Open-Circuit Fault Diagnosis and Fault-Tolerant Control for a Grid-Connected NPC Inverter

• Published in: IEEE transactions on power electronics Vol. 31; no. 10; pp. 7234 - 7247
• Main Authors: Ui-Min Choi, June-Seok Lee, Blaabjerg, Frede, Kyo-Beum Lee
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Circuit faults; Circuit protection; Clamping; Diodes; Distortion; Electricity distribution; Fault detection; Fault diagnosis; Fault tolerance; Fault tolerant systems; fault-tolerant control; Faults; grid-connected inverter; Inverters; NPC inverter; open-circuit fault; reliability; Simulation; Switches; fault-tolerant control; neutral-point clamped (NPC) inverter; Fault detection; grid-connected inverter; open-circuit fault; reliability
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2015.2510224

This paper presents an open-circuit fault detection method for a grid-connected neutral-point clamped (NPC) inverter system. Further, a fault-tolerant control method under an open-circuit fault in clamping diodes is proposed. Under the grid-connected condition, it is impossible to identify the location of a faulty switch by the conventional methods which usually use the distortion of outputs because the distortion of the outputs is the same in some fault cases. The proposed fault detection method identifies the location of the faulty switch and the faulty clamping diode of the NPC inverter without any additional hardware or complex calculations. In the case of the clamping diode faults, the NPC inverter can transfer full rated power with sinusoidal currents by the proposed fault-tolerant control. The feasibility of the proposed fault detection and the fault-tolerant control methods for the grid-connected NPC inverter are verified by simulation and experimental results.