Capacitor Ripple Reduction with Novel Modulation Scheme in Modular Multilevel Converters

فاقد چكيده فارسي

The modular multilevel converter (MMC) is a potential candidate for high power and high voltage applications[1]. Capacitor voltage balancing, circulating current suppression, low switching frequency and high capacitive energy storage should be considered about this topology. This paper presents a new modulation scheme to tackle three of the aforementioned problems by considering the capacitor reduction. An adequate amount of negative voltage in full-bridge submodules (FBSMs) at normal operation has been used to reduce the capacitor ripple through the proposed scheme. The modification has been made in the existing voltage-balancing algorithm used in the literature [2,3] to select and insert modules negatively according to the signal modulation, which improves the performance of the MMC. The resulting reduction in capacitor voltage fluctuations eventuate in reduction of capacitance of submodules which is a space-saving and capacitance optimization solution in MMC topology. The effectiveness of the proposed method has verified, using MATLAB/SIMULINK software. The results of the proposed method in terms of capacitor voltage ripple compared with the conventional and the proposed method in [2] to verify the performance of the proposed method. The results suggest 43% reduction respect to the conventional method as well as 43% increase in transmitted power.