Research On AC-AC Mode AC/AC Converters With High Frequency Link

The present status, development trend and application field of AC/AC converters are firstly presented in the thesis.Then novel circuit structure and circuit topologies family of voltage mode (based on Forward converter) and current mode (based on Flyback converter)AC-AC mode AC/AC converters with high frequency link , are proposed. The circuit structure of this kind of converters is constituted of input cycloconverter, high frequency transformer (high frequency storage transformer), output cycloconverter, input and output filter. The circuit topologies family of voltage mode AC-AC mode AC/AC converters with high frequency link include eight circuit topologies, such as single forward mode, interleaved-forward mode, push pull-full wave mode, push pull-full bridge mode, half bridge-full wave mode, half bridge-full bridge mode, full bridge-full wave mode, and full bridge-full bridge mode etc.The circuit topologies family of current mode AC-AC mode AC/AC converters with high frequency link include single four-quadrant power switch mode, push-pull mode, half-bridge mode, and full-bridge mode circuits.Taking full bridge-full bridge mode circuit as an example, principle of Uni-polarity Phase shifting Controll is introduced. The twelve kinds of modes and equivalent circuits of voltage mode AC-AC mode AC/AC converters with high frequency link within one high frequency switching period are carefully analyses.By using the state-space averaging approach,the converter's averaging model is presented, and the design criterion of key circuit parameters and the output characteristic curve are given.Taking single four-quadrant power switch mode circuit as an example, the operational mode, steady principles, transient voltage feedback control strategy of current mode AC-AC mode AC/AC converters with high frequency link are investigated. The output characteristic curve and the design for the key circuit parameters are given.Prototypes for 1kVA 220V + 10%(50Hz)/110V(50Hz) uni-polarity phase-shifted controlled voltage mode AC-AC mode AC/AC converter with high frequency link and 500VA 220V+15%(50Hz)/220V(50Hz) single four-quadrant power switch mode current mode AC-AC mode AC/AC converter with high frequency link, are successfully designed and developed. The prototype test results indicate: voltage mode and current mode AC-AC mode AC/AC converters with high frequency link have the advantages such as high frequency electrical isolation .simple topology, two-stage power conversions, high power density, bidirectional power flow, good line current waveform, no audio noise,high converting efficiency,and high input power factor etc. This kind of converter lay the key technical foundation on new type regulated sinusoidal ac power supply, electronic transformer ,ac regulator,and wave converter etc.