A Fault-tolerant Technique using New SVM Switching States for Three-phase CHB Multilevel Inverters

A cascaded H-Bridge multilevel inverter (CHB MLI) can generate very high-quality voltage waveform due to the number of H-bridge cells. Ironically, its structure with many components is vulnerable to failures. This research proposes a fault-tolerant technique using a new space vector modulation (SVM) switching states for three-phase CHB MLIs. By applied the proposed technique, the CHB MLIs can continue to operate and generate three-phase balanced voltages, although there are some fault cells in the system. The proposed technique tracks the fault-cell scenarios assigns an appropriate combination of switching in the SVM hexagon plane to those switches of the remaining healthy cells. To explain and verify the performance of the proposed technique, a three-phase 5-level CHB MLI is used as an example in the simulation. All possible fault modes have been studied and analyzed. The simulation results indicates that the proposed technique can control the three-phase 5-level CHB MLI to operate and ride-through the given fault conditions. In practical, a CHB MLI with the proposed technique can continuously working with some limited power and lead to a safe shutdown if necessary.