MAX713的大功率多功能充電器
充電器參數設計
本文設計的充電器可對鉛酸、鎳氫、鎳鎘三種電池充放電。充電電流最大為16A，可充6V、12V、24V、30V、36V五檔位的電池，充電容量從10Ah到240Ah，供電電源為AC187V~252V、50Hz，充電器體積為250mm×164mm×90mm，重量為3kg。
圖(tu)1 MAX713封裝圖(tu)
MAX713的封裝及(ji)引腳功(gong)能編(bian)程描述
MAX713的封裝及引(yin)腳功(gong)能
1腳VLIMIT：設置單(dan)節電(dian)(dian)池(chi)最大(da)電(dian)(dian)壓(ya)，電(dian)(dian)池(chi)組(BATT+―BATT-)的最大(da)電(dian)(dian)壓(ya)Em不(bu)能(neng)超過VLIMIT×(電(dian)(dian)池(chi)數量(liang)n)，且VLIMIT不(bu)能(neng)超過2.5V，當VLINIT接V+時(shi)，Em=1.65n(V)，通常(chang)將VLIMIT與VREF連接。
圖2 電池數量編程
2腳BATT+：電池組正極(ji)。
3腳(jiao)PGM0：可編程引腳(jiao)。
4腳(jiao)(jiao)PGM1：可編程引腳(jiao)(jiao)。通過對PGM0和PGM1腳(jiao)(jiao)電(dian)壓的設定可設置(zhi)充電(dian)電(dian)池(chi)的的數量(liang)，從1到16。
5腳THI：溫(wen)度比(bi)較器的(de)上限電(dian)(dian)壓(ya)。當(dang)TEMP電(dian)(dian)壓(ya)大上升到(dao)THI時，快速充電(dian)(dian)結束。
6腳TLO：溫度比較器的(de)下限(xian)電(dian)(dian)壓(ya)。充電(dian)(dian)初始，當TEMP電(dian)(dian)壓(ya)低于TLO時快速充電(dian)(dian)被禁止，直(zhi)到(dao)TEMP電(dian)(dian)壓(ya)高于TLO。
7腳TEMP：溫度傳(chuan)感器輸入。
8腳FASTCHG：快速充電(dian)狀態輸出。
9腳(jiao)PGM2：可編(bian)程引腳(jiao)。通過(guo)對PGM2和PGM3腳(jiao)電壓的設(she)(she)定(ding)可設(she)(she)置快速充電的最大允(yun)許時(shi)間(jian)(33min～264min)。
圖3 最大(da)充電時間的設定
圖4 充(chong)電速率的設定
10腳(jiao)PGM3：可(ke)編程引腳(jiao)。除設定最大允許時間外(wai)，還可(ke)設定快速充電和涓流充電的速率。
11腳CC：恒流補償輸(shu)入(ru)。
12腳(jiao)BATT-：電池(chi)組(zu)負極
13腳GND：系統地。
14腳(jiao)DRV：驅(qu)動外圍“PNP”。
15腳(jiao)V+：分(fen)路調節(jie)器。V+對BATT-電(dian)壓為+5V，為芯片提(ti)供分(fen)路電(dian)流(5mA～20mA)。
16腳REF：參考(kao)電壓輸出2V。
MAX713引(yin)腳(jiao)編程控制
1. 可(ke)充(chong)電電池(chi)數量控制
通過對(dui)可編程引腳(jiao)3腳(jiao)PGM0、4腳(jiao)PGM1進行簡單的電壓配置編程，實現對(dui)充電電池支數(shu)的控制，如圖2所示(shi)。
2. 電池充滿電判斷
電(dian)(dian)(dian)(dian)(dian)池(chi)充滿(man)電(dian)(dian)(dian)(dian)(dian)時，應立即切斷充電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)路，防止(zhi)過充，保(bao)護電(dian)(dian)(dian)(dian)(dian)池(chi)安全。判斷電(dian)(dian)(dian)(dian)(dian)池(chi)充滿(man)電(dian)(dian)(dian)(dian)(dian)的方法很多，如最高(gao)電(dian)(dian)(dian)(dian)(dian)壓(ya)控(kong)制(zhi)、最小電(dian)(dian)(dian)(dian)(dian)流控(kong)制(zhi)、最高(gao)溫度控(kong)制(zhi)等(deng)。
MAX713采用(yong)電(dian)(dian)壓負(fu)斜率(lv)(lv)的(de)方(fang)法來判(pan)斷電(dian)(dian)池充(chong)(chong)(chong)(chong)滿電(dian)(dian)。當電(dian)(dian)池電(dian)(dian)壓增長出現負(fu)斜率(lv)(lv)后(hou)，MAX713發出充(chong)(chong)(chong)(chong)滿關(guan)機信號，充(chong)(chong)(chong)(chong)電(dian)(dian)器(qi)停止充(chong)(chong)(chong)(chong)電(dian)(dian)。電(dian)(dian)壓負(fu)斜率(lv)(lv)控制是(shi)一種綜合(he)效果(guo)較(jiao)好的(de)電(dian)(dian)池充(chong)(chong)(chong)(chong)滿電(dian)(dian)判(pan)斷方(fang)法。即電(dian)(dian)池充(chong)(chong)(chong)(chong)電(dian)(dian)到達峰(feng)點(dian)前，電(dian)(dian)壓曲線的(de)斜率(lv)(lv)是(shi)正值，到達峰(feng)點(dian)后(hou)電(dian)(dian)壓曲線的(de)斜率(lv)(lv)為負(fu)值。
3. 充電速率、充電時間控制
通過對PGM2和PGM3引腳的編程電壓設置可設定電池的充電速率和充電時間的控制。
圖(tu)5 AC/DC/變換電路
軍用大功率多功能充電器的設計
充電器由AC/DC/變(bian)換、充電控制電路、蓄電池激(ji)活電路三部分組成(cheng)。(見圖5)
AC/DC變(bian)換(huan)器(qi)
它由(you)橋(qiao)式整(zheng)流(liu)器、全橋(qiao)逆變器、高頻變壓整(zheng)流(liu)器及PWM發生器組成(cheng)，把220V交流(liu)電變換成(cheng)所需要(yao)的各種直流(liu)充電電壓。
充電控制電路
充電(dian)控制電(dian)路，由(you)可編程(cheng)芯片(pian)(MAX713)、電(dian)壓取(qu)樣電(dian)路、電(dian)流(liu)取(qu)樣電(dian)路等組成。
電(dian)(dian)壓取(qu)樣(yang)電(dian)(dian)路(lu)、電(dian)(dian)流(liu)(liu)取(qu)樣(yang)電(dian)(dian)路(lu)將采樣(yang)到(dao)的充電(dian)(dian)電(dian)(dian)壓、電(dian)(dian)流(liu)(liu)信號經PID補償電(dian)(dian)路(lu)送(song)誤差放大電(dian)(dian)路(lu)放大后，控制PWM電(dian)(dian)路(lu)和(he)過壓、過流(liu)(liu)保護(hu)電(dian)(dian)路(lu)。
可(ke)編程芯片(MAX713)是充(chong)(chong)電(dian)控制(zhi)電(dian)路(lu)的核心器件，在本項目中根據(ju)對充(chong)(chong)電(dian)電(dian)池(chi)容(rong)量、電(dian)壓性質的綜合考慮，對MAX713設定的最(zui)大充(chong)(chong)電(dian)時間(jian)為264分鐘，充(chong)(chong)電(dian)電(dian)流為C。MAX713的電(dian)路(lu)原(yuan)理圖如圖6所(suo)示(shi)。
圖6 MAX713充(chong)電(dian)控制電(dian)路(lu)圖
蓄電池激活電路
蓄電(dian)(dian)池(chi)放(fang)電(dian)(dian)激活電(dian)(dian)路(lu)，用于對記憶(yi)、鈍(dun)化(hua)、老化(hua)電(dian)(dian)池(chi)進(jin)行容(rong)量恢復(fu)。激活回路(lu)采用一(yi)個簡單的比較運放(fang)器對激活電(dian)(dian)壓、電(dian)(dian)流(liu)進(jin)行控制(zhi)。
綜上所述，本文設計的大功率多功能充電器充分利用了(le)集成(cheng)電(dian)路MAX713的控制功能，優化了(le)各種電(dian)路組(zu)合方式。具有體積小、重量輕(qing)、充電(dian)電(dian)池范圍廣等優點(dian)。