The Diagnose Research Of Open-Circuit Fault For Auxiliary Inverter In Urban Rail Train

In the background of our country’s civilization speeding up and the citizens’rapid increase, city traffic problems appear to be serious. As a modern public transportation with large capacity, high speed, low pollution and ride comfort, city rail traffic has been being developed rapidly in recent years in china. The auxiliary power supply system is an indispensable part of the train, maintaining for many important functions of the train, but also related to the passenger ride comfort. Fault diagnosis of the auxiliary inverter is the basic of the auxiliary inverter power system fault diagnosis. The fault diagnosis and protection measures of the auxiliary inverter is not perfect, can only be used to diagnose such as the fault of over-current, under voltage and high-temperature, there is no good diagnostic methods to deal with open-circuit fault of IGBT in the main circuit. In this paper, two kinds of commonly used auxiliary inverters’open circuit fault were researched respectively, and a new fault diagnosis approach is proposed accordingly. Through simulation testing in various fault conditions, the correctness and effectiveness of the proposed theory and method were verified. Mainly completed the following work:Firstly, I learned the auxiliary power supply system’s structure, the Working principle of auxiliary inverter, and gave a detailed analysis of the power inverter tube failure causes and its influence on the output of the system. Then, the main thoughts of the diagnosis for open circuit fault were put forward. On this basis, after a detailed calculation of filter circuit parameters and control parameters of the auxiliary inverter is achieved, the simulation model is established in Simulink, and the IGBT open circuit fault simulation and analysis are carried out.Secondly, through a detailed analysis of the working process of two level auxiliary inverter modulated by SPWM, and do a comparison on the flow path and corresponding power of the currents’positive and negative parts between the normal condition and open circuit condition, the relationship between the output power of each phase current’s positive, negative part and the output power through up-down bridge arm’s IGBT was clear. On this basis, a diagnose method is proposed by testing each phase power of the currents’positive and negative parts to reflect the working status of each IGBT. The fault feature’s concept of the proposed method is clear and can distinguish fault or not clearly, which can better reflect the working state of power tube. The accuracy and reliability of this method was verified though simulation tests.For the diagnose of another widely used auxiliary inverter for city rail train--twelve pulse step wave inverter. The fault component’s transmission and its effect on output after each son inverter have a fault was analyzed in this paper, and a diagnose method was proposed which detect the fault by three-phase voltage’s mutual reference and contrast after shifting1/3fundamental period. After fault is detected, localization of the fault son inverter and the fault bridge arm will be realized according to the fault transmission mode. Finally, the proposed method is verified by the simulation.The raise of two inverter open-circuit fault diagnose method based on object structure and fault propagation increase and improve the idea and method of open circuit diagnosis of power tube, help to improve the safety and reliability level of operation of auxiliary inverter power supply system of domestic urban rail train.