1 引言

　　該航空蓄電池充電器為飛機某(mou)型號蓄電(dian)(dian)(dian)(dian)(dian)池(chi)專門設計(ji)，主要實現兩階段充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)功能，即恒流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)狀(zhuang)態（以(yi)20A的(de)(de)(de)大電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)）和涓(juan)流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)狀(zhuang)態（以(yi)3A的(de)(de)(de)小(xiao)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)）。蓄電(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)器使用的(de)(de)(de)工作電(dian)(dian)(dian)(dian)(dian)源(yuan)為115V/400Hz的(de)(de)(de)航(hang)空(kong)電(dian)(dian)(dian)(dian)(dian)源(yuan)，充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)器能在(zai)1小(xiao)時內完(wan)成恒流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)，隨后(hou)以(yi)涓(juan)流(liu)(liu)狀(zhuang)態對蓄電(dian)(dian)(dian)(dian)(dian)池(chi)組進行充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)直至(zhi)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)結束(shu)，每(mei)個(ge)充(chong)(chong)電(dian)(dian)(dian)(dian)(dian)過程在(zai)2個(ge)小(xiao)時內完(wan)成。

　　2　充電器總體設計方案
 

圖1 充(chong)電(dian)器主電(dian)路結(jie)構框圖

 　　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的開關頻率。

　　3 SG3525芯片介紹
 

圖2　SG3525芯片的結構圖

　　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芯片各點的工作波形

 　　SG3525芯片各點的(de)(de)工(gong)作波(bo)形如圖(tu)3所示，由誤差(cha)放大(da)器輸(shu)出(chu)的(de)(de)電壓Ve與鋸齒波(bo)的(de)(de)交點可(ke)(ke)得(de)一負的(de)(de)PWM信(xin)(xin)號。由PWM信(xin)(xin)號、時鐘(zhong)信(xin)(xin)號及分相(xiang)器輸(shu)出(chu)的(de)(de)Q (或 )信(xin)(xin)號，根(gen)據或非門的(de)(de)邏輯(ji)可(ke)(ke)得(de)兩(liang)個或非門的(de)(de)輸(shu)出(chu)信(xin)(xin)號Va和(he)Vb。由波(bo)形圖(tu)可(ke)(ke)以(yi)看出(chu)，PWM比較器的(de)(de)反(fan)相(xiang)輸(shu)入端電平越(yue)高，輸(shu)出(chu)脈沖Va和(he)Vb的(de)(de)占空比越(yue)大(da)；反(fan)之越(yue)小。根(gen)據這一規(gui)律來實現該控制器的(de)(de)調壓、軟啟(qi)動及保護(hu)功能。另外，可(ke)(ke)以(yi)通(tong)過(guo)改變5腳和(he)7腳之間的(de)(de)外接電阻的(de)(de)大(da)小，使(shi)時鐘(zhong)脈沖寬度(du)變化來實現死(si)區大(da)小的(de)(de)調節[2]。

　　4 充電器的控制與(yu)保護策略

　　航空(kong)蓄電(dian)池充(chong)電(dian)器的(de)控制原(yuan)理框圖(tu)如圖(tu)4所示。芯(xin)片SG3525產生的(de)兩路(lu) PWM波(bo)經過(guo)光耦(ou)隔離以后(hou)，被送入IR2130從(cong)而(er)驅(qu)動(dong)開關(guan)管工作，由于充(chong)電(dian)器的(de)負載為電(dian)壓(ya)時刻變(bian)化(hua)的(de)航空(kong)蓄電(dian)池，因此在(zai)控制電(dian)路(lu)中還采用了電(dian)壓(ya)電(dian)流(liu)雙閉環控制、過(guo)流(liu)及過(guo)溫保護(hu)電(dian)路(lu)，從(cong)而(er)能保證充(chong)電(dian)器高效、可靠(kao)的(de)完成整個(ge)充(chong)電(dian)過(guo)程。

圖4 充電器控制原理框(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(zuo)并進入(ru)(ru)恒流(liu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)狀態，此時由(you)外部的電(dian)(dian)(dian)(dian)壓(ya)傳感器和(he)電(dian)(dian)(dian)(dian)流(liu)傳感器采集來的電(dian)(dian)(dian)(dian)壓(ya)、電(dian)(dian)(dian)(dian)流(liu)信號傳送(song)到控制電(dian)(dian)(dian)(dian)路(lu)進行電(dian)(dian)(dian)(dian)壓(ya)、電(dian)(dian)(dian)(dian)流(liu)雙閉環調節，保持(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)恒定；當充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓(ya)達(da)到另一定值（第(di)二定值）電(dian)(dian)(dian)(dian)壓(ya)時，蓄(xu)電(dian)(dian)(dian)(dian)池充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)器進入(ru)(ru)涓流(liu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)狀態，當蓄(xu)電(dian)(dian)(dian)(dian)池充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)器檢(jian)測到蓄(xu)電(dian)(dian)(dian)(dian)池兩端電(dian)(dian)(dian)(dian)壓(ya)不再發生明顯變化時，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)過程(cheng)結束(shu)。

　　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(dian)器的軟件流程圖

　　6 試驗結果

圖6 蓄電池充(chong)電過程(cheng)示意圖

　　使用該蓄電(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)(chong)電(dian)(dian)(dian)(dian)器對(dui)某(mou)型(xing)號航(hang)空(kong)蓄電(dian)(dian)(dian)(dian)池(chi)(chi)進行了充(chong)(chong)電(dian)(dian)(dian)(dian)試驗，最大(da)充(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流限(xian)制為(wei)30A，溫度限(xian)制值定為(wei)350C。蓄電(dian)(dian)(dian)(dian)池(chi)(chi)的(de)初始電(dian)(dian)(dian)(dian)壓(ya)為(wei)20V，充(chong)(chong)電(dian)(dian)(dian)(dian)開始時，充(chong)(chong)電(dian)(dian)(dian)(dian)器以(yi)20A的(de)電(dian)(dian)(dian)(dian)流對(dui)蓄電(dian)(dian)(dian)(dian)池(chi)(chi)持續充(chong)(chong)電(dian)(dian)(dian)(dian)約58分鐘(zhong)，然(ran)后(hou)以(yi)較小的(de)電(dian)(dian)(dian)(dian)流3A對(dui)蓄電(dian)(dian)(dian)(dian)池(chi)(chi)進行涓(juan)流充(chong)(chong)電(dian)(dian)(dian)(dian)，直(zhi)至蓄電(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)壓(ya)上升(sheng)(sheng)到32.45V時，蓄電(dian)(dian)(dian)(dian)池(chi)(chi)兩(liang)端的(de)電(dian)(dian)(dian)(dian)壓(ya)不再發生明顯的(de)上升(sheng)(sheng)現(xian)象，此時充(chong)(chong)電(dian)(dian)(dian)(dian)器停止(zhi)充(chong)(chong)電(dian)(dian)(dian)(dian)，歷時150分鐘(zhong)，充(chong)(chong)電(dian)(dian)(dian)(dian)過程曲線示意圖(tu)如圖(tu)6所示。

　　7 結論

　　本文(wen)提出了(le)(le)(le)一種鎘鎳航(hang)空蓄(xu)電(dian)(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian)(dian)器(qi)的(de)設計方(fang)案和控制原理，精確(que)實(shi)現(xian)了(le)(le)(le)恒流充(chong)電(dian)(dian)(dian)(dian)(dian)和涓流充(chong)電(dian)(dian)(dian)(dian)(dian)功能，該充(chong)電(dian)(dian)(dian)(dian)(dian)器(qi)實(shi)現(xian)了(le)(le)(le)輸出與電(dian)(dian)(dian)(dian)(dian)網的(de)高頻電(dian)(dian)(dian)(dian)(dian)氣(qi)隔(ge)離，充(chong)電(dian)(dian)(dian)(dian)(dian)效(xiao)率高，使(shi)用(yong)方(fang)便，工(gong)作穩(wen)定，有(you)效(xiao)地縮短了(le)(le)(le)充(chong)電(dian)(dian)(dian)(dian)(dian)時(shi)間，提高了(le)(le)(le)充(chong)電(dian)(dian)(dian)(dian)(dian)質量，便于現(xian)場(chang)應用(yong)，滿足航(hang)空蓄(xu)電(dian)(dian)(dian)(dian)(dian)池的(de)使(shi)用(yong)要求，現(xian)已(yi)經裝備使(shi)用(yong)，效(xiao)果(guo)良好。