中点钳位型H桥级联单相逆变器新型空间矢量脉宽调制方法

A Novel SVPWM Method for Single-phase Cascaded NPC H-bridge Inverter

通过对中点钳位型H桥级联单相逆变器开关状态分析,得到了27种有效开关矢量。提出一种适用于该拓扑结构的单相空间矢量脉宽调制(space vector pulse width modulation,SVPWM)方法,该方法将单相一维空间矢量图分为8个区间。根据期望电压矢量幅值和矢量所在区间以及上一个开关周期的终止矢量进行输出脉冲合成类型判断,并基于开关次数最小原则提出3种矢量合成规则。根据伏秒平衡原理对每种脉冲类型的矢量作用时间进行了计算。提供一种兼顾电压均衡、开关次数最小和开关器件均衡利用的冗余矢量使用法则。利用DSP和FPGA芯片实现所提出的算法。仿真和实验验证了提出调制方法的正确性和可行性。

Through the analysis of single-phase cascaded neutral-point-clamped（NPC） H-bridge inverter＇s switch states, 27 useful switch vectors are obtained. A space vector pulse width modulation（SVPWM） method for this nine-level inverter was proposed. Based on the proposed method, the one-dimensional space vector diagram can be divided into eight sectors. The output pulse type is determined by the magnitude of reference voltage vector, the section in which the vector lies and the terminative voltage vector in the last switching period. Based on the rule of minimum switching times, three vector synthesis methods were proposed. According to the volt-second balance principle, the effective time for every pulse type of voltage vector was calculated. Further, a rule for using redundant vectors was offered so as to make the capacitor voltage balance, the switching times reach the minimum and the power switch devices be used equitably. The proposed algorithm was realized using the DSP and FPGA chip. Simulation and experimental results show that the proposed modulation method is correct and feasible.