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关键词： Bond wires diagnosis   condition monitoring (CM)   insulated gate bipolar transistor (IGBT)   modular multilevel converter (MMC)   prognosis   reliability  

摘要： Condition monitoring of insulated gate bipolar transistor (IGBT) modules is an effective way to improve the transient performance and reliability of modular multilevel converters (MMC). This article proposes a novel bond wire failure monitoring method for the multichip IGBT modules in the MMC half-bridge submodule (SM) structure. The collector voltage undershoot V-CA(np) of the complementary IGBT switch is measured during the turn-off switching transition of the controlled IGBT switch. V-CA(np) is sensitive to the induced voltage over the stray inductance of the IGBT bond wires and provides high sensitivity as a health indicator. The non-intrusive measurement technique is demonstrated using a half-bridge circuit during the turn-off transition of the controlled IGBT, while its complementary switch (i.e., the device under test) is in the off state. Theoretical analysis and experimental results show that the parametric drift due to wire bonding failures can be effectively monitored with high specific relative sensitivity and granularity. To ensure its effectiveness in practical applications, the influence of load current, SM capacitor voltage, and junction temperature is discussed. In addition, a readout circuit is designed featuring the integrated desaturation detection and voltage peak detection, which offers both the short-term overcurrent fault protection and long-term bond wire aging monitoring functions.

关键词： Temperature measurement   Insulated gate bipolar transistors   Turning   Fatigue   Temperature sensors   Thermal resistance   Steady-state   Condition monitoring (CM)   insulated gate bipolar transistor (IGBT) module   pre-heating stage   thermal fatigue   turning point  

摘要： This letter utilizes the turning point of preheating stage of case temperature T-c as an efficient indicator for condition monitoring of insulated gate bipolar transistor modules, which could be extracted from dynamic response of T-c. Theoretical analysis shows that the turning point will increase with aging process, and its effectiveness is experimentally verified. This method only requires temperature sensor to measure T-c without strict-measurement requirements. Thus, it brings negligible hardware burden, which is low cost and has more flexibility in online application. Besides, the installation of case temperature sensor does not cause intrusive change to the original system, and the measurement does not affect the normal operation of converter. These features make it more practical for noninvasive and real-time monitoring.

关键词： Impact ionization   lateral insulated-gate bipolar transistor (LIGBT)   safe operating area (SOA)   silicon-on-insulator (SOI)   SOI LIGBT   turn-off failure  

摘要： In this article, the inductive turn-off failure mechanism of U-shaped channel silicon-on-insulator lateral insulated-gate bipolar transistor (SOI-LIGBT) under high-voltage and high-current is investigated by experiments and numerical simulations. First, the measured turnoff waveforms before and after failure are compared to infer the cause of the failure. Then, the failure is reproduced by calibrated three-dimensional simulations using Sentaurus TCAD. According to the simulation and measured results, the turn-off failure is resulted from the high impact ionization in the bird's beak region. To reveal the failure mechanism, the turn-off failure process is divided into two phases. In phase I, the electrons generated by drastic impact ionization in the bird's beak region act as the base current to keep the operation of parasitic PNP transistor after channel pinching off. In phase II, the parasitic NPN transistor is activated due to the hole current amplified by PNP, and thus, turn-off failure occurs. Based on the revealed turn-off failure mechanism, an improved U-shaped channel SOI-LIGBT with a P-top is proposed. The P-top is arranged in the bird's beak region to reduce the impact ionization rate. The measured results demonstrate that no failure occurs when the improved device turns off under high-voltage and high-current conditions. Compared with the conventional U-shaped channel SOI-LIGBT, the improved device obtains 275% and 23% improvements in turn-off current at a bus voltage of 450 V and reverse bias safe operation area, respectively.

关键词： FEA thermal model   IGBT power module   Liquid cold plate   Thermal management   Traction inverter  

摘要： Estimation of accurate IGBT junction temperature is crucial for reliability assessment. The well-known RC lumped approach can help predict junction temperature. However, this method suffers from inaccuracy while characterizing the thermal behaviour of several IGBT modules mounted to the liquid-cooled heatsink. Specifically, the thermal challenge originates from the thermal cross-coupling and module-to-module heat spreading and the converter cooling condition. This article demonstrates a methodology to study the impact of heat spreading, thermal interface material, and massive size liquid cold-plate on the overall thermal behaviour. A case study of 50 kW traction inverter is chosen to demonstrate the benefit of early assessment of electro-thermal simulation before making costly prototype design. Power loss is initially estimated using an analytical loss model and later the estimated power loss is used in FEA (Finite Element Analysis) thermal model. This paper also compares the performance of single-phase and two-phase liquid cooling and various thermal interface materials (TIM) to determine which type of cooling system and TIM is most suitable for real applications. Simulation results suggest that combination of two-phase liquid cooling and TIM can improve the thermal performance and reduce junction temperature by 4.5%, 4.2%, 4.6% for the traction power load 30 kW, 40 kW, and 50 kW, respectively. The proposed methodology can be used as useful reference guidance for thermal design and modelling of IGBT based power converter applications. © 2023 The Author(s)

关键词： Al metallization layer   power cycling   surface roughness   macro-mesoscale modeling   crystal thermo-elasto-plasticity finite element  

摘要： One of the main failure modes of an insulated-gate bipolar transistor (IGBT) module is the reconstruction of an aluminum (Al) metallization layer on the surface of the IGBT chip. In this study, experimental observations and numerical simulations were used to investigate the evolution of the surface morphology of this Al metallization layer during power cycling, and both internal and external factors affecting the surface roughness of the layer were analyzed. The results indicate that the microstructure of the Al metallization layer evolves during power cycling, where the initially flat surface gradually becomes uneven, such that the roughness varies significantly across the IGBT chip surface. The surface roughness depends on several factors, including the grain size, grain orientation, temperature, and stress. With regard to the internal factors, reducing the grain size or orientation differences between neighboring grains can effectively decrease the surface roughness. With regard to the external factors, the reasonable design of the process parameters, a reduction in the stress concentration and temperature hotspots, and preventing large local deformation can also reduce the surface roughness.

关键词： 准谐振反激电路   一次侧反馈   斜率检测谷底导通   电磁干扰   开关损耗  

摘要： 针对准谐振工作模式的反激电路的开关管开通损耗高、开通时du/dt大导致EMI差的问题,提出一种斜率检测谷底导通控制方法。有效提高了谷底电压的检测精度,降低了开关管的开通电压,降低了开通损耗;减小了开通时开关管的du/dt,改善了电路的电磁干扰(EMI)性能。详细分析反激电路及所提控制方法的原理和工作过程,以及所提控制方法对电路EMI特性的影响,并设计了关键参数。最后,仿真和实验给出了样机在功率20~40 W,输入电压DC 430 V,输出恒流DC 1.05 A的效率曲线和EMI特性曲线,并与目前广泛运用的去磁检测法对比,验证了所提出控制方法的有效性。

关键词： 冷盘管   通断控制   比例调节   静特性   传热特性   冷水平衡   自动控制  

摘要： 为夯实大型公共建筑集中空调冷水系统末端冷盘管设备控制的研究基础,分别对某公共建筑末端冷盘管设备调节阀进行了通断控制和比例调节2种不同变流量调节方式的对比试验。通过冷盘管传热特性的变流量分析和讨论,对“用一个反向非线性特性的控制阀补偿末端设备的非线性特性”的控制理论提出了质疑,指出了末端冷盘管供回水温差控制策略存在的缺陷和不足。在同时满足冷水系统在役末端冷盘管设计供水温度和设计流量的前提下,提出了一种基于末端冷盘管冷水平衡的分布式控制技术,实现了集中空调冷水系统的冷水平衡自动调节和控制。

关键词： PROFIBUS-DP   MODBUS-TCP   变频器   以太网  

摘要： 随着车间生产线上设备的控制要求不断提高,需要检测的相关电气数据越来越多,不同类型的变频器回路也不同,常规的电气设计图纸复杂且接线困难,若要增加变频器设备就需要完成大量的接线工作,其可扩展性有限,并且不同类型的变频器通讯协议也不同,故单一网络已无法满足其控制需求。针对这些问题,本文设计了多总线的PLC与变频器通信控制系统。其PLC采用了西门子S7-1500系列产品,变频器选用了施耐德ATV320、ATV610及ATV930系列产品。本文在博途软件下进行了硬件的组态和编程,选用了WINCC上位机软件进行数据的监控和控制信号的给定等。本文的设计具有一定的应用参考价值。

关键词： 产品创新   工艺创新   参考质量  

摘要： 考虑消费者参考质量影响的基础上,建立了一个垄断厂商关于产品创新和工艺创新的动态控制模型,其中,产品的需求不仅依赖于价格和质量,还与消费者的参考质量有关。采用最优控制理论分别对厂商实现利润最大化以及政府实现社会福利最大化两种情况下厂商的创新投入决策问题进行研究,并通过数据模拟比较分析了稳态均衡附近两种创新投入和产品价格随时间变化的路径。结果表明:两种情形下分别存在一个唯一的鞍点稳态均衡;两种投入的变化率随参考质量的增加而增加,而稳态投入则随之下降;在其他参数不变的情况下,随着记忆参数的减小,厂商将增加对产品创新的稳态投入;厂商对两种创新投入的社会激励均高于私人激励。

关键词： 异步电机   电压模型   磁链观测   IF流频比  

摘要： 针对异步电机电压模型磁链观测器低速时存在定子电阻敏感、磁链估算不准和发电状态不稳定等问题,提出在低频阶段通过励磁电流偏差在线调整获得定子电阻补偿值,以提高低频速度估算准确性,同时提出在进入低速区域时,采用IF流频比控制技术实现特定负载下励磁电流和转矩电流分量的自动分配保证系统运行稳定,从而提高了无速度传感器矢量控制系统低频段运行稳定性和带载能力,通过仿真和实验验证了该方法的有效性。