阶梯波调制级联逆变器触发角的一种简便算法

A simple algorithm of trigger angle for step wave modulated cascade inverters

级联多电平逆变器除有效降低开关器件电压应力外,它还可以通过波形叠加改善输出波形的质量。阶梯波调制还可以减少开关次数、提高转换效率、降低EMI,是级联逆变器常用的一种工作模式。但目前国内外文献介绍的阶梯波调制的级联逆变器的触发角的计算方法存在计算复杂,而且只适用等电压差的问题,针对这种情况,本文提出了一种不同电压级差的阶梯波调制级联逆变器触发角的计算方法。该方法特别适用于太阳能电池级联逆变器、燃料电池级联逆变器的应用。此方法遵循等面积法原则,通过一定的约束条件,实现在线计算,利于工程实现,最后通过仿真验证了该方法的正确性。

Besides effectively reducing the voltage stress of switches, the cascaded multilevel inverter could also improve the quality of the output waveforms by addition of waveforms. The step waveform modulation ways can reduce the switching frequency, raise the transition efficiency, and reduce the EMI. It is an usual method for the cascaded inverter, but the usual introduced calculating methods of the cascaded inverters trigger angles based on step waveform modulation are not only complex, but also are suitable for cascaded inverters with the same voltage step only. In the light of this situation, the calculating method for the trigger angles of the step waveform modulation cascaded inverters with the different voltage step is proposed in this paper. The method is very suitable for the applica- tions of solar battery cascaded inverters and fuel battery cascaded inverters. The method follows the equal area principle, and the online calculation is realized by some constraint conditions. Finally, the correctness of the method is validated by simulation results.