Multilevel converters as a utility interface for renewable energy systems

Multilevel inverter structures have been developed to overcome shortcomings in solid-state switching device ratings so that they can be applied to high-voltage electrical systems. The general function of the multilevel inverter is to synthesize a desired AC voltage from several levels of DC voltages. For this reason, multilevel inverters are ideal for connecting either in series or in parallel an AC grid with renewable energy sources such as photovoltaics or fuel cells or with energy storage devices such as capacitors or batteries. In this paper the cascaded H-bridges multilevel inverter is described.