1 引言

　　該航空蓄電池充電器為飛(fei)機某型號蓄(xu)(xu)電(dian)(dian)池(chi)專門設計，主要實現兩階段充電(dian)(dian)功(gong)能，即恒流(liu)充電(dian)(dian)狀態（以20A的大電(dian)(dian)流(liu)充電(dian)(dian)）和涓流(liu)充電(dian)(dian)狀態（以3A的小(xiao)電(dian)(dian)流(liu)充電(dian)(dian)）。蓄(xu)(xu)電(dian)(dian)池(chi)充電(dian)(dian)器使(shi)用的工作電(dian)(dian)源(yuan)為115V/400Hz的航空(kong)電(dian)(dian)源(yuan)，充電(dian)(dian)器能在(zai)1小(xiao)時內(nei)完成恒流(liu)充電(dian)(dian)，隨后(hou)以涓流(liu)狀態對蓄(xu)(xu)電(dian)(dian)池(chi)組進行充電(dian)(dian)直至充電(dian)(dian)結束，每個充電(dian)(dian)過程在(zai)2個小(xiao)時內(nei)完成。

　　2　充電器總體設計方案
 

圖(tu)1 充電(dian)器(qi)主電(dian)路結(jie)構框圖(tu)

 　　航空蓄電池充電器的主電路如圖1所示，電源變換器采用了由半橋變換器、高頻變壓器和輸出整流濾波電路組成的半橋變換器[1]，該電路結構簡單，工作可靠，功率管為場效應管，而且開關管承受的電壓為電源電壓，故可在電源電壓較高的場合應用。通常高頻大功率變換器開關頻率一般都大于15kHz，為了使功率電路小型化、減小失真并保持高的變換效率，該充電器采用了20kHz的開關(guan)頻率。

　　3 SG3525芯片介紹
 

圖(tu)2　SG3525芯片的結構圖(tu)

　　SG3525是美國通用公司的產品，如圖2所示，內部電路主要由基準電源、振蕩器、誤差放大器、PWM比較器與鎖存器、分相器、欠電壓鎖定、輸出級、軟啟動以及關斷電路等組成。基準電源是一個典型的三端穩壓器，精度可達，采用了溫度補償。作為內部電路的供電電源，并可向外輸出40mA電流。振蕩器由一個雙門限比較器，一個恒流源及電容充放電電路組成，在芯片外部由5腳對地接一電容器，6腳對地接一電阻，5腳和7腳之間外接電阻即可構成該振蕩器。
 

圖3 SG3525芯片各點的工作波(bo)形

 　　SG3525芯片(pian)各點(dian)(dian)的(de)(de)(de)工作波(bo)形如圖3所(suo)示，由誤差放(fang)大(da)器(qi)(qi)(qi)輸(shu)出(chu)的(de)(de)(de)電壓(ya)Ve與鋸齒波(bo)的(de)(de)(de)交點(dian)(dian)可得(de)一(yi)負的(de)(de)(de)PWM信(xin)號(hao)(hao)。由PWM信(xin)號(hao)(hao)、時鐘信(xin)號(hao)(hao)及分相(xiang)器(qi)(qi)(qi)輸(shu)出(chu)的(de)(de)(de)Q (或 )信(xin)號(hao)(hao)，根(gen)據或非(fei)門的(de)(de)(de)邏輯(ji)可得(de)兩個或非(fei)門的(de)(de)(de)輸(shu)出(chu)信(xin)號(hao)(hao)Va和(he)Vb。由波(bo)形圖可以看出(chu)，PWM比(bi)較器(qi)(qi)(qi)的(de)(de)(de)反(fan)相(xiang)輸(shu)入端電平越高，輸(shu)出(chu)脈(mo)沖(chong)Va和(he)Vb的(de)(de)(de)占(zhan)空(kong)比(bi)越大(da)；反(fan)之越小(xiao)。根(gen)據這一(yi)規律(lv)來實現該控制(zhi)器(qi)(qi)(qi)的(de)(de)(de)調壓(ya)、軟啟(qi)動(dong)及保護(hu)功能(neng)。另外，可以通過改變(bian)5腳和(he)7腳之間的(de)(de)(de)外接電阻(zu)的(de)(de)(de)大(da)小(xiao)，使(shi)時鐘脈(mo)沖(chong)寬度變(bian)化來實現死區大(da)小(xiao)的(de)(de)(de)調節[2]。

　　4 充電器的控(kong)制與保護策略

　　航空(kong)蓄電(dian)(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)(dian)器的(de)控制(zhi)(zhi)原理框(kuang)圖如圖4所示。芯片SG3525產生(sheng)的(de)兩路 PWM波經過光耦隔離(li)以(yi)后(hou)，被送入IR2130從而(er)驅動開關管工作，由于充電(dian)(dian)(dian)(dian)器的(de)負載(zai)為電(dian)(dian)(dian)(dian)壓時(shi)刻變化的(de)航空(kong)蓄電(dian)(dian)(dian)(dian)池(chi)，因此(ci)在(zai)控制(zhi)(zhi)電(dian)(dian)(dian)(dian)路中還采(cai)用(yong)了電(dian)(dian)(dian)(dian)壓電(dian)(dian)(dian)(dian)流雙閉環控制(zhi)(zhi)、過流及過溫保護(hu)電(dian)(dian)(dian)(dian)路，從而(er)能(neng)保證充電(dian)(dian)(dian)(dian)器高效(xiao)、可(ke)靠的(de)完(wan)成整個充電(dian)(dian)(dian)(dian)過程。

圖4 充電器控(kong)制原理框(kuang)圖

　　該充電器的工作過程可以簡單的描述為：當充電器檢測到蓄電池兩端的電壓低于某一定值電壓（第一定值）時，充電器開始工作并進入恒流(liu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)狀(zhuang)態(tai)，此時由外部(bu)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)傳感器(qi)和電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)傳感器(qi)采集來的(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)、電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)信號傳送到控制電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)進行電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)、電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)雙閉(bi)環調節，保持(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)恒定(ding)；當充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)達到另一定(ding)值（第(di)二定(ding)值）電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)時，蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)進入涓流(liu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)狀(zhuang)態(tai)，當蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)檢測(ce)到蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)兩端電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不再發生明(ming)顯(xian)變化時，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)過程結束。

　　5 軟件設計

　　單片機系統以AD公司的數據采集系統芯片ADuC812為核心，采用單片機C語言進行編程，該芯片以8951為內核，集成了高精度的多通道ADC和 DAC，具有在線可編程功能，該系統的主要功能是通過人機接口（按鍵，LED顯示）來設置對蓄電池的充電電流的大小，用采集到的電流和電壓值與設定值進行數字式PID調節，以控制D/A輸出，并在充電的過程中實時顯示蓄電池電壓、電流值和充電時間。
　　軟件設計的流程圖如圖5所示，在恒流充電階段，電壓傳感器產生的電壓信號、電流傳感器產生的電壓信號傳送到單片機以后，單片機產生2V的D/A信號給調理電路，在檢測到蓄電池兩端電壓達到第二定值時，充電器進入涓流充電階段，單片機電路產生較小的D/A值，使蓄電池以較小的電流充電(涓流充電)，當檢測到蓄電池電壓不再上升（或者發生明顯的變化）時，單片機電路給出關斷充電器信號，蓄電池充電過程結束。
 

圖5 充電器的軟件(jian)流程圖

　　6 試(shi)驗結(jie)果

圖(tu)(tu)6 蓄(xu)電池充電過程示意圖(tu)(tu)

　　使(shi)用(yong)該蓄電(dian)(dian)池(chi)充(chong)電(dian)(dian)器(qi)對(dui)某型(xing)號航空蓄電(dian)(dian)池(chi)進行(xing)了充(chong)電(dian)(dian)試驗，最大充(chong)電(dian)(dian)電(dian)(dian)流限(xian)制為30A，溫(wen)度限(xian)制值定(ding)為350C。蓄電(dian)(dian)池(chi)的(de)(de)初始(shi)電(dian)(dian)壓為20V，充(chong)電(dian)(dian)開始(shi)時(shi)，充(chong)電(dian)(dian)器(qi)以20A的(de)(de)電(dian)(dian)流對(dui)蓄電(dian)(dian)池(chi)持續(xu)充(chong)電(dian)(dian)約(yue)58分(fen)鐘，然后(hou)以較(jiao)小的(de)(de)電(dian)(dian)流3A對(dui)蓄電(dian)(dian)池(chi)進行(xing)涓(juan)流充(chong)電(dian)(dian)，直至蓄電(dian)(dian)池(chi)電(dian)(dian)壓上升到(dao)32.45V時(shi)，蓄電(dian)(dian)池(chi)兩(liang)端的(de)(de)電(dian)(dian)壓不再發(fa)生明顯的(de)(de)上升現象，此時(shi)充(chong)電(dian)(dian)器(qi)停止(zhi)充(chong)電(dian)(dian)，歷時(shi)150分(fen)鐘，充(chong)電(dian)(dian)過程(cheng)曲線示(shi)(shi)意圖如圖6所示(shi)(shi)。

　　7 結論

　　本文(wen)提出(chu)了一種鎘鎳航空蓄電(dian)(dian)池(chi)充(chong)(chong)電(dian)(dian)器(qi)的(de)設計(ji)方(fang)案(an)和控制原理(li)，精確(que)實現了恒流(liu)充(chong)(chong)電(dian)(dian)和涓流(liu)充(chong)(chong)電(dian)(dian)功能，該充(chong)(chong)電(dian)(dian)器(qi)實現了輸出(chu)與電(dian)(dian)網(wang)的(de)高(gao)頻(pin)電(dian)(dian)氣隔離(li)，充(chong)(chong)電(dian)(dian)效率高(gao)，使(shi)(shi)用方(fang)便，工作穩定，有效地(di)縮短了充(chong)(chong)電(dian)(dian)時間，提高(gao)了充(chong)(chong)電(dian)(dian)質量，便于現場應用，滿足(zu)航空蓄電(dian)(dian)池(chi)的(de)使(shi)(shi)用要求(qiu)，現已經裝備使(shi)(shi)用，效果良好。