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关键词： Germanium   Logic gates   Power electronics   Bonding   Wire   Threshold voltage   Insulated gate bipolar transistors   Current measurement   Voltage measurement   Safety   Die failure sensitive parameters (DFSPs)   gate-auxiliary emitter turn-off voltage overshoot and undershoot   insulated-gate bipolar transistor (IGBT) die failure   multidie IGBT power module (MDPM)  

摘要： High-power converters often employ insulated-gate bipolar transistor (IGBT) modules with multiple dies connected in parallel. Evaluating the die open-circuit failure degree caused by all bonding wire liftoffs can provide failure warnings to enhance reliability. This article proposes the undershoot ( $V_{\text {ge}<^>{\prime }\_{\text {us}}}$ ) and overshoot ( $V_{\text {ge}<^>{\prime }\_{\text {os}}}$ ) based on the gate-auxiliary emitter voltage during the turn-off process as two novel die failure sensitive parameters (DFSPs) for evaluating die failure degrees. First, the analysis reveals that die open-circuit failure leads to a decrease in $V_{\text {ge}<^>{\prime }\_{\text {us}}}$ and $V_{\text {ge}<^>{\prime }\_{\text {os}}}$ , which are unaffected by operating conditions. Then, a double-pulse test platform is constructed to investigate the effects of die failure and various factors on $V_{\text {ge}<^>{\prime }\_{\text {us}}}$ and $V_{\text {ge}<^>{\prime }\_{\text {os}}}$ . The experimental results demonstrate that as the number of failed dies increases, the proposed DFSPs decrease. Moreover, the failure sensitivity is enhanced, and the method remains insensitive to variations in operating conditions. Finally, a pulse counting-based evaluation method and a circuit are proposed. This method relies solely on pulse pattern recognition without requiring precise DFSP sampling, thus offering a novel evaluation mode. The proposed circuit supports plug-and-play functionality without needing high-performance analog-to-digital converters (ADCs) or timers. This method improves robustness and simplicity while ensuring safety, providing a new perspective for failure warning of the multidie modules.

关键词： Insulated gate bipolar transistors   Bonding   Wires   Temperature measurement   Junctions   Degradation   Power electronics   Switches   Monitoring   Temperature sensors   Bonding wires   discrete insulated gate bipolar transistor (IGBT)   health status   stress wave  

摘要： Effective condition monitoring (CM) technology ensures the safe operation of insulated gate bipolar transistors (IGBTs). Most CM methods for IGBTs focus on extracting electrical, thermal, and magnetic parameters. Recent studies indicate that at the switching moment, IGBTs can emit the switching stress wave (SSW) that is detectable by the acoustic emission (AE) sensors. However, using these SSWs to monitor the health status of IGBTs, even for discrete devices with relatively simple package structures, remains challenging. This article investigates how SSWs from discrete IGBTs during power cycling change as bonding wires degrade and whether these waves are promising for monitoring the condition of internal bonding wires. In this work, a power cycle test platform and an SSW test platform for discrete IGBTs are built, and SSWs from discrete IGBTs during power cycling are analyzed. Results show that SSWs vary with the degradation of the device's bonding wires, with changes in the time domain indicator of signal energy, reflecting SSW strength, and the frequency domain indicator of the center of gravity (COG) frequency, reflecting frequency shifts. These findings suggest the possibility for developing AE-based detection technology (AEDT) in CM of the IGBT.

关键词： Insulated gate bipolar transistors   Reliability   Thermal degradation   Degradation   Monitoring   Thermal stresses   Stress   Maintenance   Rail transportation   Multichip modules   IGBT device   power cycling test (PCT)   reliability   traction system of electric locomotives  

摘要： In electric locomotive system, the function of traction converter depends heavily on insulated gate bipolar transistor (IGBT) module, and IGBT module is prone to failure. Traditionally, ensuring safety has involved expensive and wasteful "mileage maintenance," which includes regular replacement of IGBT modules. Therefore, assessing the residual reliability of these modules, taking into account their different service miles, is meaningful. First, the dynamic and static characteristics of IGBT modules under different service mileage are compared and analyzed. Second, the power cycling test for different mileage IGBT modules is carried out to analyze the differences between them. Then, the microscopic analysis of the failure module further confirms the results of the failure analysis. Finally, the fatigue accumulation state of IGBT modules can be deduced from the power cycling test data to predict the remaining life of IGBT modules. This study reveals that the health state is unevaluable using dynamic or static characteristic parameters. It is proved that the power cycling tested results are significantly different for different service-mileage devices. Finally, a remaining lifetime predicted method of power devices is proposed, where the health status is inverted by the power cycling tests.

关键词： Wire   Bonding   Insulated gate bipolar transistors   Impedance   Feature extraction   Analytical models   Reflection   Fault detection   Degradation   Circuits   Bond wire fault detection   impedance analysis   signal feature decoupling identification   spread spectrum time domain reflectometry (SSTDR)  

摘要： Based on the principle of reflectometry, this article proposes and constructs a spread spectrum time domain reflectometry signal testing scheme and system platform for insulated gate bipolar transistor (IGBT) device-level detection. Subsequently, a signal preprocessing algorithm for the sampling aliasing phenomenon is proposed based on the platform's signal transmission model. Building on this foundation, this article conducts a modeling study on the dynamic impedance analysis of devices under IGBT chip bond wire fault conditions from two aspects: the signal parameters and the transmission path. Subsequently, a bond wire lift-off fault detection method based on the mapping correlation between signal, impedance, and fault is proposed. The experimental results demonstrate that the proposed method can achieve independent detection of bond wire lift-off faults in IGBT chips and FWD chips based on signal feature decoupling. This provides a scientific theoretical basis for the quantitative assessment of bond wire degradation trends.

关键词： Cause analysis   Abnormal defect   Al-Ni interface   IGBT   Vacuum evaporation  

摘要： IGBT dies are widely applied in power modules for new energy vehicles at present, and meanwhile, the reliability has been a research emphasis. As addressed in this paper, abnormal defects at the Al-Ni interfaces of IGBT dies resulted in the failure of power modules for new energy vehicles during the power cycling tests. Based on the failure characteristics, a systematical investigation was conducted to explore the root causes of these defects through a series of study methods such as process traceability, characterization analysis and theoretical analysis. At last, the root causes of the failure were determined through the comprehensive analysis. Furthermore, the formation processes of abnormal defects under different states were reverted, and the detailed formation mechanisms were also confirmed from the special separation characteristics at the Al-Ni interface. Besides, the corresponding countermeasures were also proposed according to the conclusions obtained. It was believed that the achievements would help improve the preparation quality of metal layers of IGBT dies and enhance the integral reliability of power modules for new energy vehicles.

关键词： Magnetic resonance   Transient analysis   Inductance   Design methodology   Capacitors   Magnetic tunneling   Voltage   Time-domain analysis   Transformers   Discontinuous conduction mode (DCM)   insulated gate bipolar transistor (IGBT)   LLC dc-dc transformer (LLC-DCX) converter   magnetizing inductance   turn-off transient model   turn-off transient model  

摘要： In medium-voltage and medium-frequency (MVMF) applications, LLC dc-dc transformer (LLC-DCX) converters with high-power insulated gate bipolar transistor (IGBT) modules are favored for their compact size, high efficiency, and cost-effectiveness. In these applications, the turn-off behavior of the IGBT is significantly influenced by the dynamic charge stored in the N-base region, which directly affects the turn-off transition time and the associated losses, making traditional LLC-DCX converter design methodologies inapplicable. To address this limitation, this article presents a design methodology that combines a simplified time-domain analytical expression for the resonant current with the IGBT turn-off behavior, resulting in an IGBT turn-off transient model that accurately captures the dynamic charge effects. Based on the IGBT turn-off transient model, a parameter optimization design enables the LLC-DCX converter to operate in discontinuous conduction mode (DCM) with the highest efficiency is carried out. Compared to existing methodologies, this methodology provides a more accurate estimation of the IGBT turn-off transition time and associated losses, enabling precise determination of the maximum magnetizing inductance and the optimal efficiency of the LLC-DCX converter in DCM operation. The effectiveness of the proposed design methodology is experimentally validated using a 9.6-kW LLC-DCX converter.

关键词： Power device   Failure analysis   Scanning Electron Microscopy (SEM)   Thermal fatigue   COMSOL Multiphysics  

摘要： This paper discusses the fatigue failure mechanisms associated with the packaging of Insulated Gate Bipolar Transistors (IGBTs) and investigates the failure behavior of aluminum wires and die-attached solder layers within IGBTs. The study utilizes an electro-thermal-mechanical finite element model, temperature shock tests, and power cycle tests. Using finite element analysis with COMSOL Multiphysics software, the failure process of aluminum wires and solder layers in IGBT power modules was simulated, and the temperature and stress distribution of the devices during the power cycle were determined. The Anand model was employed to analyze the creep mechanism of the solder layer. Through Electron Backscatter Diffraction (EBSD) analysis, the macroscopic failure behavior was correlated with the microstructure, revealing the grain size and grain boundary evolution in the crack tip region during the crack propagation of the Al bonding wires. The research aims to enhance the understanding of fatigue failure mechanisms and improve the reliability of IGBT devices.

关键词： Insulated gate bipolar transistor   Junction temperature estimation   Hybrid electric vehicles  

摘要： The Insulated Gate Bipolar Transistor (IGBT) is a crucial component in hybrid electric vehicle electric drive systems. Estimating the IGBT junction temperature is essential for forecasting its lifespan and managing the heat within the power module. This paper presents and applies two methods for predicting IGBT junction temperature: the thermal network model and the empirical relationship method. Among them, the thermal impedance method is analyzed and extended to engine application by introducing a coefficient beta = f (speed, coolant boundary). The empirical relationship is first proposed considering the effect of thermal boundary. Both methods are applied in CHANGAN Plug-in Hybrid Electric Vehicles (PHEV). Experimental results indicate that the thermal network method provides fast and accurate temperature estimates with the absolute error remaining below +/- 5 % under over 99 % operating conditions. In contrast, the empirical relationship method offers lower frequency but solid predictions under separate working conditions. Both methods were evaluated through road tests and demonstrated the capability to provide reasonable temperature variations of the power module.

关键词： Stress   Logic gates   Degradation   Temperature measurement   Voltage measurement   Robustness   Insulated gate bipolar transistors   Threshold voltage   Stress measurement   Thermal variables control   Degradation mechanism   high-gate voltage stress   insulated gate bipolar transistor (IGBT)   negative gate bias causes a negative drift (NBTI)   robustness  

摘要： In this study, the robustness of insulated gate bipolar transistors (IGBTs) under extreme high-gate voltage stress (both positive and negative) is comprehensively investigated. The results indicate that all IGBTs maintain essential electrical characteristics, demonstrating considerable robustness to extreme gate voltage stress. However, varying degrees of degradation are observed depending on the polarity of the applied stress. Specifically, under high-positive gate voltage stress, the threshold voltage remains nearly stable, whereas under high-negative gate voltage stress, a significant increase in the threshold voltage is noted. Based on these findings, the degradation mechanism is proposed and experimentally validated. For negative gate voltage stress, degradation primarily results from electron injection from the gate, with elevated temperatures accelerating this process. In contrast, under positive gate voltage stress, the hole injection efficiency is much lower than that of electrons, and part of the gate voltage is absorbed by the depletion region. Additionally, G-V measurement, C-V measurement, and simulation are conducted to support the proposed mechanism. This work contributes to a deeper understanding of IGBT degradation mechanisms under high-gate voltage stress, offering insights relevant for their application in high-stress operational environments.

关键词： Four-wheel independent drive electric vehicle   IGBT temperature   Vehicle stability control   Robust model predictive control  

摘要： When the four-wheel independent drive electric vehicle (4WIDEV) operates continuously under high-load conditions, the temperature of the insulated-gate bipolar transistor (IGBT) module will rapidly rise, making it susceptible to triggering the predesigned thermal protection strategy (TPS). This will cause a sudden drop in corresponding motor output torque, leading to a reduction in vehicle power performance and potentially causing instability. To solve this problem, a robust model predictive control (MPC)-based vehicle stability control strategy for 4WIDEV considering IGBT thermal effect is proposed. Firstly, a control-oriented IGBT thermal model is established to represent the electro-thermal effects of the IGBT module. A test bench is built to verify the IGBT thermal model and obtain the boundaries of uncertain parameters in this model. Secondly, considering uncertain parameters with known boundaries, a linear parameter varying (LPV) discrete system model is established, composed of the IGBT thermal model and vehicle dynamics model. Then a robust MPC-based vehicle stability controller is proposed. IGBT temperature constraints are constructed to keep the temperature below the threshold, considering parameter uncertainties. Additionally, three constraints are established to satisfy the stability conditions and robustness requirements of the 4WIDEV. Finally, the proposed control strategy is verified by hardware-in-the-loop (HIL) experiments. The simulation results under scenarios where IGBT temperatures are approaching the threshold demonstrate that the proposed strategy improves tracking performance for velocity and yaw rate by 54.7% and 87.2%, respectively, compared to the existing method, while effectively avoiding triggering the TPS.