中文摘要：

IGBT模块在退化过程中内部材料的物理属性会发生变化，进而引起模块结壳热阻的变化，因此通过研究结壳热阻的变化情况，可以对IGBT模块的退化程度进行评估。首先研究IGBT模块的结构及热扩散特性，并利用定义法计算出初始结壳热阻，指出模块在退化过程中各层封装材料、物理参数及导热面积的变化会导致结壳热阻的变化；然后，对IGBT模块进行了温度循环老化试验，并在老化过程中测量模块的结壳热阻，研究结壳热阻在老化过程中的变化情况，发现其按指数规律退化，进而建立热阻的指数退化模型；最后，提出一种IGBT模块的模糊状态评估方法，建立了基于热阻的模糊状态评估模型，采用均匀划分的方法以IGBT模块的结壳热阻作为评估参数将模块的退化状态分为7个评估等级，并对老化后的某IG?BT模块进行了模糊状态评估。

英文摘要：

The physical property of the IGBT module′s internal material may change in its degradation process,and lead tothe variation of the junction-to-case thermal resistance of the module.The study on variation of the junction-to-case thermal resis-tance can evaluate the degradation process of IGBT module.The structure and thermal diffusion characteristics of IGBT moduleare studied.The definition method is used to calculate the initial junction-to-case thermal resistance.It is pointed out that thevariation of the each layer′s encapsulating material physical parameters and heat conduction area in degradation process maycause the change of the module′s junction-to-case thermal resistance.The temperature cycle and aging test were conducted forIGBT module.The junction-to-case thermal resistance of the module is detected in the aging process.The variation situation ofthe junction-to-case thermal resistance is studied in the aging process to find out its degradation according to index law,so as toestablish the index degradation model of the thermal resistance.A fuzzy state assessment method of IGBT module is proposed toestablish the fuzzy state assessment module based on thermal resistance.The uniform division method is adopted to divide themodule′s degradation state into seven assessment grades by means of taking the junction-to-case thermal resistance of IGBT moduleas the assessment parameter,and performs the fuzzy state assessment for the aged certain IGBT.