期刊文献+
共找到144篇文章
< 1 2 8 >
每页显示 20 50 100
Reliability of DC-link capacitor in pulsed power supply for accelerator magnet
1
作者 Jie Wang Da-Qing Gao +2 位作者 Wan-Zeng Shen Hong-Bin Yan Li-Jun Mao 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第9期28-40,共13页
Capacitors are widely used in pulsed magnet power supplies to reduce ripple voltage,store energy,and decrease power variation.In this study,DC-link capacitors in pulsed power supplies were investigated.By deriving an ... Capacitors are widely used in pulsed magnet power supplies to reduce ripple voltage,store energy,and decrease power variation.In this study,DC-link capacitors in pulsed power supplies were investigated.By deriving an analytical method for the capacitor current on the H-bridge topology side,the root-mean-square value of the capacitor current was calculated,which helps in selecting the DC-link capacitors.The proposed method solves this problem quickly and with high accuracy.The current reconstruction of the DC-link capacitor is proposed to avoid structural damage in the capacitor’s current measurement,and the capacitor’s hotspot temperature and temperature rise are calculated using the FFT transform.The test results showed that the error between the calculated and measured temperature increases was within 1.5℃.Finally,the lifetime of DC-link capacitors was predicted based on Monte Carlo analysis.The proposed method can evaluate the reliability of DC-link capacitors in a non-isolated switching pulsed power supply for accelerators and is also applicable to film capacitors. 展开更多
关键词 Aluminum electrolytic capacitor dc-link current DC–DC power converter Hotspot temperature
下载PDF
风电变流器DC-Link电容器准在线状态监测方法 被引量:2
2
作者 朱城昊 王晗 +3 位作者 高少亭 陈文强 高超 蔡旭 《高电压技术》 EI CAS CSCD 北大核心 2023年第1期373-381,共9页
DC-Link电容是风电变流器中最核心但又最易失效的元件之一,对其进行状态监测可有效提高系统运行的可靠性。该文提出一种风电变流器DC-Link电容器准在线状态监测方法。首先,利用预充电阶段的交流电流重构DC-Link电容器的直流充电电流;采... DC-Link电容是风电变流器中最核心但又最易失效的元件之一,对其进行状态监测可有效提高系统运行的可靠性。该文提出一种风电变流器DC-Link电容器准在线状态监测方法。首先,利用预充电阶段的交流电流重构DC-Link电容器的直流充电电流;采用二阶指数函数对电容器在预充电阶段的电压和电流波形进行精确拟合;取拟合函数的参数作为特征值,将实测的电容器状态参数(C和RESR)作为特征值对应的输出,并通过实验获得的样本数据,构建特征值与其输出的映射关系;最后利用多输出最小二乘支持向量回归算法对数据集合进行学习训练,建立特征值与电容器状态参数的回归模型。该方法无需增加额外传感器和改变变流器控制算法。实验结果验证了本方法的有效性。 展开更多
关键词 风电变流器 dc-link电容器 状态监测 预充电电路 支持向量回归算法
下载PDF
大功率储能变流器功率模组DC-link电容器的试验研究 被引量:2
3
作者 杨轶成 丁明进 +2 位作者 孙婷 霍利杰 胡炫 《电源学报》 CSCD 北大核心 2021年第3期52-58,共7页
从满足最恶劣运行工况下纹波电流和满足动态响应的电容容值这两方面,对三相大功率储能变流器功率模组中的DC-link电容进行了计算设计。在简化模型下,定性分析了功率模组间连接铜排寄生电感对电容纹波电流的放大效应,并采取实验验证的方... 从满足最恶劣运行工况下纹波电流和满足动态响应的电容容值这两方面,对三相大功率储能变流器功率模组中的DC-link电容进行了计算设计。在简化模型下,定性分析了功率模组间连接铜排寄生电感对电容纹波电流的放大效应,并采取实验验证的方式在整机装置上进行了测试验证。测试发现,模组采用铜排连接方式的原有设计不合理,电容纹波电流放大明显,不能满足设计要求。针对该问题进行了改良设计,模组间更换采用叠排方式连接,改进后模组内DC-link电容的纹波电流放大现象得到了明显抑制,满足整机设计要求。 展开更多
关键词 变流器 功率模组 dc-link电容 电容纹波电流
下载PDF
基于DC-Link保护的直驱风机低电压穿越特性 被引量:1
4
作者 艾斯卡尔 朱永利 +2 位作者 唐彬伟 乔元 王海龙 《电源技术》 CAS CSCD 北大核心 2014年第5期906-908,980,共4页
研究了基于DC-Link保护回路的直驱风机在电网故障状态下的低电压穿越特性。研究了国家标准GB/T19963-2011对风机低电压穿越能力的要求。结合直驱永磁风力发电机组(PMSG)风机运行原理,构建了PMSG在PSCAD环境下的系统控制模型。结合电网... 研究了基于DC-Link保护回路的直驱风机在电网故障状态下的低电压穿越特性。研究了国家标准GB/T19963-2011对风机低电压穿越能力的要求。结合直驱永磁风力发电机组(PMSG)风机运行原理,构建了PMSG在PSCAD环境下的系统控制模型。结合电网三相对称短路故障,对加装和未加装DC-Link保护回路的PMSG的LVRT特性进行了分析和比较。仿真结果不仅证明了所用系统模型是合理的,控制策略是有效可行的,而且还表明加装DC-Link保护回路的PMSG具备较为优越的低电压穿越特性。 展开更多
关键词 风力发电 永磁直驱风机 dc-link保护 低电压穿越 PSCAD
下载PDF
森吉米尔轧机MV7000三电平变频器直流母线电压不平衡故障处理
5
作者 孙俊 刘沛迪 +1 位作者 丁孟予 陶桂林 《电工钢》 CAS 2024年第2期48-52,共5页
某森吉米尔轧机采用GE公司MV7309型中压变频器作为主传动。自投产以来,该变频器发生数次因右卷取机逆变器直流侧正负极电压之间的差值大于阈值导致的跳闸事故,影响生产效率。本文从该变频器采用的NPP型拓扑结构及直流电压调节方式等方... 某森吉米尔轧机采用GE公司MV7309型中压变频器作为主传动。自投产以来,该变频器发生数次因右卷取机逆变器直流侧正负极电压之间的差值大于阈值导致的跳闸事故,影响生产效率。本文从该变频器采用的NPP型拓扑结构及直流电压调节方式等方面入手,分析了可能造成直流侧正负极电压不平衡的各种原因,逐步排查,彻底解决了右卷取逆变器直流正负极电压不平衡的故障,对类似故障的处理具有较强的参考意义。 展开更多
关键词 森吉米尔轧机 MV7000 三电平变流器 直流母线 电压不平衡
下载PDF
Influence of Femtosecond Laser Parameters on Autler-Townes Splitting of Three-Level Ladder Molecules
6
作者 李月华 略兴强 +1 位作者 郭玮 姚洪斌 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2015年第2期128-133,I0001,共7页
We theoretically investigate the Autler-Townes (AT) splitting in the photoelectron spectra of three-level ladder K2 molecule driven by a pump-probe pulse via employing the time- dependent wave packet approach. The d... We theoretically investigate the Autler-Townes (AT) splitting in the photoelectron spectra of three-level ladder K2 molecule driven by a pump-probe pulse via employing the time- dependent wave packet approach. The dependence of AT splitting on two laser intensities and wavelengths are studied in detail. We firstly quantify these effects on peak shift and AT separation. The photoelectron spectra show double splitting with symmetric profiles, but with asymmetric profiles when the wavelength is changed. The magnitude of AT splitting increases with the pump laser intensity, but does not vary with probe intensity. The shifts of the absorption peaks and the splitting between AT doublet are predicted by using an analyt- ical fitting function when the intensity/wavelength of one of the two fields is changed. These novel results are of importance for the molecular spectroscopy and may further stimulate the first principles theoretical studies analytically. 展开更多
关键词 Autler-Townes splitting Photoelectron spectra three-level ladder K2 molecule
下载PDF
单闭环与去磁控制相协调的DFIG高电压穿越控制策略研究
7
作者 王艳娟 孙潇 李万禹 《微电机》 2024年第4期71-76,共6页
双馈感应风力发电机(DFIG)高电压穿越(HVRT)过程中,传统的网侧换流器(GSC)双闭环控制中,不仅外环对DC-link电压振荡反应有延时,且对内环的补偿也有一定的滞后效应;此外,传统的转子侧换流器(RSC)控制对其容量利用率较低,在HVRT时,存在向... 双馈感应风力发电机(DFIG)高电压穿越(HVRT)过程中,传统的网侧换流器(GSC)双闭环控制中,不仅外环对DC-link电压振荡反应有延时,且对内环的补偿也有一定的滞后效应;此外,传统的转子侧换流器(RSC)控制对其容量利用率较低,在HVRT时,存在向转子注入无功不足等问题。针对上述情况,本文提出一种单闭环控制与去磁控制相协调的HVRT控制方案。仿真结果表明,GSC单闭环与RSC去磁相协调的HVRT控制策略,不仅有效抑制了HVRT过程中DC-link电压的波动,克服了传统控制的弊端,而且在保证功率平衡及RSC容量完全利用的状态下向转子侧注入了无功,提高了RSC利用率,成功实现DFIG的故障穿越。 展开更多
关键词 双馈感应风力发电机 高电压穿越 dc-link电压 单闭环 去磁控制
下载PDF
Innovative Teaching Research on Literary Theory and Criticism
8
作者 HOU Xia 《Sino-US English Teaching》 2024年第7期309-313,共5页
As a core compulsory course for English majors majoring in teacher education,Literary Theory and Criticism plays an important role in enhancing text understanding,cultivating critical thinking,and shaping correct valu... As a core compulsory course for English majors majoring in teacher education,Literary Theory and Criticism plays an important role in enhancing text understanding,cultivating critical thinking,and shaping correct values in the future development of students.Influenced by traditional teaching ideas,students have many difficulties when learning this course,such as insufficient theoretical understanding,inadequate ability improvement,and not enough investment in course learning.In response to the above issues,this course focuses closely on the fundamental task of“cultivating virtue and nurturing people”,relying on modern information technology and introducing research methods of digital humanities.This course uses“7C”teaching mode under the“three-level integration”,in which“teaching”and“education”are carried out synchronously,and“teacher”and“student”are developed together,in order to greatly enhance students’learning participation and course satisfaction. 展开更多
关键词 literary theory and criticism double helix 7C teaching mode three-level integration participation rate satisfaction level
下载PDF
双馈风力发电系统DC-link电压振荡抑制策略 被引量:2
9
作者 高仕红 毛承雄 +1 位作者 王丹 陆继明 《电力系统及其自动化学报》 CSCD 北大核心 2018年第8期7-11,43,共6页
针对网侧变流器双闭环控制中电压外环对DC-link电压振荡抑制响应慢及电流内环对前馈补偿延时的问题,提出了一种直接控制DC-link电容器充电功率的网侧变流器单闭环控制策略。本策略中引入的前馈补偿直接施加在控制电压的节点上,以及一个... 针对网侧变流器双闭环控制中电压外环对DC-link电压振荡抑制响应慢及电流内环对前馈补偿延时的问题,提出了一种直接控制DC-link电容器充电功率的网侧变流器单闭环控制策略。本策略中引入的前馈补偿直接施加在控制电压的节点上,以及一个跟踪-微分器用于外界扰动动态前馈补偿的获取。在Matlab/Simulink平台中通过两种典型情况研究了所提出的网侧变流器控制策略对DC-link电压振荡抑制的有效性。结果表明,所提出的网侧变流器控制策略能有效抑制DC-link电压的冲击幅值及振荡,提出的前馈补偿方案及跟踪-微分器解决了电流内环对前馈补偿的延时以及经典微分器的噪声放大效应。 展开更多
关键词 双馈风力发电系统 网侧变流器 dc-link电压 跟踪-微分器 前馈补偿
下载PDF
Population Dynamics and Emission Spectrum of a Cascade Three-Level Jaynes-Cummings Model with Intensity-Dependent Coupling in a Kerr-like Medium 被引量:3
10
作者 ZHOU Qing-Chun 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第4期727-731,共5页
By using the method of eigenvectors, the atomic populations and emission spectrum are investigated in a system that consists of a cascade three-level atom resonantly interacting with a single-mode tield in a Kerr-like... By using the method of eigenvectors, the atomic populations and emission spectrum are investigated in a system that consists of a cascade three-level atom resonantly interacting with a single-mode tield in a Kerr-like medium. The atom and the field are assumed to be initially in the upper atomic state and the Fock state, respectively. Results for models with intensity-dependent coupling and with intensity-independent coupling are compared. It is found that both population dynamics and emission spectrum show no indications of atom-field decoupling in the strong field limit if the intensity-dependent coupling is taken into account. 展开更多
关键词 POPULATION emission spectrum cascade three-level atom Kerr-like medium
下载PDF
Decoupling Bang-Bang Group for Adiabatic Decoherence Control in a Three-Level Atom 被引量:3
11
作者 LIU Xiao-Shu WU Re-Bing +2 位作者 LIU Yang LIU Wen-Zhang LONG Gui-Lu 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第5X期810-814,共5页
In this paper, we study the control problem of adiabatic decoherence in a three-level atom. We will find the decoupling bang-bang group for various configurations, including the V configuration and the cascade type of... In this paper, we study the control problem of adiabatic decoherence in a three-level atom. We will find the decoupling bang-bang group for various configurations, including the V configuration and the cascade type of three-levelatom subjected to adiabatic decoherence. We also give the programs to design a sequence of periodic twinborn pulses to suppress the decoherence. 展开更多
关键词 decoupling bang-bang group three-level atom adiabatic decoherence
下载PDF
DC-link纹波电流分析与研究 被引量:9
12
作者 王世平 陈燕平 +2 位作者 熊辉 谢稳 窦泽春 《机车电传动》 北大核心 2016年第1期35-37,共3页
对DC-link电容寿命及使用稳定性起关键作用的是电容本身的温升,而温升与系统施加在电容两端纹波电流的大小有直接关系。通过理论计算、仿真验证、实测验证等方法,总结归纳DC-link纹波电流的计算方法,为工程人员合理选择DC-link电容、设... 对DC-link电容寿命及使用稳定性起关键作用的是电容本身的温升,而温升与系统施加在电容两端纹波电流的大小有直接关系。通过理论计算、仿真验证、实测验证等方法,总结归纳DC-link纹波电流的计算方法,为工程人员合理选择DC-link电容、设计散热方式及计算散热能力提供依据。 展开更多
关键词 dc-link电容 功率组件 纹波电流 电容寿命 温升 交直交系统
下载PDF
Generation of the nonlocal quantum entanglement of three three-level particles by local operations 被引量:2
13
作者 金星日 张英俏 +1 位作者 金哲 张寿 《Chinese Physics B》 SCIE EI CAS CSCD 2005年第10期1936-1941,共6页
We propose a scheme to realize the nonlocal quantum entanglement of three three-level particles by using a threeparticle entangled state of three levels as a quantum channel with the aid of some local unitary transfor... We propose a scheme to realize the nonlocal quantum entanglement of three three-level particles by using a threeparticle entangled state of three levels as a quantum channel with the aid of some local unitary transformations. This scheme can be directly generalized to the nonlocal quantum entanglement of N three-level particles. 展开更多
关键词 quantum entanglement three-level particle unitary transformation
下载PDF
A scheme for conditional quantum phase gate via bimodal cavity and a∧-type three-level atom 被引量:3
14
作者 蔡建武 方卯发 +1 位作者 廖湘平 郑小娟 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第11期2518-2522,共5页
We propose a scheme to implement a two-qubit conditional quantum phase gate for the intracavity field via a single three-level ∧-type atom driven by two modes in a high-Q cavity. The quantum inforraation is encoded o... We propose a scheme to implement a two-qubit conditional quantum phase gate for the intracavity field via a single three-level ∧-type atom driven by two modes in a high-Q cavity. The quantum inforraation is encoded on the Fock states of the bimodal cavity. The gate's averaged fidelity is expected to reach 99.8%. 展开更多
关键词 quantum phase gate ∧-type three-level atom bimodal cavity FIDELITY
下载PDF
Teleportation of Three-Level Multi-partite Entangled State by a Partial Three-Level Bipartite Entangled State 被引量:2
15
作者 DAI Hong-Yi ZHANG Ming LI Cheng-Zu 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第4期891-894,共4页
We present a scheme for probabilistically teleporting an unknown three-level bipartite entangled state by using a partial entangled three-level bipartite state as quantum channel This scheme can be directly generalize... We present a scheme for probabilistically teleporting an unknown three-level bipartite entangled state by using a partial entangled three-level bipartite state as quantum channel This scheme can be directly generalized to probabilistically teleport an unknown three-level k-particle entangled state by a partial three-level bipartite entangled state. A11 kinds of unitary transformations are given in detail We calculate the successful total probability and the total classical communication cost required for this scheme. 展开更多
关键词 TELEPORTATION three-level multi-partite entangled state classical communication cost
下载PDF
Schemes for Probabilistic Teleportation of an Unknown Three-Particle Three-Level Entangled state 被引量:2
16
作者 ZHAN You-Bang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第2期275-278,共4页
In this paper, two schemes for teleporting an unknown three-particle three-level entangled state are proposed. In the first scheme, two partial three-particle three-level entangled states are used as the quantum chann... In this paper, two schemes for teleporting an unknown three-particle three-level entangled state are proposed. In the first scheme, two partial three-particle three-level entangled states are used as the quantum channels, while in the second scheme, three two-particle three-level non-maximally entangled states are employed as quantum channels. It is shown that the teleportation can be successfully realized with certain probability, for both two schemes, ira receiver adopts some appropriate unitary transformations. It is shown also that the successful probabilities of these two schemes are different. 展开更多
关键词 probabilistic teleportation three-particle three-level entangled state unitary transformation
下载PDF
薄膜电容替代电解电容在DC-Link电容中的运用分析 被引量:8
17
作者 罗荣海 《电子世界》 2013年第13期71-72,共2页
随着新能源产业的发展,变流技术相应得到普遍运用,DC-Link电容作为其中的关键器件选型尤为重要。直流滤波器中DC-Link电容一般要求大容量、大电流处理以及高电压等特性,本文通过薄膜电容和电解电容特性对比以及相关运用分析,得出在要求... 随着新能源产业的发展,变流技术相应得到普遍运用,DC-Link电容作为其中的关键器件选型尤为重要。直流滤波器中DC-Link电容一般要求大容量、大电流处理以及高电压等特性,本文通过薄膜电容和电解电容特性对比以及相关运用分析,得出在要求工作电压高、承受高纹波电流(Irms)、有过电压要求、有电压反向现象、处理高冲击电流(dV/dt)以及长寿命要求的电路设计中,随着金属化蒸镀技术以及薄膜电容器技术的发展,薄膜电容在性能及价格方面替代电解电容将成为设计者今后选择的一种趋势。 展开更多
关键词 dc-link电容 薄膜电容 电解电容 替代
下载PDF
应用于DC-Link电容器的金属化膜自愈特性分析 被引量:7
18
作者 邹林 赵正涛 《电力电容器与无功补偿》 2014年第2期69-74,共6页
金属化DC-Link电容器较传统电解电容器具有很多优势,如何减少金属化膜电容器在自愈过程中的电容量衰减是一个重要研究课题。文章分析了金属化电容器自愈特性,研究了自愈特性与压强关系,通过自愈特性试验,结果表明压强的增大可减少自愈... 金属化DC-Link电容器较传统电解电容器具有很多优势,如何减少金属化膜电容器在自愈过程中的电容量衰减是一个重要研究课题。文章分析了金属化电容器自愈特性,研究了自愈特性与压强关系,通过自愈特性试验,结果表明压强的增大可减少自愈能量、优化自愈性能、减少自愈面积,对提升DC-Link电容器的性能具有指导意义。 展开更多
关键词 dc-link 金属化膜 电容器 自愈特性
下载PDF
双馈风电机组dc-link电压的直接电容电流控制策略 被引量:3
19
作者 高仕红 崔佳咪 胡唐超 《电力系统保护与控制》 EI CSCD 北大核心 2019年第8期152-158,共7页
传统GSC双闭环控制中存在电压外环对dc-link电压波动抑制响应慢及电流内环对前馈补偿延时的问题。对此提出一个dc-link电容电流直接控制的GSC单闭环控制策略。控制策略中引入的前馈补偿直接施加在GSC控制电压的节点上,消除了电流内环对... 传统GSC双闭环控制中存在电压外环对dc-link电压波动抑制响应慢及电流内环对前馈补偿延时的问题。对此提出一个dc-link电容电流直接控制的GSC单闭环控制策略。控制策略中引入的前馈补偿直接施加在GSC控制电压的节点上,消除了电流内环对扰动前馈补偿的延时。同时,对外界扰动动态的前馈补偿采用了一个"跟踪-微分器"技术。在Matlab/Simulink仿真平台中构建了GSC控制策略的研究模型,研究了两种典型情况下GSC控制策略对dc-link电压波动抑制的效果。结果表明所提出的GSC控制策略能有效抑制dc-link电压的波动幅值及振荡。 展开更多
关键词 双馈风力发电机组 网侧变流器 dc-link电压 跟踪-微分器 前馈补偿
下载PDF
Suppression of Phase and Amplitude Damping Decoherence in a Three-Level Atom in A-Configuration Using Bang-Bang Controls 被引量:1
20
作者 WANG Yan-Hui LIU Xiao-Shu LONG Gui-Lu1 Key Laboratory for Atomic and Molecular NanoSciences and Department of Physics,Tsinghua University,Beijing 100084,China2 Tsinghua National Laboratory for Information Science and Technology,Tsinghua University,Beijing 100084,China 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第7期71-74,共4页
In this paper,we present decoupling bang-bang operations for the suppression of general decoherence,bothamplitude and phase damping,in a three-level system in A-configuration.We give a program to design a sequence ofp... In this paper,we present decoupling bang-bang operations for the suppression of general decoherence,bothamplitude and phase damping,in a three-level system in A-configuration.We give a program to design a sequence ofperiodic twinborn pulses to suppress the decoherence in such the system. 展开更多
关键词 bang-bang operation general decoherence three-level system
下载PDF
上一页 1 2 8 下一页 到第
使用帮助 返回顶部