关键词: 模糊优化, 混合式, 中点电位平衡算法, 调制度

Abstract:

Aiming at neutral-point unbalance not only increases the voltage stress of the power device but also results in the output current distortion, a hybrid neutral-point balancing algorithm based on fuzzy optimization is proposed. The hybrid neutral-point balancing algorithm clarifies the sector selection according to whether or not contains medium vector. In the area of no the medium vector, two-level space vector control algorithm based on seven segment switching sequence is used to solve voltage deviation caused by the redundancy small vector. In the rest area, time controlling element of the redundant small vector is optimized by the fuzzy control to achieve the meticulous control of the neutral voltage. The simulation and experiment results shows the algorithm is better to neutral-point balance than time control factor method and the smooth transition of different balancing algorithm between the high modulation index and the low one is realized.

Key words: fuzzy optimization, hybrid, neutral-point balancing algorithm, modulation index