Novel family of quasi-z-source AC/AC converter with safe-commutation

In this paper, a novel family of quasi-z-source AC/AC converter with buck/boost ability is described. After analysis of basic AC/AC safe-commutation, new commutation strategies for those converters are proposed and safe commutation can be achieved without snub circuit only by sampling the output voltage, which considerably simplifies the control circuit. In all converter family members, two switches in one phase loop are always turned on for current commutation in dead time, resulting in less switch loss. From the proposed converter family, the voltage-fed quasi-z-source is analyzed, the operating modes are explained and the voltage ration is analyzed based on state-space average. The presented experiment results of a prototype voltage-fed quasi-z-source (VQZS) confirm the theoretical analysis. The safe-commutation strategies can also be easily extended to other converters of the proposed family.