Research On Thermal Reliability And Fault Monitoring Of IGBT Module

As the main component of new energy power system,the reliability of power converter has attracted much attention in the industry.Insulated gate bipolar transistor(IGBT),as the core component of power converter,is widely used because of its fast switching speed,low loss,small driving current,simple control circuit and so on.However,the working environment of IGBT module is usually bad,and its thermal reliability determines whether the whole system can operate stably.As one of the mainstream methods of thermal reliability monitoring,temperature sensitive electrical parameter method(TSEP)mainly monitors various temporary and steady-state temperature sensitive electrical parameters in the switching process of IGBT chip to achieve the effect of real-time monitoring module junction temperature.However,there are differences in temperature characteristics among temperature sensitive electrical parameters,and they are affected by different coupling factors.At the same time,the internal temperature distribution of multi chip IGBT module is uneven due to its structure and packaging,which further increases the difficulty of its reliability monitoring.Therefore,starting with the study of the switching characteristics of IGBT module,this paper analyzes the temperature sensitive characteristics and coupling factors of various temperature sensitive electrical parameters,and puts forward a more accurate method to extract the junction temperature of IGBT module;At the same time,the working temperature distribution and mechanism of multi chip IGBT module are studied,and a bonding wire aging damage location method is proposed.The main research contents are as follows:1.Firstly,the structure,output characteristics and switching characteristics of IGBT module are introduced,and then several common temperature sensitive electrical parameters and their influencing factors are analyzed.Secondly,several common types and occurrence mechanism of aging damage of IGBT module are described.Finally,the coupling effect of various aging damage on module and temperature sensitive electrical parameters is analyzed.2.Firstly,the advantages of temperature sensitive characteristics of saturated voltage and various influencing factors are studied.Then,the basic theory of artificial neural network algorithm is introduced,and its excellent nonlinear problem processing ability is proposed to solve the problem of temperature characteristic change of saturated voltage caused by on-state current change and module aging damage.Secondly,Miller platform voltage is proposed to be used as common input,The reliability of the model is increased.Finally,by building an experimental platform to obtain the training data set of the training neural network,and comparing the error between the trained neural network model and the conventional mathematical fitting model,it is verified that the neural network model constructed in this paper can still ensure a high-precision extraction of the module junction temperature even if the module has aging damage.3.Firstly,the structure and working principle of multi chip IGBT module are analyzed,and on this basis,the finite element model is established to study the heat distribution law of the module.Then,by studying the equivalent circuits of series and parallel chips,a reliability monitoring method for localized bonding aging damage chips is proposed.Finally,by building the infrared temperature measurement platform and test platform,the accuracy of the heat distribution model and the feasibility of the damage monitoring method are verified.