【正文】 er, realtime water level determine whether water full automatic closing valves and alarm. The control system use simple part converter, and easy to be installed, economic and practical. The system uses 4N26 photoelectric coupler for photoelectric isolation, enhance the system antiinterference function to ensure that the system is safe accurate operation. This manual and expounds the system design principle, and gives overall system principle diagram and diagram. Keywords converter, DS18B20, resistive sensor 第 I 頁 共 Ⅱ 頁 目 錄 1 引言 ................................................................................................................................ 1 太陽能熱水器的國內(nèi)外發(fā)展現(xiàn)狀 ............................................................................. 1 市場上各類熱水器的特點(diǎn) ......................................................................................... 2 課題研究的目的和意義 ............................................................................................. 3 課題研究的問題和設(shè)計(jì)思路 ..................................................................................... 3 2 太陽能熱水器上水控制系統(tǒng)總體設(shè)計(jì) ........................................................................ 3 系統(tǒng)方案設(shè)計(jì)原理 ..................................................................................................... 3 數(shù)據(jù)信息采集與轉(zhuǎn)換 ................................................................................................. 4 水位信號(hào)采集 .......................................................................................................... 4 溫度信息采集 .......................................................................................................... 5 時(shí)鐘 —— DS1302..................................................................................................... 7 單片機(jī)選擇 .................................................................................................................. 9 ATC89C52 單片機(jī) .................................................................................................... 9 鍵盤設(shè)計(jì)與顯示電路 ............................................................................................... 10 非編碼鍵盤的控制方式 ........................................................................................ 11 非編碼鍵盤接口設(shè)計(jì) ............................................................................................ 11 顯示設(shè)計(jì) ................................................................................................................ 11 光電隔離 ................................................................................................................... 12 太陽能熱水器上水 控制系統(tǒng)上水電磁閥的選用 ................................................... 12 報(bào)警電路設(shè)計(jì) ........................................................................................................... 13 3 變換器部分設(shè)計(jì) .......................................................................................................... 14 電容式水位傳感器 ................................................................................................... 14 調(diào)頻電路 ................................................................................................................ 14 交流電橋電路 ........................................................................................................ 15 雙 T 型充放電網(wǎng)絡(luò) ............................................................................................... 16 運(yùn)算放大器電路 .................................................................................................... 18 差動(dòng)脈沖調(diào)寬電路 ................................................................................................ 18 電阻式水位傳感器 ................................................................................................... 21 電阻式水位傳感器原理 ........................................................................................ 21 測量電路 ................................................................................................................ 23 方案比較 ................................................................................................................... 24 電磁閥驅(qū)動(dòng)電路 ....................................................................................................... 25 4 控制器電源設(shè)計(jì) .......................................................................................................... 25 直流電源設(shè)計(jì) ............................................................................................................ 25 第 II 頁 共 Ⅱ 頁 5 變換器部分電路調(diào)試 .................................................................................................. 26 6 軟件設(shè)計(jì)流程圖 .......................................................................................................... 28 結(jié)論 .................................................................................................................................. 29 參考文獻(xiàn) .......................................................................................................................... 30 附錄： .............................................................................................................................. 31 第 1 頁 共 32 頁 1 引言 太陽能熱水器 的 國內(nèi)外發(fā)展 現(xiàn)狀 目前，太陽能供暖技術(shù)和供熱水已經(jīng)相對比較成熟，太陽能制冷技術(shù)尚處于研發(fā)階段。 據(jù)國際能源機(jī)構(gòu)發(fā)布的數(shù)據(jù)， 20