Research On AC/AC Converters With High Frequency AC Link

AC/AC conversion technology with high frequency ac link is a leading content of power electronics, and key technical foundation of new-type regulated sinusoidal ac power supply, electronic transformer, ac regulator, waveform converter with same frequency. Design of circuit configuration and topologic family, control strategy, steady principle characteristics, design criteria of the key circuit parameters, and performance comparison of the novel AC/AC converters with high frequency ac link are investigated in this dissertation. Based on theory and simulation research, 1kVA bi-polarity and uni-polarity phase-shifted controlled voltage mode prototype and 500VA current mode prototype are designed and developed. The present status, development and application field of AC/AC converters are firstly presented. Novel concept of the AC/AC converters with high frequency ac link, i.e., circuit configuration and circuit topologic family of the voltage mode based on Forward converter and the current mode based on Flyback converter AC/AC converters with high frequency ac link, is proposed. A reference sinusoidal circuit, which is synchronous with the signal of n or 1/n times line voltage frequency, is proposed and developed. The reference circuit has the advantages such as base on digital technique, synchrony with the signal of n or 1/n times line voltage frequency, low THD, adjustable maximum voltage free from the fluctuation of the line voltage, simplicity and utility, low cost. Three realization schemes of the bi-polarity phase-shifted control strategy, uni-polarity phase-shifted control strategy and three realization schemes for the voltage mode AC/AC converters with high frequency ac link are proposed, so the inherent voltage spike of cycloconverter is effectively resolved. Control strategy, steady principle characteristics, and design criteria of the key circuit parameters of the voltage mode converters are deeply investigated. By using the state-space averaging approach, the averaging models of the converters are presented and the output characteristic curves are given. Control strategy with polarity selection of the input voltage and operation mode selection, steady principle characteristics, and design criteria of the key circuit parameters of the current mode AC/AC converters with high frequency ac link are deeply investigated. The output characteristic curve is given. The designed and developed prototypes for 1kVA 220V±10%(50Hz)/110V(50Hz) bi-polarity and uni-polarity phase-shifted controlled voltage mode AC/AC converter and 500VA 220V ± 15%(50Hz)/220V(50Hz) current mode AC/AC converter with high frequency ac link demonstrate that the converters have the advantages such as high frequency electrical isolation, compact topology, two-stage power conversion, high power density, bidirectional power flow, high power density, high conversion efficiency, high input power factor, no audio noise, small bulk and weight etc. The bi-polarity and the uni-polarity phase-shifted controlled voltage mode AC/AC converters with high frequency ac link, the voltage mode and the current mode AC/AC converters with high frequency ac link, are comparatively investigated. Finally, conclusions of the dissertation are given, and further work in the future is prospected.