An Improved Loss Calculation Method for MMCs

Abstract

Abstract Accurate loss calculation of power devices in the submodules of the modular multilevel converter (MMC) is significant. The loss calculation of MMC is closely related to its control strategies, such as the nearest level modulation (NLC) method and the capacitor voltage balancing method based on sequencing. The loss distribution characteristics and calculation of power devices are different in different control methods, and the loss distribution characteristics are complex and difficult to calculate. This shorting adversely affects MMC parameter design and reliability analysis. However, the existing methods cannot achieve an accurate calculation of MMC loss. To address the above problems, an improved loss calculation method is presented by detailed analyzing the working principle and the loss distribution of variable submodules (SM). The proposed loss calculation method can accurately calculate the power devices’ loss under various control methods and different topologies. The correctness and effectiveness of the improved loss calculation method are verified through Matlab/Simulink software.