Highly Reliable Multi-Port Smart Inverter Modules for PV-Based Energy Systems: Preprint

Generally large electrolytic capacitors (e-caps) are required to decouple the double line frequency power fluctuation inherent in all the single-phase dc-ac or ac-dc converters. These e-caps pose the weak-link in the PV inverter as they have poor reliability due to short life expectancy and higher ESR leading to lower system efficiency. In this paper, the multi-port smart dual inverter modules are proposed for PV string inverter systems which eliminate the requirement of large decoupling capacitors, thus leading to more reliable and highly efficient inverter modules. The balanced dual outputs are controlled in phase quadrature such that the double frequency current is completely eliminated. One of the phases supports the stand-alone residential loads and the other phase interfaces to the grid, which is synchronized to the utility grid. Also the proposed modular configuration is scalable to accommodate higher power rating by stacking and paralleling multiple modules. Simulation results for the dual inverter modules rated for 1 kW each are presented to validate the proposed concept, the hardware-in-the-loop based experimental platform is developed and the results will be presented in the final version of the paper.