Inversor fotovoltaico monofásico sem transformador com atenuação de corrente de fuga

Abstract

This dissertation presents a new transformerless photovoltaic inverter topology for photovoltaic systems. The main challenge in transformerless systems is the leakage current that flows through the parasitic capacitances of the photovoltaic panels. To reduce this current, it is necessary to ensure that the common mode voltage does not exhibit highfrequency oscillations. Inverter topologies that mitigate leakage current can be divided into three main groups: common-ground inverters, zero-state decoupling inverters, and midpoint clamping inverters. In this work, a transformerless inverter with AC decoupling and DC bus midpoint clamping is proposed. In addition to reducing leakage current, it is expected that the inverter exhibits high efficiency compared to existing transformerless inverter topologies in the literature. Throughout the dissertation, an extensive review of transformerless inverter topologies in the literature is conducted. Subsequently, the common-mode model of a three-level converter is derived and the frequency response of the system is analyzed. The operation modes of the proposed inverter, including the principles of the clamping branch, are described. Simulations are performed to compare the performance of the proposed converter with other topologies based on various performance parameters, such as leakage current level, number of devices, voltage across the switches, and conduction and switching losses. Finally, the proposed transformerless inverter is experimentally validated.