A Fast Open-Circuit Fault Diagnosis Method for Two-Level Converter in Railway Traction Systems

Traditional diagnosis algorithms generally only diagnose switch faults in rectifiers and inverters, respectively. However, in the traction converter containing both a rectifier and an inverter, the combination of two diagnostic algorithms increases the complexity of fault diagnosis and the compatibility between diagnostic algorithms needs to be fully considered. Therefore, an individual detection variable is expected to detect faults of the traction converter. Based on the above considerations, in this paper, a unified diagnostic algorithm using dc-link voltage residuals as an individual detection variable is proposed to identify single and multiple switch faults that occur simultaneously in both rectifier and inverter. The proposed method can complete the fault detection and location within one line cycle for the single or multiple switch faults, where no additional sensors are required and all the parameters required are available from the control system. The simulation results have verified the effectiveness of the proposed method.