Metodologia de projeto para um filtro LCL modificado com adição de um indutor de modo-comum para aplicações fotovoltaicas sem transformador conectadas à rede

Diego Chaves; Felipe Grigoletto; Fernanda Carnielutti; Humberto Pinheiro

doi:10.20906/sbse.v2i1.3091

Diego Chaves Grupo de Eletrônica de Potência e Controle (GEPOC), Universidade Federal de Santa Maria, Santa Maria, RS
Felipe Grigoletto Grupo de Eletrônica de Potência e Controle (GEPOC), Universidade Federal de Santa Maria, Santa Maria, RS
Fernanda Carnielutti Laboratório de Processamento de Energia e Controle (LAPEC), Universidade Federal do Pampa, Alegrete, RS
Humberto Pinheiro Grupo de Eletrônica de Potência e Controle (GEPOC), Universidade Federal de Santa Maria, Santa Maria, RS

DOI: https://doi.org/10.20906/sbse.v2i1.3091

Keywords: MLCL filter, common-mode inductor, common-mode voltage, transformerless photovoltaic system

Abstract

Grid-connected transformerless photovoltaic (PV) systems have become very popu- lar, due to their smaller size/weight, greater efficiency and lower cost. However, the common- mode voltage (CM) generated in power inverters causes leakage current, which according to PV standards, must be limited. Among different methods to limit leakage current, the modified LCL (MLCL) filter with passive damping is an efficient and simple solution. However, it is necessary to oversize the components of the MLCL filter to keep the leakage current below 300 mA rms, established by PV standards, increasing the size of the differential inductors. On the other hand, a CM inductor can be added to limit the leakage current. These inductors process less energy, and therefore considerably reduce the total volume of magnetic devices in the power stage. This paper presents a methodology to size the elements of an MLCL filter with a CM inductor that complies with the PV standards, in a transformerless three-phase two-level grid-connected inverter. Simulation results are presented to confirm the theoretical analyses.