Fault-Tolerant Voltage Source Inverter for Permanent Magnet Drives

In this paper, a two-level fault-tolerant voltage source inverter (VSI) for permanent magnet drives is systematically designed and tested. A standard two-level inverter consists of three legs. In this case of fault-tolerant inverter, a redundant leg is added that replaces the faulted leg. Faulted leg isolation and redundant leg insertion are done by using independent back-to-back-connected thyristors. The proposed inverter provides tolerance to both short-circuit and open-circuit faults of the switching devices. The postfault performance is the same as the normal prefault operation and fault compensation is fast enough such that there is negligible disturbance in the drive operation. The fault tolerance of the inverter is verified using field-oriented control of a permanent magnet synchronous motor.