單片機在恒壓供(gong)水(shui)變頻調速系統(tong)中的(de)應用

1、恒壓供水變頻調(diao)速系(xi)統(tong)工(gong)作原(yuan)理(li) 

      恒壓供(gong)(gong)水變(bian)(bian)頻(pin)(pin)調(diao)(diao)速系統(tong)與水塔或樓頂的(de)高(gao)位水箱供(gong)(gong)水相比,具有投資省(sheng)?節約能源?水質遭二次污染(ran)的(de)機會少等優點,越(yue)來越(yue)多的(de)城市和(he)生(sheng)活小區已經(jing)或正(zheng)打算采用(yong)變(bian)(bian)頻(pin)(pin)調(diao)(diao)速恒壓供(gong)(gong)水?變(bian)(bian)頻(pin)(pin)調(diao)(diao)速恒壓供(gong)(gong)水系統(tong)構成(cheng)如圖1? 

      恒壓(ya)(ya)供水(shui)(shui)變頻(pin)調速系(xi)統其(qi)工作原理是:控(kong)制器(qi)通過檢測實(shi)際(ji)水(shui)(shui)壓(ya)(ya)值,比(bi)較設定水(shui)(shui)壓(ya)(ya)值和(he)實(shi)際(ji)水(shui)(shui)壓(ya)(ya)值的差(cha)別(bie),按(an)PID控(kong)制規律(lv)運算后,輸出控(kong)制信號至變頻(pin)器(qi),變頻(pin)器(qi)則(ze)根(gen)據控(kong)制器(qi)的輸入信號調節水(shui)(shui)泵電(dian)(dian)機(ji)的供電(dian)(dian)電(dian)(dian)壓(ya)(ya)和(he)頻(pin)率? 

      當(dang)用水(shui)(shui)量增(zeng)加時,控(kong)(kong)制(zhi)器(qi)控(kong)(kong)制(zhi)變頻(pin)(pin)器(qi)使(shi)(shi)電(dian)動機的(de)電(dian)壓(ya)和(he)頻(pin)(pin)率加大,水(shui)(shui)泵(beng)轉速升高,出水(shui)(shui)量增(zeng)加;當(dang)用水(shui)(shui)量減少時,控(kong)(kong)制(zhi)器(qi)控(kong)(kong)制(zhi)變頻(pin)(pin)器(qi)使(shi)(shi)電(dian)動機的(de)電(dian)壓(ya)和(he)頻(pin)(pin)率降(jiang)低,水(shui)(shui)泵(beng)轉速下降(jiang),出水(shui)(shui)量減少?通過(guo)這種(zhong)控(kong)(kong)制(zhi)方式,就可以使(shi)(shi)自來水(shui)(shui)管道壓(ya)力保持(chi)在設定值(zhi)上? 

      由于(yu)(yu)變頻(pin)器的價格較高,變頻(pin)調速(su)恒(heng)壓供水(shui)(shui)系(xi)統通常采用多(duo)臺(tai)水(shui)(shui)泵(beng)并(bing)聯運(yun)(yun)行,幾臺(tai)水(shui)(shui)泵(beng)共(gong)用一臺(tai)變頻(pin)器?工作時,控(kong)(kong)制器根(gen)據用水(shui)(shui)量的大小,控(kong)(kong)制配電系(xi)統自動(dong)選擇所需(xu)投入運(yun)(yun)行的水(shui)(shui)泵(beng)數量,一般方法是保(bao)持其中一臺(tai)水(shui)(shui)泵(beng)處于(yu)(yu)變頻(pin)器控(kong)(kong)制下(xia),其它水(shui)(shui)泵(beng)則根(gen)據供水(shui)(shui)量的變化,在工頻(pin)下(xia)全速(su)運(yun)(yun)行或停機待命? 

2、恒壓供水(shui)變頻調速系(xi)統單片機控制器(qi)設計 

2.1 硬件設計 

      單片機控制(zhi)器及變(bian)頻調速恒壓供(gong)水(shui)系統(tong)的(de)(de)(de)(de)原理接(jie)線圖如圖2?系(xi)統采用Atmel公司的(de)(de)(de)(de)AT89C51單(dan)片(pian)(pian)機作為(wei)(wei)控(kong)制(zhi)CPU(因(yin)為(wei)(wei)該單(dan)片(pian)(pian)機片(pian)(pian)內具有4KB的(de)(de)(de)(de)Flash Memory);為(wei)(wei)確保系(xi)統穩定(ding)可靠運行,采用MAX813作為(wei)(wei)系(xi)統的(de)(de)(de)(de)電(dian)(dian)壓(ya)監控(kong)及Watchdog電(dian)(dian)路(lu);壓(ya)力(li)變送器(qi)送來的(de)(de)(de)(de)4~20mA的(de)(de)(de)(de)壓(ya)力(li)信(xin)(xin)號(hao)經IC7轉換為(wei)(wei)0~5V的(de)(de)(de)(de)電(dian)(dian)壓(ya)信(xin)(xin)號(hao);由A/D轉換電(dian)(dian)路(lu)ADC0809將壓(ya)力(li)傳感器(qi)的(de)(de)(de)(de)檢測水(shui)壓(ya)值(zhi)和(he)設定(ding)電(dian)(dian)位器(qi)的(de)(de)(de)(de)設定(ding)值(zhi)轉換為(wei)(wei)數字量(liang),供單(dan)片(pian)(pian)機使用;D/A轉換電(dian)(dian)路(lu)采用DAC0832,將單(dan)片(pian)(pian)機輸入(ru)的(de)(de)(de)(de)控(kong)制(zhi)量(liang)轉換為(wei)(wei)4~20mA電(dian)(dian)流(liu)環(huan),控(kong)制(zhi)變頻器(qi)的(de)(de)(de)(de)輸出頻率?由單(dan)片(pian)(pian)機到配電(dian)(dian)部分的(de)(de)(de)(de)控(kong)制(zhi)信(xin)(xin)號(hao)及系(xi)統的(de)(de)(de)(de)一(yi)些控(kong)制(zhi)開關命令,均通過光電(dian)(dian)耦合電(dian)(dian)路(lu)進行隔(ge)離(li),以減(jian)少強(qiang)電(dian)(dian)回路(lu)對單(dan)片(pian)(pian)機的(de)(de)(de)(de)影響? 

2.2 軟件設計(ji) 

假(jia)設(she)供水(shui)(shui)系統共(gong)有2臺水(shui)(shui)泵(beng),其(qi)中水(shui)(shui)泵(beng)1為變(bian)頻運行,水(shui)(shui)泵(beng)2為工(gong)頻運行,由接觸(chu)器分別啟動或停(ting)止,單片(pian)機通(tong)過繼電器控(kong)制接觸(chu)器的(de)工(gong)作?軟件設(she)計如下(xia): 

2.2.1 單(dan)片機(ji)接(jie)口地址分配和控制端口功能 

A/D轉(zhuan)換器ADC0809:80XXH~87XXH;壓(ya)力傳(chuan)感器為(wei)IN0通道,設定電位器為(wei)IN1通道? 

D/A轉換(huan)器DAC0832:08XXH? 

水(shui)泵1繼電器控制P1.0:當P1.0=0時(shi),水(shui)泵1開;當P1.0=1時(shi),水(shui)泵1停? 

水泵2繼(ji)電器(qi)控制(zhi)P1.1:當P1.1=0時(shi) ,水泵2開;當P1.1=1時(shi),水泵2停? 

開機(ji)命令P1.2:當P1.2=0時(shi)(shi),系統開始工作,當P1.2=1時(shi)(shi),系統停止工作? 

2.2.2 軟件程(cheng)序設(she)計 

恒壓(ya)供水變頻調(diao)速系統的(de)單片機控制(zhi)器(qi)軟件包括主程(cheng)序?控制(zhi)量計算(suan)子(zi)程(cheng)序?繼電器(qi)控制(zhi)子(zi)程(cheng)序?A/D轉換子(zi)程(cheng)序?延時(shi)子(zi)程(cheng)序等? 

A/D轉換采(cai)用(yong)定時(shi)(shi)轉換方(fang)式(shi),啟動A/D后(hou),用(yong)軟件延時(shi)(shi)150μs,再讀出轉換結果? 

      繼電器(qi)控(kong)制(zhi)(zhi)(zhi)子程序(xu)(xu)完成(cheng)水(shui)(shui)泵(beng)(beng)(beng)2的(de)運(yun)轉(zhuan)和停(ting)止控(kong)制(zhi)(zhi)(zhi)?由于(yu)變(bian)(bian)頻器(qi)的(de)控(kong)制(zhi)(zhi)(zhi)量(liang)與(yu)水(shui)(shui)泵(beng)(beng)(beng)1的(de)運(yun)轉(zhuan)速度直接相(xiang)(xiang)關,因此程序(xu)(xu)根據變(bian)(bian)頻器(qi)的(de)控(kong)制(zhi)(zhi)(zhi)量(liang)大(da)小就可(ke)判(pan)斷水(shui)(shui)泵(beng)(beng)(beng)1的(de)工作(zuo)狀態?如(ru)控(kong)制(zhi)(zhi)(zhi)量(liang)為(wei)零,說(shuo)明(ming)系(xi)統(tong)(tong)(tong)壓(ya)力過(guo)高(gao)(gao),水(shui)(shui)泵(beng)(beng)(beng)1已經調(diao)至(zhi)最(zui)(zui)低(di)轉(zhuan)速,這時(shi)(shi)需要(yao)(yao)水(shui)(shui)泵(beng)(beng)(beng)2停(ting)止工作(zuo);如(ru)果控(kong)制(zhi)(zhi)(zhi)量(liang)為(wei)最(zui)(zui)大(da)值,說(shuo)明(ming)系(xi)統(tong)(tong)(tong)壓(ya)力過(guo)低(di),水(shui)(shui)泵(beng)(beng)(beng)1已經調(diao)至(zhi)最(zui)(zui)高(gao)(gao)轉(zhuan)速,這時(shi)(shi)需要(yao)(yao)水(shui)(shui)泵(beng)(beng)(beng)2投入運(yun)行?由于(yu)供水(shui)(shui)系(xi)統(tong)(tong)(tong)壓(ya)力的(de)變(bian)(bian)化慣(guan)性較大(da),所以當(dang)控(kong)制(zhi)(zhi)(zhi)量(liang)出現最(zui)(zui)大(da)值或最(zui)(zui)小值后,需延(yan)時(shi)(shi)一(yi)段時(shi)(shi)間,在延(yan)時(shi)(shi)階(jie)段經過(guo)反復測量(liang),如(ru)果控(kong)制(zhi)(zhi)(zhi)量(liang)一(yi)直不(bu)變(bian)(bian),再進行切換?系(xi)統(tong)(tong)(tong)多于(yu)2臺(tai)水(shui)(shui)泵(beng)(beng)(beng)時(shi)(shi),切換原理相(xiang)(xiang)同,但需增(zeng)加判(pan)斷多臺(tai)水(shui)(shui)泵(beng)(beng)(beng)開?停(ting)狀態的(de)循環判(pan)斷程序(xu)(xu)? 

控制量(liang)(liang)計(ji)算(suan)子程序包括變頻器(qi)控制量(liang)(liang)的(de)計(ji)算(suan)和控制量(liang)(liang)的(de)輸出,其中控制規律(lv)采用PID調節(jie)規律(lv)? 

3、結論 

      恒壓供(gong)水(shui)變(bian)頻(pin)調速系統是(shi)現(xian)代化城市和(he)生活小區供(gong)水(shui)的(de)發展(zhan)方(fang)向,采(cai)用(yong)單片機(ji)控制的(de)變(bian)頻(pin)供(gong)水(shui)系統具有工(gong)作(zuo)可靠?實現(xian)容易?價格低(di)廉等特點,是(shi)較理想的(de)控制器?