Open-Switch Fault Detection and Tolerant Control Based on DC Link Voltage Observation for T-type Rectifiers

This paper proposes a novel open-switch fault detection algorithm for the T-type rectifiers based on the DC link voltage variation. The pattern of the variation of the DC link voltage is observed for each fault scenario under different power levels. The DC link voltage is continuously monitored and compared with the recognized pattern to detect and localize the open-switch fault. When a fault is detected and localized, the algorithm is proposed to change the switching function of the faulty leg. This can be done by using a classical two-level function instead of the three-level switching function. The proposed algorithm focuses on the auxiliary switches faults as they have severe effects on the response of the rectifier. The proposed methodology requires only one voltage sensors and without complex computations or estimation. The validity of the proposed method is demonstrated using hardware experiments.