A Fault-Tolerant Control Strategy for Cascaded Multilevel Converter

The cascaded multilevel convertor has the following advantages: simple structure, less harmonic, and less switching loss. It also can easily achieve high voltage and large power capacity. However, due to the structure of cascaded, the number of the device increases with the increment of capacity, meanwhile the reliability of the system reduces. Based on the cascaded multilevel system's possible failures and the characteristic of carrier phase shift modulation, this paper proposes a fault diagnosis method suitable for the cascaded multilevel system. Firstly, the paper introduces the basic principle of the proposed approach, and then it deduces the major implementation steps, finally the correctness and reliability of the method are validated by the simulation.