Research On Characteristics For Traction Converter Power Device In Service

Traction converter is the key power equipment of electric locomotives and EMUs,and its reliability directly affects the safe operation of trains.Insulated gate bipolar transistor(IGBT)is a device with high failure rate in the converter,and it is prone to overmaintenance in the traditional maintenance mechanism.Studying the characteristics of IGBT modules and understanding their degradation trends are conducive to formulating a reasonable maintenance plan,so that aging devices can be replaced in time,and the maintenance cost can be reduced.Based on the effect of thermal stress on the aging of the device,a multi-physics coupling simulation model is established in this thesis,aiming to analyze the working state of the IGBT module under the specified operating conditions of the train.The life of the power device is related to its working state and environmental conditions.According to the structure and working principle of the traction drive system,a simulation model is established to reflect the operating conditions of the train on the IGBT module of the traction converter,which provides conditions for the life evaluation of the device.On this basis,the calculation method of power loss and thermal network model of the IGBT module are built up,and the current waveform reflecting the working state of the IGBT module is used to obtain the power loss and junction temperature fluctuation curves of the power devices.Finally,thermo-mechanical coupled analysis of the IGBT module is carried out,the heating power of the power device is used as the load to obtain the corresponding temperature and stress distribution inside the module.Under different operating conditions of the train,this thesis analyzes the state of the IGBT module using the above method.In this process,the relationship between the thermal stress of the power device and the train running state is obtained,the failure mechanism of the module is analyzed,and the service life prediction model and fatigue damage theory are used to evaluate the damage of the IGBT module,the effect of the train operating conditions on the aging of the IGBT module is preliminarily obtained.