A dual modular multilevel converter with shared capacitor sub-module for MV open-end stator winding machine drives

Diab, Mohamed S. and Massoud, A. M. and Ahmed, Shehab and Williams, Barry W. (2018) A dual modular multilevel converter with shared capacitor sub-module for MV open-end stator winding machine drives. In: The 9th International Conference on Power Electronics, Machines and Drives, 2018-04-17 - 2018-04-19.

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Abstract

This paper proposes a new dual modular multilevel converter (MMC) topology as a medium-voltage drive for adjustablespeed applications incorporating open-end stator winding machines. A novel concept of sharing one capacitor between each two adjacent-arm sub-modules (SMs) of MMC phaselegs, operating with out-of-phase modulation, is realized through new SM arrangement. This concept allows the MMC to utilize 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. Further, the proposed MMC can efficiently operate at near zero frequency, therefore a machine speed-range from zero speed to the rated speed is possible under rated torque operating condition. The proposed MMC topology is elucidated in detail, and its effective performance is verified through simulation.