Estudo de um conversor ressonante bidirecional isolado baseado na topologia LLC

Abstract

The growing demand for electricity by society has led to the search for new forms of generation, requiring an increase in the share of renewable energy sources in the global energy matrix, given the environmental constraints. In this way, the smartgrids introduce concepts in the electrical system, such as microgrids and nanogrids, which have their generation based on renewable sources such as wind and solar. The production of energy from these sources is linked to natural factors such as solar irradiation and wind, which leads to the need of energy storage systems in battery banks to guarantee the supply to the nanorede with low or no dependence of the electricity distribution network. In this context, this work presents a study about a bidirectional DC-DC converter, for interfacing between a power storage system and a nanogrid DC bus. This converter has the purpose of controlling the power flow between these elements, either by charging the battery bank of 24V (forward mode) or by maintaining the voltage of 380V in the DC bus (backward mode). In front of several bidirectional topologies, a converter was chosen based on a resonant structure. These converters are characterized by processing power with soft switching on the electronic switches. Among the several resonant topologies, the LLC series-parallel resonant Half-bridge converter was chosen, adapting it to its bidirectional structure, leading to a little explored topology in the literature. The structure of the nanoread is presented and tests are performed to analyze the performance of the converter in forward and backward modes.