Modelagem e controle de um conversor CC-CC isolado aplicado a sistemas fotovoltaicos

Abstract

World energy consumption grows annually and this growth results in a fast depreciation of non-renewable resources and adds a concern for the environmental consequences of using them. Photovoltaic energy is the greatest growing renewable energy source in the world and it will soon become one of the most significant sources of the world’s energy matrix and thus one of the main renewable solutions to this demand. This work presents the modeling and control of an isolated DC-DC converter applied to Photovoltaic Systems. DC-DC converters have advantages when being used as the first stage of energy conversion in a photovoltaic system, since it can convert a voltage level variable from the output of the panels to a constant level required by the second inverter stage, execute the MPPT algorithm (Maximum Power Point Tracking), etc. In applications that require a high voltage gain, isolated topologies are better candidates, because in these cases they can achieve a higher efficiency than non-isolated topologies through a correct transformer design. In addition, an isolated converter provides galvanic insulation between the input and the output of the system, which is desired from a safety point of view. In general, the energy dissipation resulting from losses in a power semiconductor device implies an increase of its operating temperature, which could compromise its useful life and the efficiency of the converter. In order to avoid losses in conduction input, the studied topology will operate under zero voltage switching, where it is ensured that the voltage applied under the switch falls to zero and only then the current circulates through the device, causing the converter to have a better efficiency.