三电平NPC整流器空间矢量脉宽调制及中点电位平衡控制

为了减少开关损耗和避免不同区域矢量在扇区切换中发生突变,提出了一种最优的空间矢量脉宽调制算法,即所有输出矢量的首发矢量全部采用负小矢量。具体给出了参考电压矢量在矢量空间中具体位置的判定、相应的输出电压矢量作用顺序,推导了三角形顶点各开关矢量的作用时间以及脉冲的输出。基于检测到的三相输出电流、中点电流方向和直流侧电容电压,提出了利用冗余电压小矢量精确控制中点电位平衡的策略,并用实验结果验证了中点控制策略和调制算法的正确性。

SVPWM and neutral-point-potential balance control of three-level NPC rectifier

In order to lower the switching loss and avoid the abrupt change of output voltage vectors,an optimal SVPWM(Space Vector Pulse Width Modulation) algorithm is proposed,in which the negative small vector is used as the first output vector.The location determination of reference vector in vector space and the action sequence of output voltage vectors are given,and the duty time of active vector on triangle vertex and the output pulse are deduced.The strategy of using the redundant voltage small vectors to precisely control the neutral point potential balance is realized based on the detected three phase output currents,the direction of neutral point current and the capacitance voltage,which are verified by experimental results.