Study On IGBT Performance Degradation Based On High Speed Railway Conditions

Insulated gate bipolar transistor(IGBT),as a core control component in rail transit industry applications,is used for traction converters and various auxiliary converters to achieve rapid variable voltage and variable frequency control.The aging of IGBT is mainly related to the thermal and thermomechanical load constraints acting on the device.Its working characteristics and complex working environment determine its high failure rate in converter devices.The reliability of IGBT devices is studied To a certain extent,it helps to improve the reliability of the entire device.This paper takes the IGBT module for rail transit as the research object,establishes a simplified finite element model,and equivalently simulates the boundary conditions and loading imposed on the real operating conditions of the high-speed railway rail rolling stock.Based on the theoretical basis of thermal stress,frequency response analysis,random vibration fatigue analysis,etc.,the research on the evaluation method of IGBT high-cycle fatigue life with the coupling of electric-thermal-force multiphysics is carried out.A prediction method for IGBT fatigue damage and remaining life under thermal-vibration coupling conditions based on the fatigue analysis software nCode is proposed,which reveals the effects of on-current,damping ratio,ambient temperature,structural materials and dimensions on the stress fatigue life and thermal-vibration coupling The effect of random vibration on fatigue life.(1)Conduct electro-thermal-mechanical coupling simulation on the IGBT,obtain the thermodynamic response characteristics under its working conditions,analyze the thermal response characteristics,mechanical response characteristics of the dangerous parts of the module,and the factors that affect the temperature of the module junction and case.Use the fatigue analysis software nCode Designlife to calculate the stress fatigue life of the frequency response results under thermal stress obtained previously,and obtain the cumulative damage under thermal stress fatigue and the distribution and size of fatigue life.(2)Carry out static modal analysis on the IGBT,and then carry out its modal analysis and frequency response analysis under the combined action of electrical and thermal stress,compare and analyze the modal analysis results of the module under normal temperature and thermal environment conditions,and obtain the module in the thermal environment The first six natural frequencies of the lower natural frequency are lower than the natural frequency of the structure at room temperature,the deformation of the next natural frequency of the thermal environment is smaller than that of the normal temperature,and the deformations of the other modes are basically the same.(3)Use nCode to perform random vibration fatigue analysis on the IGBT module,and obtain the vibration fatigue life when only vibration fatigue and thermal vibration coupling are considered,as well as the hazardous location and size of the cumulative damage and fatigue life results;explore the ambient temperature,damping ratio and parts The influence of structural(solder layer)damage as a variable on the fatigue damage and fatigue life of IGBT.(4)Combined with the actual working environment of the IGBT module,the power cycle and thermal cycle test principles and test schemes are introduced and designed,and the junction and case temperature real-time online monitoring temperature measurement system is designed.The relevant factors affecting the fatigue life of the module are explored,and the optimal design measures for the structure size and materials are proposed.Based on the electrical-thermal-mechanical coupling of IGBT modules,this paper has carried out research on the calculation method of vibration load high-cycle fatigue life considering the influence of thermal load,and carried out related research on IGBT module structural design optimization,heat dissipation performance improvement,and structural reliability.