1 引言

　　該航空蓄電池充電器為(wei)飛(fei)機某型(xing)號蓄電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)專(zhuan)門設計，主要實(shi)現兩階(jie)段充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)功能，即恒流充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)狀(zhuang)態（以(yi)(yi)20A的(de)(de)大(da)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)）和(he)涓流充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)狀(zhuang)態（以(yi)(yi)3A的(de)(de)小(xiao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)）。蓄電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器使用的(de)(de)工作電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)為(wei)115V/400Hz的(de)(de)航空電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)，充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)器能在(zai)1小(xiao)時內完成恒流充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)，隨后(hou)以(yi)(yi)涓流狀(zhuang)態對蓄電(dian)(dian)(dian)(dian)(dian)(dian)(dian)池(chi)組(zu)進(jin)行充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)直至(zhi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)結束(shu)，每個(ge)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)過程(cheng)在(zai)2個(ge)小(xiao)時內完成。

　　2　充電器總體設計方案
 

圖(tu)1 充電器主電路結構框圖(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，該充電器采用了20kHz的開關頻率。

　　3 SG3525芯片介紹
 

圖2　SG3525芯片的(de)結(jie)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(xin)片各(ge)點(dian)的(de)(de)工作波(bo)形如圖3所示，由(you)誤差放大器輸(shu)(shu)出(chu)的(de)(de)電壓Ve與鋸齒波(bo)的(de)(de)交點(dian)可(ke)得一負的(de)(de)PWM信(xin)(xin)號。由(you)PWM信(xin)(xin)號、時鐘信(xin)(xin)號及分相器輸(shu)(shu)出(chu)的(de)(de)Q (或 )信(xin)(xin)號，根據(ju)或非(fei)門(men)的(de)(de)邏輯(ji)可(ke)得兩個或非(fei)門(men)的(de)(de)輸(shu)(shu)出(chu)信(xin)(xin)號Va和(he)Vb。由(you)波(bo)形圖可(ke)以(yi)看出(chu)，PWM比較器的(de)(de)反相輸(shu)(shu)入(ru)端電平越(yue)高，輸(shu)(shu)出(chu)脈沖(chong)Va和(he)Vb的(de)(de)占空比越(yue)大；反之(zhi)越(yue)小(xiao)。根據(ju)這一規律(lv)來(lai)實現(xian)該(gai)控制器的(de)(de)調壓、軟啟動及保護功能(neng)。另外(wai)，可(ke)以(yi)通過改變(bian)5腳(jiao)和(he)7腳(jiao)之(zhi)間的(de)(de)外(wai)接電阻的(de)(de)大小(xiao)，使時鐘脈沖(chong)寬(kuan)度變(bian)化(hua)來(lai)實現(xian)死區大小(xiao)的(de)(de)調節[2]。

　　4 充電器的控制與(yu)保護策略

　　航空(kong)蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)(dian)(dian)(dian)器的控制(zhi)原(yuan)理框(kuang)圖(tu)(tu)如圖(tu)(tu)4所示。芯片(pian)SG3525產生的兩(liang)路 PWM波經(jing)過(guo)光(guang)耦隔離以后，被送(song)入IR2130從而(er)驅(qu)動開關管工作，由(you)于充電(dian)(dian)(dian)(dian)(dian)(dian)器的負(fu)載為(wei)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)時刻(ke)變化的航空(kong)蓄(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)，因此(ci)在控制(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)路中還采用了電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)電(dian)(dian)(dian)(dian)(dian)(dian)流雙(shuang)閉環控制(zhi)、過(guo)流及(ji)過(guo)溫保護電(dian)(dian)(dian)(dian)(dian)(dian)路，從而(er)能(neng)保證充電(dian)(dian)(dian)(dian)(dian)(dian)器高效、可靠的完成整個充電(dian)(dian)(dian)(dian)(dian)(dian)過(guo)程。

圖4 充(chong)電器控制原(yuan)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(gong)作(zuo)并進入恒流充電(dian)(dian)(dian)狀態，此時(shi)由(you)外部的(de)電(dian)(dian)(dian)壓傳(chuan)感器(qi)和(he)電(dian)(dian)(dian)流傳(chuan)感器(qi)采(cai)集(ji)來的(de)電(dian)(dian)(dian)壓、電(dian)(dian)(dian)流信號傳(chuan)送到(dao)控制電(dian)(dian)(dian)路進行電(dian)(dian)(dian)壓、電(dian)(dian)(dian)流雙閉環調節(jie)，保(bao)持充電(dian)(dian)(dian)電(dian)(dian)(dian)流恒定；當充電(dian)(dian)(dian)電(dian)(dian)(dian)壓達到(dao)另一定值(zhi)（第(di)二(er)定值(zhi)）電(dian)(dian)(dian)壓時(shi)，蓄電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)器(qi)進入涓流充電(dian)(dian)(dian)狀態，當蓄電(dian)(dian)(dian)池(chi)充電(dian)(dian)(dian)器(qi)檢測到(dao)蓄電(dian)(dian)(dian)池(chi)兩端(duan)電(dian)(dian)(dian)壓不再(zai)發生明顯變化時(shi)，充電(dian)(dian)(dian)過(guo)程結(jie)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)5 充電器的軟件(jian)流程圖(tu)

　　6 試驗(yan)結果

圖(tu)(tu)6 蓄(xu)電池充電過程示(shi)意圖(tu)(tu)

　　使用該蓄電(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)器(qi)對(dui)某型號航空蓄電(dian)(dian)(dian)池進行了充(chong)電(dian)(dian)(dian)試驗，最大充(chong)電(dian)(dian)(dian)電(dian)(dian)(dian)流限制為(wei)30A，溫(wen)度限制值定(ding)為(wei)350C。蓄電(dian)(dian)(dian)池的(de)初始電(dian)(dian)(dian)壓為(wei)20V，充(chong)電(dian)(dian)(dian)開始時，充(chong)電(dian)(dian)(dian)器(qi)以20A的(de)電(dian)(dian)(dian)流對(dui)蓄電(dian)(dian)(dian)池持續充(chong)電(dian)(dian)(dian)約58分鐘，然(ran)后以較(jiao)小的(de)電(dian)(dian)(dian)流3A對(dui)蓄電(dian)(dian)(dian)池進行涓(juan)流充(chong)電(dian)(dian)(dian)，直至蓄電(dian)(dian)(dian)池電(dian)(dian)(dian)壓上(shang)(shang)升(sheng)到32.45V時，蓄電(dian)(dian)(dian)池兩端的(de)電(dian)(dian)(dian)壓不再(zai)發生(sheng)明(ming)顯(xian)的(de)上(shang)(shang)升(sheng)現象，此時充(chong)電(dian)(dian)(dian)器(qi)停止(zhi)充(chong)電(dian)(dian)(dian)，歷時150分鐘，充(chong)電(dian)(dian)(dian)過程曲線示意圖如(ru)圖6所(suo)示。

　　7 結論

　　本文提(ti)出了一種鎘(ge)鎳(nie)航空(kong)蓄電(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)器的設計方(fang)案和控制(zhi)原(yuan)理，精(jing)確實現(xian)(xian)了恒流充(chong)電(dian)(dian)(dian)(dian)和涓流充(chong)電(dian)(dian)(dian)(dian)功能，該充(chong)電(dian)(dian)(dian)(dian)器實現(xian)(xian)了輸(shu)出與電(dian)(dian)(dian)(dian)網的高頻電(dian)(dian)(dian)(dian)氣(qi)隔離，充(chong)電(dian)(dian)(dian)(dian)效率高，使用方(fang)便，工(gong)作穩定(ding)，有效地縮短了充(chong)電(dian)(dian)(dian)(dian)時間，提(ti)高了充(chong)電(dian)(dian)(dian)(dian)質量，便于現(xian)(xian)場應用，滿足航空(kong)蓄電(dian)(dian)(dian)(dian)池(chi)的使用要求，現(xian)(xian)已經裝(zhuang)備使用，效果(guo)良好。