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隨著新(xin)能(neng)源(yuan)及(ji)電(dian)(dian)動(dong)汽(qi)車的(de)(de)迅速發(fa)展，能(neng)量密度比更高的(de)(de)鋰電(dian)(dian)池(chi)得到(dao)了(le)更多運用，而鋰電(dian)(dian)池(chi)串聯使(shi)用過(guo)程中(zhong)，為(wei)了(le)保證電(dian)(dian)池(chi)電(dian)(dian)壓的(de)(de)一致性，必然會用到(dao)BMS來提(ti)升電(dian)(dian)池(chi)的(de)(de)使(shi)用性能(neng)和使(shi)用壽(shou)命。
上海航芯(xin)通用MCU ACM32F0系(xi)列以(yi)其低功耗+1路CAN+10萬次擦(ca)寫128K 片上Flash+125度高(gao)溫支持；ACM32F4系(xi)列以(yi)其180MHz M33內核+Flash加速+10萬次擦(ca)寫512K片上Flash+2路CAN+125度高(gao)溫支持，被廣泛應(ying)用到(dao)BMS場(chang)景中。BMS的(de)主要功能(neng)包括：電(dian)量管(guan)理、電(dian)壓檢測、電(dian)池均(jun)衡等。
電池均衡概述(shu)
電(dian)(dian)池(chi)均(jun)(jun)(jun)衡是通(tong)過對(dui)多節串聯(lian)電(dian)(dian)池(chi)進行容(rong)量最大(da)化處理(li)，確保各個(ge)電(dian)(dian)池(chi)單元能量可(ke)用，以(yi)此來延長(chang)電(dian)(dian)池(chi)使用壽命的技(ji)術。電(dian)(dian)池(chi)均(jun)(jun)(jun)衡是指在一(yi)個(ge)系列電(dian)(dian)池(chi)組(zu)(zu)中對(dui)不同的電(dian)(dian)池(chi)使用差動(dong)電(dian)(dian)流。電(dian)(dian)池(chi)均(jun)(jun)(jun)衡器是電(dian)(dian)池(chi)管理(li)系統中的一(yi)種(zhong)功(gong)能組(zu)(zu)件，用于(yu)執行鋰電(dian)(dian)池(chi)電(dian)(dian)動(dong)汽車和ESS應用中常見的電(dian)(dian)池(chi)均(jun)(jun)(jun)衡。
通常(chang)，電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組的(de)(de)各(ge)個單元具有不同的(de)(de)容量，并且(qie)處于不同的(de)(de)SOC水平（SoC是(shi)指個別電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)隨(sui)著充電(dian)(dian)(dian)(dian)(dian)和(he)放電(dian)(dian)(dian)(dian)(dian)，相(xiang)對于其(qi)最大容量的(de)(de)剩余容量）。如果(guo)沒有重新分配，當(dang)容量最低的(de)(de)電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)被(bei)放空時，放電(dian)(dian)(dian)(dian)(dian)必須停(ting)止，即(ji)使其(qi)他電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)仍未被(bei)放空，這限制了電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組的(de)(de)能量輸送(song)能力。而平衡的(de)(de)電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)是(shi)指一個電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)組中的(de)(de)每節電(dian)(dian)(dian)(dian)(dian)池(chi)(chi)都具備(bei)相(xiang)同的(de)(de)電(dian)(dian)(dian)(dian)(dian)荷狀(zhuang)態 (SoC)。
在均衡(heng)的(de)過程中(zhong)，較高容量(liang)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)經(jing)歷了一(yi)個(ge)完(wan)整(zheng)的(de)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)/放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)循環。如果沒有電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)均衡(heng)，容量(liang)最低的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)就(jiu)是(shi)一(yi)個(ge)薄弱(ruo)點，即使其(qi)他(ta)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)單元(yuan)仍有許多電(dian)(dian)(dian)(dian)(dian)(dian)(dian)量(liang)剩余，整(zheng)個(ge)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)組也只能(neng)(neng)在其(qi)最弱(ruo)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)單元(yuan)完(wan)全放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)之后才能(neng)(neng)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)。因此(ci)，對各(ge)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)單元(yuan)進行平衡(heng)可(ke)以(yi)更大(da)限(xian)度地提(ti)高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)組的(de)容量(liang)，并確保(bao)其(qi)中(zhong)所有能(neng)(neng)量(liang)均可(ke)利用，從而(er)提(ti)高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)壽(shou)命。除了更大(da)限(xian)度提(ti)高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)容量(liang)外，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)平衡(heng)功(gong)(gong)(gong)能(neng)(neng)還可(ke)防止(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)單元(yuan)過充(chong)(chong)和過放，從而(er)確保(bao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)安全運行。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)均衡(heng)是(shi)BMS的(de)核心功(gong)(gong)(gong)能(neng)(neng)之一(yi)，此(ci)外還有溫度監控、充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，以(yi)及其(qi)他(ta)有助于延長電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)(chi)組壽(shou)命的(de)功(gong)(gong)(gong)能(neng)(neng)。
電池均衡的必(bi)要性
當(dang)您需(xu)要將(jiang)(jiang)多個電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)合在(zai)一(yi)起(qi)為(wei)(wei)設(she)備供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)時(shi)，則需(xu)要進(jin)行電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)均衡。因(yin)為(wei)(wei)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)單元較(jiao)為(wei)(wei)脆弱，如果充電(dian)(dian)(dian)(dian)(dian)(dian)或(huo)(huo)放電(dian)(dian)(dian)(dian)(dian)(dian)過多，就(jiu)會(hui)(hui)死亡或(huo)(huo)損(sun)壞(huai)。對于(yu)具有不同SoC的電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)，并開始(shi)使用它(ta)們時(shi)，它(ta)們的電(dian)(dian)(dian)(dian)(dian)(dian)壓開始(shi)下降，直到(dao)其(qi)中存儲的能(neng)量最少的電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)達到(dao)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的放電(dian)(dian)(dian)(dian)(dian)(dian)截(jie)止電(dian)(dian)(dian)(dian)(dian)(dian)壓。那時(shi)，如果能(neng)量繼續流經電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)，它(ta)就(jiu)會(hui)(hui)受(shou)到(dao)無法修復(fu)的損(sun)壞(huai)。如果嘗(chang)試(shi)將(jiang)(jiang)這組電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)到(dao)正確的組合電(dian)(dian)(dian)(dian)(dian)(dian)壓，健康的電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)會(hui)(hui)過度充電(dian)(dian)(dian)(dian)(dian)(dian)并因(yin)此受(shou)到(dao)損(sun)壞(huai)，因(yin)為(wei)(wei)它(ta)們將(jiang)(jiang)要吸收已經損(sun)壞(huai)的電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)不再能(neng)夠存儲的能(neng)量。不均衡的鋰電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)在(zai)第一(yi)次(ci)嘗(chang)試(shi)使用時(shi)就(jiu)會(hui)(hui)損(sun)壞(huai)，這就(jiu)是為(wei)(wei)什么需(xu)要電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)均衡。
電池(chi)均衡(heng)的其(qi)他原因包括：
熱失(shi)控
電(dian)(dian)池(chi)，尤其是鋰電(dian)(dian)池(chi)，對(dui)過(guo)充和過(guo)放(fang)非常敏感。當內部(bu)熱(re)量的產生速(su)度(du)(du)超過(guo)散失(shi)速(su)度(du)(du)，就會(hui)導(dao)致(zhi)熱(re)失(shi)控。溫(wen)(wen)度(du)(du)升高會(hui)導(dao)致(zhi)鋰電(dian)(dian)池(chi)結構變化并在(zai)電(dian)(dian)極上形成表面膜，使(shi)鋰電(dian)(dian)池(chi)衰減(jian)速(su)度(du)(du)更(geng)快(kuai)。另(ling)外(wai)，積熱(re)過(guo)多可(ke)能會(hui)導(dao)致(zhi)電(dian)(dian)池(chi)平衡開關和電(dian)(dian)阻的損(sun)壞。通過(guo)使(shi)用電(dian)(dian)池(chi)均衡，電(dian)(dian)池(chi)組中的每個(ge)無缺陷(xian)電(dian)(dian)池(chi)應(ying)均衡到與其他無缺陷(xian)電(dian)(dian)池(chi)相同的相對(dui)容量。由于(yu)熱(re)量是導(dao)致(zhi)熱(re)失(shi)控的主(zhu)要因素之(zhi)一(yi)，因此，除電(dian)(dian)池(chi)均衡器以外(wai)，還(huan)可(ke)以使(shi)用冷卻(que)系統，保(bao)持電(dian)(dian)池(chi)組處于(yu)室溫(wen)(wen)環(huan)境，最(zui)大化的減(jian)少(shao)熱(re)量留存。
電池老化
當(dang)鋰電池(chi)被過(guo)度充電，甚至(zhi)略高于(yu)其(qi)推(tui)薦(jian)值(zhi)時，電池(chi)的(de)(de)能量(liang)容(rong)量(liang)、效率、生命周期都(dou)會降低。電池(chi)老化主要是由(you)以下(xia)原因引起的(de)(de)：
1. 袋型電池(chi)中電極(ji)的(de)機械退化或(huo)堆壓損(sun)失。
2. 陽極上固體電解(jie)質(zhi)界面（SEI）的增(zeng)長。當充電電壓保持(chi)在(zai)3.92v/cell以(yi)下時，SEI被視為大多數基于石墨的鋰(li)電池容(rong)量(liang)損失的原(yuan)因(yin)。
3. 在正(zheng)極形成電解(jie)質(zhi)氧化 (EO)，可(ke)能導致(zhi)容(rong)量突然損(sun)失。
4. 由高充電率產生的陽極表面的鍍(du)鋰(li)。
電池組的不完全充(chong)電
電(dian)(dian)池(chi)(chi)以0.5到(dao)1.0倍率的恒定電(dian)(dian)流充(chong)電(dian)(dian)，電(dian)(dian)池(chi)(chi)電(dian)(dian)壓隨(sui)著充(chong)電(dian)(dian)的進行而上升，充(chong)滿電(dian)(dian)后(hou)(hou)達到(dao)峰值，然(ran)后(hou)(hou)下降(jiang)。考慮三個(ge)分別(bie)具有77Ah、77Ah和(he)76Ah且(qie)100% SoC的電(dian)(dian)池(chi)(chi)，然(ran)后(hou)(hou)所有電(dian)(dian)池(chi)(chi)都(dou)被放(fang)電(dian)(dian)，并且(qie)SoC下降(jiang)。很快能(neng)發(fa)現3號(hao)電(dian)(dian)池(chi)(chi)會首先(xian)耗盡能(neng)量，因(yin)為它的容量最低(di)。
當給電(dian)(dian)池(chi)(chi)(chi)組(zu)通電(dian)(dian)，相同(tong)的電(dian)(dian)流(liu)流(liu)過(guo)電(dian)(dian)池(chi)(chi)(chi)時，電(dian)(dian)池(chi)(chi)(chi)3在充電(dian)(dian)過(guo)程中再次滯后(hou)，可以(yi)認為(wei)是(shi)完(wan)全(quan)充電(dian)(dian)，因為(wei)其他(ta)兩(liang)個電(dian)(dian)池(chi)(chi)(chi)已完(wan)全(quan)充電(dian)(dian)。這意味著由(you)于電(dian)(dian)池(chi)(chi)(chi)的自熱導致(zhi)電(dian)(dian)池(chi)(chi)(chi)不均衡，電(dian)(dian)池(chi)(chi)(chi)3的庫(ku)侖效(xiao)率 (CE) 較低。
電池組能量的不完(wan)全(quan)使用
消(xiao)耗(hao)超過(guo)電(dian)(dian)(dian)池(chi)設(she)計容量的(de)電(dian)(dian)(dian)流或使電(dian)(dian)(dian)池(chi)短路，最可能導致電(dian)(dian)(dian)池(chi)過(guo)早(zao)失效(xiao)。在對電(dian)(dian)(dian)池(chi)組放(fang)電(dian)(dian)(dian)時，較弱的(de)電(dian)(dian)(dian)池(chi)比(bi)健康電(dian)(dian)(dian)池(chi)放(fang)電(dian)(dian)(dian)更(geng)快(kuai)，它們比(bi)其(qi)他(ta)電(dian)(dian)(dian)池(chi)更(geng)快(kuai)達(da)到最低電(dian)(dian)(dian)壓。在電(dian)(dian)(dian)池(chi)運行過(guo)程中，提供定期的(de)休息(xi)時間，使電(dian)(dian)(dian)池(chi)中的(de)化學轉換能夠保持對電(dian)(dian)(dian)流的(de)需求。
電池均衡的類型
主動均衡
主(zhu)動電(dian)池(chi)(chi)(chi)均(jun)衡(heng)通(tong)常將能(neng)量(liang)(liang)從一(yi)個(ge)電(dian)池(chi)(chi)(chi)傳輸到(dao)另一(yi)個(ge)。即從高(gao)電(dian)壓/高(gao)SoC的(de)(de)(de)電(dian)池(chi)(chi)(chi)轉(zhuan)移到(dao)低SoC的(de)(de)(de)電(dian)池(chi)(chi)(chi)。主(zhu)動均(jun)衡(heng)的(de)(de)(de)目的(de)(de)(de)是(shi)，如果您(nin)有一(yi)組容量(liang)(liang)較(jiao)低的(de)(de)(de)電(dian)池(chi)(chi)(chi)，您(nin)可以通(tong)過從電(dian)池(chi)(chi)(chi)組中的(de)(de)(de)一(yi)個(ge)比另一(yi)個(ge)能(neng)量(liang)(liang)更高(gao)的(de)(de)(de)電(dian)池(chi)(chi)(chi)轉(zhuan)移能(neng)量(liang)(liang)來延長電(dian)池(chi)(chi)(chi)組的(de)(de)(de)壽命(ming)或SoC。
主(zhu)動(dong)電(dian)池(chi)(chi)(chi)(chi)均衡(heng)通過微型(xing)轉(zhuan)換器電(dian)路高(gao)效(xiao)地將(jiang)能(neng)(neng)量從高(gao)電(dian)壓(ya)的電(dian)池(chi)(chi)(chi)(chi)傳遞到低(di)電(dian)壓(ya)的電(dian)池(chi)(chi)(chi)(chi)，避免了熱量導致的能(neng)(neng)量損耗。主(zhu)動(dong)電(dian)池(chi)(chi)(chi)(chi)均衡(heng)方法有兩種不同類(lei)別：電(dian)荷轉(zhuan)移(yi)和能(neng)(neng)量轉(zhuan)換。電(dian)荷轉(zhuan)移(yi)用于(yu)主(zhu)動(dong)地將(jiang)電(dian)荷從一個電(dian)池(chi)(chi)(chi)(chi)傳輸(shu)到另一個電(dian)池(chi)(chi)(chi)(chi)，以實現相等(deng)的電(dian)池(chi)(chi)(chi)(chi)電(dian)壓(ya)，能(neng)(neng)量轉(zhuan)換是(shi)用變壓(ya)器和電(dian)感在電(dian)池(chi)(chi)(chi)(chi)組的電(dian)池(chi)(chi)(chi)(chi)之間移(yi)動(dong)能(neng)(neng)量。
其他(ta)有源電(dian)(dian)池均衡電(dian)(dian)路通常基于電(dian)(dian)容、電(dian)(dian)感或變壓器以及電(dian)(dian)力電(dian)(dian)子接(jie)口，這些需要：
基于(yu)電容器
? 單個(ge)電(dian)容器，這種方(fang)法(fa)很簡單，因為(wei)它使用單個(ge)電(dian)容器，而與電(dian)池(chi)中連接的電(dian)池(chi)數量(liang)無關。然而，這種方(fang)法(fa)需要大量(liang)的開(kai)關和對開(kai)關的智能(neng)控制。
? 多個(ge)(ge)電容器，這種方法將多個(ge)(ge)電容器連(lian)接到(dao)每個(ge)(ge)電池，通過多個(ge)(ge)電容器傳輸不(bu)相等的(de)電池能量，它不(bu)需要(yao)電壓(ya)傳感器或閉環控制。
基于電感器或變(bian)壓器
? 單/多(duo)電(dian)感，單電(dian)感的(de)電(dian)池(chi)(chi)均衡(heng)電(dian)路體積小(xiao)，成本低，而多(duo)電(dian)感的(de)均衡(heng)速度快，電(dian)池(chi)(chi)均衡(heng)效率高。
? 單變壓器，這種方法均衡速度快，磁損耗低。
? 多變(bian)壓(ya)器，這種電池均(jun)衡器具有快(kuai)速(su)的(de)均(jun)衡速(su)度，然而，它需要(yao)一個昂貴且復(fu)雜的(de)電路來防(fang)止變(bian)壓(ya)器被淹沒。
基于電力(li)電子接口(kou)
? 反激/正激轉換器，高(gao)壓(ya)電池的能量存儲在變壓(ya)器中，該(gai)電池均衡器具有(you)高(gao)可靠性。
? 全橋(qiao)轉換器，這種(zhong)電池均衡(heng)器具有快速(su)的均衡(heng)速(su)度和(he)高(gao)效率。
有(you)源均衡器能夠(gou)將大(da)量(liang)電流從一(yi)個電池推到另一(yi)個電池。
主動(dong)均衡的優點：
? 它提高了(le)容(rong)量(liang)使用率，當一個系列(lie)中具有不同(tong)的電池容(rong)量(liang)時，它會(hui)表現出色。
? 它(ta)提高了能源效率，它(ta)通過(guo)將(jiang)多余(yu)(yu)的能量(liang)轉移(yi)到能量(liang)較低的電(dian)池中來節省(sheng)能量(liang)，而不是燃燒電(dian)池中的多余(yu)(yu)能量(liang)。
? 壽命延長，它提高了(le)電(dian)池的預期壽命。
? 快(kuai)速均衡。
主動(dong)均衡的缺點：
? 當能量(liang)從一個(ge)電(dian)池轉(zhuan)移(yi)到另一個(ge)電(dian)池時，大約會損失10-20%的能量(liang)。
? 電荷只能(neng)從高(gao)位電池轉移到低位電池。
? 盡管有源電池均衡器具有較高(gao)的能量效率，但其(qi)控(kong)制算法(fa)可(ke)能很復雜，并且其(qi)生產成本昂貴，因為(wei)每個電池都(dou)應與額外的電力電子(zi)接(jie)口(kou)連接(jie)。
被動均衡
通(tong)常把能(neng)量(liang)(liang)消(xiao)耗(hao)(hao)型均衡(heng)定義為被動均衡(heng)，被動均衡(heng)運用電(dian)(dian)阻，將(jiang)高(gao)電(dian)(dian)壓或高(gao)電(dian)(dian)荷量(liang)(liang)電(dian)(dian)芯(xin)的(de)能(neng)量(liang)(liang)消(xiao)耗(hao)(hao)掉(diao)，以達到減小不同(tong)電(dian)(dian)芯(xin)之間(jian)差距的(de)目的(de)，是一(yi)種(zhong)能(neng)量(liang)(liang)消(xiao)耗(hao)(hao)性均衡(heng)。如果將(jiang)電(dian)(dian)池串聯在一(yi)起，并且某些電(dian)(dian)池的(de)能(neng)量(liang)(liang)高(gao)于其他能(neng)量(liang)(liang)較(jiao)低的(de)電(dian)(dian)池，可以通(tong)過(guo)在電(dian)(dian)池上連接一(yi)個(ge)電(dian)(dian)阻來均衡(heng)頂部(bu)電(dian)(dian)池的(de)燃燒能(neng)量(liang)(liang)，從而將(jiang)能(neng)量(liang)(liang)釋放到熱(re)量(liang)(liang)，以此(ci)來均衡(heng)電(dian)(dian)池組的(de)能(neng)量(liang)(liang)。
被(bei)動(dong)均(jun)(jun)衡可(ke)使所有(you)電(dian)池看起來(lai)具有(you)相同的(de)容(rong)量。有(you)兩種不同類別的(de)無(wu)源電(dian)池均(jun)(jun)衡方法：固定(ding)分(fen)流(liu)電(dian)阻(zu)和(he)開關分(fen)流(liu)電(dian)阻(zu)。
固定(ding)分流電(dian)阻(zu)電(dian)路(lu)通常連(lian)接到固定(ding)分流器，以防止其被過度充電(dian)。在電(dian)阻(zu)器的(de)(de)(de)幫助下，無(wu)源均衡(heng)電(dian)路(lu)可以控制(zhi)每個(ge)電(dian)池電(dian)壓的(de)(de)(de)極(ji)限值，而不會損壞電(dian)池。這些電(dian)阻(zu)器為均衡(heng)電(dian)池而消耗的(de)(de)(de)能量可能會導致(zhi)BMS的(de)(de)(de)熱損失。因此，這證(zheng)明固定(ding)分流電(dian)阻(zu)器方法是一種低效的(de)(de)(de)電(dian)池均衡(heng)電(dian)路(lu)。
開關(guan)(guan)分流電(dian)阻(zu)電(dian)池均(jun)(jun)衡電(dian)路(lu)是目(mu)前電(dian)池均(jun)(jun)衡中最常(chang)用(yong)的方(fang)法(fa)。該方(fang)法(fa)有連續模(mo)式和感應模(mo)式，在(zai)連續模(mo)式下，所(suo)有開關(guan)(guan)都被控制在(zai)同一時間開啟或關(guan)(guan)閉。在(zai)感應模(mo)式下，每個電(dian)池都需要(yao)一個實時電(dian)壓(ya)傳感器。該電(dian)池均(jun)(jun)衡電(dian)路(lu)通過均(jun)(jun)衡電(dian)阻(zu)消耗了高能量。這種電(dian)池均(jun)(jun)衡電(dian)路(lu)適用(yong)于在(zai)充(chong)電(dian)或放電(dian)時需要(yao)低電(dian)流的電(dian)池系統。
被動均衡的優(you)點(dian)：
? 不(bu)必主動平衡電池組(zu)也依然能完(wan)美的(de)工作。
? 電池單元(yuan)在(zai)沒有(you)(you)電量時(shi)不會有(you)(you)任何損耗(hao)，一旦電池充滿，僅(jin)會在(zai)其(qi)有(you)(you)足(zu)夠額能量時(shi)進行均衡操作。
? 它會讓所有(you)電池(chi)單元具有(you)相同的SoC。
? 它提(ti)供(gong)了一種低成本(ben)的(de)電池(chi)均衡方法。
? 它(ta)可以糾正電(dian)池與電(dian)池之間自放電(dian)電(dian)流的長(chang)期失配情(qing)況。
被動均衡的缺點(dian)：
? 熱管理不良(liang)。
? 它們在滿SoC時(shi)不會(hui)進行均衡。僅在每個單元的頂部以95%左右(you)保(bao)持均衡，這是(shi)因為電池容量不同(tong)時(shi)，會(hui)被(bei)強制燃燒掉多余(yu)的能量。
? 它的(de)能(neng)量(liang)傳輸效率通常很低。電能(neng)在電阻器(qi)中以(yi)熱(re)量(liang)的(de)形式耗散，電路也造成了開關損耗，換(huan)句話說，被動(dong)均衡電路會導致大量(liang)的(de)能(neng)量(liang)損失。
? 它(ta)不會提(ti)高(gao)電(dian)池供電(dian)系統的運行時間(jian)。
上海空間電源研究所Wangbin Zhao提供的例子
多繞組變(bian)壓(ya)(ya)器的(de)主(zhu)動均(jun)(jun)(jun)衡(heng)電(dian)(dian)(dian)路(lu)分為功率模塊(kuai)和控(kong)制模塊(kuai)。電(dian)(dian)(dian)源模塊(kuai)由電(dian)(dian)(dian)池(chi)單(dan)元、均(jun)(jun)(jun)衡(heng)變(bian)壓(ya)(ya)器和開關(guan)晶體管（MOSFET）組成。同時，模塊(kuai)也可(ke)以根(gen)據實際需(xu)要(yao)進行擴展(zhan)。每(mei)節電(dian)(dian)(dian)池(chi)通(tong)過MOSFET與(yu)(yu)電(dian)(dian)(dian)池(chi)組串聯，采用(yong)固定占空比的(de)周期信號(hao)(hao)控(kong)制對電(dian)(dian)(dian)壓(ya)(ya)較(jiao)高(gao)的(de)電(dian)(dian)(dian)池(chi)進行放(fang)電(dian)(dian)(dian)。控(kong)制模塊(kuai)包括FPGA控(kong)制單(dan)元、AD采樣單(dan)元。每(mei)個電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓(ya)(ya)信號(hao)(hao)通(tong)過一階低(di)通(tong)濾波(bo)器進入(ru)AD采樣。將所(suo)有(you)電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓(ya)(ya)的(de)AD采樣信號(hao)(hao)處理后送到FPGA中，利用(yong)FPGA內部(bu)的(de)均(jun)(jun)(jun)衡(heng)算法實現電(dian)(dian)(dian)池(chi)組的(de)均(jun)(jun)(jun)衡(heng)控(kong)制。MOSFET的(de)開關(guan)周期與(yu)(yu)均(jun)(jun)(jun)衡(heng)變(bian)壓(ya)(ya)器峰值電(dian)(dian)(dian)流的(de)關(guan)系(xi)如下：
TS – 切換周期；
TON – MOSFET的開啟時間；
TOFF – MOSFET的關斷時間；
Lpri – 初級磁化電感；
Ipri-peak – 初級峰值電流；
Ubat – 單節電池電壓；
Lsec – 第二磁化電感；
Isec – peak-次峰電流；
UOFF – 電池組總電壓；
均衡變壓器(qi)的設計關(guan)(guan)系到均衡電(dian)(dian)路的工作性能。因此(ci)，必須正(zheng)確設計變壓器(qi)參(can)數。在電(dian)(dian)池(chi)組充(chong)電(dian)(dian)過程(cheng)中，一旦主動均衡電(dian)(dian)路檢(jian)測到某個電(dian)(dian)芯的電(dian)(dian)壓過高，就(jiu)會啟動相(xiang)應的均衡開關(guan)(guan)為該電(dian)(dian)芯放電(dian)(dian)。均衡變壓器(qi)初級側的平均放電(dian)(dian)電(dian)(dian)流為：
同理，可以(yi)得到均衡變壓器二(er)次電(dian)池(chi)的平均充電(dian)電(dian)流為：
N——串聯電(dian)池的數(shu)量(liang)；
k——變壓(ya)器初級(ji)和次級(ji)的匝數比；
分(fen)析方程（1）到（3），得出結論，在固定占空比控制方法下，均衡平均電流(liu)僅與變壓器(qi)初級和次(ci)級繞組的匝數比、電池數量和電流(liu)峰值有(you)關。
電(dian)池(chi)組(zu)所需的均衡(heng)電(dian)流是(shi)多少？
均(jun)(jun)衡電池(chi)是指在某些SoC上，所有(you)電池(chi)都完全處于(yu)相同的SoC。均(jun)(jun)衡電池(chi)所需的電流取決于(yu)電池(chi)失(shi)衡的原(yuan)因。它(ta)分為2類：總均(jun)(jun)衡、維護均(jun)(jun)衡。
總均衡(heng)
如果電(dian)(dian)池組(zu)在制(zhi)造(zao)或維修(xiu)時(shi)沒有考慮到單個電(dian)(dian)池的(de)初始(shi)SoC，平衡器可能會被(bei)期望完成總(zong)的(de)平衡工作。在這(zhe)種情(qing)況下，平衡電(dian)(dian)池組(zu)所需的(de)最(zui)大(da)時(shi)間長(chang)度取決于(yu)電(dian)(dian)池組(zu)的(de)大(da)小和平衡電(dian)(dian)流。所需的(de)均衡電(dian)(dian)流與電(dian)(dian)池組(zu)的(de)大(da)小成正比，與所需的(de)均衡時(shi)間成反比：
均衡電流 [A] = 包裝尺寸 [Ah] / 總均衡時(shi)間 [小時(shi)]
對于一(yi)個100Ah有空有滿的(de)電(dian)池(chi)(chi)組(zu)來(lai)說，均(jun)(jun)(jun)衡(heng)電(dian)流(liu)為1A的(de)BMS需要(yao)將近一(yi)周的(de)時(shi)間來(lai)進(jin)行(xing)均(jun)(jun)(jun)衡(heng)。而一(yi)個均(jun)(jun)(jun)衡(heng)電(dian)流(liu)為10 mA BMS無法在(zai)其使用壽命(ming)內(nei)均(jun)(jun)(jun)衡(heng) 一(yi)個1000 Ah的(de)電(dian)池(chi)(chi)組(zu)。或者說，如果希望BMS在(zai)合理(li)的(de)時(shi)間內(nei)均(jun)(jun)(jun)衡(heng)一(yi)個大容量且極不(bu)均(jun)(jun)(jun)衡(heng)的(de)電(dian)池(chi)(chi)組(zu)，則需要(yao)它提供一(yi)個相對較高的(de)均(jun)(jun)(jun)衡(heng)電(dian)流(liu)。
維護均衡(heng)
如果一個(ge)電(dian)(dian)池組(zu)開始時是(shi)均衡(heng)的，那(nei)么(me)保持均衡(heng)將變得容易。如果所有電(dian)(dian)池的自放電(dian)(dian)泄(xie)漏相(xiang)同，則(ze)不需(xu)要均衡(heng)；電(dian)(dian)池的SoC緩慢下降完(wan)全相(xiang)同，因此電(dian)(dian)池組(zu)保持均衡(heng)。如果電(dian)(dian)池組(zu)中有一個(ge)電(dian)(dian)池單元(yuan)其自放電(dian)(dian)泄(xie)漏電(dian)(dian)流為1mA或更多(duo)而其他電(dian)(dian)池單元(yuan)的泄(xie)漏電(dian)(dian)流相(xiang)同，則(ze)BMS從所有其他電(dian)(dian)池平(ping)均取1mA 或僅對(dui)該電(dian)(dian)池增加1mA，這被認為是(shi)平(ping)均均衡(heng)電(dian)(dian)流。
在很多應用中，BMS除了(le)不斷地漏電放(fang)電外，還無法做(zuo)到無限均衡(heng)。因此，均衡(heng)電流必(bi)須更高，與BMS均衡(heng)電池(chi)組可(ke)用的(de)時間(jian)成(cheng)反比(bi)。
例如：
如(ru)果BMS可以持續均(jun)衡(heng)，均(jun)衡(heng)電流可以是1mA，而如(ru)果BMS每天(tian)只(zhi)能均(jun)衡(heng)1小時，均(jun)衡(heng)電流應(ying)該是24mA，才能達(da)到1mA的平均(jun)值。
更(geng)重要的(de)是，如果BMS可以運行比所需最小值更(geng)多的(de)均衡(heng)電流，則BMS可以：
? 保(bao)持均衡始終開啟，但(dan)降低(di)其值以匹配電(dian)池自放(fang)電(dian)泄漏增量。
? 通過占(zhan)空比打開和關閉均衡，平均而言，電(dian)流(liu)與電(dian)池的漏電(dian)流(liu)增(zeng)量(liang)相匹配。
所需的均衡電流與(yu)泄漏電流的差和可(ke)用(yong)于均衡的時間(jian)百分比成正比：
均(jun)衡電流 [A] = (最(zui)大漏電流 [A] – 最(zui)小(xiao)漏電流 [A]) / (每日均(jun)衡時(shi)間(jian) [小(xiao)時(shi)] / 24 [小(xiao)時(shi)])
均衡(heng)電流(liu)是(shi)均衡(heng)器對滿電量電池(chi)(chi)進行分(fen)流(liu)時(shi)的(de)電流(liu)量，以求可同時(shi)繼(ji)續允(yun)許相同的(de)電流(liu)流(liu)入(ru)非(fei)滿電池(chi)(chi)。正確的(de)量取決于想(xiang)要多(duo)快結束均衡(heng)。
結論
均衡補償單個電池的SoC，而不是容量不均衡。電池組均衡的好處是，如果電池組在工廠均衡，BMS只需要處理均衡電流。這對于構建已經均衡的電池組更有意義，無需使用可以執行總均衡的BMS。
為了最大限度地減少電池電壓漂移的影響，必須適當調節不均衡。任何均衡方案的目標都是讓電池組以預期的性能水平運行并延長其有用容量。對于希望最小化成本并糾正電池之間自放電電流的長期失配的客戶，被動均衡是最佳選擇。
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