Reliability comparison for 3L-NPC and 3L-ANPC converters for drives application

Compared with NPC converters, Active NPC (ANPC) converters improve the loss distribution among semiconductor devices and thus increase the converter output power rating and switching frequency. However, since more switches with their gate drivers are used in ANPC converters, the impact on the converter reliability is one of the main concerns for drives application. In this paper, the analysis on fault tolerant operation of 3L-ANPC converters under single and multiple device failure conditions is presented. Furthermore, the methodology for reliability function calculation and the reliability comparison of 3L-ANPC and 3L-NPC converters are investigated for drives application. Finally, the results and conclusions are presented.