高(gao)效(xiao)提升電池壽命和安全性 | 基(ji)于ACM32 MCU的(de)BMS應(ying)用方案
電(dian)(dian)(dian)(dian)池(chi)管(guan)理(li)系統(BMS)通過監(jian)控電(dian)(dian)(dian)(dian)池(chi)的狀(zhuang)態,智(zhi)能化管(guan)理(li)及(ji)維護各個電(dian)(dian)(dian)(dian)池(chi)單元,從而防止(zhi)電(dian)(dian)(dian)(dian)池(chi)出(chu)現過充電(dian)(dian)(dian)(dian)和(he)過放電(dian)(dian)(dian)(dian)。優質(zhi)的電(dian)(dian)(dian)(dian)池(chi)管(guan)理(li)系統能夠最大限度地延長(chang)電(dian)(dian)(dian)(dian)池(chi)整體使用壽命(ming),有效保障設備安(an)全(quan)。
BMS電池管(guan)理概述(shu)
BMS,即(ji)電(dian)(dian)池(chi)(chi)(chi)管理系統(Battery Management System),隨著鋰(li)電(dian)(dian)池(chi)(chi)(chi)的(de)(de)(de)廣泛應(ying)用,BMS作(zuo)為鋰(li)電(dian)(dian)池(chi)(chi)(chi)的(de)(de)(de)“保姆(mu)”也越(yue)來越(yue)被大眾所(suo)關(guan)注。相較于傳統電(dian)(dian)池(chi)(chi)(chi),鋰(li)電(dian)(dian)池(chi)(chi)(chi)具有更(geng)(geng)好的(de)(de)(de)能(neng)力密度,更(geng)(geng)高的(de)(de)(de)工作(zuo)電(dian)(dian)壓,更(geng)(geng)低(di)的(de)(de)(de)放(fang)電(dian)(dian)率。但鋰(li)電(dian)(dian)池(chi)(chi)(chi)在(zai)(zai)面對過充、過放(fang)等(deng)問(wen)題時,相對脆弱。由于鋰(li)電(dian)(dian)池(chi)(chi)(chi)組在(zai)(zai)生(sheng)產制造和使用過程中存在(zai)(zai)的(de)(de)(de)差異性(xing),會導致(zhi)(zhi)電(dian)(dian)池(chi)(chi)(chi)單(dan)體之間天(tian)然就存在(zai)(zai)著不(bu)(bu)一(yi)(yi)致(zhi)(zhi)性(xing)。這種不(bu)(bu)一(yi)(yi)致(zhi)(zhi)性(xing)主要表現在(zai)(zai)單(dan)體容(rong)量、內阻、自放(fang)電(dian)(dian)率、充放(fang)電(dian)(dian)效率等(deng)方面。單(dan)體的(de)(de)(de)不(bu)(bu)一(yi)(yi)致(zhi)(zhi),會進(jin)一(yi)(yi)步導致(zhi)(zhi)過充、過放(fang)等(deng)問(wen)題,進(jin)而造成電(dian)(dian)池(chi)(chi)(chi)壽命下降甚至(zhi)死(si)亡(wang)或(huo)損壞。
圖(tu)1 | 容量不一(yi)致時充放電過程示意(yi)圖(tu)
如圖1所示,由于(yu)(yu)電(dian)(dian)池單(dan)體(ti)的(de)(de)差異(yi),在充電(dian)(dian)時,低容(rong)量(liang)(liang)電(dian)(dian)池充電(dian)(dian)已(yi)飽和,而較(jiao)大(da)容(rong)量(liang)(liang)的(de)(de)電(dian)(dian)池電(dian)(dian)量(liang)(liang)未滿,此(ci)時對于(yu)(yu)小容(rong)量(liang)(liang)單(dan)體(ti)來(lai)說,則處(chu)于(yu)(yu)過充狀(zhuang)態。相反,放電(dian)(dian)時,較(jiao)大(da)容(rong)量(liang)(liang)的(de)(de)電(dian)(dian)池仍然處(chu)于(yu)(yu)放電(dian)(dian)狀(zhuang)態,而小容(rong)量(liang)(liang)電(dian)(dian)池電(dian)(dian)量(liang)(liang)已(yi)空。有研究表明,單(dan)體(ti)電(dian)(dian)芯20%的(de)(de)容(rong)量(liang)(liang)差異(yi),會帶來(lai)超過40%的(de)(de)容(rong)量(liang)(liang)損(sun)失(shi)。
而BMS模(mo)塊則(ze)是為避免(mian)該(gai)問題的(de)(de)(de)(de)(de)出現而存在。BMS會實(shi)時(shi)監(jian)測單體的(de)(de)(de)(de)(de)容量,并采用電池(chi)均衡手段來保證電池(chi)的(de)(de)(de)(de)(de)正常(chang)工作。將不同容量的(de)(de)(de)(de)(de)單體比作體積不同的(de)(de)(de)(de)(de)水(shui)桶(tong),而電池(chi)的(de)(de)(de)(de)(de)電量好比是水(shui)桶(tong)中(zhong)存留的(de)(de)(de)(de)(de)水(shui)。充(chong)放電時(shi),BMS會將快滿(man)的(de)(de)(de)(de)(de)“水(shui)桶(tong)”里(li)面(mian)的(de)(de)(de)(de)(de)“水(shui)”轉移到(dao)較空(kong)的(de)(de)(de)(de)(de)“水(shui)桶(tong)”中(zhong),以此來保證整體電池(chi)電量的(de)(de)(de)(de)(de)均衡,避免(mian)出現過充(chong)和過放的(de)(de)(de)(de)(de)問題。如圖2所(suo)示。
圖2 | BMS電池均衡示意圖
上海(hai)航芯BMS應(ying)用方案
上海航芯推出的BMS應(ying)用方案(an),采用ACM32F403/ACM32G103系列MCU作(zuo)為主控(kong)芯片,最(zui)高(gao)工(gong)作(zuo)頻(pin)率(lv)可達180MHz/120MHz,內置(zhi)(zhi)最(zui)大(da)(da)512KB的eFlash和最(zui)大(da)(da)192KB SRAM,滿足一般BMS算法庫的需求。內置(zhi)(zhi)2Msps/3Msps采樣(yang)率(lv)12位ADC,實(shi)現對電(dian)芯電(dian)壓、電(dian)流、溫(wen)度(du)等(deng)信號的高(gao)頻(pin)采樣(yang)。具有USB/UART/CAN/SPI等(deng)多種通(tong)(tong)訊接口(kou),足以應(ying)對大(da)(da)多數應(ying)用場合(he)(如需要(yao)485通(tong)(tong)信的兩輪電(dian)動車(che),需要(yao)CAN接口(kou)的新能源汽車(che)等(deng))。基于ACM32F403/ACM32G103的BMS方案(an)結(jie)構示(shi)意圖(tu)如下(xia)圖(tu)所示(shi):
圖(tu)3 | BMS系(xi)統(tong)框(kuang)圖(tu)
ACM32F4/ACM32G1主(zhu)控芯(xin)片,通過ADC對敏感信號(hao)進行采樣,并依照BMS算法庫計算得到當前電(dian)池的(de)SOC、SOH等(deng)數(shu)據,執行均衡以及熱(re)管理控制,保證(zheng)電(dian)池處于正常(chang)的(de)工作狀態。當出現問(wen)題時,支持在線警報同時給(gei)出LED指示信號(hao)。整個(ge)系統的(de)運行參數(shu)可以通過CAN/USB/UART等(deng)接口進行上報。