A Fault-Tolerant Single-Phase Grid-Connected Inverter Topology With Enhanced Reliability for Solar PV Applications

Reliability is an essential requirement for a grid-connected Photovoltaic (PV) system, especially in remote military secured areas, which are difficult to access for the purpose of maintenance. However, the reliability of inverters used in the PV system is mainly affected due to the vulnerability of power semiconductor devices to failure. To improve the reliability of inverters, several fault-tolerant topologies are proposed in the literature. A redundant leg is used in most of these topologies to incorporate redundancy in the inverter operation. However, these topologies require an additional leg and four TRIACs, which increase the device count, and hence are not cost-effective. In this paper, a single-phase fault-tolerant inverter topology is proposed, which does not use the redundant leg and achieves the fault-tolerant feature with minimal device count. Moreover, the reliability of the proposed topology is calculated to be more than that of the redundant leg-based topologies. The operation of the proposed topology is explained under various device fault conditions, and validated through simulation and experimental studies. Finally, the reliability of the proposed topology is evaluated using the Markov reliability model.