Analysis of the Power Balance in the Cells of a Multilevel Cascaded H-Bridge Converter

Multilevel cascaded H-bridge (CHB) converters have been presented as a good solution for high-power applications. In this way, several control and modulation techniques have been proposed for this power converter topology. In this paper, the steady-state power balance in the cells of a single-phase two-cell CHB is studied. The capability to be supplied with active power from the grid or to deliver active power to the grid in each cell is analyzed according to the dc-link voltages and the desired ac output voltage value. The limits of the maximum and minimum input active powers for a stable operation of the CHB are addressed. Simulation results are shown to validate the presented analysis.