An in-situ self-etching enabled high-power electrode for aqueous zinc-ion batteries

Sluggish storage kinetics is considered as the main bottleneck of cathode materials for fast-charging aqueous zinc-ion batteries(AZIBs).In this report,we propose a novel in-situ self-etching strategy to unlock the Palm tree-like vanadium oxide/carbon nanofiber membrane(P-VO/C)as a robust freestanding electrode.Comprehensive investigations including the finite element simulation,in-situ X-ray diffraction,and in-situ electrochemical impedance spectroscopy disclosed it an electrochemically induced phase transformation mechanism from VO to layered Zn_(x)V_(2)O_5·nH_(2)O,as well as superior storage kinetics with ultrahigh pseudocapacitive contribution.As demonstrated,such electrode can remain a specific capacity of 285 mA h g^(-1)after 100 cycles at 1 A g^(-1),144.4 mA h g^(-1)after 1500 cycles at 30 A g^(-1),and even 97 mA h g^(-1)after 3000 cycles at 60 A g^(-1),respectively.Unexpectedly,an impressive power density of 78.9 kW kg^(-1)at the super-high current density of 100 A g^(-1)also can be achieved.Such design concept of in-situ self-etching free-standing electrode can provide a brand-new insight into extending the pseudocapacitive storage limit,so as to promote the development of high-power energy storage devices including but not limited to AZIBs.

Numerical Investigation on Thermal Performance of Two-Phase Immersion Cooling Method for High-Power Electronics

The power density of electronic components grows continuously,and the subsequent heat accumulation and temperature increase inevitably affect electronic equipment’s stability,reliability and service life.Therefore,achieving efficient cooling in limited space has become a key problem in updating electronic devices with high performance and high integration.Two-phase immersion is a novel cooling method.The computational fluid dynamics(CFD)method is used to investigate the cooling performance of two-phase immersion cooling on high-power electronics.The two-dimensional CFD model is utilized by the volume of fluid(VOF)method and Reynolds StressModel.Lee’s model was employed to calculate the phase change rate.The heat transfer coefficient along the heatedwalls and the shear-lift force on bubbles are calculated.The simulation data are verified with the literature results.The cooling performance of different coolants has been studied.The results indicate that the boiling heat transfer coefficient can be enhanced by using a low boiling point coolant.The methanol is used as the cooling medium for further research.In addition,the mass flow rate and inlet temperature are investigated to assess the thermal performance of twophase immersion cooling.The average temperature of the high-power electronics is 80℃,and the temperature difference can be constrained to 8℃.Meanwhile,the convective heat transfer coefficient reaches 2740 W/(m2・℃)when the inlet temperature is 50℃,and the mass flow rate is 0.3 kg/s.In conclusion,the results demonstrated that two-phase immersion cooling has provided an effective method for the thermal management of high-power electronics.

An Improved Behavioral Model for High-voltage and High-power IGBT Chips

High-voltage and high-power IGBT chips have a noticeable carrier storage effect,which is related to the load current.However,the research on the carrier storage effect of existing IGBT behavior models is insufficient.In this paper,An improved behavioral model for high-voltage and high-power insulated gate bipolar transistor(IGBT)chips is proposed,which could be used under different load conditions.The problems for applying the traditional behavioral model to more load conditions are discussed.Carrier behavior,in the wide base region,is analyzed,and the analytical expression of the carrierstorage-effect equivalent capacitance and the initial value of the tail current are provided to establish an improved IGBT behavioral model.A corresponding parameter extraction method is proposed.In order to verify the improved behavioral model,an experimental platform is built for resistive load and inductive load,and the results show that the accuracy of the improved behavioral model is much better than that of the traditional model.In addition,the errors of the improved model are within 12.5%under different current and load types.Considering that the maximum error of other models,which could be applied in a variety of load conditions,is more than 25%,the accuracy of the model proposed in this paper is excellent.

Applications of Wide Bandgap Semiconductor Materials in High-Power Electronic Devices

Wide bandgap semiconductor materials are driving revolutionary improvements in the performance of high-power electronic devices. This study systematically evaluates the application prospects of wide bandgap semiconductor materials in high-power electronic devices. The research first compares the physical properties of major wide bandgap materials (such as silicon carbide SiC and gallium nitride GaN), analyzing their advantages over traditional silicon materials. Through theoretical calculations and experimental data analysis, the study assesses the performance of these materials in terms of high breakdown field, high thermal conductivity, and high electron saturation velocity. The research focuses on the application of SiC and GaN devices in power electronics, including high-voltage DC transmission, electric vehicle drive systems, and renewable energy conversion. The study also discusses the potential of wide bandgap materials in RF and microwave applications. However, the research also points out the challenges faced by wide bandgap semiconductor technology, such as material defect control, device reliability, and cost issues. To address these challenges, the study proposes solutions, including improving epitaxial growth techniques, optimizing device structure design, and developing new packaging methods. Finally, the research looks ahead to the prospects of wide bandgap semiconductors in emerging application areas such as quantum computing and terahertz communications. This study provides a comprehensive theoretical foundation and technology roadmap for the application of wide bandgap semiconductor materials in high-power electronic devices, contributing to the development of next-generation high-efficiency energy conversion and management systems.

Analysis of high-power disk laser welding stability based on classification of plume and spatter characteristics

Classification of plume and spatter images was studied to evaluate the welding stability. A high-speed camera was used to capture the instantaneous images of plume and spatters during high power disk laser welding. Characteristic parameters such as the area and number of spatters, the average grayscale of a spatter image, the entropy of a spatter grayscale image, the coordinate ratio of the plume centroid and the welding point, the polar coordinates of the plume centroid were defined and extracted. Karhunen-Loeve transform method was used to change the seven characteristics into three primary characteristics to reduce the dimensions. Also, K-nearest neighbor method was used to classify the plume and spatter images into two categories such as good and poor welding quality. The results show that plume and spatter have a close relationship with the welding stability, and two categories could be recognized effectively using K-nearest neighbor method based on Karhunen-Loeve transform.

计及IGBT结温约束的光伏高渗透配电网无功电压优化控制策略

光伏电源参与配电网无功电压调节是提升光伏高渗透配电网运行经济性和可靠性的有效手段,但光伏电源提供无功支撑会使得光伏电源IGBT最大结温升高、结温波动加剧,进而影响光伏电源和配电网的安全稳定运行。为此,该文提出一种计及IGBT结温约束的光伏高渗透配电网无功电压优化控制策略。首先,利用CatBoost算法计算IGBT结温,提高了IGBT结温计算效率,避免了传统结温算法对IGBT热模型参数的依赖;然后,建立考虑IGBT结温约束的有源配电网多目标无功优化模型,利用二分法求解IGBT结温约束下的光伏电源最大输出功率,实现了IGBT结温约束向二阶锥约束的转换;最后,利用IEEE33节点典型配电系统验证了所提策略在光伏高渗透配电网无功电压优化、光伏电源运行可靠性提升方面的有效性,并提出了综合考虑配电网网损、光伏电源可靠性的光伏电源IGBT结温限值整定原则。

基于注意力机制的CNN-BiLSTM的IGBT剩余使用寿命预测

针对绝缘栅双极型晶体管(IGBT)可靠性问题,提出了一种融合卷积神经网络(CNN)、双向长短期记忆(BiLSTM)网络和注意力机制的剩余使用寿命(RUL)预测模型,可用于IGBT的寿命预测。模型中使用CNN提取特征参数,BiLSTM提取时序信息,注意力机制加权处理特征参数。使用IGBT加速老化数据集对提出的模型进行验证。结果表明,对比自回归差分移动平均(ARIMA)、长短期记忆(LSTM)、多层LSTM(Multi-LSTM)、 BiLSTM预测模型,在均方根误差和决定系数等评价指标方面该模型的性能最优。验证了提出的寿命预测模型对IGBT失效预测是有效的。

用于IGBT模块温度观测的3-D降阶混合型热模型

IGBT模块温度在线监测是提高大容量变流器可靠性的关键技术。在IGBT模块在线温度监测方法中,热阻模型法可对IGBT模块内部的温度分布进行估计,因而受到关注。结合了传感器数据的温度观测器可基于热阻模型,实时修正材料老化、参数温度依赖性和功率损耗计算误差等不确定因素对温度估计造成的影响。然而现有热模型无法同时兼顾系统可观性和建模准确性,且阶数相对较高,难以应用于温度观测器的在线运行。因此,该文提出了一种适用于风冷散热多芯片IGBT模块3-D温度观测器,同时满足可观性、准确性和实时性要求的混合型降阶热模型。首先,分析了热阻模型的拓扑结构及其参数辨识的方法,并探究了模型的状态空间生成规律;然后,基于非线性优化算法对该模型的参数进行修正,以减小因计算流体力学(CFD)仿真模型参数与实际参数不一致所引入的热阻模型与实验物理对象间的误差;随后,使用平衡截断法对热阻模型降阶,相对于现有集总参数热阻模型,进一步提高了实时求解效率;最后,通过仿真和实验验证了所提模型的准确性。

基于Bo-BiLSTM网络的IGBT老化失效预测方法

针对绝缘栅双极型晶体管(IGBT)受热应力冲击后对其进行老化失效预测精度不高的情况,提出一种基于贝叶斯优化(Bo)-双向长短期记忆(BiLSTM)网络的IGBT老化失效预测方法。首先分析IGBT模块老化失效原理,然后基于NASA老化实验数据集建立失效特征数据库,最后利用Matlab软件构造Bo-BiLSTM网络预测失效特征参数数据。选取常用回归预测性能评估指标将长短期记忆(LSTM)网络模型、BiLSTM网络模型与Bo-BiLSTM网络模型的预测结果进行对比分析。结果表明,Bo-BiLSTM网络的模型拟合精度更高,基于Bo-BiLSTM网络的IGBT老化失效预测方法具有较好的预测效果,能够应用于IGBT的失效预测。

增强牵引变流器过载的IGBT泵升驱动技术

轨道交通牵引变流器在车辆启动加速和紧急制动过程中,会运行在过载工况,即流过IGBT的电流超过设计的额定电流。此时虽然仍在器件允许电流范围内,但IGBT损耗会出现较大增幅,导致变流器温升大幅波动。研究一种集成门极电压泵升技术的IGBT驱动电路,在需要短时加大IGBT通流能力时,可以将门极开通电压升高,降低IGBT的导通压降,减小IGBT的损耗和温升波动。分析过载工况下的牵引变流器工作特性,并在此基础上计算IGBT的损耗和温升情况;分析门极开通电压升高对IGBT导通压降的影响,并设计具有门极电压泵升功能的IGBT驱动电路。通过仿真和双脉冲动态开关实验,验证此设计功能的有效性。

基于EMR与V_(eE_peak)组合电参数的IGBT模块封装老化监测

该文提出一种基于电磁辐射干扰(EMR)与V_(eE_peak)组合电参数监测IGBT模块封装老化的方法,旨在监测多种老化同时发生时IGBT模块的健康状态。首先,分析V_(eE_peak)和EMR的产生机理以及模块内部寄生参数对VeE和EMR的影响;其次,分析不同老化对IGBT模块内部寄生参数的影响;最后,结合实验结果证明所提方法的正确性。这是一种不需要复杂监测电路的非侵入式监测方法,可有效降低多种老化耦合对IGBT模块健康状态监测结果产生的误差。

并联IGBT占空比的温度特性建模与分析

并联IGBT是解决托卡马克(Tokamak)装置中等离子体垂直位移快速控制电源容量逐渐增大问题的有效途径。而并联IGBT之间的结温平衡是并联系统安全稳定运行的关键因素之一。因此,研究结温对并联IGBT功率损耗差异的影响对提高并联系统的稳定性至关重要。然而现有的研究成果主要集中在单个器件损耗模型或者是并联IGBT的最佳工作频率范围而未涉及对并联IGBT最佳工作占空比范围的讨论。研究发现,当IGBT工作在正温度系数区间时,结温差异造成的通态损耗差异与开关损耗差异呈不同的温度特性。因此,提出零温度-占空比的概念来估计并联IGBT之间结温失配趋势。该文建立零温度-占空比模型,并以此来分析电路设计参数、IGBT器件参数以及结温差异对并联IGBT最佳工作占空比范围的影响。实验结果表明,通过零温度-占空比模型可以对并联IGBT的可靠性、电路设计参数以及器件选型提供可行的参考。

基于改进DBO优化BiLSTM的IGBT老化预测模型

为了表征逆变器故障中IGBT模块的老化趋势,提高老化过程的预测精度,本文提出一种基于改进蜣螂搜索算法(IDBO)优化双向长短期神经网络(BiLSTM)超参数的IGBT老化预测模型。首先提取老化过程中Vce.on的时频域特征,利用核主成分分析进行降维构建归一化综合指标。其次,针对蜣螂搜索算法(DBO)的不足,通过引入改进Circle混沌映射、Levy飞行和自适应权重因子提升了DBO寻优能力和收敛性能,利用IDBO对BiLSTM预测模型超参数实现全局寻优。最后,通过实际IGBT退化数据验证了基于IDBO优化BiLSTM老化预测模型的有效性和优越性。结果表明,所构建的IDBO-BiLSTM模型与BiLSTM模型相比RMSE平均下降36.42%、MAE平均下降31.77%、MAPE平均下降41.03%。

基于干冰微粒喷射冷却的高速列车IGBT散热器设计

针对高速列车IGBT模块的高效散热问题,设计了一种应用于干冰微粒喷射冷却的针肋散热器。建立了3组不同针肋参数模型,通过数值模拟研究分析了针肋数量、直径、高度对散热效果的影响,得出最优针肋散热器的针肋数量为64、直径为12 mm、高度为45 mm,相比于无肋散热器其换热基板表面温度降低了10.57℃,散热器内部干冰升华率提高了17.2%。通过实验观测到了干冰微粒冷却流体在管内流动状态以及干冰微粒在散热器内部扰动碰撞过程,验证了模拟结果,干冰微粒喷射冷却使热源功率为1.6 kW的IGBT模块保持在约25℃,满足其散热需要,为深入研究干冰微粒喷射冷却技术提供指导。

IGBT动态雪崩失效机理仿真分析

IGBT在关断过程中所发生的动态雪崩现象是导致其失效的重要原因之一。为研究IGBT动态雪崩失效机理,利用Silvaco软件对其进行仿真分析。通过对动态雪崩击穿机制、电流密度分布和温度分布的仿真分析,得出动态雪崩可以产生移动的电流丝和移动十分缓慢或固定不动的“死丝”。引起器件失效的是动态雪崩形成的死丝,死丝会导致IGBT内局部温度的急剧增加,最终因局部温度过高烧毁器件导致IGBT的失效。在此基础上分析了死丝产生的原因并进一步提出防止IGBT动态雪崩失效的具体措施。

基于稳态集-射极饱和电压的IGBT功率模块疲劳失效模型的研究

随着绝缘栅双极型晶体管(insulated gate bipolar transistor, IGBT)功率模块在民用和军用领域应用的不断深入,IGBT功率模块在长时间电-热应力下的疲劳老化问题越来越突出。本文基于半导体物理和器件可靠性理论,研究IGBT功率模块封装失效的产生原因,分析焊料层和键丝失效的作用机理和表现特征。在研究IGBT通态电压模型的基础上,提出了一种基于稳态集-射极饱和电压的IGBT功率模块疲劳老化模型,实现对焊料层疲劳和键丝疲劳等封装老化问题的综合表征。搭建IGBT功率模块的电-热老化实验测试平台,进行了功率循环老化实验验证,结果表明本文模型可以较为准确地评估IGBT功率模块封装的疲劳老化程度。

电动汽车IGBT剩余使用寿命预测

引入一种基于贝叶斯优化(BOA)的双向长短时记忆网络(Bi-LSTM),同时结合注意力机制,应用于绝缘栅双极型晶体管(IGBT)剩余使用寿命预测,所提方法可有效提高IGBT剩余使用寿命预测的准确性.通过IGBT加速老化试验收集V CE-on,验证了其作为失效特征参数的可行性,并将其作为实验数据集对所提方法进行仿真验证.实验分析结果表明,所提的混合预测模型与经典LSTM及其他预测模型相比,有更低的退化预测误差,具备较高的理论意义和实践价值.

IGBT感应发热热效机制及其工艺因素分析

建立IGBT感应电源进行感应发热的物理模型,热力学分析金属物块的电磁感应能力和材料物理特性等因素对感应发热效果的影响;试验对比铁、铜、铝三种不同金属物块的感应发热的升温时效和温度分布,探讨调整感应电源的电参数及感应线圈的形状,优化感应发热效果,进一步分析其热效机制。试验结果表明:感应发热热效主要受电磁感应的电参数、工件材料物理特性、感应发热条件工况等的直接影响,实际应用中合理调整电源频率、感应电流等电参数,优化电源电气条件,匹配感应线圈的结构形状,可以有效提高感应发热热效。

基于失效演化模拟的电力机车用IGBT模块解析剩余寿命建模研究

牵引变流器作为电力机车系统中最关键且故障率最高的设备,影响系统的安全运行,其中绝缘栅双极晶体管(insulated gate bipolar transistor,IGBT)模块是导致牵引变流器失效的主要部件。开展IGBT模块剩余寿命准确评估,对降低运维成本和系统故障率具有重要的战略价值和经济意义。目前采用“里程修”的运维方式,未考虑机车运行线路、工况、负载差异等因素对寿命的影响,导致一些线路过早更换的高昂运维成本和一些线路过晚替换的系统停运风险。因此,在牵引系统IGBT模块故障率高、运行线路间可靠性差异大且采用不合理的“里程修”方式背景下,目前业界普遍关心的问题是各线路基于固定里程修更换的IGBT模块剩余寿命是多少。该文针对电力机车用IGBT模块剩余寿命准确评估的问题,以IGBT模块焊料层不同服役里程空洞尺寸分布规律为基础,建立考虑焊料层空洞空间分布规律的精细化多物理场模型,开展多芯片并联IGBT模块失效演化物理过程模拟,提出以焊料层空洞分布统计规律为老化状态的电力机车用IGBT模块解析剩余寿命预测模拟,并通过功率循环试验验证改进模型准确性。研究成果丰富功率器件的寿命预测和可靠性评估理论,为系统从“里程修”向“状态修”转变提供科学依据。

基于焊层裂纹扩展的IGBT性能退化建模与分析

在疲劳载荷作用下,绝缘栅双极型晶体管(insulated gate bipolar transistor,IGBT)会发生结构损伤与性能退化,影响电力电子系统可靠性。对此,首先基于传热学理论推导焊层疲劳裂纹长度与热阻的关系,并以Darveaux模型表征IGBT焊层裂纹演化规律,提出一种IGBT性能退化模型及其待定系数的估计方法。其次,考虑实际工况的非平稳特征,利用响应面法建立IGBT变幅疲劳载荷模型,并基于雨流计数法与线性累积损伤准则实现IGBT性能退化量的评估。最后,以一款IGBT产品为例,实施功率循环试验,基于试验数据开展性能退化建模与分析,验证了模型与算法的有效性。