Coupling Failure Analysis Of Electro-Thermal-Mechanical Multiphysics Based On IGBT Dynamic Model

Insulated gate bipolar transistor(IGBT)is widely used in aerospace,military,new energy,and other fields,its reliability directly determines the reliability of the entire circuit system.As IGBT devices are widely used in harsh environments such as space,ocean,and desert,their reliability-related research is also increasingly difficult.Due to the complexity of the IGBT device usage environment,the traditional reliability model is no longer suitable for high-reliability requirements.Besides,the accuracy of the existing IGBT dynamic model needs to be further improved.In response to the above problems,this thesis specifically studies the IGBT dynamic model,power consumption calculation,and multiphysics coupling failure simulation of multilevel circuits.The main research content is divided into the following parts:(1)First,for the problem of low accuracy of the existing IGBT model,the FZ06NPA045FP01 type IGBT was taken as the research object,and a dynamic model of IGBT based on Simplorer was established.Secondly,in order to improve the calculation accuracy of power consumption,the mathematical interpolation method is used to improve the dynamic model and supplemented by experiments to verify the accuracy of the dynamic model.Finally,based on the research of the improved dynamic model,the feasibility of its application in multiphysics coupling simulation is analyzed.(2)Based on the research results of the improved IGBT dynamic model,a three-level inverter circuit based on Simplorer and MATLAB co-simulation is constructed,and the optimized power consumption is used to simulate the distribution of temperature field and stress field of the three-level inverter electro-thermal-mechanical multiphysics coupling under normal working conditions.(3)Using the finite element model to build three different defects of solder layer cavity,solder layer crack,solder layer shedding,and simulate the effects of different solder layer defects on the IGBT junction temperature and plastic strain.On this basis,the plastic strain distribution of the solder layer under different power cycles is studied,and its mathematical distribution law is obtained.The experimental results show that compared with the traditional dynamic model,the improved dynamic model has higher simulation accuracy and the power consumption calculation accuracy is improved by more than 10%.Under normal operating conditions,the stress and strain caused by the junction temperature change are much smaller than the material can withstand,and the solder layer defects will accelerate the inelastic strain growth trend and form a positive feedback effect,making the power device quickly fail.Solder layer defect simulation results show that solder layer peeling has the largest impact on junction temperature,followed by solder layer cracks,solder layer voids have the smallest impact,and solder layer cracks have the greatest impact on the plastic strain,solder layer peeling is second,solder layer voids have the smallest impact.Based on the above research,fitting the simulation results to get the mathematical relationship between the solder layer defects,power cycle,and plastic strain,then realized the solder layer life status assessment and prediction,achieved good prediction results.