关于单片机实现电力变压器保护的研究

对单片机电力变压器保护装置设计提出探究,概述了电力变压器保护要点与单片机性能要求,设计模拟量输入通道,包括电压形成回路、低通滤波、采样保持电路,并设计开关量输入与输出电路,为提高单片机电力变压器保护效率提供理论依据.     

基于推挽电路的光伏DC-DC的设计

为获取稳定的直流母线电压,设计了一种双变压器隔离型推挽光伏DC-DC升压电路,输入电压为24V,输出稳定的400V母线电压,额定功率1000w。设计了变匝比4比32的高频变压器,对高频变压器的制作方法和推挽式电路工作原理过进行了详细的分析。最后搭建实验平台验证了实验的合理性。     

Sepic直流稳压器的设计

设计了一种输入交流电压范围为130~300 V,输出12 V/8 A、工作频率为100 k Hz的Sepic直流稳压器,阐述了主电路的拓扑结构,并设计了输入保护电路、辅助电源电路、PWM控制电路、光耦隔离驱动电路与输出过压、过流保护电路,应用反馈手段和脉宽调制技术实现电压、电流的稳定。     

产生双极性输出的无变压器DC／DC变换器

要从单个正极性输入产生双极性(正和负)输出的常见方法是采用变压器.虽然这种设计比较简单,但变压器本身会带来体积问题.把一个变压器装入一台要求减小电路占用面积和高度的设备中,这是具有挑战性的.图1所示电路可以从由3V～10V输入产生±5V输出,适用于没有地方安装变压器的设备.该电路所用的一种结构,能在DC/DC变换器处于关机模式时切断两个输出,这样就使处于关机(待机)模式时的静态电流很小.     

无输入变压器的6 V100 A稳压电源

本文叙述采用脉宽调制技术的开关式电源的工作原理和设计.电路输出600W,且直接输入240V交流而不使用50赫电源变压器.总的效率约为60～65%,几乎与负载无关.可以改进电路,输入其他电压例如50V直流电压.     

康佳彩霸彩电电源电路的分析与改进

<正> 康佳彩霸系列T2510型彩电,出现不易启动故障,究其原因,在于电源电路欠合理。本文介绍该机电源电路的工作原理、故障的检查与分析以及保护电路的改进。 一、基本工作原理 1.电源输入电路 220V交流电经由电源插头、保险丝、电源开关及两级互感滤波器后进入消磁电路和整流滤波电路,输出300V直流电压。这部分的原理不再赘述。 2.主电源开关电路(见图1) 由开关管V901和开关变压器T901等主要部件组成。VD913整流输出130V电压,供给行扫描电睡,VD914整流输出20V电压供给伴音电路。开机时,由XS901的①端输入的300V直流电压通过T901的P_1、P_4绕组加于V901的集电极,又通过启动电     

微型点焊机的制作

本点焊机的电路如图1所示,结构如图2所示．主要由变压电路,整流电路和充、放电电路组成。其中降压变压器为变压电路,输入的e1为220V的交流电,经过变压器降压,输出的e2为110V的交流电。     

一种低失调运算放大器的设计

基于Bipolar工艺设计,结合激光修调技术,实现一种四通道、低失调、低功耗、高增益的运算放大器。电路整体结构包含：基准偏置电路、差分输入及偏置补偿电路、中间级电路、输出及过流保护电路。输入级选择差分输入结构,采用输入偏置补偿设计,降低了输入失调电压和偏置电流;中间级采用射随器结构,结合密勒补偿电容及零点电阻,提高电路的稳定性;输出级采用B类的输出结构,结合过流保护设计,增加电路的安全性。电路封装后测试：输入失调电压10μV,输入偏置电流0.5nA,大信号电压增益130 dB,电源电流2.4mA,增益带宽积1.5MHz,噪声电压7.34nV/√Hz。     

中国首款WAPI芯片及IP核问世

半桥IGBT模块用的双驱动器，SKHI22A与SKHI22兼容，SKHI22B具有附加功能，输入端与CMOS兼容，由VCE监控电路和关断实现短路保护，驱动顶／底互锁，由变压器隔离，电源欠压保护(13V)，误差闭锁／输出，质量只有45g     

一种快速设计反激开关电源主电路的新方法

提出了一种设计50W以上反激开关电源主电路的实用有效方法--临界条件法,该方法将变压器的设计归结为在最大输入电压(230 V)条件下确定初级侧电感,在最小输入电压(90 V)条件下验证设计参数的正确性,优点是既可简化设计过程,又可避免因传统确定初级电感(最小输入电压和满载条件)需要估计纹波因数所带来的误差.成功地设计了一款90～264 V输入19 V输出的反激开关电源,采用PSIM6.0工具仿真该电源系统,结果显示反激变换器的输出电压纹波最大为±19.35 mV,输出电压精度为±0.10%,实测已实现系统板的结果显示,输出电压纹波较之仿真结果偏小约±3.50 mV.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Call for Papers

正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its