Abstract: In view of problem that it is difficult to accurately locate device failure of inverter, a fault tolerance topology of three-level four-leg NPC inverter was proposed. In the topology, short-circuit fault and open-circuit fault can be located accurately by switching device used when topology changes, so as to provide a basis for fault-tolerant control of inverter. The topology enables half-leg replacement, and can achieve fault-tolerant control of up to three inverter legs at the same time.