The Electro-thermal Model Of IGBT Module And Research Of Life Prediction Method

In recent years,as the increase of environmental problems and the gradually reduce of fossil energy,the development and utilization of clean energy has become an important topic,wind power as a kind of the most common form of clean energy has gotten large scale development and utilization.As the world's wind power installed capacity rising,the reliability of the wind power system operation greatly affect the running reliability of the whole power system.As an important part in wind power generation system,wind power converter has very high failure rate(about 31%),and the faults due to the failure of power device IGBT are in large part.So to improve the reliability of wind power converter,should study the reliability of the IGBT module firstly.The uncertainty of the power grid load and instability of wind power makes the IGBT junction temperature fluctuates very intense in the process of working,and the influence of thermal shock which will accelerate of the failure process of IGBT module becomes one of the key factors affecting wind power system reliability.Therefore,study how to predict the lifetime of IGBT module accurately is the foundation of making wind power system running continuously.At present,the related factor is relatively single in the power module lifetime prediction research,only make the junction temperature history as the main factor generally without considering the influence of degradation in the lifetime prediction,therefore,in order to join in the power module degradation factors in the lifetime prediction,the paper main work is as follows:(1)The transient thermal impedance measurement technology of IGBT module has been further studied,then the transient thermal impedance in the process of aging was measured,and then synthesize the transient thermal impedance curve fitting the Foster thermal network model.By analyzing the degradation rule of individual parameters obtained form thermal network model,establish the Foster thermal network with degradation parameters,which is the degradation model of transient thermal impedance.The work described above lays the foundation of establishing the electric-thermal model with degradation parameters.(2)The composition of IGBT module power loss has been deeply analyzed,on this basis,establish the power loss calculation model based on the switch cycle average loss calculation,then set up the electro-thermal model of inverter using Foster thermal network model as thermal model,this model can simulate the junction temperature curve of IGBT module during the load fluctuation.Combing with the Foster thermal network model with degradation parameters,set up the electro-thermal model of IGBT module considering the degradation state,this model can simulate the junction temperature curve after the IGBT module degenerated,the research described above can provide data for the lifetime prediction of IGBT modules.(3)Damage cumulative rules,load spectrum compiling principle and life prediction models used for power device life prediction have been further studied,on this basis,a damage cumulative feedback model was proposed,this model follows the rule of Miner linear damage accumulation in the small scope of the lifetime,the damage accumulation was supposed to accelerate in the process of whole life,the damage accumulation was send back to electro-thermal model to modify the electro-thermal model constantly in the process of life prediction.Use the junction temperature obtained from the revised model to predict remaining lifetime,hope to improve the accuracy of life prediction.