太陽能電池板的泄漏問題傳統上可以采用一個與太陽能電池板相串聯的肖特基二極管來解決，但肖特基二極管的正向電壓降使得它在高電流條件下會消耗大量的功率。因此，需要采用昂貴的散熱器和精細的布局來把肖特基二極管保持于低溫狀態。那么，有沒有低成本的解決方案？太陽能電池充電器設(she)計最(zui)困擾設(she)計師的“至滿(man)充電(dian)(dian)(dian)電(dian)(dian)(dian)池(chi)的浮動電(dian)(dian)(dian)壓控制”和“在(zai)最(zui)佳發(fa)電(dian)(dian)(dian)點給電(dian)(dian)(dian)池(chi)板加載(zai)”問題(ti)又該如何(he)解(jie)決(jue)？在(zai)下文(wen)中，Linear電(dian)(dian)(dian)源專家將為你介紹該公司最(zui)新的低(di)成本解(jie)決(jue)方案(an)。

　　作為在商(shang)業和住宅環(huan)境中均具實(shi)用性(xing)的(de)(de)一種(zhong)發(fa)電(dian)(dian)方法而(er)言，太陽能(neng)(neng)電(dian)(dian)池(chi)板(ban)(ban)(ban)已經被人(ren)們(men)所廣泛接受。然而(er)，盡管在技術方面取得了進步，太陽能(neng)(neng)電(dian)(dian)池(chi)板(ban)(ban)(ban)的(de)(de)造價仍然很(hen)昂(ang)貴。這種(zhong)高昂(ang)的(de)(de)成(cheng)(cheng)本(ben)有很(hen)大部分來自于電(dian)(dian)池(chi)板(ban)(ban)(ban)本(ben)身，這里，電(dian)(dian)池(chi)板(ban)(ban)(ban)的(de)(de)尺寸(cun)(因(yin)而(er)也包(bao)括其成(cheng)(cheng)本(ben))將隨(sui)著所需(xu)輸(shu)出功率的(de)(de)增加而(er)增加。因(yin)此，為了造就外形尺寸(cun)最(zui)小(xiao)、成(cheng)(cheng)本(ben)效益性(xing)最(zui)佳的(de)(de)解決方案，最(zui)大限度地提(ti)升電(dian)(dian)池(chi)板(ban)(ban)(ban)性(xing)能(neng)(neng)是很(hen)重(zhong)要的(de)(de)。

　　一般而言(yan)，太(tai)陽(yang)能電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)板(ban)所獲取的(de)能量(liang)用于給電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)，電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的(de)儲(chu)能反過(guo)來將在沒有陽(yang)光照射的(de)情況下(xia)(xia)為終端應用電(dian)(dian)(dian)(dian)(dian)(dian)路的(de)操作提供(gong)支(zhi)持。如欲(yu)實現太(tai)陽(yang)能電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器的(de)最(zui)佳設(she)計，則(ze)必需(xu)對太(tai)陽(yang)能電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)板(ban)的(de)特性(xing)有所了解。首先，由于具有很大(da)(da)的(de)結合區，因此(ci)太(tai)陽(yang)能電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)板(ban)會發生泄漏，在黑暗條件(jian)下(xia)(xia)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)將通過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)板(ban)放電(dian)(dian)(dian)(dian)(dian)(dian)。而且(qie)，每塊太(tai)陽(yang)能電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)板(ban)都擁有一個具最(zui)大(da)(da)功率點的(de)特征IV曲線，所以(yi)(yi)，當(dang)負(fu)載特性(xing)與(yu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)板(ban)特性(xing)不(bu)相匹配時，能量(liang)提取將有所減(jian)少(shao)。理想的(de)情況是(shi)：電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)板(ban)將在最(zui)大(da)(da)功率點上被(bei)持續加載，以(yi)(yi)充(chong)分地利用可用的(de)太(tai)陽(yang)能，并(bing)由此(ci)最(zui)大(da)(da)限度地縮減(jian)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)板(ban)成本(ben)。

　　一(yi)(yi)(yi)(yi)般(ban)情況下，可以采用一(yi)(yi)(yi)(yi)個與(yu)電(dian)(dian)(dian)池(chi)板相串聯的(de)(de)肖(xiao)特(te)基(ji)(ji)二(er)極(ji)管(guan)來(lai)(lai)解(jie)決(jue)電(dian)(dian)(dian)池(chi)板的(de)(de)泄漏(lou)問(wen)題(ti)。反(fan)向泄漏(lou)被減小至(zhi)一(yi)(yi)(yi)(yi)個很低(di)的(de)(de)數值；然而，肖(xiao)特(te)基(ji)(ji)二(er)極(ji)管(guan)的(de)(de)正向電(dian)(dian)(dian)壓降(它在(zai)高電(dian)(dian)(dian)流(liu)條(tiao)件下會消耗大(da)量的(de)(de)功率(lv))仍然會造成(cheng)能量損失。因(yin)此(ci)，需(xu)要采用昂貴的(de)(de)散(san)熱(re)器和(he)精細的(de)(de)布(bu)(bu)局來(lai)(lai)把肖(xiao)特(te)基(ji)(ji)二(er)極(ji)管(guan)保持于低(di)溫狀態。解(jie)決(jue)該(gai)功率(lv)耗散(san)問(wen)題(ti)的(de)(de)一(yi)(yi)(yi)(yi)種更(geng)加有效方法是(shi)用一(yi)(yi)(yi)(yi)個基(ji)(ji)于MOSFET的(de)(de)理想二(er)極(ji)管(guan)來(lai)(lai)替(ti)代肖(xiao)特(te)基(ji)(ji)二(er)極(ji)管(guan)。這(zhe)將把正向電(dian)(dian)(dian)壓降減小到低(di)至(zhi)20mV，從而顯著地減少功耗，同時降低(di)散(san)熱(re)布(bu)(bu)局的(de)(de)復(fu)雜性、外(wai)形尺寸和(he)成(cheng)本。幸(xing)運的(de)(de)是(shi)，由于已經有一(yi)(yi)(yi)(yi)些IC供(gong)應(ying)商制造出了(le)具有這(zhe)種規格(ge)的(de)(de)理想二(er)極(ji)管(guan)(比如(ru)：由凌(ling)力爾特(te)公司提供(gong)的(de)(de)LTC4412)，因(yin)此(ci)上述目標(biao)得以輕松實(shi)現。

　　不過，有兩個問題依然存在，即：“至滿充電電池的浮動電壓控制”和“在最佳發電點給電池板加載”。這些問題常常可以通過采用一個開關模式充電器和一個高效率降壓型穩壓器來(lai)加以(yi)解決。

　　凌力爾特已經開發出了這(zhe)樣(yang)一款電(dian)路，它由LTC1625 No RESNSE(無檢測電(dian)阻器)同步降壓型控制器、LTC1541微功(gong)率運(yun)算放大器、比較(jiao)器和基(ji)準、以及LTC4412理想二(er)極管組成。下面(mian)給出了該電(dian)路以供參考(kao)：

　　圖1中(zhong)的電(dian)路(lu)被置于太陽能電(dian)池(chi)板和(he)電(dian)池(chi)之間，用于調節電(dian)池(chi)浮動電(dian)壓。基(ji)于LTC1541的附加控制環(huan)路(lu)強制充電(dian)器(qi)在最大電(dian)池(chi)板功(gong)率點上運作。這(zhe)種效率的提升縮減了所需的電(dian)池(chi)板尺(chi)寸(cun)，因而降(jiang)低(di)了總體解決方案的成本(ben)。當(dang)電(dian)池(chi)板峰值電(dian)源電(dian)壓和(he)電(dian)池(chi)電(dian)壓之間存在失配時(shi)，這(zhe)款電(dian)路(lu)的重要優(you)點表現得(de)尤為突(tu)出。