1 引言

　　該航空蓄電池充電器為飛(fei)機某(mou)型號蓄電(dian)(dian)(dian)池(chi)專門設(she)計，主(zhu)要實現兩(liang)階段充(chong)電(dian)(dian)(dian)功能(neng)，即恒(heng)(heng)流(liu)充(chong)電(dian)(dian)(dian)狀態(tai)（以(yi)20A的(de)(de)大(da)電(dian)(dian)(dian)流(liu)充(chong)電(dian)(dian)(dian)）和涓流(liu)充(chong)電(dian)(dian)(dian)狀態(tai)（以(yi)3A的(de)(de)小(xiao)(xiao)電(dian)(dian)(dian)流(liu)充(chong)電(dian)(dian)(dian)）。蓄電(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)器使用的(de)(de)工作電(dian)(dian)(dian)源為115V/400Hz的(de)(de)航空(kong)電(dian)(dian)(dian)源，充(chong)電(dian)(dian)(dian)器能(neng)在1小(xiao)(xiao)時內(nei)完(wan)成(cheng)恒(heng)(heng)流(liu)充(chong)電(dian)(dian)(dian)，隨后(hou)以(yi)涓流(liu)狀態(tai)對蓄電(dian)(dian)(dian)池(chi)組進行充(chong)電(dian)(dian)(dian)直至充(chong)電(dian)(dian)(dian)結束，每個充(chong)電(dian)(dian)(dian)過程在2個小(xiao)(xiao)時內(nei)完(wan)成(cheng)。

　　2　充電器總體設計方案
 

圖1 充電(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(le)20kHz的(de)開關頻率。

　　3 SG3525芯片介紹
 

圖2　SG3525芯片的(de)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(tu)3 SG3525芯片各點的工作波(bo)形(xing)

 　　SG3525芯片各點(dian)的(de)(de)工作波(bo)形(xing)如圖(tu)3所示，由(you)誤差放大(da)器(qi)輸出的(de)(de)電壓Ve與鋸齒(chi)波(bo)的(de)(de)交點(dian)可得(de)一負的(de)(de)PWM信號。由(you)PWM信號、時鐘(zhong)信號及(ji)分相器(qi)輸出的(de)(de)Q (或 )信號，根據(ju)或非門(men)的(de)(de)邏輯(ji)可得(de)兩個或非門(men)的(de)(de)輸出信號Va和(he)(he)Vb。由(you)波(bo)形(xing)圖(tu)可以看出，PWM比(bi)較器(qi)的(de)(de)反(fan)相輸入端(duan)電平越高(gao)，輸出脈沖Va和(he)(he)Vb的(de)(de)占空比(bi)越大(da)；反(fan)之越小。根據(ju)這一規(gui)律來實現該(gai)控制(zhi)器(qi)的(de)(de)調(diao)壓、軟啟動及(ji)保護功能。另外(wai)(wai)，可以通過改變5腳(jiao)和(he)(he)7腳(jiao)之間的(de)(de)外(wai)(wai)接電阻的(de)(de)大(da)小，使時鐘(zhong)脈沖寬度變化來實現死區大(da)小的(de)(de)調(diao)節[2]。

　　4 充電(dian)器的控制與保(bao)護策略

　　航空蓄電(dian)(dian)池充電(dian)(dian)器的(de)控制(zhi)原理框圖如圖4所示(shi)。芯片(pian)SG3525產(chan)生(sheng)的(de)兩路(lu) PWM波(bo)經過光耦隔離以后，被送入IR2130從(cong)而驅動開關(guan)管工作，由(you)于充電(dian)(dian)器的(de)負載為電(dian)(dian)壓時刻變化(hua)的(de)航空蓄電(dian)(dian)池，因此在控制(zhi)電(dian)(dian)路(lu)中還采(cai)用了電(dian)(dian)壓電(dian)(dian)流雙(shuang)閉(bi)環控制(zhi)、過流及過溫保護電(dian)(dian)路(lu)，從(cong)而能保證(zheng)充電(dian)(dian)器高效、可靠的(de)完成整個充電(dian)(dian)過程。

圖(tu)4 充電器(qi)控(kong)制(zhi)原理框(kuang)圖(tu)

　　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(gong)作并進(jin)入恒(heng)流(liu)(liu)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)狀態，此時(shi)由外(wai)部的電(dian)(dian)(dian)(dian)(dian)(dian)壓傳(chuan)感器(qi)和電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)傳(chuan)感器(qi)采集來的電(dian)(dian)(dian)(dian)(dian)(dian)壓、電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)信號傳(chuan)送到(dao)控制電(dian)(dian)(dian)(dian)(dian)(dian)路(lu)進(jin)行電(dian)(dian)(dian)(dian)(dian)(dian)壓、電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)雙(shuang)閉環調節，保持(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)恒(heng)定(ding)；當充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)壓達到(dao)另一定(ding)值（第(di)二定(ding)值）電(dian)(dian)(dian)(dian)(dian)(dian)壓時(shi)，蓄電(dian)(dian)(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)進(jin)入涓流(liu)(liu)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)狀態，當蓄電(dian)(dian)(dian)(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)檢測到(dao)蓄電(dian)(dian)(dian)(dian)(dian)(dian)池兩端電(dian)(dian)(dian)(dian)(dian)(dian)壓不再發生明顯變化時(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(tu)(tu)5 充電器的軟件流程圖(tu)(tu)

　　6 試(shi)驗結(jie)果

圖6 蓄電池(chi)充電過程示意圖

　　使(shi)用該蓄(xu)電(dian)(dian)(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)(dian)(dian)器(qi)對某型號航空(kong)蓄(xu)電(dian)(dian)(dian)(dian)(dian)池(chi)進行了(le)充電(dian)(dian)(dian)(dian)(dian)試驗(yan)，最大充電(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)流限(xian)制為30A，溫度限(xian)制值定為350C。蓄(xu)電(dian)(dian)(dian)(dian)(dian)池(chi)的(de)初始(shi)電(dian)(dian)(dian)(dian)(dian)壓(ya)為20V，充電(dian)(dian)(dian)(dian)(dian)開始(shi)時，充電(dian)(dian)(dian)(dian)(dian)器(qi)以20A的(de)電(dian)(dian)(dian)(dian)(dian)流對蓄(xu)電(dian)(dian)(dian)(dian)(dian)池(chi)持續充電(dian)(dian)(dian)(dian)(dian)約58分鐘，然(ran)后以較小的(de)電(dian)(dian)(dian)(dian)(dian)流3A對蓄(xu)電(dian)(dian)(dian)(dian)(dian)池(chi)進行涓流充電(dian)(dian)(dian)(dian)(dian)，直至蓄(xu)電(dian)(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)(dian)壓(ya)上升到(dao)32.45V時，蓄(xu)電(dian)(dian)(dian)(dian)(dian)池(chi)兩端的(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)不再發生明顯的(de)上升現象，此時充電(dian)(dian)(dian)(dian)(dian)器(qi)停止充電(dian)(dian)(dian)(dian)(dian)，歷時150分鐘，充電(dian)(dian)(dian)(dian)(dian)過(guo)程曲線示意圖如圖6所示。

　　7 結論

　　本文提出了(le)(le)一種鎘鎳(nie)航空蓄電(dian)(dian)池充(chong)電(dian)(dian)器(qi)的(de)設(she)計(ji)方案和(he)控制原理，精確實現(xian)了(le)(le)恒(heng)流充(chong)電(dian)(dian)和(he)涓流充(chong)電(dian)(dian)功能，該充(chong)電(dian)(dian)器(qi)實現(xian)了(le)(le)輸出與電(dian)(dian)網的(de)高頻電(dian)(dian)氣隔(ge)離，充(chong)電(dian)(dian)效(xiao)(xiao)率高，使(shi)用方便，工作穩定，有(you)效(xiao)(xiao)地縮短了(le)(le)充(chong)電(dian)(dian)時間，提高了(le)(le)充(chong)電(dian)(dian)質量，便于現(xian)場應用，滿足航空蓄電(dian)(dian)池的(de)使(shi)用要求，現(xian)已經裝(zhuang)備使(shi)用，效(xiao)(xiao)果(guo)良好。