| Recent years,with the rapid development of power electronics technology,the design of various power systems tends to high frequency and miniaturization.Double-switch forward converter has been used in many high voltage input occasions as it has series of advantages,such as low switch voltage stress,low circulation loss,high reliability and simple structure.So the research of it has important significance.Then we add the parallel technology to the converter.The use of parallel technology not only saves the advantages of double-switch forward converter,but also increases the conversion efficiency and the reliability of the converter,and improves the work environment of freewheeling diode.Then we add soft-switching technology into parallel double-switch forward converter.With the help of soft-switching technology,we can reduce the switch loss of switches and further increase the conversion efficiency.Based on the extensive research on forward converter,we compare several different types of parallel double-switch forward converters.Then we use the parallel in freewheeling diode double-switch forward converter to continue the research.We add soft-switching technology to it,and introduce several classic soft-switching parallel double-switch forward converters.Aiming at the difficult to achieve soft-switching,and high circulation loss in these converters,a interleaving double-switch forward converter based on coupled inductor has been proposed.We analyze the operating modes and the current and voltage stress,and find the coupled inductor ratio has large impact on the current stress of switches and the voltage stress of freewheeling diode.Aiming at these disadvantages,we propose a novel interleaving double-switch forward converter using passive auxiliary resonant circuit.This novel converter has a very simple auxiliary circuit.It can not only achieve soft-switching of all switches under different loads and reduce the circulation loss,but also reduce the current and voltage stress of switches and freewheeling diode.The resonant current can be reduced under light load,so it can reduce the current loss of auxiliary circuit,and further improve the conversion efficiency.In this thesis,we propose a novel interleaving double-switch forward converter.The operating modes,current and voltage stress,output characteristics,soft-switching conditions,and operating conditions under light load are analyzed.The design of parameters and the loss analysis are given,and we use Cadence Pspice 16.3 simulation platform to build a 500W/100kHz simulation model to confirm the superior performance of this novel converter. |
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