消除偶次谐波的三电平NPC逆变器调制方法

Even Order Harmonic Elimination Method of Three-level Neutral Point Clamped Inverter

针对传统空间矢量脉宽调制(SVPWM)方法的矢量选取方案使得二极管箝位型(NPC)三电平逆变器输出电压产生偶次谐波的缺陷,提出了一种能消除偶次谐波的改进型矢量选取方案。该方案在分析传统SVPWM产生偶次谐波机理的基础上,通过改进SVPWM中各矢量的作用顺序,使得逆变器输出电压半波奇对称,从而达到消除偶次谐波、抑制中点电压漂移的目的。同时,为避免进行复杂的三角运算,采用了基于60°坐标系的SVPWM方法以利于实时控制。仿真证明了上述方案的有效性。

To overcome the drawback of the conventional space vector pulse with modulation（SVPWM）method applied to neutral point clamped（NPC）three-level inverter,which produces even order harmonics in the inverter output voltages,a new SVPWM shceme was proposed.The even order harmonics can be eliminate and the neutral voltage drift is suppressed by rearranging the vectors in the propsed method.Furthermore,the 60°coordinate frame is introduced to alleviate the computation cost.Simulation results results verify the validity of the scheme.