Online Lifetime Assessment Method Of IGBT Module Considering The Failure Of Bonding Wire

The welded IGBT(insulated gate bipolar transformer)module is widely used in inverters,and the stable working ability of the device is closely related to the reliable operation of the system.Among them,the failure of the bonding wire is one of the main failure modes of the IGBT module,and there are currently mature online monitoring methods for realizing the perception of bonding wire fracture.However,the existing lifetime assessment methods for IGBT modules do not consider the impact of bonding line failure status on the device,and cannot incorporate online monitoring data of bonding line failure into the evaluation and correction of module lifetime,resulting in optimistic lifetime prediction results that cannot reflect the true remaining lifetime.This article proposes an online lifetime assessment method for IGBT modules that takes into account the failure of bonding wires.The lifetime is evaluated by updating the RC thermal network model of the bonding wire failure module.The main work and achievements of this article are as follows:Firstly,a finite element model of the device and a power loss model are constructed,and the transient thermal impedance curves of the 1200V/50A IGBT module are calculated through electrical thermal coupling simulation under the failure of different remaining bonding lines.And a transient thermal impedance measurement experimental platform is established to analyze the transient thermal impedance curves under different injection currents and the number of bonding wires.The mutual verification of simulation and experimental results indicates that as the number of bonding line failures increases,the transient thermal impedance curve rises,the steady-state thermal impedance increases,and the variation of thermal impedance increases.Afterwards,the Foster thermal network model is introduced to calculate the junction temperature.Based on the changing transient thermal impedance curve,the fourth order thermal network model parameters Ri and Ci of the device are updated.An RC equivalent circuit is established in MATLAB/Simulink,with DC/SPWM operating conditions set,input environmental temperature and load current,and electrical parameters iterate to obtain the junction temperature variation curves over time.Analysis shows that the failure of the bonding line increases the thermal resistance,which in turn leads to an increase in internal junction temperature.The module withstands a more severe thermal field environment and reaches a new thermal equilibrium state.The junction temperature curve will serve as the data basis for subsequent lifetime assessment.Finally,the distribution of junction temperature load is calculated using the rain flow counting method.The Lesit life prediction model and linear fatigue accumulation theory are used to calculate the power cycle life of bonding line failure devices under DC and SPWM operating conditions.The method can be used for online real-time correction of module full cycle life.In addition,this article also provides an online evaluation process for the lifetime of IGBT modules in inverters.The number of bonding wires and current electrical quantities can be obtained through online monitoring methods,matched with corresponding thermal network models,and the true remaining lifetime of the calculation module can be evaluated,effectively improving equipment control efficiency.