Direct waveform synthesis with continuous variable level multilevel converter using extended commutation cells

Abstract

The extended commutation cell is a four-port, four-switch cell that allows for bidirectional energy transport in two orthogonal directions throughout the cell. The voltage across each cell capacitor can be adjusted independently of the load, resulting in high flexibility in output levels. By placing the capacitors in (anti-) series while adjusting their voltage level a continuous waveform can be constructed. The analysis is given for a single and two-cell converter including load current correction. Additionally the waveform synthesis is simulated and experimentally verified on a 3.7 kW two-cell prototype.