Reduced switching-frequency voltage balancing technique for modular multilevel converters

This paper deals with a carrier phase-shifted pulse width-modulation (CPS-PWM) scheme based modular multilevel converters (MMC). The modular multilevel converter (MMC) is a one of the most promising converter topologies for high voltage and high power application, specifically for high-voltage direct current (HVDC) transmission systems. One of the technical issue associated with the control of an MMC is to carry out the submodule (SM) capacitor voltages balancing without unnecessary switching of among the SMs. Average device switching frequency can be reduce by reduced switching-frequency (RSF) voltage balancing algorithm. In this paper results of voltage balancing techniques with RSF algorithm is compared with without RSF techniques.