1 引言

　　該航空蓄電池充電器為飛機某(mou)型號(hao)蓄(xu)(xu)電(dian)(dian)(dian)池(chi)專(zhuan)門設(she)計，主要實現兩階段充(chong)(chong)電(dian)(dian)(dian)功能，即恒流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)狀態（以(yi)20A的(de)大電(dian)(dian)(dian)流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)）和涓(juan)流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)狀態（以(yi)3A的(de)小(xiao)電(dian)(dian)(dian)流(liu)(liu)充(chong)(chong)電(dian)(dian)(dian)）。蓄(xu)(xu)電(dian)(dian)(dian)池(chi)充(chong)(chong)電(dian)(dian)(dian)器使用的(de)工作電(dian)(dian)(dian)源為115V/400Hz的(de)航空(kong)電(dian)(dian)(dian)源，充(chong)(chong)電(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)，隨后(hou)以(yi)涓(juan)流(liu)(liu)狀態對蓄(xu)(xu)電(dian)(dian)(dian)池(chi)組進(jin)行充(chong)(chong)電(dian)(dian)(dian)直至充(chong)(chong)電(dian)(dian)(dian)結束，每個充(chong)(chong)電(dian)(dian)(dian)過程在(zai)2個小(xiao)時內完(wan)成。

　　2　充電器總體設計方案
 

圖1 充電器主電路(lu)結(jie)構框(kuang)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(cai)用了20kHz的開關頻率。

　　3 SG3525芯片介紹
 

圖(tu)2　SG3525芯片的結(jie)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(pian)各點的(de)工作(zuo)波形

 　　SG3525芯(xin)片各點的(de)(de)(de)工作波形如圖3所示，由(you)誤差放(fang)大器(qi)輸(shu)(shu)(shu)出(chu)(chu)的(de)(de)(de)電(dian)壓(ya)Ve與鋸齒波的(de)(de)(de)交點可得一負的(de)(de)(de)PWM信號。由(you)PWM信號、時鐘信號及分相器(qi)輸(shu)(shu)(shu)出(chu)(chu)的(de)(de)(de)Q (或(huo) )信號，根據或(huo)非門的(de)(de)(de)邏輯(ji)可得兩個或(huo)非門的(de)(de)(de)輸(shu)(shu)(shu)出(chu)(chu)信號Va和(he)(he)Vb。由(you)波形圖可以(yi)看出(chu)(chu)，PWM比較器(qi)的(de)(de)(de)反相輸(shu)(shu)(shu)入端(duan)電(dian)平(ping)越(yue)高(gao)，輸(shu)(shu)(shu)出(chu)(chu)脈沖(chong)(chong)Va和(he)(he)Vb的(de)(de)(de)占空比越(yue)大；反之越(yue)小。根據這一規律來(lai)實(shi)現(xian)該控制器(qi)的(de)(de)(de)調(diao)壓(ya)、軟啟(qi)動及保(bao)護功能。另外(wai)(wai)，可以(yi)通過改變5腳和(he)(he)7腳之間的(de)(de)(de)外(wai)(wai)接(jie)電(dian)阻(zu)的(de)(de)(de)大小，使時鐘脈沖(chong)(chong)寬度變化來(lai)實(shi)現(xian)死區大小的(de)(de)(de)調(diao)節[2]。

　　4 充電器的控制與保護策略

　　航(hang)空蓄電(dian)池充電(dian)器(qi)的控制(zhi)原理框圖(tu)如圖(tu)4所示。芯片SG3525產生的兩路(lu) PWM波經過(guo)(guo)(guo)光(guang)耦隔離以后，被(bei)送入IR2130從而驅動開關管(guan)工(gong)作，由于充電(dian)器(qi)的負載為電(dian)壓(ya)時(shi)刻(ke)變化的航(hang)空蓄電(dian)池，因此(ci)在(zai)控制(zhi)電(dian)路(lu)中還采用(yong)了電(dian)壓(ya)電(dian)流雙閉環(huan)控制(zhi)、過(guo)(guo)(guo)流及(ji)過(guo)(guo)(guo)溫保(bao)護電(dian)路(lu)，從而能(neng)保(bao)證(zheng)充電(dian)器(qi)高(gao)效、可靠的完成整個充電(dian)過(guo)(guo)(guo)程。

圖4 充電器控制原(yuan)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，充電器開始工作并進(jin)入(ru)恒(heng)(heng)流(liu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)狀態，此時由(you)外部的(de)電(dian)(dian)(dian)(dian)壓傳感(gan)器和電(dian)(dian)(dian)(dian)流(liu)傳感(gan)器采集來的(de)電(dian)(dian)(dian)(dian)壓、電(dian)(dian)(dian)(dian)流(liu)信號(hao)傳送到控制電(dian)(dian)(dian)(dian)路進(jin)行電(dian)(dian)(dian)(dian)壓、電(dian)(dian)(dian)(dian)流(liu)雙閉環(huan)調節，保持(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)恒(heng)(heng)定；當(dang)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓達到另一定值（第二定值）電(dian)(dian)(dian)(dian)壓時，蓄(xu)電(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)器進(jin)入(ru)涓流(liu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)狀態，當(dang)蓄(xu)電(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)器檢測到蓄(xu)電(dian)(dian)(dian)(dian)池(chi)兩端(duan)電(dian)(dian)(dian)(dian)壓不再發生明顯變化時，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)過(guo)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(chong)電器的軟件流程圖

　　6 試驗結(jie)果

圖6 蓄(xu)電(dian)池充電(dian)過程示意圖

　　使(shi)用該(gai)蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)對某(mou)型號航空蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)進(jin)行了充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)試(shi)驗，最(zui)大充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)限制(zhi)為30A，溫度限制(zhi)值定為350C。蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)的初始(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓為20V，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)開始(shi)(shi)時，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)以(yi)20A的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)對蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)持續充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)約58分(fen)鐘，然后以(yi)較小的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)3A對蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)進(jin)行涓流(liu)充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，直至(zhi)蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓上升(sheng)到32.45V時，蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)(chi)(chi)兩端的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓不再發生明顯的上升(sheng)現(xian)象(xiang)，此時充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)停止充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，歷時150分(fen)鐘，充(chong)(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)過程(cheng)曲線示(shi)(shi)意圖如圖6所示(shi)(shi)。

　　7 結論

　　本文提出(chu)了(le)一種鎘鎳航空蓄電(dian)(dian)池(chi)充(chong)電(dian)(dian)器的(de)設計方案(an)和(he)控制原理，精(jing)確實(shi)現了(le)恒流充(chong)電(dian)(dian)和(he)涓(juan)流充(chong)電(dian)(dian)功能，該充(chong)電(dian)(dian)器實(shi)現了(le)輸出(chu)與電(dian)(dian)網的(de)高(gao)頻電(dian)(dian)氣隔離，充(chong)電(dian)(dian)效率(lv)高(gao)，使(shi)(shi)用(yong)方便，工作穩定，有效地縮短(duan)了(le)充(chong)電(dian)(dian)時間(jian)，提高(gao)了(le)充(chong)電(dian)(dian)質(zhi)量，便于現場應(ying)用(yong)，滿足(zu)航空蓄電(dian)(dian)池(chi)的(de)使(shi)(shi)用(yong)要求，現已經(jing)裝備(bei)使(shi)(shi)用(yong)，效果(guo)良好(hao)。