The Junction Temperature Prediction And Fault Diagnosis Of Power Devices Based On The Thermo-Sensitive Electrical Parameters

The development of global economy and society promoted the extensive application of power electronic systems,and the power electronic systems also have played a huge role in promoting new energy development and utilization.However,as the widespread application of power electronic systems,more and more problems have been highlighted gradually.Among them,the reliability problem is the key of the scholars focusing on.Power electronic systems once in the event of failure,the economic losses will be incalculable.Power devices is one of the important components of power electronic systems,it is also one of the fault factors affecting system reliable operation.Therefore,in order to enhance the reliability of the power electronic systems,researching the reliability of power devices is necessary.At present,the fault diagnosis through the junction temperature estimation is one of the most effective means and methods to improve the power devices reliability.Based on it,this paper chose the IGBT power module as the research object,mainly from the IGBT junction temperature monitoring and its internal key connection failure two aspects to carry out the research,the concrete research contents are as follows:1.The failure mechanism research of IGBT module.The IGBT module is a complex structure composed of seven layers of different materials.Except the IGBT chip and the FWD diode,it includes materials like copper,aluminum bonding wires and solder.As high-power IGBT module in harsh environments for a long term,its internal materials and chips have to withstand greater temperature and temperature fluctuations,which have a tremendous impact on their performance.This paper analyzes the main failure mechanism and pattern of the IGBT module,and put forward the standard to judge its failure.IGBT module failure is mainly divided into package failure and chip failure.And the bonding wires and solder layer is the most vulnerable part in encapsulation structure.2.Internal parameters extraction and modeling of the IGBT module.This paper analyzed the working mechanism and established the equivalent circuit of the IGBT module.According to the geometry and material properties of internal structure of the IGBT module,a 3D model was established,and the internal parameter extraction is studied by the software.Finally,the correctness of the model is proved by the experiment system.3.Research on junction temperature estimation of the IGBT module.On the basis of acquiring IGBT module encapsulation structure and technical parameters,this paper proposed a junction temperature estimation method which considered the influence of parasitic parameters on the junction temperature and made corresponding compensation.First of all,according to the IGBT module structure size and internal material parameter extraction results,and combined with the resistance temperature characteristic of metal materials,the simplified mathematical model to estimate the junction temperature of the IGBT module was established.At last,by compared with the infrared camera measurement results,the effectiveness of the model was verified.4.Research on fault extraction method of bonding wires based on measurable electrical parameters of the IGBT modules.The method was put forward through online observation the change rules of external electrical signals of the IGBT module to judge the bonding wires fault degree,thus establishing the relationship between the bonding wires fault degree and external electrical signals(collector current I_c,collector-emitter voltage V_ce and gate-emitter voltage V_ge)of the IGBT module.Finally,the feasibility of the proposed method was verified by experimental tests.