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关键词： IGBT   power modules   aluminum wires   power cycling   electron backscatter diffraction (EBSD)   texture   crack  

摘要： The texture and microstructure evolution of aluminum (Al) wire bonds of power semiconductor devices during power cycling tests were investigated using electron backscatter diffraction (EBSD). Power cycling tests in pulse width modulation (PWM) mode were performed on power modules during which the cycled devices were extracted from the test bench at different stages of the aging for analysis. The results improve our understanding of microstructural transition after wire bonding and during power cycling. After the wire was subjected to an ultrasonic bonding process, the evolution of a distinct brass textured area within the bonded interface was observed by EBSD analysis. The brass texture is discussed as a result of plastic deformation. During power cycling, grain coarsening as well as local low angle boundary conversion to high angle boundary occurs and the wire-metallization interface texture changes to an overall random orientation. Effects of microstructure and texture on the crack initiation and propagation are discussed.

关键词： 生物学  

ISBN: (纸本)9787030734983

摘要： 《混杂生物种群模型的最优控制》以混杂系统优化控制及其在生物数学领域的应用研究为主旨，系统介绍了连续动力系统、时滞动力系统和脉冲微分动力系统的最优控制理论与方法。内容涉及传染病防控、疾病的治疗方案设计、渔业资源管理、具有农药残留效应的生物控制、状态脉冲反馈控制生态模型、基于综合管理策略的蚜虫个体模型的优化控制问题等研究成果。

关键词： Distinguished method   dynamic latch-up   insulated gate bipolar transistor (IGBT)   marked signatures   secondary breakdown  

摘要： Turn-OFF failure under clamped inductive load, is one of the most concerns in insulated gate bipolar transistor (IGBT) chips. Besides, this turn-OFF failure can be attributed to two causes, i.e., the dynamic latch-up and the secondary breakdown. Despite great simulation work investigated previously, the experimental research should be further focused. Up to now, the typical features and differences for these two turn-OFF failures still remain unclear. In this article, two failures' waveforms are first compared in experiment. Moreover, their internal current, electric field, and temperature distributions are compared by simulation in detail. Then, two different failure features, focusing on the failure cell structures, are summarized from the scanning electronmicroscope (SEM) results for the first time. The marked signatures of these failures, such as the current filament path and the mixture region, are further analyzed in this article. According to the SEM results, the lateral and vertical current paths can be observed in dynamic latch-up chip and secondary breakdown chip, respectively. These failure signatures in waveforms and SEM results can contribute to the distinguished method to the failure causes in IGBT device, and enhance the chip's performance more effectively.

关键词： Dynamic capacitance   insulated gate bipolar transistor (IGBT)   inductive switching  

摘要： Small-signalcapacitancein everydatasheet of insulated gate bipolar transistor (IGBT) is not accurate for understandingIGBT's switchingbecausethe bipolar current in the device creates abnormal depletion profiles. IGBT's reverse transfer dynamic capacitance is extracted for the first time with a five-contact method. While small-signal capacitance does not allow any current flow in the drift region due to the ground gate, the dynamic capacitance is the output of the time-dependent bipolar carriers during the inductive switching. For this reason, the magnitude and the shape of the dynamic capacitance are quite different from the small-signal capacitance found in most of the commercial datasheet. The discrepancy between the dynamic C-GC and the small-signal C-GC raises a fundamental question of whether the small-signal C-GC in the datasheet is useful for considering the device's dynamic performance.

关键词： Silicone gel   Moisture intrusion   Depth effect   Delayed degradation effect   Mass loss   IGBT  

摘要： In the applications of offshore wind turbines and high-speed trains, the power electronic devices suffer in harsh working conditions of high humidity. The moisture invades devices and induces failure of power modules. Therefore, it is necessary to investigate the degradation behaviors of encapsulation material with moisture intrusion. In this paper, the moisture absorption, chemical, and electrical properties of silicone gel under 85 degrees C&85%RH with long aging time is characterized. And the aging at 85 degrees C is chosen as a control. The influence of moisture absorption on the performance of silicone gel is discussed. The results showed that the wettest position locates at the mid-depth in silicone gels after desorption, which can be called as "depth effect" and is first discovered. Besides that, the mass loss during the aging is also observed and a comprehensive explanation considering the competition of absorption and dissolution is given here. Furthermore, a new phenomenon defined as "delayed degradation effect" is discovered. It is that the effect of moisture intrusion on electrical performance degradation in thin samples is delayed. In conclusion, moisture intrusion will degrade the electrical properties of silicone gel, so attention should be paid to power electronic devices working in high humidity conditions.

关键词： Temperature measurement   Insulated gate bipolar transistors   Junctions   Voltage measurement   Estimation   Current measurement   Logic gates   Fault diagnosis   insulated gate bipolar transistor (IGBT)   junction temperature estimation   Miller voltage plateau  

摘要： Junction temperature monitoring and fault diagnosis of power semiconductor devices can provide critical information to ensure the reliable operation of power electronic systems. In this article, an online condition monitoring method for insulated gate bipolar transistors (IGBTs), which is not affected by the collector current, is proposed based on the Miller voltage plateau of the conduction process. The relationship between the Miller voltage plateau and the junction temperature is analyzed, and an analytical model of the Miller voltage against junction temperature is established. By using this model and the conducting-state characteristics of the device, a reverse current phase measuring strategy is proposed to decouple the influence of the collector current on the junction temperature estimation, and an online measurement circuit of the Miller voltage is designed. In addition, the characteristics of the trigger voltage under different faults are analyzed to recognize fault types. The experimental results show that the proposed method has high sensitivity and good linearity. It is proven that the proposed measurement strategy is independent of the collector current, which can accurately distinguish the fault forms of IGBTs.

关键词： IGBT   insulating material   poly(imide-siloxane)   crosslinking   thermal property  

摘要： Insulated gate bipolar transistor (IGBT) is an important power device for the conversion, control, and transmission of semiconductor power, and is used in various industrial fields. The IGBT module currently uses silicone gel as an insulating layer. Since higher power density and more severe temperature applications have become the trend according to the development of electronic device industry, insulating materials with improved heat resistance and insulation performances should be developed. In this study, we intended to synthesize a new insulating material with enhanced thermal stability and reduced thermal conductivity. Poly(imide-siloxane) (PIS) was prepared and crosslinked through a hydrosilylation reaction to obtain a semi-solid Crosslinked PIS. Thermal decomposition temperature, thermal conductivity, optical transparency, dielectric constant, and rheological property of the Crosslinked PIS were investigated and compared to those of a commercial silicone gel. The Crosslinked PIS showed high thermal stability and low thermal conductivity, along with other desirable properties, and so could be useful as an IGBT-insulating material.

关键词： automotive   electric drive   IGBT   inverter   MOSFET   power electronics   power semiconductors   wide-bandgap materials  

摘要： In the automotive industry, the design and implementation of power converters and especially inverters, are at a turning point. Silicon (Si) IGBTs are at present the most widely used power semiconductors in most commercial vehicles. However, this trend is beginning to change with the appearance of wide-bandgap (WBG) devices, particularly silicon carbide (SiC) and gallium nitride (GaN). It is therefore advisable to review their main features and advantages, to update the degree of their market penetration, and to identify the most commonly used alternatives in automotive inverters. In this paper, the aim is therefore to summarize the most relevant characteristics of power inverters, reviewing and providing a global overview of the most outstanding aspects (packages, semiconductor internal structure, stack-ups, thermal considerations, etc.) of Si, SiC, and GaN power semiconductor technologies, and the degree of their use in electric vehicle powertrains. In addition, the paper also points out the trends that semiconductor technology and next-generation inverters will be likely to follow, especially when future prospects point to the use of "800 V" battery systems and increased switching frequencies. The internal structure and the characteristics of the power modules are disaggregated, highlighting their thermal and electrical characteristics. In addition, aspects relating to reliability are considered, at both the discrete device and power module level, as well as more general issues that involve the entire propulsion system, such as common-mode voltage.

关键词： IGBT modules   Particle filter   Improved state -space model   Long short-term memory   Fault prediction  

摘要： Insulated Gate Bipolar Transistor (IGBT) modules, being widely applied in many fields, are prone to aging and even fail under high voltage or temperature operation, so it is necessary to conduct IGBT modules fault pre-diction to avoid critical failures. Particle filter (PF) has strong applicability in IGBT modules fault prediction due to the fact that hidden state of IGBT modules can be evaluated from observed measurements containing noises. Nevertheless, the analytic form of state transition equation for PF is insufficient to represent nonlinear charac-teristics of complex systems, and the degradation process of IGBT modules in practical engineering does not conform to Markov property. Hence, a novel fault prediction method for IGBT modules based on improved particle filter is proposed in this paper, which has an improved nonlinear characteristics representation of state -space model. Specifically, long short-term memory (LSTM) model and curve fitting function are utilized to construct the state transition equation and the measurement equation, respectively. The IGBT accelerated aging test data published by NASA PCoE research center are used to verify the proposed fault prediction method, and the comparison studies show effectiveness and superiority of the proposed method in the IGBT modules fault prediction.

关键词： Capacitors   Switching frequency   Insulated gate bipolar transistors   Voltage control   Stress   Thermal stresses   Indexes   Conduction loss   insertion index   loss balancing   modular multilevel converter (MMC)  

摘要： Modular multilevel converter (MMC) is the state-of-the-art converter topology in HVdc transmission applications. The reliability and lifetime of MMCs are strongly dependent on the health of the internal power semiconductors. The operating loss of power semiconductors, which is one of the dominant factors affecting component aging, is not uniformly distributed between the top and bottom switches in the same submodule (SM) due to the dc bias in the arm current. Such loss imbalance leads to differences in lifetime of semiconductors and reduces the reliability of SM. Especially under inverter conditions, the bottom insulated gate bipolar transistor (IGBT) in SM is subjected to a severe thermal stress and has a relatively high failure rate for the thermal vulnerability of IGBT. To extend the lifetime and improve the reliability, this article proposes a component-level loss balancing method. It is achieved by insertion index modification based on a feed-forward gain controller. The proposed method can improve the loss distribution among the top and bottom semiconductors without side effects on ac and dc outputs. Its effectiveness and feasibility are validated through simulation and experimental results.