A new cascaded multilevel converter topology with energy exchange unit for STATCOM application

Abstract

The star-connected H-bridge cascaded converter has the disadvantage of capacitors unbalance especially when the unbalance occurs between phases. This paper analyzed one novel topology with energy exchange unit (EEU) to realize the phase capacitors voltage balance. After analyzing the converter structure and balance operation concept, this paper provided detailed modulation and capacitors balance control, including maintaining the EEU capacitor voltage stable, sharing the energy storage between phases and in same phase. The simulation results demonstrate the correction of the topology and control.Index Terms--H-bridge cascaded converter, STATCOM, phase balance control, energy exchange unit.