Design Of IGBT Chip Junction Temperature Dynamic Monitoring System Based On Fiber Bragg Grating

Junction temperature is a key factor affecting the performance and reliability ofhigh-voltage high-power power electronics devices.For high-power IGBT devices,which are structurally hermetically integrated,the interior of the device consists of multiple chips,making it difficult to obtain the junction temperature distribution characteristics of the internal chips from outside,which can effectively assess the remaining life ofthe device.This,combined with the strong coupling ofthe physical fields inside the device,makes accurate measurement of the junction temperature of IGBT devices extremely difficult.This paper is designed to address the thermal failure issue caused by IGBT module heating and heating in flexible DC converter station of power grid,a dynamic monitoring system based on fiber grating temperature sensing technology was developed,which can give early warning of IGBT module heating and carry out multi-point online monitoring ofjunction temperature.In this paper,the failure reasons of IGBT module,the existing monitoring methods and shortcomings are analyzed.Aiming at these needs and problems,considering the complex internal operating environment of power system,an online monitoring scheme of IGBT chip junction temperature based on fiber Bragg grating is proposed.The principle of FBG temperature sensing,loss characteristics,various optical demodulation technologies and the combined multiplexing technology of air separation and wave division in engineering are studied.The finite element fluid-structure coupling thermal simulation analysis of IGBT and its radiator module is carried out by ANSYS Workbench software.The IGBT module and its heat dissipation system are modeled according to the existing engineering structure,and then the parameters such as heat conduction coefficient of each material,ideal boundary conditions and chip heating power are input for simulation calculation.The temperature distribution cloud map is obtained,and the optimization design is carried out according to the simulation results.The final results provided a reference for embedding temperature sensors and verifying the internal temperature distribution of IGBT module.Temperature calibration experiments and a series of verification experiments to improve the accuracy of monitoring results are carried out for the grating used,the embedment scheme of temperature sensor in different type IGBT module is designed to achieve more accurate temperature measurement of hot spot.Meanwhile,the power loss of different optical paths is verified by using the combination of wave division and air division multiplexing technology,and the better scheme is obtained by comparative analysis,which improves the reliability of the system.Finally,package design for the whole system,and complete the development of upper computer software,including data transmission module,temperature processing module,image display,user setting module and parameter adjustment module,convenient in different measurement schemes to adjust the relevant parameters at any time,flexible use.In this paper,according to the actual requirements of the project,the installation and burying scheme suitable for the site and transparent human-computer interaction software are designed and applied in Xiamen flexible HVDC transmission project.The reliable operation in the project proves the effectiveness of the FBG temperature sensing monitoring system.