A multilevel soft-switching inverter with inductor coupling

This paper proposes a new soft-switching flying capacitor multilevel inverter that can be generalized and be extended from three levels to any number of levels. The proposed inverter has the advantages of lower voltage and current ratings for auxiliary switches and diodes, achieved by using a coupled inductor and midpoint rail between the DC capacitors. Various aspects, including operation, design, control, and switching patterns are presented. Furthermore, voltage balancing for stability along with safe operation is studied through simulation and experiment. Results indicate that the proposed inverter achieves a zero-voltage condition in all of the main switches and a zero-current trim-off to the auxiliary switches during commutation processes.