A Fault Diagnosis Method in Three-Phase Voltage Inverters Based on the Normalized Current Trajectory Centroid

A fault diagnosis method based on the normalized current trajectory centroid is proposed for open-circuit and short-circuit faults in three-phase voltage inverters. The method involves performing a normalized Park’s transformation on the currents to obtain trajectories represented as semicircles and ellipses for open-circuit (OC) and short-circuit (SC) faults at different positions. The current trajectory offset is then introduced to determine the occurrence of a fault in real time qualitatively. More importantly, the current trajectory centroid coordinates, which include the modulus and the phase angle, are constructed to quantify the fault characteristics. The modulus threshold is optimized using the iterative algorithm. Accordingly, the paper can precisely distinguish the fault type and position between OC and SC by the modulus and the phase angle. An experimental platform was constructed to validate the diagnosis results for various faults and load mutations. The results demonstrate that the method can simultaneously diagnose OC and SC faults with an average diagnosis time of only 24.3 ms. Furthermore, the diagnosis results remain unaffected by load changes, showing strong robustness.