A Voltage-Based Open-Circuit Fault Diagnosis Approach for Single Phase Two-Level Converters

The insulated-gate bipolar transistors (IGBTs) are important components in power converters, and open-circuit fault is the most common fault occurred in IGBTs. An online voltage-based fault diagnosis approach for IGBTs in single phase two-level converters is proposed in this paper. Compared with other diagnosis methods, the proposed method does not affect system operation because the controlled Pulse-Width Modulation (PWM) signals are not forced given off-signal during the diagnosis process. Furthermore, both rectifier and inverter IGBTs are diagnosed online with existing sensors.To be specific, firstly, a mixed-logic-dynamic (MLD) model of direct-current-link(DC-link) in two-level converter is constructed. Then, the fault feature is acquired according to the residual of the actual and the estimated DC-link voltages. Moreover, control signals switching matching method is used to locate the fault by comparing the fault characteristic factor with the diagnosis threshold. Finally, simulation results show the effectiveness of the proposed method.