A Real-Time Fault Diagnosis for Neutral-Point-Clamped Inverters Based on Failure-Mode Algorithm

The fault diagnosis in multilevel converters is of great importance since they are comprised of more solid-state switches, compared with the conventional two-level converters. In this article, we propose a fast and efficient real-time fault detection and faulty component identification for an open-switch fault diagnosis based on the failure-mode algorithm for a single-phase five-level neutral-point-clamped inverter. Component modeling, complicated calculations, and load parameters are not required for realizing the proposed approach. Furthermore, the proposed strategy does not require any extra sensors. The signals already available in the control system, such as the applied switching pattern and terminal voltage, fulfill the fault diagnosis. Thanks to the proposed fault detection strategy, any misdiagnosis arising from noise existence, response time of the sensors, turn ON and turn OFF delay times of the power switches, and measurement errors are avoided. The simulations and experiments are carried out to confirm the performance and effectiveness of the presented strategy.