五电平NPC/H桥逆变器的调制策略

摘要

在分析了五电平NPC/H桥逆变器拓扑结构和工作原理的基础上,设计了载波层叠脉冲宽度调制(pulse width modulation,PWM)和三段式空间矢量脉冲宽度调制(space vector pulse width modulation,SVPWM)的策略,并介绍了这2种调制策略的原理.通过Simulink软件搭建仿真模型,对比了不同调制度和不同载波频率下逆变器的输出特性,得出结论:输出电压波形的电平数与调制度有关;提高载波频率可使主要高次谐波频率增大,减小谐波含量.以DSP+FPGA工控开发板为控制器搭建实验平台,实验结果表明调整策略有效.%On the basis of analyzing topology structure and working principles of the five-level NPC/H bridge-type converter, this paper designs strategies of carrier overlapping pulse width modulation (PWM)and three-stage space vector pulse width modulation (SVPWM)and introduces principles of these two modulating strategies. By simulation on Simulink software,it compares output characteristics of the converter under different modulation degrees and carrier frequencies. Conclusion indi-cates that level numbers of output voltage wave are related with modulation degrees and it is able to increase frequency of the main higher harmonic and reduce harmonic content by improving carrier frequency. An experimental platform was estab-lished with DSP+FPGA as the controller. Experimental results obtained indicate that this modulating strategy is feasible.