A selective harmonic elimination system for restoring and equalising DC link voltages in a multilevel active rectifier

This paper presents a reduced switching frequency, selective harmonic elimination technique for balancing DC link capacitor voltages in a cascaded H-bridge multilevel rectifier. The method controls power flow through the individual cells of the converter in an attempt to ensure that the DC link capacitor voltages for the cells converge, even when unbalanced loads are attached. Simulation and experimental results are presented to show the functionality and operation of the proposed technique.