A Study On The Working Status Analysis And Lifetime Prediction Method For Power IGBT Module

With the rapid development of the electric car industry,the power loss,junction temperature and lifetime of electric car inverter IGBT module get more and more attention.Along with the change of running status,the IGBT module at electric vehicle inverter withstands continuously intense electrical stress shock,and consequently has gradually cumulative failure due to cumulative fatigue damage.To study the operation condition and the lifetime prediction method of the electric vehicle inverter IGBT module,regarding the electric vehicle inverter IGBT module as research objects,the junction temperature calculation model which is applicable for the electric vehicle driving condition is analyzed and established.Then the lifetime prediction method used for the driving conditions is studied.Finally,influence of driving state of electric vehicle on the IGBT module power loss,junction temperature and lifetime is studied in detail based on the lifetime prediction method.Research results have an important reference value for the electric vehicle cooling system and vehicle performance design and optimization and the IGBT module selection.The main contents and results of this paper include:1.Take permanent magnet synchronous motor drive system as an example to analyze the force balance of electric vehicles in the course of running.And then,the relationship between the operating parameters of driving motor and the running state of electric vehicle is established,which provides the basis for obtaining the operating parameters of inverter IGBT module.2.Analyze the method of obtaining the operating parameters of inverter IGBT under SVPWM mode,than the difference between IGBT module junction temperature calculation model based on switching period average power loss and IGBT module junction temperature calculation model based on average power loss of output cycle is analyzed and compared in the application of electric vehicle.Through the difference between the two,the IGBT module junction temperature calculation model based on switching period average power loss is suitable for the condition of electric vehicle.3.Establish a model of junction temperature calculation for IGBT module of electric vehicle based on operating condition.The model is used to analyze the IGBT module power loss and junction temperature under the driving conditions of 1.2 times New Europe Driving Cycle’s urban mode,furthermore,study the influence of running state,such as running speed,acceleration and climbing angle,on IGBT module power loss and junction temperature.4.The life prediction method of IGBT module for electric vehicle based on working condition is studied.Based on the junction temperature-time curve of IGBT module under given driving cycle,the temperature cycle of IGBT module is extracted by rain flow algorithm,so as to calculate the fatigue damage degree of IGBT module under given operating conditions and predict the IGBT module useful lifetime.The main reasons leading to fatigue damage of IGBT module in electric vehicle are analyzed under typical driving conditions.After that,the method is used to study the influence of operating conditions such as traveling speed,acceleration and climbing angle on the lifetime of IGBT module.The results show that: this lifetime prediction method can be used to predict the lifetime of IGBT module under driving conditions,the main influence factors of IGBT module for electric vehicle is the driving status change,the value of acceleration and road slope.