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关键词： degradation state assessment   Changing working conditions   insulated gate bipolar transistor (IGBT)   degradation state assessment   long short-term memory (LSTM)-autoencoder (AE)   long short-term memory (LSTM)-autoencoder (AE)   inter- pretability   inter- pretability   priori knowledge   priori knowledge   priori knowledge   inter- pretability   inter- pretability   inter- pretability   long short-term memory (LSTM)-autoencoder (AE)   priori knowledge  

摘要： Researches indicate that the insulated gate bipolar transistor (IGBT) module is a crucial yet failure-prone constituent of power electronic devices. As a result, assessing the degradation state of IGBT module is significant to guarantee safe device operation. However, existing studies are usually conducted under constant working conditions, which is inconsistent with the strong nonlinearity of the degradation process and strong coupling of parameters of the IGBT module caused by changing working conditions. Additionally, the designed models often lack interpretability, making it less credible. Some of them may even need to be processed with the full life data after the degradation state is obtained, which does not satisfy the requirements of online applications. Therefore, this article proposes an interpretable long short-term memory (LSTM)-autoencoder (AE) modeling method for degradation state assessment of IGBT modules under changing working conditions. First, the interpretability of the model is improved by designing a contrastive output structure. Then, by analyzing the characteristics of IGBT module degradation process, the properties of the degradation are summarized, and the prior knowledge is integrated into the model as a constraint to enhance the accuracy of the degradation state assessment and further improve the interpretability. Afterward, a variable working condition power cycle experiment system is designed and constructed to collect degradation data. Finally, the performance of the proposed method is verified. The results show that the degradation state extracted by the proposed method are more consistent with the theoretical analysis results, which can accurately assess the degradation state of IGBT modules.

关键词： Electro-thermal coupling   fatigue life   IGBT   power cycling   variable conditions   Electro-thermal coupling   fatigue life   IGBT   power cycling   variable conditions  

摘要： Fatigue life of insulated gate bipolar transistor modules (IGBTs) is critical to the reliable application during their long-term servicing. At present, time-consuming and costly power cycling tests are commonly used to obtain the fatigue life model of power electronics devices. In this article, a lower cost and higher efficiency method for the evaluation on the fatigue life of IGBTs was proposed based on variable-parameter power cycling. First, theoretical feasibility of the proposed method was discussed based on fatigue theory. Then, details concerning on the proposed method were described combining with the power cycling data obtained from electro-thermal coupling simulations. Finally, power cycling under both constant and variable parameter was carried out to IGBT modules for experimental verifications. Results dedicate that the fitted fatigue life deduced from the degradation curve of electro-thermal characteristics of IGBTs under variable-parameter power cycling was well consistent with that directly measured from constant-parameter power cycling. It results in an order of magnitude increase in test efficiency and an order of magnitude decrease in costs, which brings huge economic benefit and high efficiency to the fatigue life evaluation of IGBTs.

关键词： Temperature measurement   Thermal resistance   Electrical resistance measurement   Heating systems   Transistors   Resistance heating   Power measurement   Multichip modules   Current measurement   Pulse measurements   Cross-couple thermal resistance   insulated gate bipolar transistor (IGBT) power module   modulation method   thermal impedance matrix  

摘要： This article shows that the results of experimental studies of thermoelectric properties of the insulated gate bipolar transistor (IGBT) power modules aimed at developing methods and means for measuring cross-couple thermal resistances between module transistors. The research has shown that the modulation method, which uses heating of a measured object with power modulated according to the harmonic law, has a number of advantages over standard methods based on measuring the transient thermal characteristics. It was possible to measure thermal resistance components "junction-top copper layer of the direct bond copper (DBC) board," "junction-Al2O3 layer of the DBC board," "junction-baseplate of the module body," and "junction-heatsink" using the modulation method for all the IGBTs of the GD35PIT1205SN power module. Analysis of the results showed that the cross-couple thermal resistance between the transistors of the module may contain one or two components. If the transistors are located on the same DBC board and the heat flows between the module transistors within the same DBC board, then only one component appears. If the transistors are located on different DBC boards separated by a gap, then two components of thermal resistance appear.

关键词： Insulated gate bipolar transistors   Reliability   Stress   Power harmonic filters   Inverters   Damping   Thermal stresses   Insulated-gate bipolar transistor (IGBT) module   LCL filter   lifetime   mission profile   reliability   resonant current  

摘要： Reliability is critical for the efficient operation, maintenance, and cost reduction of LCL-type photovoltaic (PV) inverter. The generation of resonant currents from filter oscillations leads to increased electrothermal stress on the insulated-gate bipolar transistor (IGBT) module, causing notable inaccuracies in lifetime prediction. This article conducts a thorough analysis of IGBT module reliability to quantify the estimation error induced by the resonant current. Two power loss models are derived by the Fourier transform, which makes the loss analysis away from simulation and becomes easy to modify and optimize. In addition, a thermal model of the power semiconductor, considering the thermal cross-coupling effect between components is established. It is further transformed into components' annual damage by lifetime and damage accumulation models. Then, the reliability curves of the modules are developed by reliability block diagrams using Monte Carlo simulation and Weibull analysis. The electrical stress on the IGBT module is experimentally verified. Detailed electrothermal comparisons between systems with and without resonant currents are provided. These comparisons indicate significant impacts on the modules' reliability from resonant currents. Failure of the damping method results in a 40.8% reduction in the lifetime. The results of the investigation provide a novel perspective on the design of LCL-type PV inverters.

关键词： insulated gate bipolar transistors (IGBT)   thermal-stress analysis   temperature distribution   equivalent stress and strain   crack and void damage  

摘要： Insulated gate bipolar transistors (IGBTs), as an important power semiconductor device, are susceptible to thermal stress, thermal fatigue, and mechanical stresses under high-voltage, high-current, and high-power conditions. Elevated heat dissipation within the module leads to fluctuating rises in temperature that accelerate its own degradation and failure, ultimately causing damage to the module as a whole and posing a threat to operator safety. Through ANSYS Workbench simulation analysis, it is possible to accurately predict the temperature distribution, equivalent stress, and equivalent strain of solder materials under actual working conditions, thus revealing the changing laws of the heat-mechanical interaction in solder materials. Simulation analysis results show that, under steady-state operating conditions, the highest point of the IGBT module's overall junction temperature occurs in the center of the chip. Nanogold exhibited the best performance in terms of temperature and equivalent stress-strain among the five solders studied in this paper;defects near the edges caused greater harm to the module compared to those closer to the solder layer's center. In terms of stress, defects located near the edge corners produced larger strains. Crazing damage in joints allows for a faster transfer of heat sources away from the center;in terms of stress, crazing has fewer detrimental effects on the integrity of the module as compared to through cracks. Simulation analysis can model the interaction of heat and equipment under realistic work conditions, comparing and evaluating different types of solder materials to select the most suitable solder material for product design and material selection. This aids in enhancing design precision and reliability.

关键词： Insulated gate bipolar transistors   Silicon   Metals   Resistance   Iron   Integrated circuit modeling   Voltage measurement   Evolution behavior   failure analysis   press-pack insulated gate bipolar transistor (IGBT)  

摘要： The formation and the evolution behavior of short-circuit paths in press-pack IGBT (PP-IGBT) are investigated by combining test and finite element (FE) simulation. First, the large current impact test is conducted, and the characteristic parameters in the limited vision zone from the thermal runaway to the short-circuit path formation are obtained. The FE model of a short-circuit path with time-varying resistance is proposed to simulate the formation of a short-circuit path. Second, the durability test is conducted on a failed 3.3-kV/50-A submodule, and the FE model of the short-circuit path with the length-varying is proposed to simulate the evolution behavior in the submodule. Third, the durability test is conducted on a 3.3-kV/1.5-kA multichip module with a preembedded failed submodule. The FE model of a short-circuit path with failed submodule numbers-varying is proposed to simulate the evolution behavior in a multichip module. The results indicate that Al-Si fusion is an important reason for the short-circuit path formation. In the submodule, the short-circuit path extends around the edge of the active area. In the multichip module, the short-circuit path rapidly spreads from the central submodule to the edge submodule, then expands along the edge, exhibiting a thermal infection pattern, and finally forms a relatively stable short-circuit path.

关键词： Couplings   Insulated gate bipolar transistors   Thermal analysis   Mathematical models   Analytical models   Thermal conductivity   Junctions   Compact thermal model   decoupling condition   positive and negative mutual thermal coupling   thermal coupling  

摘要： To accurately characterize the thermal behavior of the multichip insulated-gate bipolar transistor (IGBT) modules, the thermal coupling effects in a thermal network model must be considered, which will increase the model complexity significantly. The thermal coupling effects are related to the macro operating condition. In some operating conditions, the thermal coupling effects can be ignored and the coupled thermal model can be simplified or decoupled. However, in the existing literature, the relationship between the thermal coupling and operating conditions has not been comprehensively analyzed. Therefore, in this study, based on the compact thermal model, we propose a general methodology to analyze the thermal coupling and decouple the coupled thermal model in the multichip IGBT modules. By studying the "decoupled" form of the simplest compact thermal model with only two chips, the concepts of the positive and the negative mutual thermal coupling are proposed and some important mathematical relations between the Cauer-type and the Foster-type thermal models are found. With these concepts and findings, we deduce the general expression of the decoupling condition. Furthermore, the above-obtained conclusions are extended to the compact thermal model with n chips. Under the given power loss inputs, the decoupling condition for an average compact thermal model with four chips is obtained. Finally, both the simulation and experimental results verify the validity of the theoretical analysis and the correctness of the obtained decoupling condition.

关键词： MOSFET   IGBT   zero current switching   IGBT driver   resonant circuits   overcurrent sensor  

摘要： The control of IGBT (insulated gate bipolar transistor) and MOSFET (metal oxide semiconductor field effect transistor) is of great interest nowadays as they are widely used in electric vehicles, photovoltaic applications, and a multitude of systems. The field of power electronics and their correct activation ensures that the transistors are operated without being destroyed. In this work, a double resonant transformer was built and used to produce very high currents. These currents are switched by a full bridge of resonant IGBT transistors to demonstrate the feasibility of exceeding the maximum permissible transistor currents in a resonant system. The system is controlled by the feedback from two current sensors. In this case the currents exceed in a 170% the peak current of the transistor without problems. In this way, resonant circuits with IGBT transistors can be designed with currents lower than the maximum currents of the resonant circuit, therefore reducing the cost of the circuit and reducing the switching losses to nearly zero.

关键词： battery charger   LLC   boost PFC   Kelvin connection   IGBT   MOSFET   TO-247 package  

摘要： This research investigates the advantages of Kelvin-connected 4-pin discrete transistors, both MOSFETs and IGBTs, in onboard battery chargers for electric vehicles. The study compares the standard 3-pin and the extended 4-pin packages based on averaged data collected from leading manufacturers. The investigation shows significant potential power loss reduction, thermal operation mitigation, and reduced gate-drive oscillation for the 4-pin package. The benefits have been quantified by analysing the operation of actual switches in an automotive battery charger based on Boost-PFC and DC-DC LLC converters. The converters' practical design demonstrates a procedure for integrating the Kelvin-connected package into the design methodology. The results have been verified experimentally.

关键词： Dynamic sharing   parasitic parameters   reliability   static equilibrium   thermal equilibrium   Dynamic sharing   parasitic parameters   reliability   static equilibrium   thermal equilibrium  

摘要： Multichips paralleled insulated gate bipolar transistor (IGBT) power modules are widely employed in industrial and automotive power conversion systems. The asymmetry of the circuit topology and the differences in chip characteristics are the main reasons for the unbalanced current distribution among parallel chips, leading to excessive electrical stress in power modules, which in turn forces the power modules to operate at a reduced rated current. Additionally, the unbalanced current distribution inevitably results in different chip losses, which are further amplified under high current loading conditions, causing some chips to be overheated, and significantly reducing the reliability. Optimizing the circuit topology is a common method to improve current distribution, but global changes often entail higher costs and longer development cycles. Moreover, the electrical parasitic of the fast recovery diodes (FRD) chip branches are not given sufficient attention in circuit topology research. Under rectification and blocked conditions in electric vehicles, FRDs often become the bottleneck for lifespan due to excessively high junction temperatures. Therefore, this article conducts a comparative analysis of the circuit parasitic in IGBT and FRD loops with several typical layouts, without changing the substrate and chip dimensions, and proposes a current sharing slot structure design to balance the parasitic parameters. Compared with the direct bonded copper (DBC) layout of the typical EconoDUAL power module, the optimized module reduces the current imbalance of FRD from 45.5% to 11.6% and the switching loss can be reduced by 8.6%. By adopting the current sharing groove, the parasitic parameter distribution can be further improved while maintaining a fixed DBC layout, considering the IGBT and FRD branches in concert. Finally, the steady-state and transient current sharing characteristics were verified under constant current and inverter conditions. Under constant current co