【正文】 系統(tǒng)中還應(yīng)該加入軟啟動器，軟起動是使電動機的電壓逐漸從零逐漸的增加到額定電壓的過程，該過程使得對啟動電流有了一定的控制，防止沖擊電流對電網(wǎng)造成損害，減輕了電機啟動的機械轉(zhuǎn)矩對于電機的損傷，可以延長電機壽命。在基板上集成了像 PID調(diào)節(jié)器和可編程控制器 （ PLC） 等這樣的硬件，通過指令代碼實現(xiàn) PID、 PLC等電控 恒壓 變頻供水系統(tǒng)設(shè)計 3 系統(tǒng)的控制，后續(xù)只要搭載配套的恒壓供水單元就可以直接控制內(nèi)置的電磁接觸器去工作，其最多可以控制 七臺電機（泵）達成供水系統(tǒng)。 變頻調(diào)速是當(dāng)今社會最先進的調(diào)速方式，它比調(diào)壓調(diào)速、串級調(diào)速，變極調(diào)速性能都更好，可以實現(xiàn)電動機的無級調(diào)速，調(diào)速性能高、經(jīng)濟效益好、應(yīng)用范圍寬、是目前最有發(fā)展的電機調(diào)速技術(shù)。采用交流變頻恒壓供水方式組成系統(tǒng)可解決以上問題。s requirements are getting higher and higher. Variable frequency constant pressure water supply system has bee an inevitable trend. This paper designs a set of PLC based variable frequency speed regulation constant pressure water supply system. The system consists of a programmable logic controller, 2 soft starters, 2 converters, 7 pump motors. One is the use of low voltage state at night, the rest of these are used to be cyclic operation mode. In the operation of the system by the pressure sensor measured the pipeline pressure, the pressure and expectation values are pared, after that by the PLC control converter output frequency of different power, and then change the speed of the pump motor to track the desired value of the water pressure. This paper introduces how to select the main ponents, connection mode, operation principle, and the software design of the system. The emphasis is on the analysis of the program design method, describes the overall design ideas. Key words: variable frequency speed regulation, constant pressure water supply, converter, PLC III 目 錄 摘要 .................................................................................................................................................................................. I ABSTRACT.................................................................................................................................................................. II 1 緒論 ............................................................................................................................................................................ 1 選題背景 ....................................................................................................................................................... 1 選題依據(jù) ....................................................................................................................................................... 1 國內(nèi)外發(fā)展概況 ......................................................................................................................................... 2 設(shè)計 內(nèi)容及要求 ......................................................................................................................................... 3 2 恒壓變頻供水系統(tǒng)的方案設(shè)計 ........................................................................................................................... 4 系統(tǒng)的基本工作原理 ................................................................................................................................ 4 本課題研究的對象 ..................................................................................................................................... 4 控制方式的選擇 ......................................................................................................................................... 5 系統(tǒng) 原理與 組成 ......................................................................................................................................... 6 系統(tǒng)的組成及原理圖 .................................................................................................................... 6 變頻控制 原理 .................................................................................................................................. 7 系統(tǒng)水泵切換控制分析 ................................................................................................................ 8 3 恒壓變頻供水系統(tǒng)的硬件設(shè)計 ........................................................................................................................... 9 系統(tǒng)主要設(shè)備電路的設(shè)計 ....................................................................................................................... 9 PLC的設(shè)計 ....................................................................................................................................... 9 變頻器的設(shè)計 ................................................................................................................................ 11 軟啟動器的設(shè)計 ........................................................................................................................... 16 系統(tǒng)控制電路的設(shè)計 .............................................................................................................................. 18 4 恒壓變 頻供水系統(tǒng)的軟件設(shè)計 ......................................................................................................................... 20 主程序循環(huán) 流程圖 ................................................................................................................................... 20 系統(tǒng)上電 步驟 ................................................................................................................................ 20 變頻器選擇 .................................................................................................................................... 20 軟啟動 器 選擇 ................................................................................................................................ 21 故障檢測 ......................................................................................................................................... 22 夜間工作模式 ................................................................................................................................ 23 啟動子程序 .................................................................................................................................... 24 系統(tǒng)整體的軟件設(shè)計 ........