基于PLC电气控制在数控系统上的应用

针对传统数控机床采用的继电器控制,对比分析证明了采用PLC控制的优点。以搬运机械手在机床上的控制为例,介绍了采用PLC实现控制的方法,包括控制总体方案、PLC选型、控制原理及梯形图的设计。试验结果表明,该控制系统能达到预定控制要求,灵活性和可靠性得到提高。     

PLC在煤矿提升机电控系统中的应用

阐述了煤矿提升机电控系统改造中控制系统结构、PLC梯形图,通过改造有效提高了电控系统的安全性和稳定性,达到预期节能的目标。     

浅谈电梯的节能降耗技术

随着高层建筑的快速发展,电梯在用电量也越来越大,电梯的节能降耗已经引起业界高度重视。基于此,笔者对电梯的节能降耗技术进行探讨,期望从而降低电梯的能耗,更好的节约电量。     

台阶气隙对电感非线性特性影响分析

台阶气隙结构有助于提高功率滤波电感的初始电感量,从而调整功率电感的非线性特性,提高开关电源轻载特性。通过电磁场有限元分析对此进行了深入研究,从磁通分布角度深入研究了台阶气隙对非线性特性控制的作用机理及影响,为设计电感量能随指定负载而变化的台阶气隙电感提供设计指导。     

新型WLAN平面倒F双频天线的设计

提出了一种新型的应用于2.4/5GHz蓝牙和无线局域网的双频内置平面倒F天线。该天线结构紧凑,可以方便地植入无线通信设备中,有较强的实用性。通过加载F形槽和阶梯形槽使天线能够满足无线局域网中小型化双频天线的技术要求。天线在蓝牙频段阻抗带宽达到300MHz(2.21~2.51GHz),在无线局域网频段阻抗带宽达到1070MHz(4.95~6.02GHz),辐射方向图表明该天线全向性能较好,增益在3.1~6.7dBi范围内。     

电力机车上真空断路器控制系统的研究

真空断路器是一种技术性能先进的断路器,在电力机车上具有控制和保护的双重功能.但在控制电压波动较大时容易因冲击而损坏.在阐述真空断路器结构和工作原理的基础上,设计了一种单稳态真空断路器控制系统.介绍了控制系统的硬件结构和电流跟踪控制算法,对流过真空断路器线圈中的电流实现了反馈控制.采用阶梯电流模拟正弦电流输出,减轻了信号中谐波成分对开关器件的冲击,并且取得了比标准正弦波更好的控制效果.实验结果表明,采用电流跟踪控制后的最大输出电流减小了30%,有效地延长了真空断路器的使用寿命.     

An FPGA implementation of hard‐wired sequence control system based on PLC software

Although a programmable logic controller (PLC) has been widely adopted for the sequence control of industrial machinery, its performance does not always satisfy the recent requirements in large and highly responsive systems. With the state‐of‐the‐art field programmable gate array (FPGA) technology, it is possible to implement a control program with hard‐wired logic for higher response and reduced implementation cost/space. This approach is also worthwhile for transmigration of legacy PLC software into forthcoming FPGA‐based control hardware. This study presents a systematic method to implement a hard‐wired sequence control from PLC software. PLC instructions are converted into VHDL codes, and then implemented as logic circuit with various peripheral functions. Productive PLC programs were examined with Mitsubishi Electric FX2N PLC and Altera Stratix II FPGA, and were shown to fit into a common FPGA chip. A straightforward Sequential design was estimated to be 184 times faster than PLC, while a performance‐oriented Flat design was estimated to be 44 times faster than Sequential design (i.e., 8050 times faster than PLC). A practical perfect layer winder system was actually built and successfully operated with our FPGA control board, whose logic design was implemented with our tools. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Sensitivity Analysis on Ladder Network Equivalent Circuit Parameters of Power Transformer

In this article, novel methods and ideas are introduced, which altogether lead to an accurate model of power transformer windings. First, by the determination of non-dominant (hidden) resonances from frequency-response tests, a ladder model is proposed. Next, it is improved by assigning different values for similar elements of each section of the model. The parameters are obtained by minimizing the error function via a genetic algorithm. Sensitivity analysis is then applied to the obtained model to achieve further examinations and tests. Measurements have been driven from the windings of a 20/0.4-kV, 1600-kVA transformer. Modeling, methodologies, and sensitivity analysis in this article can be very useful for future research aiming to find internal faults of the transformer with the frequency response analysis.     

PLC梯形图语言编辑功能的软件实现

利用Visaul C 开发PLC梯形图编辑功能的仿真软件，模拟PLC编程器的功能。该软件能够实现梯形图符号的编辑、语法检查、逻辑错误检查等功能，具有学习和应用的实际价值。本软件使用二叉树和链表数据结构，实现了梯形图语言和语句表语言的互换算法。     

可编程序控制器在钢管壁面喷砂除锈作业线中的应用

用可编程序控制器控制钢管壁面喷砂除锈作业线，提高了自动化程度，操作方便，运行可靠。介绍了作业线的主要设备和工艺流程，电气系统总体设计和程序设计，给出了自动控制程序顺序功能图和梯形图。