A Modified Cascaded Inverter for PV Integration into Grid Without Transformer

There has been an increasing interest in transformer less inverter for the integration of the PV system into the grid. Cascaded Multilevel Level Inverter is most suitable for this integration, as the separate DC sources can be directly fed by the PV arrays and it is suitable for medium to high power applications. However one of the technical challenges of transformer less inverter is the issue of leakage current which has to be addressed carefully. This paper describes a Modified Cascaded Multilevel Inverter, appropriate for PV grid integration. This analysis has emphasis on transformer less feeding, leakage current minimization and reduction in switching and conduction loss. This topology reduces the high frequency fluctuation in terminal and common mode voltages and thereby achieves the minimization of leakage current as per the German DIN VDE 0126-1-1 standard. The analysis is carried out with Matlab simulation platform.