無需MCU的低成本太陽能電池充電器
太陽(yang)(yang)能電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)板的(de)泄(xie)漏問題傳統上可以采用(yong)一個(ge)與太陽(yang)(yang)能電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)板相(xiang)串(chuan)聯的(de)肖特(te)基(ji)(ji)二極管(guan)來解決,但肖特(te)基(ji)(ji)二極管(guan)的(de)正(zheng)向電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)降使(shi)得它在(zai)高(gao)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)條件下(xia)會消耗大量的(de)功率。因此,需(xu)要采用(yong)昂貴(gui)的(de)散熱(re)器和精細的(de)布局(ju)來把(ba)肖特(te)基(ji)(ji)二極管(guan)保持于低(di)溫狀態。那么,有沒有低(di)成本的(de)解決方案?太陽(yang)(yang)能電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)器設計(ji)最困擾設計(ji)師的(de)“至滿充電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的(de)浮動(dong)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)控制”和“在(zai)最佳(jia)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)點給電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)板加載”問題又該如何解決?在(zai)下(xia)文中,Linear電(dian)(dian)(dian)(dian)(dian)(dian)源專家將(jiang)為你介紹該公(gong)司最新的(de)低(di)成本解決方案。
作為(wei)(wei)在(zai)商(shang)業和住宅(zhai)環境(jing)中均具(ju)實用性(xing)的(de)(de)(de)一種發電(dian)方法(fa)而(er)言,太(tai)陽能電(dian)池(chi)板已經被人(ren)們所廣泛(fan)接受。然而(er),盡(jin)管(guan)在(zai)技術方面取(qu)得了進步,太(tai)陽能電(dian)池(chi)板的(de)(de)(de)造(zao)價仍然很(hen)(hen)昂貴。這種高昂的(de)(de)(de)成(cheng)本有很(hen)(hen)大部分來(lai)自于電(dian)池(chi)板本身,這里,電(dian)池(chi)板的(de)(de)(de)尺寸 (因而(er)也(ye)包括(kuo)其(qi)成(cheng)本) 將隨著所需輸出功(gong)率(lv)的(de)(de)(de)增加而(er)增加。因此,為(wei)(wei)了造(zao)就外形尺寸最小、成(cheng)本效益性(xing)最佳(jia)的(de)(de)(de)解決(jue)方案,最大限(xian)度(du)地提升(sheng)電(dian)池(chi)板性(xing)能是(shi)很(hen)(hen)重要的(de)(de)(de)。
一般而言,太陽能電池板所獲取的能量用于給電池充電,電池的儲能反過來將在沒有陽光照射的情況下為終端應用電路的操作提供支持。如欲實現太陽能電池充電器的(de)(de)最(zui)(zui)佳(jia)設計,則(ze)必需對太陽能(neng)(neng)電(dian)(dian)池(chi)(chi)板的(de)(de)特(te)性(xing)(xing)有(you)所了解。首先,由于具(ju)有(you)很大的(de)(de)結合(he)區(qu),因此太陽能(neng)(neng)電(dian)(dian)池(chi)(chi)板會發生泄(xie)漏,在黑暗條件下電(dian)(dian)池(chi)(chi)將(jiang)(jiang)通(tong)過電(dian)(dian)池(chi)(chi)板放電(dian)(dian)。而(er)且,每(mei)塊太陽能(neng)(neng)電(dian)(dian)池(chi)(chi)板都擁(yong)有(you)一個具(ju)最(zui)(zui)大功(gong)率(lv)點(dian)的(de)(de)特(te)征IV曲線,所以,當負載(zai)特(te)性(xing)(xing)與電(dian)(dian)池(chi)(chi)板特(te)性(xing)(xing)不(bu)相(xiang)匹配時,能(neng)(neng)量提取(qu)將(jiang)(jiang)有(you)所減(jian)少。理(li)想的(de)(de)情(qing)況是:電(dian)(dian)池(chi)(chi)板將(jiang)(jiang)在最(zui)(zui)大功(gong)率(lv)點(dian)上被持續加載(zai),以充分地利用可用的(de)(de)太陽能(neng)(neng),并由此最(zui)(zui)大限(xian)度(du)地縮減(jian)電(dian)(dian)池(chi)(chi)板成(cheng)本。
一(yi)般情(qing)況下,可以(yi)采(cai)用(yong)一(yi)個(ge)與(yu)電(dian)(dian)池(chi)(chi)板(ban)相串聯的(de)(de)(de)(de)肖(xiao)(xiao)(xiao)(xiao)特(te)(te)(te)基二極(ji)(ji)(ji)(ji)管(guan)來解決電(dian)(dian)池(chi)(chi)板(ban)的(de)(de)(de)(de)泄漏(lou)問(wen)題。反向(xiang)泄漏(lou)被減小(xiao)至一(yi)個(ge)很低的(de)(de)(de)(de)數值;然(ran)而(er),肖(xiao)(xiao)(xiao)(xiao)特(te)(te)(te)基二極(ji)(ji)(ji)(ji)管(guan)的(de)(de)(de)(de)正向(xiang)電(dian)(dian)壓降 (它在高電(dian)(dian)流條件(jian)下會消耗大量的(de)(de)(de)(de)功(gong)(gong)率) 仍然(ran)會造成(cheng)能量損失。因此,需(xu)要采(cai)用(yong)昂(ang)貴的(de)(de)(de)(de)散(san)熱(re)器和(he)精細的(de)(de)(de)(de)布局(ju)來把肖(xiao)(xiao)(xiao)(xiao)特(te)(te)(te)基二極(ji)(ji)(ji)(ji)管(guan)保持于(yu)低溫狀態。解決該(gai)功(gong)(gong)率耗散(san)問(wen)題的(de)(de)(de)(de)一(yi)種更加有效方法是(shi)用(yong)一(yi)個(ge)基于(yu)MOSFET的(de)(de)(de)(de)理(li)想二極(ji)(ji)(ji)(ji)管(guan)來替代肖(xiao)(xiao)(xiao)(xiao)特(te)(te)(te)基二極(ji)(ji)(ji)(ji)管(guan)。這將把正向(xiang)電(dian)(dian)壓降減小(xiao)到低至20mV,從而(er)顯著地減少功(gong)(gong)耗,同時(shi)降低散(san)熱(re)布局(ju)的(de)(de)(de)(de)復雜性、外(wai)形尺寸和(he)成(cheng)本。幸運的(de)(de)(de)(de)是(shi),由(you)于(yu)已經有一(yi)些(xie)IC供應商制(zhi)造出了具有這種規(gui)格(ge)的(de)(de)(de)(de)理(li)想二極(ji)(ji)(ji)(ji)管(guan) (比(bi)如:由(you)凌(ling)力爾特(te)(te)(te)公(gong)司提供的(de)(de)(de)(de)LTC4412),因此上述目標(biao)得以(yi)輕松實現。
不過(guo),有兩個問題依然存(cun)在,即:“至滿充(chong)電電池(chi)的浮動電壓(ya)控制”和“在最佳發電點給電池(chi)板加載”。這(zhe)些問題常(chang)(chang)常(chang)(chang)可以通過(guo)采用(yong)一(yi)個開關模式充(chong)電器和一(yi)個高(gao)效率降壓(ya)型穩壓(ya)器來加以解決。
凌力爾(er)特已(yi)經開發出了這(zhe)樣一(yi)款電路,它由(you)LTC1625 No RESNSE(無檢測(ce)電阻器)同步(bu)降壓型(xing)控制器、LTC1541微功率運(yun)算放大器、比(bi)較器和(he)基準(zhun)、以及LTC4412理(li)想(xiang)二極管(guan)組(zu)成。
電路被置于太陽能電池板和電池之間,用于調節電池浮動電壓。基于LTC1541的附加控制環路強制充電器在(zai)最(zui)大電(dian)池(chi)板功(gong)率(lv)(lv)點(dian)上運作。這種效(xiao)率(lv)(lv)的(de)提升縮減了(le)所(suo)需的(de)電(dian)池(chi)板尺(chi)寸(cun),因而降低了(le)總(zong)體(ti)解(jie)決(jue)方案(an)的(de)成本。當電(dian)池(chi)板峰(feng)值電(dian)源(yuan)電(dian)壓和電(dian)池(chi)電(dian)壓之間存在(zai)失(shi)配時,這款電(dian)路的(de)重要優點(dian)表現得尤為突出。
