부산대학교 도서관

This paper presents an IGBT open-circuit fault-tolerant control strategy for five-level nested neutral point pilot converters. IGBT open-circuit fault diagnosis and localization can be achieved by detecting and comparing the actual output voltages and floating capacitor voltages with their predicted values, which are based on the optimal output switching states and capacitor charging and discharging states within a sampling period. The K-nearest neighbor algorithm is used to discriminate between true and false faults. After detecting the faulty IGBT, a fault-tolerant control process is implemented based on the SVPWM method. To ensure the fault-tolerant operation of the converter, the space voltage vectors associated with the faulty IGBT are removed. The effectiveness of the proposed fault diagnosis and fault-tolerant control strategy is confirmed by simulation results on the five-level NNPP converter.