Transition and Fault-Tolerant Scheme for Single-Phase Inverter

Being a critical component of modern systems and in many machine-critical applications, reliability of power electronic converters, particularly inverters is of paramount importance. The reliability in single-phase inverter can be improved by employing redundant leg, module, etc. Redundancy (leg/module) utilises additional switches and connecting devices to provide fault tolerance for semiconductor faults. However, in a conventional fault-tolerant inverter, the redundant leg is inactive during normal/pre-fault operation, indicating the under-utilization of the redundant leg. Thus, the conventional fault-tolerant inverter needs to be modified to utilize the redundant leg in the normal as well as the post-fault conditions. This needs a highly effective transition scheme which can transform the usage of the redundant leg on occurrence of a fault. This paper investigates the potential timings of fault occurrence and their impact on the transition scheme. The detailed analysis is implemented and tested on the hardware prototype of a single-phase inverter.