Digital Twin Enabled Open-Circuit Fault Diagnosis for Five-Level ANPC Multilevel Converters

This article presents an innovative digital twin (DT) strategy for health monitoring of five-level active neutral point clamped (5L-ANPC) power converters, which are extensively utilized in high-power, safety-critical applications. Despite their widespread use, the reliability of 5L-ANPC inverters is often compromised due to the large number of semiconductor devices employed, posing challenges for their broader deployment in safety-critical applications. The proposed approach introduces a real-time DT replica that continuously monitors crucial parameters to assess the inverter's performance and detect open-circuit (OC) faults in the switches. This methodology not only enhances reliability but also reduces maintenance downtime costs. Specifically focusing on OC switching faults, this article presents a fast online DT-based fault diagnostic method. The proposed diagnostic technique leverages the existing dc-link capacitor and flying capacitor voltages, along with load current data and switching patterns, eliminating the need for any additional sensors. The detection process takes less than a fundamental period of the inverter output frequency to diagnose any faulty switch accurately. Experimental results validate the robustness and effectiveness of the proposed DT health monitoring method across various operating conditions.