我們渴望舒服一點的條件是，一個基于水霧系統而讓人涼快的解決方案，以克服困擾這片沙漠的干熱空氣。這可以用一臺由電壓源供電、連著一個帶噴嘴的噴霧水龍帶的水泵實現。噴霧系統的成功要素是電源，這個電源也可以用來給 LED 燈供電，以供夜間照明，或者給其它需要電源的外部設備充電。我們的計劃是，用太陽能電池板給一個海上用的深周期電池充電，然后用這塊電池給其它所有東西供電。隨即，我開始了太陽能電池板電池充電器的設計。

　　我(wo)(wo)有(you) 3 周時間完成設計(ji)(ji)。我(wo)(wo)向朋友 Simon 請求(qiu)幫(bang)助，Simon 以前用(yong)凌力爾特(te)公司的 IC 搞過太(tai)陽(yang)能(neng)供電(dian)設計(ji)(ji)。除了一(yi)臺顯(xian)示工作原理(li)(li)的樣機(ji)(ji)，Simon 還給了我(wo)(wo)一(yi)份原理(li)(li)圖，這臺樣機(ji)(ji)從(cong)未連上太(tai)陽(yang)能(neng)電(dian)池板測(ce)試過，但(dan)在(zai)實(shi)驗室做過仿(fang)真。我(wo)(wo)很興奮，有(you)興趣用(yong)真實(shi)的太(tai)陽(yang)能(neng)電(dian)池板測(ce)試這個(ge)設計(ji)(ji)，我(wo)(wo)們準備(bei)對樣機(ji)(ji)進行像樣的測(ce)試。

　　一位朋友借給(gei)(gei)我(wo)兩塊(kuai) BP 太(tai)陽(yang)(yang)能(neng)(neng)電(dian)池板 （BP380U）。在(zai)(zai)大約 20V 最高輸出(chu)(chu)電(dian)壓和 4A 最大輸出(chu)(chu)電(dian)流時(shi)，每塊(kuai)電(dian)池板的峰(feng)值功率都是 80W （實際規(gui)格為，在(zai)(zai) 80W 最大功率時(shi)，電(dian)壓為 17.6V，電(dian)流為 4.55A）。把這(zhe)兩塊(kuai)太(tai)陽(yang)(yang)能(neng)(neng)電(dian)池板合(he)起(qi)來，我(wo)希望在(zai)(zai)太(tai)陽(yang)(yang)光直(zhi)接(jie)直(zhi)射在(zai)(zai)電(dian)池板上(shang)時(shi)，在(zai)(zai)峰(feng)值條(tiao)件下能(neng)(neng)有 8A 的總電(dian)流。太(tai)陽(yang)(yang)能(neng)(neng)電(dian)池板連接(jie)到 Simon 的樣機上(shang)沒有幾分(fen)鐘(zhong)，系統就充分(fen)運轉了(le) （圖 1 和圖 2）。通(tong)過對樣機的初(chu)步測試，查明(ming)了(le)幾個故障，后來這(zhe)給(gei)(gei)我(wo)們節省了(le)大量時(shi)間(jian)。

　　圖 1：測試 BP 太陽能電池板， BP380U （0 至(zhi) 20V 輸(shu)出，4A 峰值功率 80W）

　　圖 2：最初的(de)太陽能充電電路(lu)樣機(ji)，采用(yong) 12V 海(hai)上用(yong)深周(zhou)期電池 。

　　樣(yang)機(ji)運行良好(hao)，因此我購買了(le)幾塊凌(ling)力爾特(te)公司的(de)(de)演示(shi)板，并稍(shao)作修改以使其更適合重(zhong)新設(she)(she)計過的(de)(de)系(xi)統規(gui)格(ge)要(yao)求。我保持(chi)樣(yang)機(ji)作為(wei)備份和參考(kao)，同時(shi)我設(she)(she)計了(le)一(yi)個新系(xi)統。我們解決了(le)一(yi)些故障后，通過這些修改改善了(le)原(yuan)來(lai)的(de)(de)樣(yang)機(ji)。總之，架構設(she)(she)計仍然是相同的(de)(de)：用 0 至 20V 的(de)(de)太陽能(neng)電池板，以 4A 的(de)(de)恒定(ding)電流給(gei)一(yi)個 12V 的(de)(de)電池充(chong)電,

   太陽能電池(chi)充電器系統設(she)計

　　用這些演示板忙活幾天之后，我成功地完成了一個產生預期效果的設計，這設計將適合我們這次旅程。系統的方框圖如圖 3 所示，該圖顯示了一些 IC 和演示板功能。系統的照片如圖 4 所示，顯示了完整的太陽能電池板電池充電器單元。

　　圖 3：系統設計(ji)方框圖

　　圖 4：最終的太陽能充電器電路

　　視太陽(yang)的(de)(de)位置不(bu)同(tong)而不(bu)同(tong)，太陽(yang)能(neng)電(dian)(dian)池板(ban)最初的(de)(de)輸出電(dian)(dian)壓(ya)(ya)在 0V 到(dao) 20V 之(zhi)間(jian)變化(hua)，那么(me)就用(yong)一個能(neng)接受這么(me)寬輸出范圍的(de)(de)穩(wen)壓(ya)(ya)器，并保持(chi)吸取低的(de)(de)電(dian)(dian)流 （每個電(dian)(dian)池板(ban)上(shang)的(de)(de)輸入(ru)電(dian)(dian)流最大值(zhi)都(dou)是 4A），同(tong)時調節一個固定(ding)的(de)(de)輸出電(dian)(dian)壓(ya)(ya)。這是在 DC1198A-B 演示(shi)板(ban)上(shang)用(yong)凌力(li)爾特公司的(de)(de)微型(xing)模塊 （μModule） DC/DC 降(jiang)壓(ya)(ya)-升壓(ya)(ya)型(xing)開關(guan)穩(wen)壓(ya)(ya)器 LTM4607 實現(xian)的(de)(de)。

　　LTM4607 是一個小型(xing)(xing)(xing) LGA 封(feng)裝 （15mm x 15mm x 2.8mm） 的(de)(de)芯片，其(qi)中包括一個復雜的(de)(de)降(jiang)壓(ya)-升壓(ya)型(xing)(xing)(xing) DC/DC 開(kai)關穩壓(ya)器(qi)所(suo)需(xu)(xu)的(de)(de)所(suo)有支持控制組件。復雜的(de)(de)開(kai)關控制電(dian)(dian)(dian)(dian)路和 FET 內置(zhi)到微型(xing)(xing)(xing)模(mo)塊穩壓(ya)器(qi)中，從而使該(gai)器(qi)件非常容易使用。結果(guo)是僅需(xu)(xu)一個微型(xing)(xing)(xing)模(mo)塊穩壓(ya)器(qi)、電(dian)(dian)(dian)(dian)感(gan)器(qi)以及幾個電(dian)(dian)(dian)(dian)容器(qi)和電(dian)(dian)(dian)(dian)阻器(qi)就完成簡潔(jie)規則的(de)(de)布(bu)局。4.5V 至 36V 的(de)(de)寬(kuan)輸(shu)入電(dian)(dian)(dian)(dian)壓(ya)范圍至固(gu)定 20V 輸(shu)出 （范圍為 0.8V 至 24V） 對于太(tai)陽(yang)能電(dian)(dian)(dian)(dian)池板(ban)的(de)(de)特(te)性 （0 至 20V 輸(shu)出） 正合適，而且該(gai)器(qi)件能加載(zai)高(gao)達 5A 的(de)(de)升壓(ya)模(mo)式和 10A 的(de)(de)降(jiang)壓(ya)模(mo)式。在太(tai)陽(yang)能電(dian)(dian)(dian)(dian)池板(ban)峰值功率時，20V 輸(shu)入至 20V/2.5A 輸(shu)出的(de)(de)效(xiao)率是 91%，而且積極利用了降(jiang)壓(ya)-升壓(ya)型(xing)(xing)(xing)寬(kuan)范圍輸(shu)入的(de)(de)好處。就這個系(xi)統(tong)設計的(de)(de)目的(de)(de)而言，輸(shu)出調節到 20V，用這個輸(shu)出給 LTC1435/LT1620 高(gao)效(xiao)率、低壓(ya)差(cha)電(dian)(dian)(dian)(dian)池充電(dian)(dian)(dian)(dian)器(qi)系(xi)統(tong)供電(dian)(dian)(dian)(dian)。

　　在(zai) 14V 穩定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)時，LTC1435/LT1620 演(yan)示板(ban) （DC133A） 將充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)控制到(dao)穩定(ding)的(de)(de) 4A.該演(yan)示板(ban)與 LT1620 數據表第一(yi)頁上的(de)(de)應(ying)用電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)類似，我將 FB 電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻器(qi)(qi)(qi) （110k） 換成(cheng)一(yi)個可(ke)變(bian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位器(qi)(qi)(qi)，以實(shi)現輸(shu)出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)調節，并將電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)浮置(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)設(she)置(zhi)到(dao) 14V.該演(yan)示板(ban)設(she)計利用 LT1620 軌(gui)至軌(gui)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)檢測(ce)放(fang)大(da)器(qi)(qi)(qi)，結合 LTC1435 開關穩壓(ya)(ya)(ya)器(qi)(qi)(qi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的(de)(de)高(gao)效率(lv)和低壓(ya)(ya)(ya)差能(neng)力(li)，形成(cheng)了一(yi)個效率(lv)超(chao)過 95% 的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)，從而(er)在(zai) 4A 充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)時僅需要(yao) 0.5V 輸(shu)入(ru)至輸(shu)出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)差。一(yi)個到(dao)地的(de)(de)編(bian)程電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)設(she)置(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu) （4A），該電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)一(yi)直是(shi)穩定(ding)的(de)(de)，直到(dao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)達到(dao)預設(she)的(de)(de)浮置(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya) （在(zai)本文情況下為 14V） 為止。隨著電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)達到(dao)其(qi)滿充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)狀態，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的(de)(de)編(bian)程將自動轉入(ru)涓流(liu)(liu)(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)狀態，并就電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的(de)(de)輸(shu)出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)而(er)言緩慢降低充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)。這減輕了由(you)于恒定(ding)過沖電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)給電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)造成(cheng)的(de)(de)壓(ya)(ya)(ya)力(li)。

　　一(yi)個(ge)理(li)(li)想二(er)極管電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)設(she)計(ji)與 DC133A 充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)系(xi)統(tong)的輸出串(chuan)聯，利用(yong)(yong) LTC4414 實(shi)現電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)保護(hu)，并(bing)允(yun)(yun)許在充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)以最小損耗運行的同(tong)時使用(yong)(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)。這種自動電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源通路(lu)(lu)(lu) （PowerPath？） 控制使外部(bu)設(she)備能(neng)夠自由地用(yong)(yong)太(tai)陽能(neng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)板(ban)(ban)或電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。當太(tai)陽能(neng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)板(ban)(ban)功率(lv)不足時，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)自動轉為從(cong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)吸(xi)取功率(lv)。該電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)設(she)計(ji)與 LTC4414 數據(ju)表(biao)第九頁上(shang)的圖(tu) 2 類似(si)。LTC4414 （8 引線 MSOP 封裝(zhuang)） 控制一(yi)個(ge)外部(bu) P 溝道 MOSFET，以產生接近理(li)(li)想的二(er)極管功能(neng)，用(yong)(yong)于電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源切換。這允(yun)(yun)許多個(ge)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源高效率(lv)進行“或” 操作(zuo)；在本文情況(kuang)下，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源是太(tai)陽能(neng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)板(ban)(ban)和(he)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)。當連接一(yi)個(ge)外部(bu)設(she)備時，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)和(he)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)系(xi)統(tong)接受(shou)負載(zai)狀(zhuang)態(tai)。在無(wu)負載(zai)時，將對電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。因(yin)此(ci)該設(she)計(ji)允(yun)(yun)許一(yi)起使用(yong)(yong)太(tai)陽能(neng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)板(ban)(ban)和(he)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，同(tong)時運行電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)過程。這一(yi)部(bu)分沒有演示(shi)板(ban)(ban)可用(yong)(yong)，因(yin)此(ci)我按照(zhao)定制電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)板(ban)(ban)上(shang)的應用(yong)(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)進行設(she)計(ji)。

　　電(dian)(dian)(dian)流(liu)檢(jian)測(ce)系(xi)統(tong)(tong)與(yu)電(dian)(dian)(dian)池(chi)串聯(lian)，利用(yong)并聯(lian)檢(jian)測(ce)電(dian)(dian)(dian)阻器測(ce)量(liang)電(dian)(dian)(dian)池(chi)的輸(shu)入充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)和(he)(he)(he)輸(shu)出(chu)(chu)放(fang)(fang)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)，而無(wu)需斷開電(dian)(dian)(dian)路。圖(tu) 3 的方(fang)框圖(tu)僅說明了輸(shu)入充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)。LTC6103 （采用(yong) 8 引線 MSOP 封裝，在 4V 至 60V 范圍內(nei)工作） 是(shi)一個(ge)雙路獨立電(dian)(dian)(dian)流(liu)檢(jian)測(ce)放(fang)(fang)大(da)器，可通(tong)過外部檢(jian)測(ce)電(dian)(dian)(dian)阻器監視電(dian)(dian)(dian)流(liu)。該器件以(yi)(yi) mV 為單位(wei)測(ce)量(liang)和(he)(he)(he)提(ti)供電(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)和(he)(he)(he)放(fang)(fang)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)的電(dian)(dian)(dian)流(liu)比率(lv)輸(shu)出(chu)(chu)。在本文情況下，它(ta)幫(bang)助指示電(dian)(dian)(dian)池(chi)充(chong)和(he)(he)(he)放(fang)(fang)了多少電(dian)(dian)(dian)量(liang)。這(zhe)是(shi)一種以(yi)(yi)低功率(lv)損耗讀取電(dian)(dian)(dian)流(liu)的方(fang)法，這(zhe)對保持(chi)一個(ge)高能效(xiao)系(xi)統(tong)(tong)至關重要。我(wo)略微(wei)調節了 LTC6103 （DC1116A） 演示板(ban)以(yi)(yi)實現這(zhe)一點。引腳 8 和(he)(he)(he) 7 分別與(yu)進(jin)入電(dian)(dian)(dian)池(chi)的電(dian)(dian)(dian)流(liu)通(tong)路 +IN_A 和(he)(he)(he) -IN_A 串聯(lian)。這(zhe)將提(ti)供進(jin)入電(dian)(dian)(dian)池(chi)的充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)。引腳 6 和(he)(he)(he) 5 相互掉(diao)換后反著(zhu)連(lian)接，以(yi)(yi)測(ce)量(liang)電(dian)(dian)(dian)池(chi)放(fang)(fang)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)通(tong)路，+IN_B （引腳 5） 連(lian)接到 -IN_A （引腳 7），-IN_B （引腳 6） 連(lian)接到 +IN_A （引腳 8）。電(dian)(dian)(dian)阻器的值以(yi)(yi) 10 為倍數改(gai)變和(he)(he)(he)調節，以(yi)(yi)便在 0.1Ω 并聯(lian)檢(jian)測(ce)電(dian)(dian)(dian)阻器與(yu)電(dian)(dian)(dian)路串聯(lian)時(shi)，輸(shu)出(chu)(chu)以(yi)(yi) 100mV/A 變化(hua)。圖(tu) 5 中的萬用(yong)表顯示整個(ge)系(xi)統(tong)(tong)的結果。太陽能電(dian)(dian)(dian)池(chi)板(ban)輸(shu)出(chu)(chu)電(dian)(dian)(dian)壓是(shi) 17.11V，電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓為 12.95V，充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)是(shi) 3.58A.

　　圖 5：萬用表顯示 17.11V 太陽能電池板輸出，12.95V 電池充電電壓；3.58A電池充電電流

ADC 和微控制器讀數(shu)

　　我決定，每次檢查電路是否(fou)正常(chang)運行時不使用(yong)電壓表(biao)，因為電壓表(biao)在沙漠中難以攜(xie)帶。為了避(bi)免攜(xie)帶多(duo)個(ge)萬(wan)用(yong)表(biao)，我用(yong)一(yi)個(ge)微控制器(qi)和 ADC 來(lai)讀取系統(tong)的(de)電壓值，并在一(yi)般的(de) LCD 顯示(shi)屏上顯示(shi)信息。這種(zhong)方法可就(jiu)電路性能提供實時數據，而(er)無需連(lian)接幾(ji)個(ge)萬(wan)用(yong)表(biao)。

　　我(wo)使用(yong) DC590B 演示板(ban)和(he)(he)(he) LTC2418 8信(xin)(xin)道(dao) / 16 信(xin)(xin)道(dao) 24 位 ADC 演示板(ban) DC571A.我(wo)的(de)(de)(de)同(tong)事 Mark Thoren 給了我(wo) PIC 微控制(zhi)器的(de)(de)(de)嵌入(ru)式源代碼樣本，我(wo)微調(diao)了這個(ge)源代碼樣本，以(yi)(yi)跨(kua) LTC2418 上(shang) ADC 的(de)(de)(de)不(bu)同(tong)通道(dao)對電(dian)(dian)壓(ya)采樣，并以(yi)(yi)可接(jie)受(shou)的(de)(de)(de)分辨率、準(zhun)確地讀出 mV 范(fan)圍的(de)(de)(de)電(dian)(dian)壓(ya)值。既然基準(zhun)電(dian)(dian)壓(ya)的(de)(de)(de)最(zui)(zui)大范(fan)圍是 2.5V，那么我(wo)用(yong)一種(zhong)電(dian)(dian)壓(ya)分壓(ya)器方(fang)法來按比例(li)將(jiang)電(dian)(dian)壓(ya)降低(di)到(dao) mV 范(fan)圍，以(yi)(yi)在 ADC 上(shang)實現正(zheng)確的(de)(de)(de)測(ce)量(liang)。通道(dao)連接(jie)到(dao)單個(ge)有(you)關(guan)(guan)的(de)(de)(de)輸(shu)(shu)(shu)入(ru)和(he)(he)(he)輸(shu)(shu)(shu)出電(dian)(dian)壓(ya)上(shang)，包括(kuo)電(dian)(dian)流(liu)(liu)檢(jian)測(ce)電(dian)(dian)壓(ya)。這么做(zuo)非常成功，無需多(duo)個(ge)萬用(yong)表(biao)。圖(tu) 6 是一個(ge)有(you)關(guan)(guan)這個(ge) LCD 顯(xian)(xian)示屏(ping)的(de)(de)(de)全功能系統的(de)(de)(de)例(li)子。我(wo)在 LCD 上(shang)得(de)到(dao)的(de)(de)(de)最(zui)(zui)后的(de)(de)(de)顯(xian)(xian)示提(ti)供(gong)了有(you)關(guan)(guan)以(yi)(yi)下電(dian)(dian)壓(ya)的(de)(de)(de)信(xin)(xin)息：變化(hua)的(de)(de)(de)太陽能電(dian)(dian)源電(dian)(dian)壓(ya) Vs、充(chong)(chong)電(dian)(dian)電(dian)(dian)路電(dian)(dian)壓(ya) Vc、電(dian)(dian)池(chi)電(dian)(dian)壓(ya) Vb、以(yi)(yi)及電(dian)(dian)池(chi)上(shang)的(de)(de)(de)輸(shu)(shu)(shu)入(ru)充(chong)(chong)電(dian)(dian)/放電(dian)(dian)電(dian)(dian)流(liu)(liu) C 和(he)(he)(he) D.在本文(wen)情況(kuang)下，是“C”，它(ta)在充(chong)(chong)電(dian)(dian)。放電(dian)(dian)時，程序將(jiang)改變到(dao)“D”。

　　圖 6:LCD 讀(du)數：Vs （太(tai)陽能(neng)電(dian)池板(ban)電(dian)壓(ya)）；Vc （充電(dian)電(dian)路電(dian)壓(ya)）；Vb （電(dian)池電(dian)壓(ya)）；C = 充電(dian)電(dian)流(liu) （4.3A），用(yong)(yong)DC590B PIC 微控制(zhi)器(qi)控制(zhi)；用(yong)(yong) LTC2418 演(yan)示(shi)(shi)板(ban) DC571 ADC 讀(du)取電(dian)壓(ya)，該演(yan)示(shi)(shi)板(ban)由 LTM4601演(yan)示(shi)(shi)板(ban) DC1041A 微型模塊降(jiang)壓(ya)型穩壓(ya)器(qi)供電(dian)。

　　注意，DC590B 演示(shi)(shi)板不是(shi)靠 12V 軌(gui)供電(dian)，而(er)是(shi)靠 5V 軌(gui)供電(dian)。需要一個降(jiang)壓型穩(wen)壓器(qi)將(jiang)電(dian)壓從(cong)電(dian)池的 12V 降(jiang)低到 5V.這個降(jiang)壓型穩(wen)壓器(qi)將(jiang)必須是(shi)高(gao)效率的，因(yin)為電(dian)源將(jiang)來自太(tai)陽能(neng)電(dian)池板和(he)電(dian)池，我不想因(yin)運行(xing) LCD 顯示(shi)(shi)屏和(he)微(wei)控制器(qi)而(er)耗(hao)費大量功率。我使用 LTM4601 微(wei)型模塊 DC/DC 開關穩(wen)壓器(qi)演示(shi)(shi)板 DC1041A.

　　LTM4601 是(shi)一(yi)個(ge)(ge) LGA 封(feng)裝的(de) 15mm x 15mm x 2.8mm 微型(xing)模塊(kuai) DC/DC 開關穩(wen)壓器(qi)，在 12A 最大負載電(dian)流(liu)時，輸(shu)(shu)入為 4.5V 至 20V，輸(shu)(shu)出(chu)為 0.6V 至 5V.LTM4601 的(de)設(she)計使得非常容(rong)易從 12V 電(dian)池提供(gong)一(yi)個(ge)(ge)穩(wen)定的(de) 5V 輸(shu)(shu)出(chu)。該微型(xing)模塊(kuai)包(bao)括所有控制支持組件，如電(dian)阻器(qi)、電(dian)容(rong)器(qi)、MOSFET 和電(dian)感器(qi)。在這個(ge)(ge)系(xi)統(tong)中，效率大約為 90%，使用最小的(de)電(dian)池電(dian)流(liu)，極大地(di)延長了電(dian)池壽命(ming)。更容(rong)易的(de)是(shi)，輸(shu)(shu)出(chu)電(dian)壓用一(yi)個(ge)(ge)電(dian)阻器(qi)設(she)置，如果我需要(yao)一(yi)個(ge)(ge)不同的(de)電(dian)壓軌 （例如 3.3V、2.5V、1.8V、1.5V 和 1.2V），那么在演示板(ban)上(shang)用一(yi)條跨接線可以(yi)非常容(rong)易地(di)改變(bian)這個(ge)(ge)輸(shu)(shu)出(chu)電(dian)壓。

　　總之，兩塊 BP 太(tai)陽能電(dian)(dian)池(chi)板(ban)，每(mei)塊在 4A 電(dian)(dian)流(liu)時(shi)都有 0 至 20V 的輸(shu)(shu)出，這兩塊太(tai)陽能電(dian)(dian)池(chi)板(ban)由 20V 輸(shu)(shu)出的 LTM4607 降壓/升壓型微型模塊開(kai)關穩壓器調節，然(ran)后再(zai)到 14V 輸(shu)(shu)入(ru)的 LTC1435/LT1620 電(dian)(dian)池(chi)充(chong)電(dian)(dian)器，通過一(yi)個(ge)(ge)理想二極管 MOSFET 控制器 LTC4414、一(yi)個(ge)(ge)串聯的電(dian)(dian)流(liu)檢測(ce)放大器 LTC6103，最(zui)終進入(ru)電(dian)(dian)池(chi)；以(yi)穩定的 4A 電(dian)(dian)流(liu)充(chong)電(dian)(dian)。在這個(ge)(ge)設計中，由 LTC2418 在不同的級(ji)獲取 ADC 讀(du)數，并將讀(du)數送至由 LTM4601 微型模塊開(kai)關穩壓器供電(dian)(dian)的 DC590B 演示(shi)板(ban)微控制器，以(yi)在 LCD 上顯示(shi)結果。圖 7 顯示(shi)正在運行的整個(ge)(ge)系統。

　　圖 7：運行中的整個系統設計

　　噴霧系統的機械設計

　　有了一個正常工作的(de)太(tai)陽能充電器(qi)和穩(wen)定的(de) 12V 輸出，我就準(zhun)備好著手組裝噴霧(wu)系統(tong)了。去(qu)一趟五金店就得到了我需(xu)要的(de)材料：艙(cang)(cang)底污水(shui)(shui)泵、水(shui)(shui)龍(long)帶(dai)(dai)(dai)連接(jie)器(qi)、水(shui)(shui)龍(long)帶(dai)(dai)(dai)夾具、轉接(jie)器(qi)和噴霧(wu)系統(tong)。水(shui)(shui)龍(long)帶(dai)(dai)(dai)長約(yue) 15 英尺，擰在轉接(jie)器(qi)螺釘上，用水(shui)(shui)龍(long)帶(dai)(dai)(dai)夾具固(gu)定到水(shui)(shui)泵上，噴霧(wu)系統(tong)固(gu)定在末端，有 5 個噴霧(wu)嘴。底艙(cang)(cang)污水(shui)(shui)泵靠最大值為 12V 的(de)電壓(ya)運行，水(shui)(shui)壓(ya)可(ke)以通過(guo)降低電壓(ya)來控(kong)制。

　　為(wei)了實(shi)現靈活性，我安裝了一(yi)(yi)個(ge)穩壓器(qi)，該穩壓器(qi)可以接受 12V 輸(shu)入，并將輸(shu)入轉(zhuan)換成可變的(de) 12V 輸(shu)出(chu)(chu)(chu)。這(zhe)要求 LTM4607 設(she)(she)計有(you)降壓/升壓特性。該器(qi)件使(shi)用一(yi)(yi)個(ge)反饋(kui)電阻器(qi)控制(zhi)輸(shu)出(chu)(chu)(chu)電壓。一(yi)(yi)個(ge) 50k 的(de)可變旋(xuan)(xuan)鈕電位器(qi)取代了電阻器(qi)，從而(er)非常容(rong)易控制(zhi) 0.8V 至 12V 的(de)輸(shu)出(chu)(chu)(chu)。還串(chuan)聯(lian)了一(yi)(yi)個(ge) 5.62k 的(de)電阻器(qi)，以限(xian)制(zhi)輸(shu)出(chu)(chu)(chu)電壓，保持輸(shu)出(chu)(chu)(chu)低于 15V.該設(she)(she)計通過旋(xuan)(xuan)轉(zhuan)一(yi)(yi)個(ge)旋(xuan)(xuan)鈕實(shi)現了水壓控制(zhi)。

　　然后(hou)，我就可以(yi)測試我的(de)全(quan)功(gong)能噴(pen)霧(wu)系統了。結果，水泵導致最大約 6A 的(de)電(dian)(dian)(dian)(dian)池放(fang)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)，這意味(wei)著，在(zai)峰(feng)值(zhi)輸出時，水泵約從每(mei)塊太(tai)陽(yang)能電(dian)(dian)(dian)(dian)池板獲得 4A 電(dian)(dian)(dian)(dian)流(liu)(liu)。控制水泵速(su)度和壓力的(de)好處是，我可以(yi)將壓力降到足夠(gou)低，以(yi)降低電(dian)(dian)(dian)(dian)池的(de)放(fang)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)(liu)，并全(quan)部靠(kao)太(tai)陽(yang)能電(dian)(dian)(dian)(dian)池板運(yun)行水泵，以(yi)節省電(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)量，這樣(yang)做非常有效。通過這種方法，我們能夠(gou)在(zai)營地(di)全(quan)天運(yun)行噴(pen)霧(wu)系統，而不必擔心電(dian)(dian)(dian)(dian)池放(fang)電(dian)(dian)(dian)(dian)，耽(dan)誤夜間用于 LED 照明系統。

　　LED 照明

　　隨著電(dian)(dian)(dian)源(yuan)的完成，我就可(ke)以(yi)(yi)(yi)增(zeng)加電(dian)(dian)(dian)路，在(zai)晚上高效率地提(ti)(ti)供(gong)照(zhao)明(ming)(ming)了(le)。LED 足夠(gou)亮(liang)(liang)，可(ke)以(yi)(yi)(yi)照(zhao)亮(liang)(liang)房(fang)間，這在(zai)以(yi)(yi)(yi)前是不可(ke)想象的，但(dan)是新(xin)的技術(shu)進(jin)步已經為(wei) LED 照(zhao)明(ming)(ming)的新(xin)時(shi)(shi)代創造了(le)條件(jian)。尤(you)其是，PhilipsLumileds Luxeon LED 在(zai) 1000mA 時(shi)(shi)可(ke)以(yi)(yi)(yi)提(ti)(ti)供(gong)超過 100 流(liu)明(ming)(ming)的光(guang)。我配備(bei)了(le)一(yi)個(ge) LumiLED 陣列，使用 LTC3475 （16 引線 TSSOP 耐熱(re)增(zeng)強(qiang)型封裝） 雙路 1.5A 恒定電(dian)(dian)(dian)流(liu) LED 驅動器 DC923A 演示板(ban)。它設計成用一(yi)個(ge)寬(kuan)范圍輸(shu)入電(dian)(dian)(dian)壓 （4V 至(zhi) 30V） 驅動兩個(ge)信(xin)道，每(mei)個(ge)信(xin)道 1.5A.12V 電(dian)(dian)(dian)池直(zhi)接(jie)連接(jie)到(dao)演示板(ban)的輸(shu)入，為(wei)每(mei)個(ge)通道 3 個(ge)串聯的 LED 燈供(gong)電(dian)(dian)(dian)，當(dang)兩個(ge)通道都接(jie)通時(shi)(shi)，總(zong)共有 6 個(ge) LED.這些 LED 出奇(qi)地亮(liang)(liang)，用一(yi)塊柔光(guang)布遮上時(shi)(shi)，足夠(gou)照(zhao)亮(liang)(liang)我們(men)(men)整個(ge)營地。晚上的放電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)全部來自電(dian)(dian)(dian)池，因為(wei)太陽能電(dian)(dian)(dian)池板(ban)夜間提(ti)(ti)供(gong)零電(dian)(dian)(dian)力。以(yi)(yi)(yi) 2A 的總(zong)放電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)，可(ke)以(yi)(yi)(yi)整晚為(wei)這些燈供(gong)電(dian)(dian)(dian)。到(dao)接(jie)近中(zhong)午(wu)或(huo)偏下(xia)午(wu)時(shi)(shi)，電(dian)(dian)(dian)池再次充滿(man)電(dian)(dian)(dian)，為(wei)給噴霧(wu)系(xi)(xi)統(tong)供(gong)電(dian)(dian)(dian)做(zuo)好(hao)了(le)準備(bei)，在(zai)早午(wu)餐后(hou)，噴霧(wu)系(xi)(xi)統(tong)就可(ke)以(yi)(yi)(yi)讓我們(men)(men)感到(dao)涼爽了(le)。