Flying capacitor four-level H-Bridge converter

This paper proposes single-phase and three-phase four-level converters with a flying-capacitor leg and a conventional two-level leg per phase. The main advantages of the proposed converter are as following: (1) the same blocking voltage for all switches employed, (2) no capacitor midpoint connection needed (i.e., no low frequency current circulating in dc-link capacitors) and (3) reduced number of flying capacitor as compared to the conventional solution. Details regarding the operation of the configuration, flying capacitor voltage balance and modulation strategy are presented as well. Simulated results are presented to validate the theoretical expectations.