Fault Detection and Tolerant Control of 3-phase NPC Active Rectifier

Compared to conventional 2-level AC/DC PWM converter, the 3-phase NPC active rectifier has a high number of power semi-conductors. Hence the possibility of the open-switch faults is much higher. Due to the many number of active elements, the detection and the tolerant control of the open-switch faults are more complicated than the conventional 2-level converter. Furthermore, the open-switch faults give rise to imbalance of the AC input currents and the fluctuation DC-link voltage. This paper proposes the open-switch fault detection method and the tolerant control method. In particular, open-switch fault case of one switch among inner six switches of NPC active rectifier is analyzed. The usefulness of this paper is verified through the computer simulation and experimentations, respectively.