Research On Front-end Converter For Inverter System

With the accelerated process of economic globalization and the fast development ofindustrial economy, demands for energy have been sharply increasing. Energy issues, mainlyinclude the gradual reduction of energy and environment pollution, have become increasinglyprominent worldwide. The effective way to solve these issues is utilizing new greenrenewable energy.As the battery voltage is low in New Energy Systems, Fuel Cell Power GenerationSystem and Energy Storage System, it used to be boosted to inverters through a dc/dcconverter with a higher gain up to10or more. Taking a limited input power into account, theefficiency of the converter becomes especially important. Therefore, it is potentially necessaryto investigate a converter with high gain and efficiency.Research on front-end converter for inverter system is conducted in this article, and thenthree kinds of converters applicable to low-voltage power supply for new energy system areproposed.Firstly, a non-isolated Flyback-Boost dc/dc converter with high gain is proposed to solvethe low gain issues of traditional Boost converter in new energy low-voltage power supplyapplication. Operating principles, voltage gain and efficiency characteristics are analyzed indetail. Further more, an experimental prototype is built, and the results have been given.Secondly, with regard to medium and small power applications with isolated outputs, azero-voltage turn-off dc/dc converter is proposed. This converter is applicable to the front-endcircuit of inverter systems. The operating principles and voltage gain characteristics of eachstage are elaborated，as well as achieving ZVS conditions and main design parameters. Theexperimental prototype is also built, and the results given.At last, a Frequency control mode, in which on-time is fixed and adjust the dead time, isadopted after improving the topology in chapterIII, and then a ZCS bridge resonant converterwith voltage doubling is proposed. The operating principles are also elaborated. The gaincharacteristics are derived, different from traditional LLC resonant circuit. A prototype is alsobuilt, and experiment results given.