Waveform synthesis using variable capacitor voltage in extended commutation cells based converter

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 and feed-forward of the variable capacitor voltages. Experimental verification is performed on a two-cell converter prototype of 3.7 kW using a trapezoidal reference waveform.