Improving the performance of modular multilevel converter by reducing the dead time effect

Modular multilevel converter (MMC) is a highly attractive and promising topology especially for high voltage applications. In this paper, the dead time effect introduced by the real power switches on the performance of MMC is analyzed. The results show that the dead time will deteriorate the output voltage and is very harmful to the buffer inductors. To alleviate the effect of the dead time, an improved method for voltage sampling of the submodules is proposed. Simulation and experimental results show substantially reduced switching frequency with the proposed method. Meantime, the narrow pulses in the output voltage and on the buffer inductors together with the harmonics in the output voltage can all be suppressed remarkably.