Open-Switch Fault-Tolerant Operation of T-Type Active Neutral-Point-Clamped Converter Using Level-Shifted PWM

The T-type active neutral-point-clamped (T-ANPC) converter is an emerging hybrid multilevel topology, which owns superior characteristics such as low conduction losses, flexible in control. Reliability improvement is essential for the T-ANPC due to the large number of power switches. For this motivation, this paper develops a carrier-based fault-tolerant control strategy for the T-ANPC converter in the case of typical open-switch faults. A modified level-shifted pulse width modulation (LS-PWM) is employed to control the converter to obtain the desired outputs under single/multiple open-switch fault modes. The fault-tolerant operations with full and reduced power ratings are realized by rearranging the carriers and modulation signals of the LS-PWM. Finally, the feasibility and effectiveness of the proposed control strategy for the T-ANPC is evaluated experimentally.