A Fault-tolerant T-type Three-Level Inverter System

Field experiences have demonstrated that semiconductor devices are vulnerable to failures (open- & short-circuit). In many critical applications, such failures are unacceptable and high system reliability is required. In this paper, a topology modification for the T-type 3-level inverter is explored to achieve the fault-tolerant operation and enhance the system reliability in the case of device open-circuit or short-circuit failures. With the proposed topology modification (via fewer additional switches), the device failure ride-through performance can be dynamically achieved without degradation of output capacity. Furthermore, the transition principles from normal operations to post-fault operations are detailed, and the reliability enhancement is calculated. The simulation results are included to verify the validity of the modified topology.