Research On Monitoring Method Of IGBT Junction Temperature Based On Digital Twin

In the application process of power devices,failures caused by overheating and thermal fatigue damage are often encountered.The junction temperature of the device is an important parameter to measure the thermal reliability.In order to improve the reliability of the power device and schieve active thermal management for it,the junction temperature of the device needs to be monitored.At present,the main problems of IGBT junction temperature monitoring are the accuracy and the ability to achieve real-time measurement.The development of digital technology provides the possibility to solve these problems.This paper uses the current implementation of digital twins,and the electrothermal coupling,junction temperature numerical calculation,temperature field reduction model and reliability of the IGBT module anr studied.The main work is as follows:First,the calculation method of the power loss of IGBT and diode is analyzed.The IGBT dynamic model is obtained by IGBT parametric modeling.Its switching process is analyzed to calculate the switching loss by fitting voltage and current.According to the actual IGBT module,the on-state loss and switching loss of the device under SPWM modulation are calculated.The relationship between power loss and junction temperature is determined,which lays the foundation for subsequent electro-thermal coupling simulation and calculation.Secondly,the Foster thermal network model of the IGBT module is established,and the numerical calculation method of the junction temperature of the IGBT module is studied based on the thermal model parameters.The transient analysis of the finite element model of the actual IGBT module is carried out,and the transient thermal impedance curves of IGBT and diode are obtained.The detailed parameters of the Foster thermal network model are determined by curve fitting.The junction temperature of IGBT and diode is predicted by electro-thermal coupling simulation and numerical calculation methods respectively.Thirdly,the reduced-order model from the temperature field finite element model on steady state of the IGBT module is obtained by using proper orthogonal decomposition.Based on the high-order governing equations of the heat conduction problem,the orthogonal basis of the subspace is extracted through the proper orthogonal decomposition,and then the reduced-order model of the IGBT module temperature field finite element model is established through the Galerkin projection.The fast calculation realized through the low-order equations of the temperature field of the IGBT module compares and analyzes the calculation effect of the original model and the reduced-order model.Finally,according to the experimental dataand actual working condition,the original junction temperature numerical calculation process is revised,and the thermal fatigue damage caused by the operation process to the IGBT is calculated.The method of numerical calculation is used to estimate the junction temperature using the current and the case temperature measured during actual operation.The accelerated life model of the IGBT was established,and the junction temperature load sequence during operation is counted by the rainflow counting method,and the number of load cycles with different junction temperature averages and fluctuation amplitudes is obtained.The linear cumulative damage model was is to calculate the degree of IGBT thermal fatigue damage.