M.S. Diab, A.M. Massoud, S. Ahmed, B.W. Williams
The Journal of Engineering, issue 17, (2019)
This paper proposes a new dual modular multilevel converter (MMC) topology as a medium-voltage drive for adjustable-speed applications incorporating open-end stator winding machines. A novel concept of sharing one capacitor between each two adjacent-arm sub-modules (SMs) of MMC phase-legs, operating with out-of-phase modulation, is realised through new SM arrangement. This concept allows the MMC to utilise half the number of the SM capacitors, compared to a traditional MMC topology. Additionally, the sizing requirement of the shared capacitor is diminished, which significantly reduces the volume of the drive system and its stored energy. The switching scheme of the shared capacitor between two oppositely modulated SMs eliminates the problem of capacitor wide-voltage fluctuations, independent of the operating frequency.