Small-Signal Modeling and Dynamic Analysis of the Quasi-Z-Source Converter

The quasi-Z-source inverter (qZSI) can operate as a single-stage buck-boost inverter with a higher step-up gain when compared with the conventional two-stage inverter. The adoption of the shoot-through state makes the qZSI possible to operate under the short-circuit and open-circuit conditions. With these features, the qZSI is suitable for photovoltaic (PV) applications, considering the low-level and intermittent output characteristics of the PV panels. However, the control of the qZSI requires more detailed modeling analysis in terms of dynamics. Thus, this paper discusses the small-signal modeling of the qZSI and its dynamics. To validate the derived models and the analysis, both the frequency-domain and time-domain performances of the qZSI are presented and compared.