Internal model control of the Zeta Converter for the grid connection of photovoltaic panels

This paper presents the study and application of resonant controllers applied to a Zeta Converter designed to synthesize a rectified sine current compatible with the power grid in order to connect solar photovoltaic (PV) panels to it. Operating in discontinuous conduction mode, the Zeta Converter is connected to a full-bridge inverter so that one semi-cycle of the output current is inverted for every cycle of the power grid voltage. The assembly formed by PV panel and inverter is known as Module-Integrated Inverter (MII). Controller design is performed by the solution of an optimization problem with restrictions in the form of Linear Matrix Inequalities (LMIs) which guarantee the closed-loop system stability and performance. Experimental results of the developed controller, whose objective is reduction of the harmonic content on the inverter output current and synchronism with the power grid, point to the viability of this solution.