節(jie)能環保一直是人們熱(re)議話題，電(dian)(dian)(dian)動(dong)(dong)和混(hun)合動(dong)(dong)力(li)汽車則提供(gong)了(le)一種節(jie)省能源和減少二氧化碳排放的(de)極好方式。然而，電(dian)(dian)(dian)動(dong)(dong)和混(hun)合動(dong)(dong)力(li)汽車重要(yao)弱點就在于其電(dian)(dian)(dian)池容(rong)量，以及由(you)此帶來的(de)行駛(shi)距離的(de)限制(zhi)。由(you)于能夠安裝進汽車的(de)最大(da)電(dian)(dian)(dian)池尺(chi)寸常(chang)常(chang)受(shou)到體積(ji)和重量限制(zhi)，因(yin)而優(you)化利(li)用現(xian)有電(dian)(dian)(dian)池容(rong)量變得越來越重要(yao)。

　　要提供用于電動汽車的現代高性能電池所需的幾百伏電壓，通常需要將幾個單獨的電池單元以串聯方式相連接。電池組中的每個電池單元，電池單元容量、自放電率、溫度特性和電池阻抗等都各有不同，而且差異會隨著電池的老化而增大。當電池單元正在充電時，這種差異便會導致一種情形，即某些電池單元還沒有充滿足夠的電能，但另一些電池單元早已充滿電荷了。除非采取額外措施，否則充電器充(chong)電(dian)過(guo)程必(bi)須(xu)終止，因為如(ru)果某(mou)個電(dian)池單元過(guo)分充(chong)電(dian)，就會(hui)發生損壞、甚至(zhi)有可(ke)能完全毀壞。

　　類似的(de)(de)情(qing)形也會(hui)(hui)在放電(dian)(dian)(dian)時(shi)發(fa)生(sheng)。與前相反，情(qing)況是某個電(dian)(dian)(dian)池(chi)單元早已(yi)完(wan)全(quan)放電(dian)(dian)(dian)，而其它(ta)的(de)(de)電(dian)(dian)(dian)池(chi)單元仍然具有足夠的(de)(de)能量可繼續為(wei)汽(qi)車提供動力（理論(lun)上的(de)(de)）。然而，這時(shi)汽(qi)車不(bu)可能繼續行(xing)走，因為(wei)這會(hui)(hui)使較弱的(de)(de)電(dian)(dian)(dian)池(chi)單元過度放電(dian)(dian)(dian)，結果會(hui)(hui)導致電(dian)(dian)(dian)池(chi)單元的(de)(de)損毀。為(wei)了避(bi)免上述兩(liang)種這些情(qing)況的(de)(de)發(fa)生(sheng)，單個電(dian)(dian)(dian)池(chi)單元之間(jian)的(de)(de)主動平衡(heng)是必須(xu)的(de)(de)。

　　被動平衡方法將可用能(neng)量轉化為熱損(sun)耗

　　目(mu)前廣泛使(shi)用的方法是(shi)被動平(ping)衡技(ji)術，就是(shi)使(shi)用電阻將早已充滿電的電池單元再次(ci)放電，以便(bian)其(qi)它電池單元能夠繼(ji)續(xu)充電。這個(ge)方法的缺點(dian)是(shi)顯而易(yi)見的：

　　* 出于(yu)平衡的目的，電池只(zhi)能被放電

　　* 旁路電(dian)阻的(de)放電(dian)電(dian)流引起功率損(sun)耗

　　* 寶貴(gui)的能量(liang)轉(zhuan)化為(wei)熱量(liang)，不能為(wei)汽車提供動力(li)

　　* 減少汽(qi)車(che)的行駛距離

　　被動(dong)平(ping)衡(heng)方(fang)(fang)法(fa)(fa)僅能將儲存在電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)單(dan)元(yuan)(yuan)中(zhong)的(de)能量(liang)轉化(hua)為(wei)(wei)熱損耗，而主動(dong)平(ping)衡(heng)則能夠(gou)將一(yi)個(ge)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)單(dan)元(yuan)(yuan)中(zhong)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)荷傳送(song)至另一(yi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)單(dan)元(yuan)(yuan)。實(shi)現電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)荷傳送(song)有(you)幾種方(fang)(fang)法(fa)(fa)，如使用(yong)開關電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)或(huo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)感。當使用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)式方(fang)(fang)法(fa)(fa)時，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)會(hui)與有(you)較(jiao)高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)單(dan)元(yuan)(yuan)并聯。一(yi)旦(dan)此電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)單(dan)元(yuan)(yuan)完成充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，它即與有(you)較(jiao)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)單(dan)元(yuan)(yuan)并聯，能夠(gou)繼續為(wei)(wei)其充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)。此過程會(hui)不斷重復，直至所有(you)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)單(dan)元(yuan)(yuan)都達(da)到相同的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓為(wei)(wei)止。

　　使用(yong)(yong)電(dian)容器的方(fang)法(fa)具有很(hen)高的成(cheng)本效(xiao)益，但有個缺點就是(shi)平均(jun)的平衡電(dian)流被限制(zhi)在50mA以下。使用(yong)(yong)電(dian)感方(fang)法(fa)則不存在此(ci)限制(zhi)，并且(qie)在此(ci)情況下，很(hen)容易便達到(dao)1A或(huo)以上的平衡電(dian)流。

　　用(yong)主(zhu)動平衡法實(shi)現快速和(he)幾乎無損(sun)耗的電(dian)荷傳(chuan)送

　　主動平衡是通(tong)過并聯電(dian)(dian)(dian)感和需獲取(qu)電(dian)(dian)(dian)荷的電(dian)(dian)(dian)池來實(shi)現(xian)的。此結果(guo)導致線圈中的電(dian)(dian)(dian)流持續增加。

　　一旦線(xian)圈已(yi)經從通過(guo)晶(jing)體管放電的(de)電池(chi)單元中去耦，電感中儲存(cun)的(de)能量(liang)可通過(guo)一個二(er)極(ji)管對(dui)鄰近電池(chi)充電。因而電荷可以在兩個單獨的(de)電池(chi)單元之間來(lai)回地移動，實(shi)現極(ji)高效率并且幾(ji)乎無損耗。此方法具有某些決定性的(de)優點：

　　* 平衡電(dian)流可(ke)能達到(dao)1A或以上

　　* 平(ping)衡(heng)在本質上是無(wu)損耗的

　　* 平衡極其快速

　　* 增加了效率和電池容量(liang)

　　* 增加了汽車的行(xing)駛距離

　　相比所(suo)提到的(de)(de)(de)其(qi)它方法，使用(yong)(yong)電(dian)感(gan)實施(shi)主(zhu)動(dong)平(ping)(ping)衡并不(bu)算(suan)是低成(cheng)本(ben)的(de)(de)(de)方法，因為當中使用(yong)(yong)了成(cheng)本(ben)相對較高(gao)的(de)(de)(de)電(dian)感(gan)元件。然(ran)而(er)，這并不(bu)完全是個問題。現代(dai)高(gao)性能電(dian)池目前的(de)(de)(de)成(cheng)本(ben)接(jie)近10,000美元。而(er)使用(yong)(yong)電(dian)感(gan)平(ping)(ping)衡方法，即使只獲(huo)得(de)了額外的(de)(de)(de)10%容量，也代(dai)表了1,000美元的(de)(de)(de)價值--此金額可以(yi)用(yong)(yong)于購買大數量的(de)(de)(de)電(dian)感(gan)器件。

　　鋰離子電池基于安全的(de)原因，必須監(jian)控(kong)單(dan)(dan)個(ge)電(dian)池單(dan)(dan)元，因為(wei)過(guo)載會發(fa)生(sheng)(sheng)燃燒(shao)，在(zai)(zai)極端情況下甚至會發(fa)生(sheng)(sheng)爆炸(zha)。與過(guo)壓、欠壓和溫(wen)度(du)監(jian)控(kong)一樣，精(jing)確的(de)充電(dian)條件(jian)測(ce)定等(deng)附加功(gong)能(neng)(neng)也是(shi)需要的(de)。在(zai)(zai)半(ban)導體市場(chang)上已提供(gong)能(neng)(neng)實現所有(you)這些功(gong)能(neng)(neng)與不同的(de)平(ping)衡(heng)方法(fa)的(de)元件(jian)。使用先進(jin)的(de)主動電(dian)池單(dan)(dan)元平(ping)衡(heng)解(jie)決方案（如愛特梅爾 ATA6870電(dian)池管理(li)電(dian)路）每一個(ge)電(dian)池單(dan)(dan)元都有(you)單(dan)(dan)獨的(de)電(dian)子監(jian)控(kong)，以便提供(gong)如充電(dian)狀態(tai)測(ce)定、主動/被動平(ping)衡(heng)或過(guo)壓、欠壓和溫(wen)度(du)監(jian)控(kong)等(deng)功(gong)能(neng)(neng)