Abstract：Buck-Boost three-level (TL) single-stage AC/AC converter circuit topology is proposed in this paper. This converter, which is suitable for high input voltage field, has many advantages such as low voltage stress of the switches, single-stage power conversion, high conversion efficiency, three-level voltage waveform of the inductor for storing energy, low THD of output voltage, strong load adapting ability, et al. The voltage stress of switches of this converter is half of that of two-level converter. So the requirement of the voltage stress of switches can be lowered in high-voltage field. The transient voltage feedback control strategy of the converter is also investigated, which can rapidly respond to the change of the input and the output voltage. According to the polarity of the output voltage and the output current, the converter contains four kinds of operation modes. Each operation mode is equal to a three-level DC/DC Buck-Boost converter. The operation principle of the converter is analyzed in details. The external characteristic of this converter is analyzed in CCM mode and DCM mode. The correction and advance of the kind of converters are verified by experiment.
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2010, Vol. 25 
