The paper presents a control strategy for the Modular Multilevel Converter (MMC), which is able to provide low frequency or even zero frequency three-phase output voltages. This feature is necessary to feed a three-phase machine at low frequency. The common mode voltage and correspondent inner currents ensure a symmetrical energy distribution in the arms of the MMC and avoid AC-currents in the DC-source.
A novel control scheme for low frequency operation of the Modular Multilevel Converter
PCIM Europe 2011, 17-19 May 2011, Nuremberg, Germany