应用于级联H桥SAPF的通用SVPWM算法研究

General SVPWM Algorithm for Cascaded H-bridge SAPF

针对级联H桥逆变器电平数增加,空间矢量脉宽调制(SVPWM)算法确定参考电压矢量位置复杂的问题,提出一种将参考矢量分解成多电平基本矢量与两电平参考矢量的方法。选择出距参考矢量终点最近的两电平参考电压矢量所在的小六边形区域,利用改进的两电平七段法合成两电平参考矢量,最后将两电平开关序列与多电平基本矢量相结合得到多电平开关序列。改进的两电平SVPWM省略了扇区识别,简化了作用时间的复杂运算。该方法应用到级联H桥并联有源电力滤波器(SAPF)中,控制逻辑简单,逆变器输出谐波含量低。仿真与实验验证了所提方法的有效性。

With the level number of the cascaded H-bridge inverter increasing, it becomes complex for the space vector pulse width modulation （SVPWM） algorithm to determine the position of the reference voltage vector. Accordingly, this paper proposes a method for decomposing a reference vector into multilevel basic vector and two-level ref- erence vector. The small hexagonal region, where the two-level reference voltage vector nearest the reference vector end locates, is selected, and the two-level reference vector is synthesized using the improved seven-segment two-level method. Then, the two-level switching sequence is combined with the multilevel basic vector to get multilevel switching sequence. The improved two-level SVPWM omits the sector identification to simplify the complex opera- tion of the action time. Application of this method to the cascaded H-bridge shunt active power filter （SAPF） can achieve simple control logic and lower harmonic content in inverter output. The effectiveness of the proposed method is verified by simulation and experiment.