【正文】 T(控制晶閘管 )發(fā)展到今天的 IGBT(絕緣柵雙極型晶體管 )、 HVIGBT(耐高壓絕緣柵雙極型晶閘管 )，器件的更新促使電力變換技術的不斷發(fā)展。該變頻器將壓力閉環(huán)調節(jié)與循環(huán)邏輯控制功能集成在變頻器內部實現，但其輸出接口限制了帶負載容量，同時操作不方便且不具有數據通信功能，因此只適用于小容量，控制要求不高的供水場所。這類設備雖微化了電路結構，降低了設備成 本，但其輸出接口的擴展功能缺乏靈活性，系統(tǒng)的動態(tài)性能和穩(wěn)定性不高，與別的監(jiān)控系統(tǒng) (如 BA系統(tǒng) )和組態(tài)軟件難以實現數據通信，并且限 遼寧科技 大學本科生 畢業(yè)設計 (論文 ) 第 2 頁 制了帶負載的容量，因此在實際使用時其范圍將會受到限制 。在早期，由于國外生產的變頻器的功能主要限定在頻率控制、升降速控制、正反轉控制、起制動控制、起制動控制、壓頻比控制及各種保護功能。目前的供水方式朝向高效節(jié)能、自動可靠的方向發(fā)展，變頻調速技術以其顯著的節(jié)能效果和穩(wěn)定可靠的控制方式，在風機、水泵、空氣壓縮機、制冷壓縮機等高能耗設備上廣泛應用，特別是在城鄉(xiāng)工業(yè)用水的各級加壓系統(tǒng)，居民生活用水的恒壓供 水系統(tǒng)中，變頻調速水泵節(jié)能效果尤為突出，其優(yōu)越性表現在： 是節(jié)能顯著；二是在開、停機時能減小電流對電網的沖擊以及供水水壓對管網系統(tǒng)的沖擊；三是能減小水泵、電機自身的機械沖擊損耗口 1。 氣壓罐供水具有體積小、技術簡單、不受高度限制等特點，但此方式調節(jié)量小、水泵電機為硬起動且起動頻繁，對電器設備要求較高、系統(tǒng)維護工作量大，而且為減少水泵起動次數，停泵壓力往往比較高，致使水泵在低效段工作，而出水壓力無謂的增高，也使浪費加大，從而限制了其發(fā)展。 關鍵字 ： 恒壓供水 ； 控制 ； 變頻器 ； PLC 遼寧科技 大學本科生 畢業(yè)設計 (論文 ) 第 II 頁 Design of Constant Pressure Water Supply System Based on PLC and Inverter Control ABSTRACT Traditional water supply system has the shortages including occupying wide surface area、 high expenses、 management plex and difficult、 water pollution again, and so on. In order to solve these problems, this paper bines control technology and transducer technology to research constant pressure water supply system. Two independent subsystems are irrespectively built with water place sensor and pressure sensor. The finished system can fulfill constantly supplying water to city day and night according to the water pressure given to assure the continuously produce. With the research and use of this project, we can save large sum of precious water、 electrical source, and decrease the produce price, reduce device management and lessen repair price. Moreover, this system also can improve the lever of produce and management, lighten the work?s strength, and increase the productivity. This paper discusses the reasonability of water scheme with much pump parallel connection， and analyses the conversion condition and the various states of water supply of the pump way of water supply as well as the switch process and the problem of a generator from variable frequency operation mode to work frequency operation mode． This paper has also given the electrical design scheme and PLC controlling program scheme that realizes effective state circulating conversion control. By researching the munication agreement between the puter and PLC， this paper has finished setting up the munication between upper and lower puter and also has described the method to pile puter monitoring program to realize the long— range monitoring and fault reporting for water supply system through munication modular. Key Words: constant water supply system； control transducer a frequency transformer； PLC 遼寧科技 大學本科生 畢業(yè)設計 (論文 ) 第 III 頁 目錄 基于 PLC 變頻器恒壓供水系統(tǒng)的設計 ............................................................ I 摘 要 .............................................................................................................. I ABSTRACT................................................................................................... II ......................................................................................................... 6 3. 1 PLC 的定義 ........................................................................................... 14 3. 2 PLC 的特點 ........................................................................................... 14 3. 3 PLC 的組成 ........................................................................................... 15 3. 4 PLC 的應用領域 .................................................................................... 17 3. 5 PLC 的工作方式 .................................................................................... 18 3. 6 PLC 工作過程 ....................................................................................... 19 3. 7 PLC 機型選擇 ....................................................................................... 20 3. 8 SIMATIC S7300 產品介紹 ................................................................... 21 S7300 控制原理 ............................................................................... 26 控制原理 .............................................................................................. 26 系統(tǒng)的軟件設計 .................................................................................. 29 PID 的相關知識 ..................................................................................... 31 PID 的參數的預置與調整 .................................................................. 31 PID 調節(jié)器在控制回路中的工作過程 ............................................... 32 壓力傳感器工作原理 ............................................................................ 32 變頻器的基本控制原理 ......................................................................... 34 系統(tǒng)組成 ................................................................................................ 36 系統(tǒng)控制工作原理 ................................................................................ 37 變頻器恒壓供水系統(tǒng)硬件設計 ............................................................. 38 變頻器恒壓供水系統(tǒng)軟件設計 ............................................................. 39 遼寧科技 大學本科生 畢業(yè)設計 (論文 ) 第 IV 頁 系統(tǒng)工作過程 ........................................................................................ 40 結 論 ............................................................................................................... 41 參考文獻 ......................................................................................................... 43 遼寧科技 大學本科生 畢業(yè)設計 (論文 ) 第 0 頁 1 緒論 課題背景及意義 眾所周知，水是人類生活、生產中不可缺少的重要