A Cascaded DC-AC-AC Grid-Tied Converter for PV Plants with AC-Link

Cascaded multilevel converters based on medium-frequency (MF) AC-links have been proposed as alternatives to the traditional low-voltage inverter, which uses a bulky low-frequency transformer step-up voltage medium (MV) levels. In this paper, three-phase cascaded DC-AC-AC converter with AC-link for medium-voltage applications is proposed. Three stages integrate each (cell): MF square generator; four windings; and an AC-AC converter. Then, k are generate topology. This converter’s topological structure avoids per-phase imbalance; simplifies control reduces problem only solve per-cell unbalance. Two sets of simulations were performed verify operation (off-grid grid-connected modes). Finally, papers present two reduced preliminary laboratory prototypes, one validating configuration other configuration.