Level-increased Model Predictive Control Method with Sub-module Circulating Current Suppression of Modular Multilevel Converter

Abstract

Level-increased nearest level modulation (NLM) has been widely used in the modular multilevel converter (MMC) due to its simple implementation and low switching frequency in recent years. However, there are some disadvantages such as the poor performance of output voltage distortion and harmonic circulating current. A harmonic circulating current (CC) suppression method based on level-increased NLM is proposed in this paper. The impact of level-increased NLM on the CC is firstly analyzed. Then, a 5-voltage-level compensation method for harmonic CC suppression is proposed. Simulation and experiment verify the effectiveness of the proposed method.