Estratégias de modulação vetorial para inversor fotovoltaico trifásico sem transformador H8

Abstract

The global population growth has led to an increasing demand for energy, however, most currently used energy sources are non-renewable, such as oil, natural gas, and coal. Faced with this reality, it is crucial to promote awareness of responsible resource usage to preserve the environment, along with an urgent quest for sustainable and economically viable alternatives to meet society’s energy needs. In this context, photovoltaic solar energy emerges as a promising solution, continuously developing and expanding. Photovoltaic systems, composed of solar panels and energy converters, enable clean energy generation, allowing for implementation even in small residences, with the option of connecting to the electrical grid for energy bill reduction, thus contributing to a transition toward a more sustainable energy model. One of the common problems with these photovoltaic systems is the emergence of parasitic capacitances between the photovoltaic panels and the ground, thus generating a leakage current that contributes to the electrical insecurity of the entire installation. To solve this problem, transformers can be used to perform galvanic isolation between the panels and the grid. However, the addition of this equipment increases losses, cost and the size of the system. The use of a three-phase transformerless inverter in grid-connected photovoltaic systems presents an economical and compact solution, but with the presence of a high leakage current. To solve this problem, several topologies are proposed and combined with modulation techniques to reduce the leakage current. The present work proposes four space vector modulation techniques applied to a transformerless three-phase inverter topology to reduce the leakage current through the assignment of a new spatial vector, where the common mode voltage will have a smaller or zero variation in certain regions. Simulation results are presented to demonstrate the performance of the new modulation techniques.