Multi-Input Transformer less Grid-Tied Invertors with Effective Control Scheme

Abstract

The proposed transformer less inverter topologies consisting of six MOSFET switches (S1-S6) and six diodes (D1-D6). L1A, L1B, L2A, L2B, L1g, L2g and Co make up the LCL type filter connected to the grid. VPV and Cdc represent the input dc voltage and dc link capacitor. The proposed topology is derived from the topology presented to overcome the low reverse-recovery issues of MOSFETs body-diode when injects reactive power into the utility grid. Therefore, the proposed topology can be implemented with MOSFET switches without reliability and efficiency penalty. The proposed topology can also employ unipolar-SPWM with three-level output voltage.