switching has many advantages over the hard switching such as newlinereducing the voltage and current stresses across the switching devices, dv/dt newlineand di/dt problems and EMI problems. Therefore, to improve the efficiency and boost the output voltage of newlinethe converter it is proposed to have ZVS/ZCS resonant switching techniques newlineto the existing Voltage Boost DC-DC Converters. The analysis, design and newlineimplementation of ZVS Quasi Resonant voltage boost converters are newlinepresented. Simulation and experimentation of these converters are carried out newlineto validate the analysis.