1 引言

　　該航空蓄電池充電器為(wei)飛機(ji)某型號蓄(xu)(xu)電(dian)(dian)(dian)池(chi)專門設計，主要實(shi)現兩階(jie)段(duan)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)功(gong)能(neng)，即恒流(liu)(liu)(liu)(liu)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)狀(zhuang)(zhuang)態(tai)(tai)（以20A的(de)(de)大電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)）和(he)涓流(liu)(liu)(liu)(liu)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)狀(zhuang)(zhuang)態(tai)(tai)（以3A的(de)(de)小電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)）。蓄(xu)(xu)電(dian)(dian)(dian)池(chi)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)器(qi)使用的(de)(de)工作電(dian)(dian)(dian)源(yuan)(yuan)為(wei)115V/400Hz的(de)(de)航空電(dian)(dian)(dian)源(yuan)(yuan)，充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)器(qi)能(neng)在1小時內(nei)完成恒流(liu)(liu)(liu)(liu)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)，隨后以涓流(liu)(liu)(liu)(liu)狀(zhuang)(zhuang)態(tai)(tai)對蓄(xu)(xu)電(dian)(dian)(dian)池(chi)組進行(xing)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)直至充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)結束，每個(ge)(ge)充(chong)(chong)(chong)(chong)電(dian)(dian)(dian)過(guo)程在2個(ge)(ge)小時內(nei)完成。

　　2　充電器總體設計方案
 

圖1 充電(dian)器主電(dian)路結構框圖

 　　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(le)20kHz的開(kai)關頻(pin)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(tu)3 SG3525芯片各點(dian)的工作波形

 　　SG3525芯片各點的(de)(de)工作波形如圖3所示(shi)，由(you)誤差放大(da)(da)器輸(shu)出(chu)的(de)(de)電壓(ya)Ve與(yu)鋸齒波的(de)(de)交(jiao)點可(ke)得一負的(de)(de)PWM信(xin)號。由(you)PWM信(xin)號、時鐘信(xin)號及(ji)分相器輸(shu)出(chu)的(de)(de)Q (或(huo) )信(xin)號，根據或(huo)非門(men)的(de)(de)邏(luo)輯可(ke)得兩個或(huo)非門(men)的(de)(de)輸(shu)出(chu)信(xin)號Va和Vb。由(you)波形圖可(ke)以(yi)看出(chu)，PWM比較器的(de)(de)反相輸(shu)入端(duan)電平越高，輸(shu)出(chu)脈沖Va和Vb的(de)(de)占空(kong)比越大(da)(da)；反之(zhi)越小。根據這一規律來實現該控制器的(de)(de)調(diao)壓(ya)、軟啟動及(ji)保護功能(neng)。另(ling)外(wai)，可(ke)以(yi)通過改變5腳(jiao)和7腳(jiao)之(zhi)間的(de)(de)外(wai)接電阻的(de)(de)大(da)(da)小，使時鐘脈沖寬(kuan)度變化來實現死區(qu)大(da)(da)小的(de)(de)調(diao)節(jie)[2]。

　　4 充電(dian)器的控制與(yu)保護策略

　　航(hang)空蓄電(dian)(dian)池充電(dian)(dian)器的控(kong)(kong)制(zhi)原(yuan)理框圖(tu)如(ru)圖(tu)4所(suo)示(shi)。芯片SG3525產生的兩(liang)路 PWM波經(jing)過(guo)(guo)光耦隔離(li)以后，被送入(ru)IR2130從(cong)而(er)驅動開關管工(gong)作，由(you)于充電(dian)(dian)器的負載為電(dian)(dian)壓時刻變化的航(hang)空蓄電(dian)(dian)池，因(yin)此在控(kong)(kong)制(zhi)電(dian)(dian)路中還采用了電(dian)(dian)壓電(dian)(dian)流雙閉環(huan)控(kong)(kong)制(zhi)、過(guo)(guo)流及過(guo)(guo)溫(wen)保護電(dian)(dian)路，從(cong)而(er)能(neng)保證(zheng)充電(dian)(dian)器高效、可(ke)靠的完成整個充電(dian)(dian)過(guo)(guo)程。

圖4 充電器控制原理框圖

　　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(shi)工作(zuo)并進入恒流充(chong)電(dian)(dian)(dian)狀態，此(ci)時由外部(bu)的電(dian)(dian)(dian)壓(ya)傳感(gan)器(qi)和電(dian)(dian)(dian)流傳感(gan)器(qi)采集(ji)來的電(dian)(dian)(dian)壓(ya)、電(dian)(dian)(dian)流信(xin)號(hao)傳送到(dao)控(kong)制(zhi)電(dian)(dian)(dian)路進行(xing)電(dian)(dian)(dian)壓(ya)、電(dian)(dian)(dian)流雙閉(bi)環調(diao)節，保持(chi)充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流恒定(ding)；當充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)達(da)到(dao)另一定(ding)值（第二定(ding)值）電(dian)(dian)(dian)壓(ya)時，蓄電(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)器(qi)進入涓流充(chong)電(dian)(dian)(dian)狀態，當蓄電(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)器(qi)檢測到(dao)蓄電(dian)(dian)(dian)池(chi)兩端(duan)電(dian)(dian)(dian)壓(ya)不再(zai)發生明顯變(bian)化時，充(chong)電(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 充電器的(de)軟件流程圖

　　6 試驗結果

圖6 蓄電(dian)池(chi)充(chong)電(dian)過程(cheng)示(shi)意圖

　　使用該(gai)蓄(xu)(xu)(xu)電(dian)(dian)(dian)池充(chong)(chong)電(dian)(dian)(dian)器對某型(xing)號航空(kong)蓄(xu)(xu)(xu)電(dian)(dian)(dian)池進(jin)(jin)行(xing)了(le)充(chong)(chong)電(dian)(dian)(dian)試驗，最大(da)充(chong)(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)限制(zhi)為(wei)30A，溫(wen)度限制(zhi)值定為(wei)350C。蓄(xu)(xu)(xu)電(dian)(dian)(dian)池的(de)初始(shi)電(dian)(dian)(dian)壓(ya)為(wei)20V，充(chong)(chong)電(dian)(dian)(dian)開(kai)始(shi)時，充(chong)(chong)電(dian)(dian)(dian)器以20A的(de)電(dian)(dian)(dian)流(liu)對蓄(xu)(xu)(xu)電(dian)(dian)(dian)池持續充(chong)(chong)電(dian)(dian)(dian)約58分鐘，然后以較(jiao)小的(de)電(dian)(dian)(dian)流(liu)3A對蓄(xu)(xu)(xu)電(dian)(dian)(dian)池進(jin)(jin)行(xing)涓流(liu)充(chong)(chong)電(dian)(dian)(dian)，直(zhi)至蓄(xu)(xu)(xu)電(dian)(dian)(dian)池電(dian)(dian)(dian)壓(ya)上升(sheng)到32.45V時，蓄(xu)(xu)(xu)電(dian)(dian)(dian)池兩端的(de)電(dian)(dian)(dian)壓(ya)不再發生明(ming)顯的(de)上升(sheng)現象，此時充(chong)(chong)電(dian)(dian)(dian)器停止(zhi)充(chong)(chong)電(dian)(dian)(dian)，歷時150分鐘，充(chong)(chong)電(dian)(dian)(dian)過程曲線示(shi)意圖如圖6所示(shi)。

　　7 結論

　　本(ben)文提出(chu)了(le)一種鎘鎳航空(kong)蓄電(dian)池充(chong)電(dian)器的(de)設計方(fang)案和(he)控(kong)制原理，精確實現了(le)恒流(liu)充(chong)電(dian)和(he)涓流(liu)充(chong)電(dian)功能(neng)，該充(chong)電(dian)器實現了(le)輸出(chu)與電(dian)網的(de)高(gao)頻電(dian)氣隔離，充(chong)電(dian)效(xiao)(xiao)率高(gao)，使(shi)用方(fang)便，工作穩(wen)定，有效(xiao)(xiao)地縮短了(le)充(chong)電(dian)時間，提高(gao)了(le)充(chong)電(dian)質量，便于現場(chang)應用，滿足航空(kong)蓄電(dian)池的(de)使(shi)用要求，現已經裝備使(shi)用，效(xiao)(xiao)果(guo)良好。