Fault diagnosis and tolerance in three-level Neutral-Point-Clamped rectifiers

Some of the main concerns in the use of power converters are their reliability and the ability to detect and maintain operation when in fault. Many techniques have been proposed to identify and respond to faults in Neutral-Point-Clamped converters. Most of these methods, however, require additional hardware and/or changes in the topology. In this paper, a NPC rectifier is investigated, including the impacts of each possible semiconductor fault in the operation. Methods for fault diagnosis and fault tolerant operation are presented. The presented diagnostic method does not require additional hardware and is not affected by the load. Open-circuit and short-circuit faults are detected in both IGBTs and diodes. Fault tolerant operation with different levels of action is presented. Experimental results are presented to demonstrate the effectiveness of the methods.