Initial Evaluation of a Multilevel Inverter with Unfolding Stage for BESS Applications

Today, the integration of renewable energy sources into power grids has increased significantly. This necessitates the development of more battery energy storage systems. A crucial component in such systems is the power electronic converters, which ensure the proper connection of the batteries to the grid. These bidirectional converters should be able not only to discharge batteries to the grid, but also to charge the batteries when it is needed. Various power converters can be identified for these systems. In particular, multilevel topologies offer several advantages, such as lower harmonic distortion of the output waveforms and lower switching losses. Among all multilevel converter topologies, the multilevel converter with independent sources provides one more benefit - battery balancing is achieved naturally by swapping the module switching order. This paper evaluates the performance of a modular multilevel converter with independent sources and unfolding stage.