Working diagnostics of thyristor arms of a rectifier-inverter converter of an ac electric locomotive

Abstract

The article considers the principle of working diagnostics in real time of a rectifier-inverter converter of an AC electric locomotive in case of shoulder control failure. The proposed principle is based on the harmonic analysis of the rectified voltage curve and identification of the relative content of individual harmonics that are missing in normal mode. To increase reliability of detection of the damaged shoulders, it is proposed to use a diagnostic criterion based on assessment of changes in the resulting energy output of the converter at certain intervals of the mains voltage period. Due to the joint application of several criteria, damage detection with the necessary level of sensitivity is achieved. For each criterion, two groups of boundary values are calculated, due to which the selectivity of determining the failed shoulder is realized. The justification of the selected boundary conditions that distinguish the emergency mode from the normal one is presented. A simulation model has been created in the MatLAB Simulink software package, which allows exploring the possibilities of diagnosing a rectifier-inverter converter for various operating conditions. The results of simulation modeling confirming correctness of the proposed solutions are presented. It is indicated that the proposed diagnostic method should be used together with the alternative converter control algorithm that ensures operability of the electric part of the electric locomotive in case of failure of one of the arms.