Voltage Vector Error Fault Diagnosis for Open-Circuit Faults of Three-Phase Four-Wire Active Power Filters

Detecting and locating the fault of IGBT rapidly and accurately are the keys to ensuring the security and reliability of the active power filters (APF) system. A fault diagnosis algorithm based on the mathematical model of ac side output voltages for three-phase four-wire three-leg two-level shunt APF is proposed in this paper. According to the different relationships between the APF's ac side output voltages and turn-on duty cycle of the corresponding IGBT under normal condition and fault condition, the fault diagnosis algorithm can detect and locate the open-circuit (OC) faults with no additional hardware or sensors required. All the signals used in this algorithm have already been employed in the APF stem controller. All possible OC fault conditions can be detected and located quickly and reliably by the algorithm. In addition, the algorithm is highly free from the load changes and can be used during the dynamic process of load changes. The efficiency of the proposed algorithm, under single and multiple faults conditions, is verified by the simulation and experimental results.