Neutral Point Potential Balance of Dual Three-level Converter Based on Fuzzy Logic Control Strategy

摘要

In dual three-level converter system, the rectifier and inverter have unified problems of the neutral point potential imbalance. This paper analyzed the reasons of imbalance of neutral point potential in detail and summarized the relationship between vector status and four-quadrant status of three-level converters. Then a method based on fuzzy logic control(FLC) is proposed, which could be automatically adjust the balance factor. Combined the balance factor with the status of the converter the duration of positive and negative small vectors action could be obtained. Finally the balance of the neutral point potential is achieved. This method could be generally used on rectifier and inverter. At last, the simulation was done on both inverter and rectifier side. The results verified the feasibility of the proposed method.