Control the Three-level Rectifier Under Unbalanced Grid Conditions

Abstract

This paper proposes a novel control method for Three-level rectifier under unbalanced grid conditions. An average model is established to analyze the influence of the unbalanced factor. It can be seen that the unbalanced factor will generate the negative-sequence current. The negative-sequence current can be suppressed by a proportional integral resonant (PIR) controller. Additionally, the unbalance of neutral-point (NP) voltage will generate in the three-level rectifier. Therefore, this paper proposes a space vector modulation for balancing the NP voltage. The simulation results confirm the performance and effectiveness.