Current Integral Comparison-Based Power Loss Balancing Control for Full-Bridge Modular Multilevel Converters

Abstract

Power loss management is one of the most important challenges for improving the reliability of modular multilevel converters (MMCs). This article proposes a current integral comparison (CIC)-based power loss balancing control (PLBC) for full-bridge submodule (FBSM)-based MMCs, where two types of bypassed modes of the FBSM are selected by comparing the current difference integral values of the semiconductors in the FBSM. The proposed control can not only improve the power loss distribution in each FBSM, but also reduce the temperature fluctuation of semiconductors, and accordingly, the proposed control significantly improves the lifetime of MMCs. Simulation studies with professional tool PSCAD/EMTDC and experimental studies with a downscale MMC prototype are conducted, and their results confirm the effectiveness of the proposed CIC-PLBC.