On the DC/DC converters for cascaded asymmetric multilevel inverters aimed to inject photovoltaic energy into microgrids

Abstract

This work presents a double stage DC/DC converter suitable for cascaded asymmetric multilevel inverters meant to inject photovoltaic energy to microgrids. For cascaded topologies, maintain the DC voltage within its expected value is crucial to obtain satisfactory performance; on the other hand, in photovoltaics, a DC/DC converter is usually included to ensure the maximum power point. For asymmetric structures, the gating patterns are fixed and therefore an additional degree of freedom is required to simultaneously keep the requested ratio and track the maximum power of the solar array. A suitable double stage buck-boost converter is used in the asymmetric inverter in order to perform both tasks; which includes a Perturb and Observe algorithm and a fuzzy logic controller for each stage, respectively. The simulated results shows a satisfactory performance of the proposed scheme.