I. INTRODUCTION
M
ULTILEVEL converters are attractive power converter topologies for medium and high power applications [1], [2]. Among the multilevel converter topologies, the modular multilevel converter (MMC) [3]–[7] offers several salient features which make it a competitive solution for high-voltage direct current transmission systems [8], [9] and flexible alternating current transmission systems [10]. The most attractive features of the MMC are [6]: 1) its modularity and scalability to different power and voltage levels, 2) its high efficiency, 3) the high quality of the output voltages, and 4) the absence of additional capacitors on the dc link, as the storage is distributed among the capacitors in the submodules (SMs) of the converter.