Modified space vector modulation for fault-tolerant operation of multilevel cascaded H-bridge inverters

In this study, fault-tolerant operation of multilevel cascaded H-bridge (CHB) inverters is presented and a novel switching strategy based on space vector modulation is proposed. A faulty power switch in high power converters can lead to expensive downtime, loss of productivity and increased costs. Various power switch faults and their influence on space vector diagram of CHB inverters are investigated. In the event of a fault, the output voltage of inverter is reduced and redundant switching states are used to generate balanced line-to-line voltages. By adding some devices to the basic structure, CHB inverter will operate with maximum achievable output voltage. Simulation and experimental results are shown for a five-level CHB inverter to validate the proposed modulation technique.