This study proposes a multi-mode fault-tolerant control (FTC) strategy, for cascaded H-bridge multilevel inverters, to provide the most suitable fault tolerance scheme for different single or double arbitrary insulated gate bipolar transistor (IGBT) faults. Firstly, all faulty modes are classified into three fault clusters according to the number and location of faulty IGBTs. Then, the matching mechanism of the multi-mode FTC strategy corresponding to the three clusters is described, and the appropriate FTC algorithm is selected for each cluster. In particular, a new FTC method has been proposed for Cluster I that includes double IGBT fault in different H-bridges and different groups. This method improves the utilisation efficiency of healthy IGBTs in the faulty H-bridges, and minimises the voltage level drop after the fault. Finally, the multi-mode FTC strategy has been applied to a seven-level inverter through simulation. Results have shown significant improvement of the output voltage waveform symmetry and harmonic distortion reduction for the three clusters. The new FTC method has been applied to an experimental five-level inverter. The obtained results confirm the validity of the methodology. With the proposed strategy, the output voltage has a lower harmonic distortion and a better symmetry thanks to the attenuation of the undesirable DC component.

中文翻译：

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级联H桥多电平逆变器的多模式容错控制策略

这项研究提出了一种用于级联H桥多电平逆变器的多模式容错控制（FTC）策略，以为不同的单或双任意绝缘栅双极型晶体管（IGBT）故障提供最合适的容错方案。首先，根据故障IGBT的数量和位置，将所有故障模式分为三个故障组。然后，描述了对应于三个群集的多模式FTC策略的匹配机制，并为每个群集选择合适的FTC算法。特别是，针对群集I提出了一种新的FTC方法，该方法包括在不同的H桥和不同的组中出现双IGBT故障。该方法提高了故障H桥中健康IGBT的利用率，并最大程度地减少了故障后的电压降。最后，通过仿真将多模式FTC策略应用于七电平逆变器。结果表明，三个群集的输出电压波形对称性得到了显着改善，谐波失真降低了。新的FTC方法已应用于实验性的五电平逆变器。获得的结果证实了该方法的有效性。利用所提出的策略，由于不想要的直流分量的衰减，输出电压具有较低的谐波失真和更好的对称性。获得的结果证实了该方法的有效性。利用所提出的策略，由于不想要的直流分量的衰减，输出电压具有较低的谐波失真和更好的对称性。获得的结果证实了该方法的有效性。利用所提出的策略，由于不想要的直流分量的衰减，输出电压具有较低的谐波失真和更好的对称性。