Research On Key Technologies Of Behavior Modeling And Reliability For Power Semiconductor Module

As the core component of power electronic converter,IGBT power module is widely used in the new energy industry and plays an important role in the safe and reliable operation of the system.Due to frequently operating in harsh environments,the service life of the IGBT power module is far less than traditional applications.To improve this situation,simulation at the design stage has become the first guarantee of reliability,meanwhile real-time junction temperature estimation and health monitoring are used as auxiliary to take the responsibility of improving reliability.However,these key technologies have some problems.The thesis starts with devices and packages,and focuses on the behavior modeling methods to improve simulation accuracy,new junction temperature estimation method,and bond-wire health monitoring method to reduce the failure rate of the IGBT power module and improve system reliability.Firstly,the thesis summarizes the technical requirements for power electronic converters in the new energy industry in recent years,and summarizes the current researches and key technologies for IGBT power modules.Circuit simulation is an important technology in the design stage of power electronic converters.Using semiconductor device behavior models can accelerate the simulation speed,but the accuracy is obviously insufficient.The article proposes a new device-package behavior modeling method for the IGBT power module.There are two reasons for the deviation of the IGBT's behavior model.One is the poor accuracy of the collector current matching under different gate-emitter voltages in the saturated operating region for the static characteristics;the other is the distortion of turn-on and turn-off transient process caused by the simplified mathematical models of the nonlinear capacitances for dynamic characteristics.The thesis starts from these two aspects,and introduces a correction function to optimize the static characteristics.Based on the measurement results,three accurate mathematical model of the nonlinear capacitances is established.In addition,the diode uses a traditional behavior model,a polynomial function and a snappiness factor to describe its forward conduction characteristic and reverse recovery characteristic,respectively.The parasitic inductances and capacitances of electrical and thermal packages are extracted using impedance measurement.The comparisons between experiment and simulations of the pre-optimized and optimized behavior models verify the accuracy of the latter from three aspects: transient process,switching losses and high-frequency characteristics of the bus current.Applying temperature-sensitive electrical parameters(TSEPs)to estimate the junction temperature of the devices has been widely used,but most of TSEPs of IGBT have two problems: due to the positive and negative temperature coefficient of IGBT,there is a temperature blind area for static parameters at the critical point;the sensitivity of the dynamic parameters is low and it is not easy to measure.To solve these two problems,the article presents a method to estimate the junction temperature of the device with the peak voltage as TSEP.By analyzing the transient process of the IGBT during turn-off and the diode during reverse recovery,the validity of this method is verified by the theories and experiments.Voltage peak is a dynamic TSEP with high sensitivity and accuracy,which has obvious characteristics that is convenient for measurement.Compared with other classical TSEPs,it has certain advantages.Aging of bond wires is one of the main failure modes for packaging.The technical indicators of bond wires health monitoring are not obvious and easy to be interfered.To avoid misjudgment,the thesis proposes a health monitoring method based on voltage ringing characteristics.By establishing the equivalent circuit of IGBT durn turn-off and diode during reverse recovery,the feasibility of the method is verified theoretically and the validity of the voltage overshoot and the oscillation frequency as technical indicators to monitor the health state of the bond wires is verified experimentally.The influence of junction temperature and working current on the voltage overshoot is studied respectively.Taking the new IGBT power module as a reference,the influence functions of the voltage overshoot are constructed and the health reference maps of the bond wires under different working conditions are drawn.An online monitoring circuit for the voltage overshoot is designed and its effectiveness is verified by experiments.Thermal management design is the guarantee of the reliable operation for the IGBT power module.In the thesis,the electrothermal coupling is explored in advance,the influence of temperature on the parameters of the optimized behavior model are analyzed,and the foster network thermal model for the circuit simulation is established.Finally,the works of the thesis is concluded.The main contributions of the article are summarized and the future work is prospected.Finally,the electric thermal coupling simulation is completed,which provides a reference for the thermal management design of IGBT power module.