三电平NPC逆变器的一种空间分区矢量提取的SHEPWM调制策略

深入分析基本空间矢量SV与特定谐波消去SHEPWM之间的内在联系,提出三电平NPC逆变器的一种基于空间分区矢量提取的SHEPWM调制策略,推导出空间电压矢量PWM的三相等效调制波规则采样的开关角矩阵,得出基本空间矢量SV的选用与规则采样的运算关系以及SHEPWM的脉冲状态由基本SV组成的矢量序列特殊解。在此基础上,在三电平NPC逆变器的矢量空间六边形所分区的两电平六边形中,研究SHEPWM脉冲序列的空间电压矢量组成的扇区分布,并提取相应的基本SV,求解作用时间。SHEPWM的脉冲状态由空间分区提取的基本SV矢量序列运算合成而实现,避开了其开关角非线性超越方程组的求解,并具有同样的消谐效果且便于实现。

A Kind of Three-level NPC Inverter SHEPWM Technique Based on Space Division and Vector Extraction

According to the studies of internal relation for the basic space vector (SV) and the selective harmonic elimination PWM (SHEPWM), this paper puts forward a kind of SHEPWM implementation strategy based on the space partition vector SV extraction to the three-level NPC inverter, deduces the space voltage vector switch angle matrix of the three-phase equivalent modulation wave regulation sampling and the operation relationship. So, on the basis of the switch angle trajectory characteristics of SHEPWM and its realization by regulation sampling, the SHEPWM waveform pulse state can be gained by the vectors sequence special solution which composed of basic SV vector. To the three-level inverter, on the Two level small hexagon which be partitioned from space vector hexagon, the work sector allocation of SHEPWM pulse state be researched, and the corresponding basic SV vector and its action time also be achieved by the experiment and FFT analysis. This method avoid the solution of SHEPWM switch angle nonlinear transcendental equations, and it has the same effect of harmonic elimination and to facilitate online implementation.