Diagnosis of Open-Circuit Faults in Three-Level ANPC Inverters Based on Digital Twin

Three-level active neutral-point-clamped (3L-ANPC) inverters are widely used in high-power and mission-critical applications due to their low switching losses and superior waveform quality. However, their complex topology and numerous semiconductor devices limit system reliability. To address this issue, this paper proposes a non-intrusive digital-twin-based fault diagnosis method. A high-fidelity real-time digital twin model is developed for dynamic monitoring of inverter operating states, and an output-current-residual-based algorithm is employed for accurate detection and device-level localization. The proposed method requires no additional sensors and completes fault diagnosis within 7ms.