1 引言

　　該航空蓄電池充電器為飛機某型號蓄(xu)電(dian)(dian)池專門設計，主要實現兩階(jie)段充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)功能，即恒流(liu)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)狀(zhuang)態(tai)（以20A的(de)大電(dian)(dian)流(liu)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)）和涓流(liu)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)狀(zhuang)態(tai)（以3A的(de)小電(dian)(dian)流(liu)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)）。蓄(xu)電(dian)(dian)池充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)器使用(yong)的(de)工作電(dian)(dian)源(yuan)為115V/400Hz的(de)航空電(dian)(dian)源(yuan)，充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)器能在1小時內完成恒流(liu)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)，隨后以涓流(liu)狀(zhuang)態(tai)對(dui)蓄(xu)電(dian)(dian)池組進行充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)直至(zhi)充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)結束，每個充(chong)(chong)(chong)(chong)(chong)電(dian)(dian)過程(cheng)在2個小時內完成。

　　2　充電器總體設計方案
 

圖(tu)1 充電(dian)器主電(dian)路結構框圖(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(cai)用了(le)20kHz的(de)開關頻(pin)率。

　　3 SG3525芯片介紹
 

圖2　SG3525芯片(pian)的結構(gou)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(dian)的工作波形

 　　SG3525芯(xin)片各點的(de)(de)工作波形(xing)如(ru)圖3所示，由(you)誤差(cha)放大(da)(da)器(qi)輸(shu)(shu)出(chu)的(de)(de)電壓(ya)Ve與鋸(ju)齒波的(de)(de)交點可得(de)一(yi)負的(de)(de)PWM信(xin)(xin)號。由(you)PWM信(xin)(xin)號、時(shi)鐘信(xin)(xin)號及分相(xiang)器(qi)輸(shu)(shu)出(chu)的(de)(de)Q (或 )信(xin)(xin)號，根(gen)據或非門的(de)(de)邏輯可得(de)兩個或非門的(de)(de)輸(shu)(shu)出(chu)信(xin)(xin)號Va和Vb。由(you)波形(xing)圖可以看出(chu)，PWM比較器(qi)的(de)(de)反相(xiang)輸(shu)(shu)入端電平越(yue)(yue)高，輸(shu)(shu)出(chu)脈(mo)沖(chong)Va和Vb的(de)(de)占空比越(yue)(yue)大(da)(da)；反之(zhi)越(yue)(yue)小。根(gen)據這一(yi)規律來(lai)實現該控制器(qi)的(de)(de)調壓(ya)、軟(ruan)啟動(dong)及保護功能(neng)。另外(wai)(wai)，可以通過改變5腳(jiao)和7腳(jiao)之(zhi)間的(de)(de)外(wai)(wai)接電阻的(de)(de)大(da)(da)小，使(shi)時(shi)鐘脈(mo)沖(chong)寬度變化來(lai)實現死區(qu)大(da)(da)小的(de)(de)調節[2]。

　　4 充電器(qi)的(de)控制與保護策略

　　航空蓄電(dian)(dian)(dian)池充電(dian)(dian)(dian)器(qi)的控(kong)(kong)制原理框(kuang)圖如(ru)圖4所示。芯片SG3525產生(sheng)的兩(liang)路 PWM波(bo)經過光(guang)耦(ou)隔離以后，被送入IR2130從(cong)而驅動開關(guan)管(guan)工作，由于充電(dian)(dian)(dian)器(qi)的負載(zai)為(wei)電(dian)(dian)(dian)壓時刻變化的航空蓄電(dian)(dian)(dian)池，因此在控(kong)(kong)制電(dian)(dian)(dian)路中還采用了電(dian)(dian)(dian)壓電(dian)(dian)(dian)流(liu)雙閉環控(kong)(kong)制、過流(liu)及過溫保護電(dian)(dian)(dian)路，從(cong)而能保證充電(dian)(dian)(dian)器(qi)高效、可靠的完成(cheng)整個充電(dian)(dian)(dian)過程。

圖4 充電器控(kong)制原理框圖

　　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(bing)進入(ru)恒流(liu)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)狀態(tai)，此時(shi)由(you)外部的電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)傳感(gan)器和電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)傳感(gan)器采集來(lai)的電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)、電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)信(xin)號傳送到控(kong)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(shuang)閉環調節，保持充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)恒定；當充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)達到另一定值（第(di)二定值）電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)時(shi)，蓄電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器進入(ru)涓(juan)流(liu)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)狀態(tai)，當蓄電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器檢測到蓄電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)兩端電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不再發生明顯(xian)變化時(shi)，充(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 充電器的軟件流程(cheng)圖

　　6 試驗結果

圖6 蓄電(dian)池充(chong)電(dian)過程示意(yi)圖

　　使(shi)用該蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器對(dui)(dui)某型號航空蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)進行了充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)試驗，最(zui)大充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流限制為30A，溫度限制值定為350C。蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)的初始電(dian)(dian)(dian)(dian)(dian)(dian)壓為20V，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)開始時(shi)，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器以20A的電(dian)(dian)(dian)(dian)(dian)(dian)流對(dui)(dui)蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)持續充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)約58分(fen)鐘，然(ran)后以較小(xiao)的電(dian)(dian)(dian)(dian)(dian)(dian)流3A對(dui)(dui)蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)進行涓流充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)，直至蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)壓上升(sheng)到32.45V時(shi)，蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)兩(liang)端(duan)的電(dian)(dian)(dian)(dian)(dian)(dian)壓不(bu)再發生(sheng)明顯的上升(sheng)現象(xiang)，此時(shi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器停(ting)止充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)，歷時(shi)150分(fen)鐘，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)過程(cheng)曲線示意(yi)圖(tu)(tu)如(ru)圖(tu)(tu)6所示。

　　7 結論

　　本文提出了(le)(le)(le)一種鎘(ge)鎳航空蓄(xu)電(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)電(dian)(dian)(dian)(dian)器的設(she)計方案和控(kong)制原理，精確實現(xian)了(le)(le)(le)恒流充(chong)(chong)電(dian)(dian)(dian)(dian)和涓(juan)流充(chong)(chong)電(dian)(dian)(dian)(dian)功能，該(gai)充(chong)(chong)電(dian)(dian)(dian)(dian)器實現(xian)了(le)(le)(le)輸(shu)出與電(dian)(dian)(dian)(dian)網的高頻電(dian)(dian)(dian)(dian)氣隔離，充(chong)(chong)電(dian)(dian)(dian)(dian)效(xiao)率高，使用(yong)方便，工作(zuo)穩定，有效(xiao)地縮(suo)短了(le)(le)(le)充(chong)(chong)電(dian)(dian)(dian)(dian)時間，提高了(le)(le)(le)充(chong)(chong)電(dian)(dian)(dian)(dian)質(zhi)量，便于現(xian)場應(ying)用(yong)，滿足航空蓄(xu)電(dian)(dian)(dian)(dian)池(chi)的使用(yong)要求(qiu)，現(xian)已經(jing)裝(zhuang)備使用(yong)，效(xiao)果(guo)良好。