A New Control Technique for Multilevel Cascaded H-Bridge Inverters

Abstract

Multi cell converters are one of the alternative topologies for medium-voltage industrial drives. For an application modulation (PWM) rectifier as front end Multi level cascaded H-bridge (CHB) converters have been presented as a good solution for high-power applications. The choice of single-phase PWM rectifiers for the input of the cells results in a reduced number of power switches and a simpler input transformer than the three phase equivalent. However, its control is not as straightforward. In this paper, the steady-state power balance in the cells of a single-phase two-cell CHB is studied. The ability to receive active power network or to deliver active power to the grid in each cell is analyzed according to the DC-link voltage and the desired output AC voltage value. Simulation results are shown to validate the presented analysis.