An Optimized Open Circuit Switch Faults Diagnosis for Three Level Active NPC Converter

Compared with three-level neutral point clamped (NPC) converter, three level active neutral point clamped (ANPC) converter provides more flow paths which can improve the balance of power loss distribution. Fault diagnosis in power electronic converters is necessary to prevent further damage, the open circuit switch fault of every device in three level ANPC converter is analyzed in this paper. An optimized open circuit switch faults diagnostic strategy for three level ANPC is proposed. This strategy can diagnose any faulty switch and diode based on the phase voltages. A low cost and fast phase voltage detection circuit based on linear photoelectric isolation is presented in this paper. Compared with the existing open circuit switch faults diagnostic strategies, this strategy has the advantages of simplicity, cost-effectiveness and faster detection speed. Simulation results verified the effectiveness of the introduced fault diagnosis method.