Abstract： Since multi-level inverter has a lot of advantages over the two-level inverter, it is widely used in high power and other situation. However, its complex topology also brings a relatively large probability of failure problem. In studying on fault diagnosis and tolerant multi-level inverter, a lot of new fault tolerant topologies were proposed. Aimed at a NPC inverter tolerant topology with asymmetrical bridge, control strategies were studied in this paper. This tolerant topology has a two-level bridge and some three-level bridges. It is proposed that the phase between triangular carrier of the twolevel bridge and multi-carrier of three-level bridges will affect the output characteristics of the circuit. When both carriers are in the same phase, the harmonic content of the output voltage waveform is relatively small. The theoretical analysis and experimental results verified the effectiveness of the topology.