消除中点电位低频振荡的三电平逆变器空间矢量脉宽调制方法  

SVPWM Method of Removing the Low-Frequency Oscillations of Neutral Point Voltage for Three-Level NPC Inverter

作　　者：张志[1] 谢运祥[1] 乐江源[1] 陈林[1] 

机构地区：[1]华南理工大学电力学院,广州510640

出　　处：《电工技术学报》2011年第3期103-109,共7页Transactions of China Electrotechnical Society

基　　金：教育部科学技术研究重点资助项目(109128)

摘　　要：提出了一种gh坐标系下基于虚拟矢量的二极管钳位型三电平逆变器空间矢量脉宽调制方法,该方法能消除直流侧电容中点电位的低频振荡,适用于任意非线性负载情况。为了减小开关频率和避免矢量在不同区域内切换过程中发生突变,提出了一种基于该方法下的最优输出电压矢量作用顺序算法。该算法将整个空间矢量转换到第一扇区后,仅需要进行简单的坐标变换和计算即可得出参考电压矢量作用的区间和输出电压矢量的作用时间,克服了传统三电平空间矢量脉宽调制方法所需要进行的大量的三角函数运算和扇区判断的缺点。同时,为了消除系统在运行过程中可能出现的电容电压不平衡,采用了调整正(负)冗余小矢量作用时间来消除直流侧电容电压不平衡的闭环控制策略。仿真和实验结果验证了本文所提方法的正确性和有效性。A space vector PWM（SVPWM） algorithm based on virtual vectors of gh coordinate system is proposed for the three-level neutral-point-clamped（NPC） inverter.This strategy can remove the low-frequency oscillations that appear on the neutral-point voltage of the NPC inverter and it can be used for any nonlinear load conditions.In order to lower the switch frequency and avoid the abrupt change of output voltage vectors,an optimal sequences of the output voltage vecotrs based on the algorithm is proposed.It requires only a simple coordinate transformation and arithmetic to determine the sector in which the reference voltage vector is and the effective time calculation of the output voltage vectors.The disadvantages of a lot of calculation of the trigonometric functions and the estimation of the sectors for the traditional SVPWM algorithm are avoided after transforming the whole space vector diagram into the first sextant.And in order to eliminate any possible imbalance of the capacitors voltage,a close loop for achieving volatge balance based on changing the effective time of the positive and the negative small vectors is proposed.The proposed method is verified by simulation and experimental results.

关 键 词：三相三电平 空间矢量脉宽调制 电容电压平衡 冗余矢量 

分 类 号：TM464[电气工程—电器]