Research On Aging State And Junction Temperature Monitoring Method Of IGBT Module Considering Thermal Parameters

Insulated Gate Bipolar Transistor(IGBT)has the advantages of low conduction voltage,low power loss,high power density,high switching frequency and so on.As an important part of power electronic system,it is widely used in new energy vehicles,aerospace,rail transit and other fields.Due to the influence of module packaging technology,heat dissipation conditions,working environment and other factors,the heat generated by IGBT chips will lead to the high junction temperature of the module,which will affect the reliability of the IGBT chip more and more in the long term,and eventually lead to the aging or even failure of the module.Relevant research shows that the failure rate caused by high junction temperature accounts for more than half of the failure of power devices,and package failure is one of the main failure modes.As an important part of IGBT module,the solder layer is considered to be one of the most prone to aging.Therefore,it is of great significance to study the monitoring methods of solder layer damage and junction temperature.Based on this,this paper studies the aging monitoring of IGBT module solder layer and the acquisition method of junction temperature.The specific research contents are as follows:Firstly,the basic structure and working principle of IGBT module are introduced,and the working characteristics and heat transfer mechanism of the IGBT module are analyzed.The common types of aging damage of IGBT modules and the traditional thermal network model are described,and the thermal resistance and heat capacity parameters in the Cauer model are extracted according to the physical structure of IGBT modules.Secondly,a method based on junction temperature transfer function is proposed to monitor void damage in solder layer of IGBT module.The relationship between thermal resistance and thermal capacity of each layer of IGBT module and Cauer model is introduced.The variation rule of thermal resistance under different void fractions of chip solder layer is explored,and the relationship between thermal resistance variation and void fraction is established.The process of calculating the parameters of the Cauer model by using the junction temperature transfer function is analyzed,and the relationship between the junction temperature transfer function and the parameters of the thermal network model is obtained.The feasibility and correctness of the monitoring method considering the void damage of solder layer are verified by experiments.Finally,by comparing the relationships between the junction temperature,base plate temperature,heat sink temperature transfer function and the thermal parameters of the Cauer model,a parameter identification method of the Cauer model based on the base plate temperature transfer function is proposed.After the base plate temperature transfer function is measured experimentally,the junction temperature transfer function can be inversely deduced,and then the junction temperature expression can be obtained to realize the junction temperature estimation of IGBT module.In addition,based on this method,the condition monitoring of the heat dissipation effect of IGBT modules,thermal interface materials(TIM)and heat sinks can be realized.