Thermal degradation management in a Fault-tolerant active NPC converter

Fault-tolerant operation of power converters has been a challenge for engineers and designers. Although several schemes have been proposed in recent years, they are typically restricted in terms of their capability to recover from successive failure events. The recently proposed Fault-tolerant ANPC converter has been shown to be able to deal with multiple failure events due to its flexible and reversible reconfiguration capability. In this paper, it is introduced a new thermal degradation management strategy, based on the FT-ANPC reconfiguration capabilities. Through an analytical lifetime estimation model, it is shown that the FT-ANPC converter can be available more than twice as much as an ordinary NPC converter. A metro-system application is studied to demonstrate the efficacy of the thermal degradation management of the FT-ANPC for mission-critical profiles.