PLC在化工厂粉体生产线中的应用

本文简单介绍了粉体生产线的工作原理，以及三菱MELSECA系列PLC在生产线改造中的应用。     

Current mode filters using two output inverting CCII

Current mode Tow Thomas filter using two‐output inverting second‐generation current conveyor is given, the circuit has low input impedance, employs two grounded capacitors and three grounded resistors and has independent control on Q. A universal current mode filter capable of realizing the five filter functions is also given. Both circuits have low sensitivities to all circuit components. Spice simulation results are included. Copyright © 2007 John Wiley & Sons, Ltd.     

A proposal for high‐performance CCII‐based analogue CMOS design

A novel fully differential CMOS second‐generation current conveyor (CCII) topology is presented. It can be considered as a universal fully differential programmable active element. The circuit operates in moderate inversion region, and features high linearity over a wide input range. Current gain between terminals X and Z can be continuously tuned in a wide range. These features are essential to extend the utilization of CCII‐based circuits to high‐performance VLSI applications. Analogue design based on this new cell is illustrated by various examples. The proposed CCII has been fabricated in a 0.5‐µm CMOS technology and its main performance characteristics have been measured. They are in good agreement with theory and demonstrate that operation in moderate inversion can lead to distortion levels much lower than those achieved in strong inversion. Experimental results for a Tow–Thomas biquadratic filter fabricated on the same chip are also presented, showing continuous frequency tuning in more than a decade. Copyright © 2005 John Wiley & Sons, Ltd.     

施耐德PLC在焦处理控制系统中的应用

主要介绍了攀钢煤化工焦处理采用的以施耐德电气公司的Quantum系列控制器为过程控制平台的自动化系统的配置、系统功能的实现及控制系统的特点，较好地满足了生产的需要。     

电流模式精密有源整流器

文中用改进型电流传输器实现了一种新的基于电流模式的精密有源整流电路，该电路可在微安或微伏数量级的信号下正常工作，因此在微弱信号的处理中优越于基于电压模式的同类电路。理论分析和计算机仿真结果证实了本文电路的正确性。     

下花园发电厂2号锅炉捞渣机改造

下花园发电厂2号锅炉底部除渣为碎渣机结合冲渣水的水力除渣方式,耗水量大,出渣时炉底的漏风容易使燃烧中心上移,影响汽温。通过把炉底除渣设备改造为捞渣机,减少了炉底漏风,节约了生产用水,提高了运行的安全性和经济性。     

胶带输送机电气运行与维护新技术

针对胶带输送机在运行与维护方面存在的问题进行研究与科技攻关,应用和改进多功能自动喷雾装置,新型故障诊断系统,盘式可控制动装置,智能真空组合开关,隔爆变频调速装置和通信、控制及保护系统等,研制出红外转轴表面温度传感器和光电式溜槽堵塞检测开关,实现采区与顺槽胶带机联锁,有效地保障了胶带输送机的安全运行。     

电压模式CCⅡ+/-双二阶滤波器

提出了一种用八个CCⅡ +/ -实现的电压模式双二阶滤波器结构 ,该结构用了两个电容和八个电阻。它无需改变输入电压和接地点的位置 ,可实现电压模式二阶低通、高通、带通、陷波和全通滤波特性 ,且各滤波电路的零点参数和极点参数均可独立调节。     

长距离胶带输送机变频调速控制系统设计及应用

针对某煤矿长距离胶带输送机采用西门子Simovert MV系列中压变频器调速驱动的实际工程应用,分析了胶带输送机及其张力特性、负载特性与机械特性,介绍了其优化的速度和加速度驱动模型。系统设计采用可编程控制器S7-300 PLC作为主从控制器,实现了多驱动器之间的协调控制,使胶带输送机在轻载及重载工况下,均能有效控制其柔性负载的软起动/软停车动态过程,实现各驱动之间的功率平衡,降低直接起动/快速停车过程对机械和电气系统的冲击,大大增加输送系统的安全性和可靠性。     

新式输粉机轴承支座的设计

分析了电厂制粉系统输粉机轴承支座易磨损毁坏的原因 ,做出了技改措施 ,延长了轴承支座使用寿命 ,节约了生产成本。     

基于PC的一种新型现场总线控制系统

PC性能的不断提高及实时操作系统内核的出现,促使了一种基于PC和现场总线的新型控制系统的诞生。由于该系统成本低,占用空间少,在联网、监控等方面有突出优点,并且PC机性能已经非常可靠,所以它可以取代传统的PLC来完成实时控制任务。为了验证系统的可行性,文章系统地介绍了这类新型控制系统的优点和整体软硬件结构,并对其中一个重要的性能指标——响应时间,进行了详细分析,然后通过一个实际系统——自动传输线系统,验证了这一控制系统的可行性。     

A novel current conveyor‐based Schmitt trigger and its application as a relaxation oscillator

The current paper presents a novel Schmitt trigger using two second‐generation current conveyors and four resistors and its application as a relaxation oscillator. The performance of the proposed circuit is examined using Cadence and the model parameters of a 0.6µm CMOS process. The obtained results demonstrate excellent agreement with the theoretical values. The measured results based on commercially available current feedback operational amplifiers (AD 844 AN) are included and the non‐idealities are also examined. The topology reports low sensitivities and has features suitable for VLSI implementation. Copyright © 2010 John Wiley & Sons, Ltd.     

Realizations of fully differential voltage second generation current conveyor with an application

Three novel CMOS realizations for the fully differential voltage second‐generation inverting current conveyor (FDVCCII‐) are proposed in this paper. The first realization has a limited input range, and the other two realizations have a rail to rail input range and show excellent features in linearity and bandwidth. As an application to the FDVCCII‐, a floating gyrator is proposed. A floating inductor is realized using the floating gyrator and it is used in realizing a second‐order low‐pass filter, which is simulated and compared with the ideal result. All circuits are simulated with SPICE using CMOS 0.35µm technology and supply voltages ±1.5V to verify the theoretical results. Copyright © 2008 John Wiley & Sons, Ltd.     

PLC技术在带式输送机自动控制系统中的应用与研究

设计了以可编程控制器 PLC 为核心的带式输送机控制系统,详细叙述了该系统的硬件电路,并给出相应的软件流程。结果表明,PLC 控制系统具有操作简单、运行可靠、低能耗和易维护等优点。     

一种新颖的电流模式高通滤波器

提出了一种利用电流传送器（ＣＣ）设计连续时间电流模式高通滤波器方法。在设计中,引入了多端输出电流传送器（ＭＯＣＣ）,并给出了ＭＯＣＣ简单的实现电路。基于典型ＦＬＦ结构的模拟,获得了一般高阶高通滤波器的电流模式ＭＯＣＣ结构。文中给出了系统的设计公式。做为例子,文中设计了一个四阶Ｂｕｔｔｅｒｗｏｒｔｈ高通滤波器,模拟仿真结果与理论分析吻合。     

用改进的电流传送器实现电流模式滤波器

本文提出了用四个改进的ＣＣⅡ器件实现二阶和一阶电流模式滤波器的新电路，为了验证理论分析的正确性，电路用ＰＳＰＩＣＥ程序进行了仿真，并且给了二价低通，带通，高通及一阶低通，高通，全通滤波器的计算机仿真结果，该电路具无源灵敏度低的特点。     

脱硫真空皮带脱水机故障分析及应对措施

邹县发电厂8台机组脱硫系统均采用石灰石石膏湿法烟气脱硫技术,该技术的优点是脱硫率高、工艺技术成熟。在石膏生成过程中,真空皮带脱水机是最关键的设备,其主要作用是充分利用物料重力和真空吸力实现固液分离,生成含固量不低于90%的可用石膏。通过对真空皮带脱水机常见问题的分析,明确故障原因,从日常维护检修的角度,提出实用、经济、安全的应对措施,确保石膏脱水系统的长周期稳定运行。     

高频有源滤波器的实用设计

本文给出了高频有源滤波器的实用设计方法。根据给定的技术指标，首先设计一个基于运算放大器的RC有源原形滤波器，然后根据网络理论，将其转换成基于电流传输器（CCⅡ－）的RC有源滤波器。由于两个滤波器具有相同的传输函数以及相同的元件值，因此，基于CCⅡ－的滤波器保留了原形滤波器的优良性能。文中给出了用AD844实现的滤波器电路以及计算机模拟结果。     

Voltage mode and current mode Tow Thomas bi‐quadratic filters using inverting CCII

A voltage mode Tow Thomas bi‐quadratic filter using the inverting second‐generation current conveyor (ICCII) is given. The filter has high input impedance, employs two grounded capacitors, and has independent control on Q, independent control on the band‐pass and low‐pass response gain. Three alternative current mode filters are generated from the voltage mode circuit. The three circuits have zero input impedance, employ grounded capacitors and have independent control on Q. Two of the circuits have also all resistors grounded and the other uses only ICCII?and has only one floating resistor. Copyright © 2007 John Wiley & Sons, Ltd.     

捞渣机密封水水位自动控制系统模糊控制器设计

针对妈湾电厂运行中捞渣机密封水水位控制问题,采用模糊控制理论对密封水水位自动控制系统的模糊控制器进行了设计,并采用MATLAB软件中的Simulink仿真工具进行仿真和分析.结果表明,该课题的研究工作注重理论与工程实际相结合,并在此研制过程中取得了较全面的设计数据和资料,为进行现场类似系统的改造设计打下了良好的理论基础...