Fault tolerant topology for two level VSI and transformerless grid connected inverters

This paper presents a fault-tolerant two-level single phase voltage source inverter (VSI). The proposed topology requires four additional bidirectional switches and it can continue to operate at rated power under both open circuit and short circuit faults of any switching device. Fault tolerant operation is achieved by swapping the inverter output terminals using the additional switches. Furthermore, this topology is extended for fault tolerant operation of transformerless inverters for grid-connected PV applications on the basis of HERIC topology. Finally, the fault-tolerant operation of the proposed topologies is validated through simulation studies.