目 录1 引 言............................................................11.1 选题背景....................................................11.2 课题意义....................................................11.3 国内外在该方向的讨论概况....................................11.4 本文的主要工作..............................................32 系统总体分析和设计...............................................42.1 系统概述....................................................42.3 恒压供水系统硬件设计........................................42.3.1 供水系统的构成........................................42.3.2 供水系统的主电路接线及其工作原理......................63 器件的选型及介绍.................................................63.1 可编程控制器 PLC............................................63.1.1 简介 PLC 的产生.........................................73.1.2 简介 PLC 的进展状况及其进展趋势.........................73.1.3 简介 PLC 的应用领域.....................................83.1.4 PLC 的工作过程..........................................83.2 变频器......................................................93.2.1 变频器的选型..........................................93.2.2 变频器的特点.........................................103.3 PID 调节器.................................................113.4 压力传感器的选择...........................................123.5 元件表.....................................................124 PLC 控制及编程...................................................144.1 系统控制要求...............................................144.2 控制系统的 I/O 点及地址分配...................................144.3 PLC 系统选型................................................154.4 系统程序设计................................................154.5 PLC 与变频器的接线.........................................16结论...............................................................18谢辞................................................................