A Dual Quasi Z-Source Based T-Type Five-Level Inverter With Improved HERIC Structure for Photovoltaic Applications

A new single-stage, T-type five-level inverter, which is based on a dual quasi Z-source, and an improved HERIC structure has been proposed in this paper. It is envisaged that the proposed power converter could find applications in the area of grid-connected PV generation. The conventional topologies, which are based on two-stage conversion are bulky and expensive. The proposed single-stage system overcomes these disadvantages. Furthermore, the issue of leakage current, which is of paramount interest in PV systems is addressed by the adaptation of a PWM scheme along with the employment of passive filters. It is shown that the leakage current is effectively suppressed by the elimination of the high-frequency transitions across the parasitic capacitance due to the combined effort of the PWM scheme and the filter. The proposed power converter also displays the capability of supporting reactive power, which is one of the essential requirements for the present-day PV inverters. The steady-state and the dynamic performances of the proposed power converter are assessed with simulation studies and are then experimentally validated. A comparative study of the proposed power converter with the existing quasi-Z-source-based power converters is also undertaken, which reveals the advantages of the proposed configuration.