Calculating Model Of IGBT Transient Junction Temperature Of Power Electronic Conversion Device Under Multiple Operating Conditions

Insulated Gate Bipolar Transistor(Insulated Gate Bipolar Transistor)is widely used in power electronic conversion devices due to its high switching frequency and low conduction loss.The safe operation of IGBT plays a vital role in improving the reliability of power electronic conversion devices.However,as the power level and voltage level of IGBT usage scenarios continue to increase,its failure rate is also increasing.During the operation of the IGBT,due to different application scenarios,random external factors such as overcurrent and overvoltage will cause the transient junction temperature to rise,causing random failures of the device.Long-term thermal stress and electrical stress under various working conditions will cyclically impact the IGBT module,resulting in fatigue of the chip and package and causing device aging failure.IGBT junction temperature is an important parameter to reduce device failure rate,predict device lifetime,and improve system reliability.Therefore,it is necessary to establish a transient junction temperature model of the power electronic conversion device under multiple operating conditions to accurately calculate the junction temperature of the IGBT during operation.First of all,the paper analyzes the basic characteristics of IGBT in the working process.Combined with the IGBT double pulse test,the working condition parameters that affect the IGBT transient loss are studied,and the relationship between the working condition parameters and the IGBT loss characteristic parameters is polynomial fitting.The switching and conduction loss models of the device are established in sections based on the loss characteristic parameters.The single-cycle transient loss of IGBT at different operating conditions is calculated and compared with the test results to verify the correctness of the IGBT transient loss model considering multiple operating conditions.Secondly,based on the heat transfer characteristics of the IGBT module,a finite element model of the IGBT is established.The effects of different input power parameters,ambient temperature parameters and heat dissipation parameters under different working conditions on the thermal parameters of each layer of the traditional multi-chip Foster model are studied.A mathematical method is used to establish a fitting relationship between the working condition parameters and the thermal resistance and heat capacity of each layer in the Foster model to modify the traditional multi-chip Foster model.Under different working conditions,the steady-state junction temperature and transient junction temperature of the IGBT module are theoretically calculated,and compared with the finite element model simulation results and the traditional thermal model calculation results,the correctness of the revised thermal model is verified.Finally,based on the basic working principle and load characteristics of the DC-DC BUCK converter,the electrical stress model of the converter when the load rate changes is established.The calculation model of the junction temperature of the IGBT module under the changing load factor is established by MATLAB simulation software.A DC-DC BUCK converter experimental platform is built to verify and analyze the established IGBT loss model and thermal model.The proposed IGBT transient junction temperature calculation model can accurately reflect the transient changes of IGBT losses and junction temperature.The above research can establish a calculation model for the transient junction temperature of the IGBT in power electronic converters under different operating conditions.Compared with the existing model,the transient change of the junction temperature of the IGBT during operation can be obtained more accurately and quickly.It can be used for IGBT module health status monitoring and life prediction,thereby improving the reliability of the system.