基于虚拟空间矢量的中点平衡混合调制策略

Neutral Point Balanced Hybrid Modulation Strategy Based on Virtual Space Vector

针对二极管箝位型三电平逆变器(NPC)的中点电压不平衡问题,首先分析中点电位不平衡的成因与影响,其次针对基于冗余小矢量的中点电位控制方法无法在高调制比区域抑制中矢量所导致的中点电位波动问题,提出一种基于虚拟空间矢量的中点电位混合调制策略。该方法在低调制比区间采用电荷守恒法,在高调制比区间引入虚拟空间矢量调制,并采用模糊控制器对虚拟小矢量的系数进行调节,使其具备闭环反馈控制的能力,能有效抑制中点电位的偏移。仿真实验结果验证了该方法的正确性和有效性。

Aiming at the neutral point voltage imbalance of diode clamped three-level inverter(NPC),the causes and effects of neutral point potential imbalance are analyzed firstly.Secondly,the neutral point potential control method based on redundant small vector can not suppress the neutral point potential fluctuation caused by medium vector in the region of high modulation ratio.A neutral point potential hybrid modulation strategy based on virtual space vector is proposed.In this method,the charge conservation method is used in the low modulation ratio range,the virtual space vector modulation is introduced in the high modulation ratio range,and the fuzzy controller is used to adjust the coefficient of the virtual small vector,so that it has the ability of closed-loop feedback control,and can effectively suppress the offset of the neutral point potential.