Fault Diagnosis and System Reconfiguration Based on Switching Sequence Technology for ANPC Three-Level Cascaded Inverter

This paper proposed a fault diagnosis and system reconfiguration based on switching sequence technology for active neutral point clamped (ANPC) three-level cascaded inverter. In this paper, the flow path of current and the clamp voltage under the single-switch and double-switch open-circuit faults for the power switches are analysed in the ANPC bridge arm. The combination of the clamp voltages corresponding to the four switch modes in each fault mode is determined uniquely. According to the uniqueness of the combination of clamp voltages with the four switch modes, a fault diagnosis method based on the switching sequence technology is proposed which can realise fault diagnosis with 10 fault types in one bridge arm. The faulty bridge arm is bypassed by the clamp power switches to achieve the goal of topology reconfiguration, and carrier phase shift strategy for the remaining module is adopted to achieve the goal of modulating reconfiguration. Finally, the correctness of theoretical analysis is verified by the simulation and experiments.