Control of the DC source balance in a series association of single phase voltage source inverters

Multilevel converters appear to be one of the most interesting solutions able to solve problems linked to high voltage applications. Various solutions exist to realise this type of converter. One constraint appearing on these converters is the balance of the voltages across capacitors used as DC voltage sources. This balance can generally be obtained by an appropriate control. This paper proposes a balance control which can easily be added to the usual process. An application to a series-association of voltage source inverters operating as an active filter is developed. The balance control is presented, simulations and experimental results validate its efficiency.