共查询到16条相似文献,搜索用时 93 毫秒
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在EAST 快控电源中采用瞬时环流反馈引入虚拟电阻的均流控制策略,可大大增加并联逆变器之间等效输出阻抗的实部,有效提高对环流低频分量的抑制能力。仿真和实验结果验证了该控制策略的可行性和有效性。 相似文献
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介绍了HL-2A装置欧姆加热电源逻辑无环流运行的基本原理和实现步骤。通过对系统的理论分析和仿真,提出了正组变流器逆变可靠运行的控制方案。对出现环流以后的控制策略进行了探讨,实验结果验证了分析的正确性。 相似文献
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高温超导变压器的漏磁场降低绕组中的临界电流并增加交流损耗;超导材料的零电阻特性使得绕组限制环流的能力极低.因此,在设计超导变压器时,进行磁场分析和环流计算显得尤其重要.本文采用场-路结合的方法,即在用ANSYS求得反映变压器各支路之间电磁耦合的电感矩阵的基础上列出电路方程,计算了变压器低压绕组5种不同形式的各支路电流分布,并进而分析了磁场.同时提出了减小环流和改善磁场分布的一些措施. 相似文献
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针对2009年11月冰冻雨雪事件,通过经验正交函数分解等方法提取10—30 d稳定分量,并第一次运用计算贡献率和相似系数判定等手段把稳定分量进一步客观地分离成气候态稳定分量和异常型稳定分量.将气候态稳定分量与低通滤波分量合成气候背景场.研究发现:气候背景场环流形势持续时间较长,随时间变化缓慢,主要提供了事件发生的气候背景,指示大尺度环流调配置和调整;气候背景场空间活动范围较大,能较好地刻画永久半永久性大气活动中心变化情况,且在垂直各层有稳定一致的配置关系;异常型稳定分量重点体现了环流相对异常特征,与2009年11月冰冻雨雪事件有较好的对应关系.在气候背景场提供确定的环流大背景下,异常型稳定分量表征了对应天气系统的相对强弱变化. 相似文献
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介绍了三相无环流交交变频控制系统设计的控制原理及其DSP控制系统硬件和软件的具体设计,并给出了在搭建的主回路平台上进行整体调试的结果。在其DSP控制系统的驱动控制下,三相交交变频器能输出频率为0~15Hz电流和电压波形,电流无环流死区时间为1.2ms,调试结果显示所研制的DSP三相交交变频数字控制系统具有较高的控制精度和实时性。 相似文献
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介绍了三相无环流交交变频控制系统设计的控制原理及其DSP控制系统硬件和软件的具体设计,并给出了在搭建的主回路平台上进行整体调试的结果。在其DSP控制系统的驱动控制下,三相交交变频器能输出频率为0~15Hz电流和电压波形,电流无环流死区时间为1.2ms,调试结果显示所研制的DSP三相交交变频数字控制系统具有较高的控制精度和实时性。 相似文献
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HT-7U装置极向场电源变流系统的研制 总被引:1,自引:0,他引:1
介绍了HT-7U极向场电源中所使用的变流系统,提出了一种新的四象限运行控制方法,解决了极向场电源设计和制造的难点。实现了15kA的有环流运行。 相似文献
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《Physica C: Superconductivity and its Applications》2007,451(1):8-12
A measurement technique was developed to identify the critical current of superconducting rings. It is based on the detection of the voltage on a secondary coil when the current induced in the superconductor by a primary one go beyond to the critical value. The technique uses a DC power supply to control the AC current circulating by the primary circuit. Such circuit mainly consists on an AC power supply which gives a constant AC voltage, a primary inducting coil and a control coil with iron core. The AC current circulating by this circuit is modified with the change in the impedance of the control coil due to the fact of the DC current supplied by the power supply in parallel with it. 相似文献
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Erdem Ozuturk 《Optik》2013
In many investigations on LEDs, the radiant power?current characteristic of LED has been drawing for high currents without giving any mathematical equation between them. The radiant power?current variation of LED can be expressed with a formula. In this study the thermal effect on radiant power of LED at pulsed high currents has been formulated and a mathematical equation has been derived between current amplitude and radiant power of LED. This equation has been examined by drawing theoretical and experimental variations on the same graph. In addition, the effect of instantaneous resistance?current variation of LED on its radiant power?current characteristic has been shown. 相似文献
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A. Drees 《Acta Physica Hungarica A》2006,25(2-4):475-486
Luminosity mainly depends on the beam intensity of the circulating beams and the beam profiles at the interaction points. By either increasing the total beam current or decreasing its size the instantaneous luminosity can be increased. In addition any method to slow down beam growth and debunching processes will further improve the luminosity which can be integrated over a store. Optimizing beam cleaning procedures such as collimation or abort gap cleaning will further increase the amount of usable luminosity for experiments. This paper will give a brief introduction to some accelerator basics of interest and the luminosity as a function of beam parameters. Limitations to the achievable integrated luminosity as well as future upgrades to overcome these limitations are presented. 相似文献
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The density matrix picture of laser coherent control current 总被引:3,自引:0,他引:3
SHOU Qian ZHANG Haichao LIU Luning & LIN Weizhu State Key Laboratory of Optoelectronic Materials Technologies Zhongshan 《中国科学G辑(英文版)》2004,47(2):231-243
The photocurrent has been widely investigated for a long time. Conventionally the current results from the directional motion of the photo-electrons accelerated by dc bias. In recent years, the development of the optical information science calls for the Tbit per second transport speed, so the related devices must work on a time scale of picosecond even femtosecond. But this requirement is limited by the lifetime of the conventional photo-electrons. With the development of ultrafast laser pul… 相似文献
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The effects of specific adsorption on the in situ resistance measurement are studied using polycrystalline gold film electrodes of various thicknesses. A differential technique is developed where the instantaneous changes in the electrode resistance are correlated to the voltammetric current in linear sweep voltammetry. With the successful separation of the interfacial processes on these measurements, it is shown that the electrode resistance has a linear response to the coverage of the specifically adsorbed Br? and I? ions, independent of the electrochemical parameters. While the sensitivity of the resistance to adsorption depends strongly on the intrinsic properties of the gold film, it is shown that the ratio of the resistance responses to these halides on the same electrode is invariant. In the framework of the scattering hypothesis of Wedler and Wissman, the apparent scattering cross section of iodide on gold is approximately 0.015 nm2 as determined by an extrapolation of the resistance response to infinite thickness. With the electrosorption valency of bromide as ?0.81, the corresponding apparent scattering cross section is accurately determined to be 0.66 times that for iodide. 相似文献