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計最(zui)(zui)困(kun)擾設計師的(de)(de)“至滿充(chong)電(dian)電(dian)池的(de)(de)浮動電(dian)壓控制”和“在最(zui)(zui)佳發電(dian)點(dian)給電(dian)池板加載(zai)”問題(ti)又該(gai)如何解(jie)決(jue)(jue)？在下文中，Linear電(dian)源專家(jia)將為你介紹該(gai)公司(si)最(zui)(zui)新的(de)(de)低成本解(jie)決(jue)(jue)方案。

　　作為(wei)在商業和(he)住宅(zhai)環境中均(jun)具實用性的(de)一種發電(dian)方法而言，太陽(yang)能(neng)電(dian)池板(ban)已經被(bei)人們所廣(guang)泛(fan)接受。然而，盡管在技(ji)術方面取得了進步，太陽(yang)能(neng)電(dian)池板(ban)的(de)造價仍(reng)然很昂貴(gui)。這(zhe)種高昂的(de)成(cheng)本(ben)(ben)有很大部分來自于(yu)電(dian)池板(ban)本(ben)(ben)身(shen)，這(zhe)里(li)，電(dian)池板(ban)的(de)尺(chi)寸(cun)(因(yin)而也包括其成(cheng)本(ben)(ben))將隨(sui)著(zhu)所需輸出功率的(de)增加(jia)而增加(jia)。因(yin)此，為(wei)了造就(jiu)外形尺(chi)寸(cun)最小、成(cheng)本(ben)(ben)效益性最佳(jia)的(de)解決方案，最大限度地提升電(dian)池板(ban)性能(neng)是很重要的(de)。

　　一(yi)般(ban)而言(yan)，太(tai)(tai)(tai)陽(yang)(yang)(yang)能電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)板(ban)(ban)所(suo)獲取的(de)(de)能量(liang)(liang)用(yong)(yong)于給電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)充(chong)電(dian)(dian)(dian)，電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)的(de)(de)儲能反過(guo)來將在(zai)(zai)沒有(you)(you)陽(yang)(yang)(yang)光照射的(de)(de)情況下為終端應(ying)用(yong)(yong)電(dian)(dian)(dian)路的(de)(de)操作提(ti)供支持(chi)。如欲實現太(tai)(tai)(tai)陽(yang)(yang)(yang)能電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)充(chong)電(dian)(dian)(dian)器的(de)(de)最佳設計，則(ze)必(bi)需對太(tai)(tai)(tai)陽(yang)(yang)(yang)能電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)板(ban)(ban)的(de)(de)特性(xing)有(you)(you)所(suo)了解。首先(xian)，由于具(ju)有(you)(you)很大的(de)(de)結(jie)合區，因此(ci)(ci)太(tai)(tai)(tai)陽(yang)(yang)(yang)能電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)板(ban)(ban)會發生(sheng)泄漏，在(zai)(zai)黑(hei)暗條(tiao)件下電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)將通(tong)過(guo)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)板(ban)(ban)放電(dian)(dian)(dian)。而且，每塊太(tai)(tai)(tai)陽(yang)(yang)(yang)能電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)板(ban)(ban)都(dou)擁有(you)(you)一(yi)個(ge)具(ju)最大功率點的(de)(de)特征IV曲線，所(suo)以，當負載(zai)特性(xing)與電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)板(ban)(ban)特性(xing)不相匹(pi)配時(shi)，能量(liang)(liang)提(ti)取將有(you)(you)所(suo)減(jian)少。理(li)想的(de)(de)情況是(shi)：電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)板(ban)(ban)將在(zai)(zai)最大功率點上(shang)被持(chi)續加載(zai)，以充(chong)分地(di)利用(yong)(yong)可用(yong)(yong)的(de)(de)太(tai)(tai)(tai)陽(yang)(yang)(yang)能，并由此(ci)(ci)最大限度地(di)縮減(jian)電(dian)(dian)(dian)池(chi)(chi)(chi)(chi)板(ban)(ban)成本。

　　一般情況下，可(ke)以采用一個與電池板相串聯的(de)(de)肖(xiao)特(te)(te)基二極(ji)管(guan)來解(jie)決(jue)電池板的(de)(de)泄漏(lou)問(wen)題(ti)。反向(xiang)泄漏(lou)被(bei)減小至一個很低(di)的(de)(de)數值(zhi)；然(ran)而，肖(xiao)特(te)(te)基二極(ji)管(guan)的(de)(de)正(zheng)向(xiang)電壓(ya)降(它在(zai)高電流條件下會(hui)消耗(hao)大(da)量的(de)(de)功(gong)率)仍(reng)然(ran)會(hui)造(zao)成能(neng)量損失。因此(ci)，需(xu)要采用昂(ang)貴的(de)(de)散(san)熱器和精細的(de)(de)布(bu)局來把(ba)肖(xiao)特(te)(te)基二極(ji)管(guan)保持于(yu)(yu)低(di)溫狀態。解(jie)決(jue)該(gai)功(gong)率耗(hao)散(san)問(wen)題(ti)的(de)(de)一種更加有效方法是用一個基于(yu)(yu)MOSFET的(de)(de)理想(xiang)二極(ji)管(guan)來替代肖(xiao)特(te)(te)基二極(ji)管(guan)。這將把(ba)正(zheng)向(xiang)電壓(ya)降減小到低(di)至20mV，從(cong)而顯著地減少功(gong)耗(hao)，同(tong)時降低(di)散(san)熱布(bu)局的(de)(de)復雜性、外(wai)形尺(chi)寸和成本。幸運(yun)的(de)(de)是，由(you)于(yu)(yu)已經(jing)有一些IC供(gong)應商制造(zao)出(chu)了具有這種規格的(de)(de)理想(xiang)二極(ji)管(guan)(比如：由(you)凌力爾特(te)(te)公司提供(gong)的(de)(de)LTC4412)，因此(ci)上(shang)述目(mu)標得以輕松實現(xian)。

　　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(he)一個高效率降(jiang)壓型(xing)穩壓器(qi)來加以解決。

　　凌力爾特已經開發出了這樣一(yi)款電(dian)路(lu)，它由LTC1625 No RESNSE(無檢(jian)測(ce)電(dian)阻(zu)器)同(tong)步降壓型(xing)控制器、LTC1541微功(gong)率運算放(fang)大器、比較器和(he)基準、以及LTC4412理想(xiang)二極管組成。下面給出了該電(dian)路(lu)以供(gong)參考(kao)：

　　圖1中的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)被置(zhi)于(yu)太陽能電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池板(ban)和(he)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池之間，用于(yu)調節電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池浮動電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)。基于(yu)LTC1541的附加控(kong)制環路(lu)強制充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器在最大電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池板(ban)功率(lv)點(dian)上運(yun)作。這種效率(lv)的提升縮減了(le)所需的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池板(ban)尺寸，因而降低(di)了(le)總體(ti)解決方案的成(cheng)本(ben)。當(dang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池板(ban)峰值電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)和(he)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)之間存在失(shi)配時，這款電(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的重要(yao)優點(dian)表現得尤為突(tu)出(chu)。