Eight-level DC-AC converter using four-switch extended commutation cells

The extended commutation cell is a four-port, four-switch cell that allows for bidirectional energy transport in two orthogonal directions throughout the cell. By cascading multiple cells a multilevel converter can be constructed with a high number of cells. The voltage across each cell capacitor can be adjusted independently of the load, resulting in high flexibility in output levels. This paper presents the analysis, design and verification of a 4.4kW eight-level dc-ac converter. The capacitor voltage control is operated with closed loop control and the output is operating in open loop. The experimental results are in agreement with the simulations are show the cell´s potential for application in multilevel power converters.