摘要桥式起重机是横架于货仓、料物和车间上空施行物料吊运的起重设备，因为架在高、陡的水泥柱或金属框架下的端部，以及类似的形状的桥。桥沿线铺设两侧的高架轨道纵向运动，从地面设备的阻碍，充分利用空间下面的桥梁运输材料。桥式起重机是使用规模最大、数目最多的一种机械。电力驱动是普通桥式起重机主要动力，司机一般是在室内操作，也有通过远距离操控的。大重量桥式起重机为方便调整和安装，万向联轴器是常被驱动配置应用的。46273
变频器是利用微电子和变频技术，改变了电机工作的电源频率来控制交流电动机的电力控制装置。滤波、制动单元、整流、检测单元、逆变、驱动和微处理单元等构成了变频器。改变电源的电压由改变电源频率来实现，所需的电源电压是根据电机的实际需求而得来的，所以能够实现它的调速和节能，变频器如过载、过压、过流保护等很多的作用，能够实现保护电机。变频器在工业化和自动化的发展道路上得到了越来越多的使用。
可编程逻辑控制器也被叫做PLC，是用来存储编好的程序的存储器，在它的内部可以发出保存程序，执行顺序控制、定时、逻辑运算、算术操作与计数等面向使用者的指示，在机械生产过程中通过数字或者模拟式输入/输出控制来实现控制的全程。
在工业矿业企业中桥式起重机是一种使用非常普遍的起重机械传统的接触器一继电器控制系统和串级调速方法存在能耗高、安全性能不高、故障率高、调速功能差等问题，利用西门子公司的S7-300PLC联合日本安川G7变频器对15 /5吨桥式起重机进行了改造。本文比较并且分析了桥式起重机变频和传统调速方式的优点和缺点，简介了安川G7变频器在钢铁公司的桥式起重机上的应用，将通过PLC实现的变频调速系统使用到传统电力拖动系统的技术改良中，从而实现操作稳定，运行效率提升，保障安全使用电机，减少人为操作失误和系统耗能，避免在生产中发生安全事故等功能，具有重要现实意义。还介绍了改造的基本思路及系统构成、变频器的型号选择等问题。桥式起重机在改造后工作稳定，故障率降低，能耗浪费减少并且性能良好。
毕业论文关键词：桥式起重机   变频器   PLC   控制系统
ABSTRACT
Bridge crane is transverse frame in warehouse, material and workshops over the implementation of the material lifting up heavy equipment, because frame in high, steep cement column or metal frame ends, and similar to the shape of the bridge. The longitudinal motion of the elevated track along both sides of the bridge, from the ground equipment obstacles, make full use of the space below the bridge transport materials. Bridge crane is one of the largest and most used machines. Electric drive is the main driving force of ordinary bridge crane, the driver is generally in the indoor operation, but also through remote control. In order to facilitate the adjustment and installation of large - weight overhead traveling crane, universal coupling is often used to drive the configuration.
Frequency converter is the application of frequency conversion technology and micro electronics technology, by changing the motor operating power frequency mode to control the AC motor power control equipment. The inverter is mainly composed of rectifier, filter, contravariant, brake unit, drive unit, detection unit and micro processing unit. By changing the frequency of the power supply to achieve the purpose of changing the supply voltage, according to the actual needs of the motor to provide the power supply voltage, so as to achieve the purpose of energy-saving and speed. In addition, inverter and a lot of protection, such as over-current, over-voltage, overload protection. With the continuous improvement of the degree of industrial automation, the transducer has been widely used. PLC安川G7变频器在桥式起重机控制的应用+梯形图:http://www.youerw.com/zidonghua/lunwen_47948.html