Construction Method Of Bidirectional Thermal Network Model Considering Solder Layer Damage Of IGBT Module

Insulated gate bipolar transistor(IGBT)modules are widely used in new energy power generation,electric vehicles,shipbuilding,aerospace and other fields due to their advantages of high capacity,high voltage level,and low power loss.Limited by production and packaging technology,heat dissipation conditions and working environment,the heat generated by IGBT chip leads to high junction temperature,aging and even failure.The solder layer is considered to be one of the most fragile parts in the IGBT module package structure,and its aging states such as voids and cracks affect the heat dissipation performance of the module and increase the junction temperature.Therefore,temperature is an important parameter that affects the health state of IGBT module and characterizes its aging.Accurate prediction of junction temperature of IGBT module is of great significance for its life evaluation and the reliability improvement of the power electronic system.Based on this,the acquisition method of IGBT module junction temperature and the influence of solder layer aging are studied in this paper.The specific contents are as follows:First of all,in view of the error of junction temperature extraction caused by ignoring the influence of silicone and shell when extracting junction temperature by traditional thermal network model,a bidirectional Cauer model of IGBT module is established in this paper,which is more consistent with the physical structure of the actual module.In the model proposed in this paper,more accurate transient junction temperature can be obtained,which is suitable for modules with small switching cycle,and the feasibility of calculating steady-state junction temperature by traditional thermal network model is verified.Through the finite element simulation results and experimental data,the correctness of the calculation results of the bidirectional Cauer model is proved.Secondly,in order to study the influence of silicone and shell on the temperature of aging module,a bidirectional finite element analysis model considering crack damage is established and compared with the traditional model.Due to the concentrated effect of silicone and shell on heat,the influence of crack damage on IGBT chip temperature is reduced and the influence on diode chip temperature is increased.Finally,through finite element analysis,the effects of silicone and shell on heat flow distribution of IGBT module with void damage are studied.A bidirectional Cauer model considering the influence of void is proposed,which solves the problems that the parameters of the traditional thermal network model are difficult to determine and the junction temperature calculation is inaccurate when there is the void in the chip solder layer.