A Modified Single-Phase Quasi-Z-Source AC–AC Converter

Nguyen Minh Khai, Lim Young Cheol, Kim Yong Jae

Abstract


A  modified  single-phase  quasi-Z-source  ac–ac  con-verter is proposed in this paper. The proposed converter has the main features in that the output voltage can be bucked or boosted and be both in-phase and out-of-phase with the input voltage. The input voltage and output voltage share the same ground, the size of a converter is reduced, and it operates in a continuous current  mode. A safe-commutation strategy for the modified single-phase quasi-Z-source ac–ac converter is used instead of a snubber circuit.The operating principles and a steady-state analysis are presented.A laboratory prototype, tested using a resistive load, a passive load,and a nonlinear load, was constructed that used an input voltage of 70 Vrms /60 Hz in order to verify the performance of the modi- fied single-phase quasi-Z-source ac–ac converter. The experimental results verified that the converter has a lower input current total harmonic distortion, a higher input power factor, and a higher effi- ciency in comparison to a conventional single-phase Z-source ac–ac converter. In addition, the experimental results show that the use of the safe-commutation strategy is a significant improvement, as it makes it possible to avoid voltage spikes on the switches.

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