A Short-Circuit Fault-Tolerant Strategy for Three-Phase Four-Wire Flying Capacitor Three-Level Inverters

Flying capacitor three-level (FCTL) inverter is one of the most important multi-level inverters, which may be used in renewable energy, motor drives, uninterrupted power supplies, etc. Fault-tolerant strategy is important for reliable operation of the inverters in critical applications. In this paper, a short-circuit fault-tolerant strategy for FCTL inverter is studied. First, short-circuit fault of power devices for FCTL inverters are analyzed. Then, operating modes transfer of inverter and rebalance of flying capacitor voltage after short-circuit fault are discussed. Implementation of the fault-tolerant strategy is presented. With the proposed strategy, the rated output voltage of FCTL inverter is guaranteed without adding any extra hardware after the short-circuit fault. Finally, prototype is built to verify the proposed strategy.