The mission profile emulator (MPE) proves to be an effective and cost-efficient approach to validate the design and reliability of the submodule (SM) in a modular multilevel converter (MMC). This article established the detailed models for the capacitor voltages of SM in the MMC system. The factors that can determine the dc component of capacitor voltages in SM of MMC are analytically solved. The difference between the capacitor voltage of SM in a complete MMC system and that of SM in MPE is discovered, explained, and verified. In order to improve the emulating accuracy for the capacitor voltage in SMs of the MPE, a novel voltage control method, which is more adaptive to the operating conditions of MMC, is proposed. The simulation models and experimental setup are built to verify the validity of the proposed methods.

Published in: IEEE Transactions on Power Electronics ( Volume: 36, Issue: 11, Nov. 2021)