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Residual alkali-evoked cross-linked polymer layer for anti-air-sensitivity liNi_(0.89)Co_(0.06)Mn_(0.05)O_(2)cathode

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Journal of Energy Chemistry 2024年第5期92卷 450-458页

作者： Chao Zhao xuebao li Yun Zhao Jingjing He Yuanpeng Cao Wei Luo Ding Wang Jianguo Duan Xianshu Wang Baohua li National and Local Joint Engineering Research Center of lithium-ion Batteries and Materials Preparation Technology Key Laboratory of Advanced Battery Materials of Yunnan ProvinceFaculty of Metallurgical and Energy EngineeringKunming University of Science and TechnologyKunming 650093YunnanChina School of Materials Science and Engineering Central South UniversityChangsha 410083HunanChina Institute of Materials Research Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055Guangdong China City College Kunming University of Science and TechnologyKunming 650051YunnanChina

High-energy density lithium-ion batteries(liBs)with layered high-nickel oxide cathodes(liNi_(x)Co_(y)Mn_(1-x-y)O_(2),x≥0.8)show great promise in consumer electronics and vehicular ***,liNi_(x)Co_(y)Mn_(1-x-y)O_(2)faces challenges related to capacity decay caused by residual alkalis owing to high sensitivity to *** address this issue,we propose a hazardous substances upcycling method that fundamentally mitigates alkali content and concurrently induces the emergence of an anti-air-sensitive layer on the cathode *** the neutralization of polyacrylic acid(PAA)with residual alkalis and then coupling it with 3-aminopropyl triethoxysilane(KH550),a stable and ion-conductive cross-linked polymer layer is in situ integrated into the liNi_(0.89)Co_(0.06)Mn_(0.05)O_(2)(NCM)*** characterization and measurements demonstrate its *** NCM material exhibits impressive cycling performance,retaining 88.4%of its capacity after 200 cycles at 5 C and achieving an extraordinary specific capacity of 170.0 mA h g^(-1) at 10 ***,this layer on the NCM efficiently suppresses unfavorable phase transitions,severe electrolyte degradation,and CO_(2)gas evolution,while maintaining commendable resistance to air *** surface modification strategy shows widespread potential for creating air-stable liNi_(x)Co_(y)Mn_(1-x-y)O_(2)cathodes,thereby advancing high-performance liBs.

关键词： lithium-ion batteries Nickel-rich layered cathode Residual alkalis Cross-linked polyme rmodification Airsensitivity

Discharge Characteristics of Bubbles at Interface Between AIN Ceramic and FC-72 liquid

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 371-380页

作者： Shenyang Mo xuebao li Zhibin Zhao Xiang Cui State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China

In order to evaluate the insulation of two-phase immersion cooling in the HV power electronic package,the insulation degradation of the dielectric interface induced by bubbles is *** this paper,a test strategy with 50 Hz unipolar DC and AC combined voltage for partial discharge(PD)at boiling interface of AlN ceramic is *** insulation threshold of an AlN ceramic surface is acquired in several dielectric environments,such as air,FC-72 liquid(FC-72,a Fluorinert^(TM) from 3^(TM)),FC-72 vapor,and boiling state of *** reveals the deterioration of boiling on the insulation of the surface immersed in the dielectric *** investigate the mechanism of the PD feature at the boiling interface,the PD patterns of the unrestricted bubble and the accumulated bubble are acquired and contrastively *** with the feature of the back discharge and the bubble behavior,the charged vapor-ceramic interface is relatively stable due to the accumulated vapor *** stability of the charged vaporceramic interface is broken if the bubble is ***,it is discovered that the vapor-liquid interface inside the bubble may be another charged interface,which can also trigger a back discharge.

关键词： Biased AC voltage bubble FC-72 partial discharge power electronic package surface discharge twophase cooling

纳米晶铁心中频变压器磁-结构场耦合数值模拟

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高压电器 2024年第1期60卷 172-181,204页

作者：陈彬席彬晟李学宝万妮娜唐波湖北省输电线路工程技术研究中心湖北宜昌443002 三峡大学电气与新能源学院湖北宜昌443002 华北电力大学电气与电子工程学院北京102206 国网湖北省电力有限公司宜昌供电公司湖北宜昌443002

中频变压器是高压大容量直流变换器的核心元件,但高频率、高功率密度会导致变压器振动噪声加剧。为了精确模拟中频变压器的铁心振动特性,文中建立了中频变压器三维瞬态磁—结构场耦合分析计算模型,利用有限元法计算空载条件下铁心振动... 详细信息

中频变压器是高压大容量直流变换器的核心元件,但高频率、高功率密度会导致变压器振动噪声加剧。为了精确模拟中频变压器的铁心振动特性,文中建立了中频变压器三维瞬态磁—结构场耦合分析计算模型,利用有限元法计算空载条件下铁心振动加速度和位移。结合纳米晶卷形铁心层合结构的特点,按照横观各向同性对纳米晶铁心的力学材料特性参数进行计算和赋值。搭建了壳式和芯式两种不同铁心拓扑结构的中频变压器仿真模型和实物模型,通过仿真和实验系统性地研究了气隙结构、铁心拓扑结构对中频变压器振动的影响。通过理论计算和实验结果的比较证实:铁心气隙表面处的麦克斯韦力是振动的主要原因,壳式中频变压器的最大麦克斯韦力密度(25257 N/m^(2))大于芯式中频变压器(20936 N/m^(2));壳式铁心的最大加速度(40 m/s^(2))大于芯式铁心(30 m/s^(2))且数值模拟的误差在10%以内。

关键词：中频变压器铁心振动磁致伸缩麦克斯韦力振动加速度

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功率器件封装结构热设计综述

中国电机工程学报 2024年第7期44卷 2748-2773,I0020页

作者：王磊魏晓光唐新灵林仲康赵志斌李学宝北京智慧能源研究院北京市昌平区102209 新能源电力系统国家重点实验室(华北电力大学) 北京市昌平区102206

半导体技术的进步使得芯片的尺寸得以不断缩小,倒逼着封装技术的发展和进步,也由此产生了各种各样的封装形式。当前功率器件的设计和发展具有低电感、高散热和高绝缘能力的属性特征,器件封装上呈现出模块化、多功能化和体积紧凑化的发... 详细信息

半导体技术的进步使得芯片的尺寸得以不断缩小,倒逼着封装技术的发展和进步,也由此产生了各种各样的封装形式。当前功率器件的设计和发展具有低电感、高散热和高绝缘能力的属性特征,器件封装上呈现出模块化、多功能化和体积紧凑化的发展趋势。为实现封装器件低电感设计,器件封装结构更加紧凑,而芯片电压等级和封装模块的功率密度持续提高,给封装绝缘和器件散热带来挑战。在有限的封装空间内,如何把芯片的耗散热及时高效地释放到外界环境中以降低芯片结温及器件内部各封装材料的工作温度,已成为当前功率器件封装设计阶段需要考虑的重要问题之一。该文聚焦于功率器件封装结构的散热方面,针对功率半导体器件在散热路径方面的结构设计进行归纳总结。通过对国内外功率器件封装结构设计的综述,梳理功率器件封装结构设计过程中在散热方面的考虑及封装散热特点,并根据功率器件散热特点对功率器件封装结构类型进行分类。最后,基于降低封装结构散热热阻、提高器件散热能力的目的,从高导热封装材料和连接工艺、芯片面接触连接、增加散热路径以及缩短散热路程4个方面对功率器件封装结构设计在散热方面未来的发展趋势进行展望。

关键词：功率器件封装结构散热路径

正极性重复方波电压下有机硅凝胶内局部放电起始特性及影响因素研究

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高压电器 2024年第10期60卷 183-190页

作者：程金金李学宝李超刘相辰赵志斌华北电力大学新能源电力系统全国重点实验室北京102206

高压大功率绝缘栅双极晶体管(insulated gate bipolar transistor,IGBT)器件封装用有机硅凝胶的绝缘性能制约着器件的绝缘性能,目前针对器件所承受的正极性重复方波下有机硅凝胶内局部放电起始特性及影响因素的研究较少。文中建立了正... 详细信息

高压大功率绝缘栅双极晶体管(insulated gate bipolar transistor,IGBT)器件封装用有机硅凝胶的绝缘性能制约着器件的绝缘性能,目前针对器件所承受的正极性重复方波下有机硅凝胶内局部放电起始特性及影响因素的研究较少。文中建立了正极性重复方波电压下有机硅凝胶内局部放电实验平台,采用光电联合检测法获得了正极性重复方波下有机硅凝胶内局部放电起始特性并分析了机制,初步掌握了正极性重复方波波形参数包括上升时间、下降时间、占空比和频率对有机硅凝胶内局部放电起始电压PDIV(partial discharge inception voltage)和放电瞬时电压的影响规律。结果表明PDIV随上升时间变化不大,但200 ms处较150 ms处下降了10.4%,当下降时间大于100 ms时PDIV呈近似线性上升趋势,当占空比在30%~70%之间时保持相对稳定,随着频率增加PDIV在100 Hz处存在极小值。文中研究成果对于器件应用工况下IGBT器件内部封装用有机硅凝胶绝缘特性的认知具有一定的指导意义。

关键词：正极性重复方波电压有机硅凝胶波形参数局部放电起始电压放电瞬时电压

Space charge characteristics of silicone elastomer for device packaging under positive square wave voltage

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High Voltage 2023年第2期8卷 401-411页

作者： Jinqiang Zhang xuebao li Zhibin Zhao Xiang Cui State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijingChina

With the rapid development of power electronic devices towards high voltage and power,the insulation challenges faced by devices have attracted widespread *** elastomer is widely used in device packaging as one insulating material,and the study of its insulating properties is helpful to the reliable operation of *** this end we obtained the space charge characteristics of silicone elastomer under positive square wave voltage by using the pulse-electroacoustic(PEA)*** based on the existing research and IEC standards,the selection criteria of the resistance and capacitance parameters of a PEA system for space charge measurement under square wave voltage are *** this experimental system,the space charge distribution under the positive square wave voltage with different waveform parameters is obtained,and the influences of the waveform parameters on the space charge accumulation are *** amounts of charges under the action of square wave voltage with different waveform parameters are calculated,and the influences of waveform parameters on the amounts of charges are *** addition,the reasons for the difference in the accumulation of positive and negative charges are explained through Schottky injection model,the synthesis reaction and the infrared spectrum of the silicone elastomer.

关键词： charge wave characteristics

压接型IGBT芯片的参数分散性对其并联时关断均流的影响

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中国电机工程学报 2024年第5期44卷 1913-1923,I0021页

作者：曹子楷崔翔代安琪李学宝范迦羽詹雍凡唐新灵新能源电力系统国家重点实验室(华北电力大学) 北京市昌平区102206 先进输电技术国家重点实验室(北京智慧能源研究院) 北京市昌平区102209

压接型绝缘栅双极晶体管(insulated gate bipolar transistor,IGBT)的多芯片并联关断期间会出现严重的不均流现象,直接影响到器件的关断可靠性。文中重点研究压接型IGBT芯片参数对其并联时关断均流的影响,首先,根据IGBT单芯片的关断机... 详细信息

压接型绝缘栅双极晶体管(insulated gate bipolar transistor,IGBT)的多芯片并联关断期间会出现严重的不均流现象,直接影响到器件的关断可靠性。文中重点研究压接型IGBT芯片参数对其并联时关断均流的影响,首先,根据IGBT单芯片的关断机理和波形,分析芯片参数对IGBT单芯片关断各个阶段内集电极电流变化的影响规律;其次,定义多芯片并联关断波形中出现的第一类及第二类电流竞争峰谷,建立针对第一类电流竞争峰谷的随机分布模型,获得芯片参数以及并联数目对关断均流的影响规律,通过并联双芯片的双脉冲实验,验证所得规律的有效性;最后,结合分析结果提出阈值电压与饱和压降的相互补偿以及保持阈值电压差与跨导差异号等芯片筛选建议。研究成果可以为并联压接型IGBT芯片的参数筛选工作提供指导。

关键词：压接型绝缘栅双极晶体管关断均流芯片参数筛选建议

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Interface Finite Element Method with Lower Calculation Amount for Step Size-varying Electro-quasistatic Field Problem

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CSEE Journal of Power and Energy Systems 2023年第5期9卷 1710-1719页

作者： Zhaocheng liu Xiang Cui xuebao li Yongfan Zhan Zhibin Zhao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China

A novel FEM called interface finite element method(I-FEM)is proposed for the step size-varying electro-quasistatic field(EQS)in this ***,the corresponding equation and interface conditions for I-FEM are ***,the numerical principle of I-FEM is *** the proposed method,by the inverse matrix modification lemma,the calculation amount of I-FEM is decreased ***,the corresponding example is given to verify the effectiveness and correctness of *** last,the error analysis and universal promotion of the proposed I-FEM are *** with the normal FEM,I-FEM can greatly decrease the calculation amount while the numerical accuracy of I-FEM is even better than the normal FEM in some case.

关键词： EQS field inverse matrix modification lemma LU decomposition

Time-domain Finite Element Method for Transient Electric Field and Transient Charge Density on Dielectric Interface

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CSEE Journal of Power and Energy Systems 2022年第1期8卷 143-154页

作者： Teng Wen Xiang Cui xuebao li Hao Ma Zhibin Zhao State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China

This paper is devoted to solving the transient electric field and transient charge density on the dielectric interface under the electroquasistatic(EQS)field conditions with high *** proposed method is suitable for both 2-D and 3-D ***,the governing equations represented by scalar electric potential are discretized by the nodal finite element method(FEM)in space and the finite difference method in ***,the transient constrained electric field equation on the boundary(TCEFEB)is derived to calculate the normal component of the transient electric field intensities on the Dirichlet boundary and dielectric interface as well as the transient charge density on the dielectric ***,a 2-D numerical example is employed to demonstrate the validity of the proposed ***,the comparisons of the numerical accuracy of the proposed method in this paper with the existing FEMs for electric field intensity and charge density on the dielectric interface are *** results show that the numerical accuracy of the proposed method for calculating the normal component of transient electric field intensities on the Dirichlet boundary and dielectric interface as well as the transient charge density on the dielectric interface is close to that of nodal electric potential and an order of magnitude higher than those of existing FEMs.

关键词： Electroquasistatic field composite insulation structure transient constrained electric field equation on the boundary finite element method interface charge time-domain