1、引言

　　萬(wan)能式斷路(lu)器除(chu)了本(ben)身(shen)具(ju)有(you)(you)高分斷能力(li)、高短(duan)時耐受性能及良好的操作性能外,還必須(xu)裝配性能的控(kong)制(zhi)器。基于微處理器的智(zhi)能控(kong)制(zhi)器具(ju)有(you)(you)多種(zhong)檢測和(he)(he)通信功(gong)能,利用總(zong)線(xian)功(gong)能實現(xian)電力(li)質量監控(kong)是一(yi)種(zhong)經濟有(you)(you)效的方案。由(you)于基于Profibus-DP現(xian)場總(zong)線(xian)的驅動和(he)(he)執行(xing)單元(yuan)被(bei)大量開發和(he)(he)應用,因此針對原有(you)(you)萬(wan)能式斷路(lu)器的控(kong)制(zhi)器系(xi)(xi)統(tong)進行(xing)改造(zao),結(jie)合(he)現(xian)場總(zong)線(xian)的優點,保留原有(you)(you)系(xi)(xi)統(tong)的投資,設計(ji)了一(yi)種(zhong)具(ju)有(you)(you)PROFIBUS現(xian)場總(zong)線(xian)接(jie)口的控(kong)制(zhi)系(xi)(xi)統(tong)。

　　2、Profibus-DP現場總線系(xi)統的(de)構成

　　Profibus現(xian)場(chang)總(zong)線(xian)(xian)系(xi)(xi)統(tong)由主(zhu)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)和(he)(he)(he)從(cong)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)構成(cheng)(cheng),主(zhu)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)具有總(zong)線(xian)(xian)存(cun)取控制權(quan),從(cong)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)是被動的(de)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan),沒有總(zong)線(xian)(xian)存(cun)取權(quan)。主(zhu)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)分為一類、二(er)類。一類主(zhu)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)包括PLC、PC等(deng),完(wan)成(cheng)(cheng)循環(huan)(huan)的(de)總(zong)線(xian)(xian)通訊(xun)控制和(he)(he)(he)管(guan)理。二(er)類主(zhu)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)指操作(zuo)員工(gong)作(zuo)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(如PC機加圖形(xing)監控軟件)、編程器、組態設(she)備(bei),完(wan)成(cheng)(cheng)非循環(huan)(huan)數據的(de)讀(du)寫、系(xi)(xi)統(tong)配置、故障(zhang)診(zhen)斷(duan)、調試等(deng)。從(cong)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)是進(jin)行(xing)輸入輸出(chu)信息采集(ji)和(he)(he)(he)發(fa)送的(de)現(xian)場(chang)設(she)備(bei)、包括輸入輸出(chu)I/O設(she)備(bei)、驅動器、執行(xing)器等(deng)。總(zong)線(xian)(xian)系(xi)(xi)統(tong)根據主(zhu)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)設(she)置的(de)個數可以分為多主(zhu)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)系(xi)(xi)統(tong)和(he)(he)(he)單主(zhu)站(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)總(zong)線(xian)(xian)系(xi)(xi)統(tong)。

　　3、從站總體結構設(she)計

　　智能(neng)控(kong)制(zhi)(zhi)器(qi)(qi)系統實現的功能(neng)包括:溫度采(cai)集、處理(li)控(kong)制(zhi)(zhi)、現場通信(xin)(xin)等(deng)(deng),能(neng)單(dan)獨完成(cheng)(cheng)現場測(ce)量(liang)控(kong)制(zhi)(zhi)等(deng)(deng)功能(neng),也(ye)可與多(duo)個從站和主(zhu)站一(yi)起(qi)構建一(yi)個大系統,完成(cheng)(cheng)整體的測(ce)量(liang)控(kong)制(zhi)(zhi)任務。智能(neng)控(kong)制(zhi)(zhi)器(qi)(qi)由微處理(li)器(qi)(qi)、信(xin)(xin)號采(cai)集電(dian)(dian)路(lu)、電(dian)(dian)源、鍵盤和液晶(jing)顯示電(dian)(dian)路(lu)、時鐘溫度檢測(ce)電(dian)(dian)路(lu)、執行(xing)電(dian)(dian)路(lu)以及Profibus-DP總線接口電(dian)(dian)路(lu)等(deng)(deng)部(bu)分組(zu)(zu)成(cheng)(cheng),組(zu)(zu)成(cheng)(cheng)框圖(tu)如圖(tu)1所示。

　　3.1  信號采集(ji)系統

　　本設計需要采集的信號是三路(lu)(lu)(lu)線電(dian)(dian)壓和(he)四(si)路(lu)(lu)(lu)相(xiang)電(dian)(dian)流(liu)(liu)信號,所(suo)需的電(dian)(dian)壓和(he)電(dian)(dian)流(liu)(liu)信號都是經過互(hu)感器形(xing)成(cheng)(cheng)的二次側(ce)感應電(dian)(dian)壓,經濾波隔離放(fang)大(da)之后形(xing)成(cheng)(cheng)適合A/D轉換(huan)的電(dian)(dian)壓范圍在3V以(yi)內(nei)。由于LPC2114本身具有A/D轉換(huan)器,所(suo)以(yi)只需要接入一個多路(lu)(lu)(lu)選擇開關(guan),即可完成(cheng)(cheng)對(dui)多路(lu)(lu)(lu)信號的采集,因此選用了單八路(lu)(lu)(lu)模擬開關(guan)CD4051。

　　CD4051的(de)(de)(de)(de)(de)特點(dian)是通(tong)道(dao)(dao)轉(zhuan)換(huan)頻率(lv)可(ke)10MHz,而且控制(zhi)(zhi)簡(jian)單,量程(cheng)(cheng)達(da)到10V,工(gong)(gong)作溫度(du)范(fan)圍(wei)(wei)-55°C~+125°C,很(hen)好的(de)(de)(de)(de)(de)解決了量程(cheng)(cheng)的(de)(de)(de)(de)(de)范(fan)圍(wei)(wei)和信號(hao)采(cai)(cai)(cai)集(ji)的(de)(de)(de)(de)(de)實(shi)時性。CD4051與LPC2114的(de)(de)(de)(de)(de)接(jie)(jie)(jie)口連接(jie)(jie)(jie)見圖2所示。電(dian)(dian)(dian)壓電(dian)(dian)(dian)流互感(gan)器二次側感(gan)應電(dian)(dian)(dian)壓信號(hao)經分(fen)壓后(hou)分(fen)別(bie)送入CD4051的(de)(de)(de)(de)(de)X0—X7引腳。CD4051的(de)(de)(de)(de)(de)各通(tong)道(dao)(dao)選通(tong)的(de)(de)(de)(de)(de)地址線引腳A、B、C分(fen)別(bie)與LPC2114的(de)(de)(de)(de)(de)p0.21、p0.22、p0.23相連,開(kai)關接(jie)(jie)(jie)通(tong)彭磊(lei):助(zhu)理實(shi)驗師(shi)在(zai)讀碩士哪一(yi)(yi)通(tong)道(dao)(dao),由LPC2114控制(zhi)(zhi)輸入的(de)(de)(de)(de)(de)3位(wei)地址碼來決定(ding)。LPC2114的(de)(de)(de)(de)(de)A/D轉(zhuan)換(huan)頻率(lv)可(ke)以達(da)到4.5MHz,轉(zhuan)換(huan)精(jing)度(du)為2-10,能夠(gou)滿足實(shi)時采(cai)(cai)(cai)集(ji)和高精(jing)度(du)要(yao)求。CD4051與LPC2114的(de)(de)(de)(de)(de)A/D初始(shi)化和轉(zhuan)換(huan)工(gong)(gong)作由主(zhu)程(cheng)(cheng)序完(wan)成。設計采(cai)(cai)(cai)用(yong)定(ding)時中斷方式要(yao)求大約每0.3ms就在(zai)3路(lu)電(dian)(dian)(dian)壓和4路(lu)電(dian)(dian)(dian)流信號(hao)上各采(cai)(cai)(cai)集(ji)一(yi)(yi)點(dian),LPC2114將采(cai)(cai)(cai)集(ji)所轉(zhuan)換(huan)的(de)(de)(de)(de)(de)數(shu)據存(cun)儲在(zai)ADDR(A/D數(shu)據存(cun)儲器)中。

　　3.2  溫度檢測與(yu)實(shi)時時鐘電路

　　傳統(tong)的(de)溫度檢測和實(shi)(shi)時(shi)(shi)時(shi)(shi)鐘是由各(ge)自獨(du)立的(de)芯片電路分別完成,這樣分散處理往(wang)往(wang)降低(di)了(le)微處理器的(de)處理效率而且也增加(jia)了(le)電路的(de)復雜性,所以本設計采用了(le)SD2304FLP高精度實(shi)(shi)時(shi)(shi)時(shi)(shi)鐘。

　　SD2304FLP是(shi)一種(zhong)具有內(nei)(nei)置晶振、兩線(xian)(xian)式串(chuan)行接口(kou)的(de)(de)(de)高精度(du)(du)(du)(du)(du)實時(shi)(shi)時(shi)(shi)鐘(zhong)(zhong)芯片(pian)。該芯片(pian)可保證(zheng)時(shi)(shi)鐘(zhong)(zhong)精度(du)(du)(du)(du)(du)為±5ppm(在(zai)(zai)-10°C~50°C下),即年誤差小于(yu)(yu)2.5分鐘(zhong)(zhong);該芯片(pian)內(nei)(nei)置始終精度(du)(du)(du)(du)(du)調(diao)整功(gong)能,通(tong)(tong)過內(nei)(nei)置的(de)(de)(de)數字(zi)(zi)溫(wen)(wen)(wen)度(du)(du)(du)(du)(du)傳(chuan)感(gan)器(qi)可設(she)定(ding)適應(ying)(ying)溫(wen)(wen)(wen)度(du)(du)(du)(du)(du)變化(hua)的(de)(de)(de)調(diao)整值(zhi),實現在(zai)(zai)寬溫(wen)(wen)(wen)度(du)(du)(du)(du)(du)范(fan)圍內(nei)(nei)高精度(du)(du)(du)(du)(du)的(de)(de)(de)計時(shi)(shi)功(gong)能;內(nei)(nei)置2K串(chuan)行E2PROM,用于(yu)(yu)存儲各溫(wen)(wen)(wen)度(du)(du)(du)(du)(du)點的(de)(de)(de)時(shi)(shi)鐘(zhong)(zhong)精度(du)(du)(du)(du)(du)補(bu)(bu)(bu)償數據(ju)。正是(shi)由于(yu)(yu)內(nei)(nei)置了I2C總線(xian)(xian)的(de)(de)(de)數字(zi)(zi)溫(wen)(wen)(wen)度(du)(du)(du)(du)(du)傳(chuan)感(gan)器(qi),所(suo)以可以很方便地通(tong)(tong)過I2C接口(kou)讀(du)取溫(wen)(wen)(wen)度(du)(du)(du)(du)(du)數據(ju)。SD2304FLP的(de)(de)(de)溫(wen)(wen)(wen)度(du)(du)(du)(du)(du)補(bu)(bu)(bu)償應(ying)(ying)用是(shi)應(ying)(ying)用的(de)(de)(de)關鍵(jian),由于(yu)(yu)時(shi)(shi)鐘(zhong)(zhong)精度(du)(du)(du)(du)(du)隨(sui)溫(wen)(wen)(wen)度(du)(du)(du)(du)(du)變化(hua)的(de)(de)(de)補(bu)(bu)(bu)償數據(ju)在(zai)(zai)出廠前已經存儲在(zai)(zai)2K容量(liang)的(de)(de)(de)E2PROM里,所(suo)以只(zhi)要(yao)通(tong)(tong)過讀(du)取片(pian)內(nei)(nei)數字(zi)(zi)溫(wen)(wen)(wen)度(du)(du)(du)(du)(du)傳(chuan)感(gan)器(qi)所(suo)檢測到溫(wen)(wen)(wen)度(du)(du)(du)(du)(du)(TMP)的(de)(de)(de)數值(zhi),確定(ding)當前溫(wen)(wen)(wen)度(du)(du)(du)(du)(du)值(zhi),根據(ju)溫(wen)(wen)(wen)度(du)(du)(du)(du)(du)值(zhi)的(de)(de)(de)高八位確定(ding)存儲在(zai)(zai)E2PROM補(bu)(bu)(bu)償數據(ju)地址,讀(du)出該補(bu)(bu)(bu)償數據(ju)并寫(xie)入時(shi)(shi)鐘(zhong)(zhong)調(diao)整寄存器(qi)。由于(yu)(yu)LPC2114本(ben)身具有高速(su)I2C總線(xian)(xian)接口(kou),硬件(jian)設(she)計和程序編寫(xie)不需(xu)要(yao)很復雜。但需(xu)要(yao)注(zhu)意(yi)的(de)(de)(de)是(shi)I2C總線(xian)(xian)的(de)(de)(de)上拉電壓應(ying)(ying)在(zai)(zai)總線(xian)(xian)需(xu)要(yao)工作的(de)(de)(de)時(shi)(shi)始終存在(zai)(zai),并在(zai)(zai)系統中先上電,后掉電,所(suo)以根據(ju)實際情況,本(ben)電路設(she)計的(de)(de)(de)上拉電阻好為4.7K。