Reliability Calculation of Multilevel Converters - Theory and Applications

International audienceMultilevel converters have many power devices and drivers. Thus, a direct reliability calculation based only on the first failure occurrence on one of the components clearly leads them to be devalued compared to two-level converters. However, taking into account that symmetrical multilevel converters such as the X-level ANPCs family are based on imbricated and / or stacked switching cells on the one hand, with an additional center tap at the DC bus in three-phase operation on other hand, several redundancies clearly appear which can be managed to increase the global reliability. For the first time, a general and theoretical methodology used to calculate reliability laws, failure rates and applied to compare 2-level, 3-level and 5-level topologies is proposed. Results show that the fault-handling of 3-level and 5-level three-phase topologies permits a great increase in reliability over a "relatively" short time duration, in addition to other benefits