New soft recovery pulse width modulation quasi resonance converter using multiple folding nnubber network

Abstract

As hard switching problem during switching transition in DC-DC converter has become main limiter in increasing out put power, many soft switching technique have been studied. The quasi resonance converter is one of the good examples to reduce above hard switching problem. This thesis has been studied and proposes another new soft switching topology, which is composed of passive elements only. The first topology to be studied, which is named to Soft Recovery (SR) Quasi Resonant converter (QRC), is combined conventional quasi resonant converter with the Folding Snubber Network that is composed of diodes and capacitors. The folding snubber network provides soft switching condition to the main rectify diode. In the second topology to be studied, which is named Fully SR PWM QRC, the switching device of MOSFET can be possible to operate in perfectly soft switching condition on account of additionally inserted auxiliary diode and capacitor. But, there are unexpected problem, which is parasitic oscillating, in the second studied topology. In the third studied topology, Completely compensated soft switching operation which is named to the Revised Fully SR PWM QRC can be accomplished by combining the second studied topology with the folding snubber network. The revised fully SR PWM QRC also includes multiple order folding snubber network. This multiple order folding snubber network enables the efficiency of output power as well as the maximum operating region in current to increase. Finally, this multiple resonance technique enables the available maximum output power to increase without loss of reverse recovery current in main rectifier diode. Stable operation is also accomplished. This proposed converter is suitable to apply to several killo watts grade out power supplier. By extension of this concept to other switching converters, a new family of Soft Recovery Pulse With Modulation Quasi Resonance Converter (SR PWM QRC) is possible to be generated.