該航空蓄電池充電器為飛機某型(xing)號蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)專(zhuan)門設計，主(zhu)要實現兩階段充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)功能，即(ji)恒(heng)流(liu)(liu)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)狀(zhuang)態（以20A的(de)大電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)）和涓流(liu)(liu)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)狀(zhuang)態（以3A的(de)小(xiao)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)）。蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器使用(yong)的(de)工作電(dian)(dian)(dian)(dian)(dian)(dian)源為115V/400Hz的(de)航空電(dian)(dian)(dian)(dian)(dian)(dian)源，充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)器能在1小(xiao)時(shi)內完成恒(heng)流(liu)(liu)充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)，隨(sui)后以涓流(liu)(liu)狀(zhuang)態對蓄(xu)(xu)電(dian)(dian)(dian)(dian)(dian)(dian)池(chi)組進行充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)直至充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)結束，每個充(chong)電(dian)(dian)(dian)(dian)(dian)(dian)過程在2個小(xiao)時(shi)內完成。

　　2　充電器總體設計方案
 
 　　航空(kong)蓄電(dian)(dian)(dian)池充(chong)電(dian)(dian)(dian)器(qi)(qi)的(de)主電(dian)(dian)(dian)路如圖1所示，電(dian)(dian)(dian)源變(bian)換(huan)器(qi)(qi)采用了(le)由半橋(qiao)變(bian)換(huan)器(qi)(qi)、高(gao)頻變(bian)壓(ya)器(qi)(qi)和(he)輸出整流濾(lv)波電(dian)(dian)(dian)路組成的(de)半橋(qiao)變(bian)換(huan)器(qi)(qi)[1]，該(gai)電(dian)(dian)(dian)路結構簡(jian)單，工作(zuo)可靠，功率管為(wei)場效應管，而且開關(guan)管承(cheng)受的(de)電(dian)(dian)(dian)壓(ya)為(wei)電(dian)(dian)(dian)源電(dian)(dian)(dian)壓(ya)，故(gu)可在電(dian)(dian)(dian)源電(dian)(dian)(dian)壓(ya)較高(gao)的(de)場合(he)應用。通(tong)常高(gao)頻大功率變(bian)換(huan)器(qi)(qi)開關(guan)頻率一般都大于15kHz，為(wei)了(le)使功率電(dian)(dian)(dian)路小型化、減小失(shi)真并保持(chi)高(gao)的(de)變(bian)換(huan)效率，該(gai)充(chong)電(dian)(dian)(dian)器(qi)(qi)采用了(le)20kHz的(de)開關(guan)頻率。

　　3 SG3525芯片介紹
 
　　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(gong)作波形

 　　SG3525芯片各點的(de)(de)(de)(de)工作(zuo)波(bo)(bo)形(xing)(xing)如圖(tu)3所(suo)示(shi)，由(you)誤差放大(da)器(qi)(qi)(qi)輸(shu)出的(de)(de)(de)(de)電壓Ve與(yu)鋸齒波(bo)(bo)的(de)(de)(de)(de)交點可(ke)(ke)得一(yi)負的(de)(de)(de)(de)PWM信(xin)(xin)(xin)號(hao)(hao)。由(you)PWM信(xin)(xin)(xin)號(hao)(hao)、時(shi)鐘信(xin)(xin)(xin)號(hao)(hao)及分相器(qi)(qi)(qi)輸(shu)出的(de)(de)(de)(de)Q (或 )信(xin)(xin)(xin)號(hao)(hao)，根據(ju)或非門(men)(men)的(de)(de)(de)(de)邏(luo)輯可(ke)(ke)得兩個(ge)或非門(men)(men)的(de)(de)(de)(de)輸(shu)出信(xin)(xin)(xin)號(hao)(hao)Va和(he)Vb。由(you)波(bo)(bo)形(xing)(xing)圖(tu)可(ke)(ke)以(yi)看出，PWM比(bi)較器(qi)(qi)(qi)的(de)(de)(de)(de)反相輸(shu)入端電平越(yue)高，輸(shu)出脈(mo)沖(chong)Va和(he)Vb的(de)(de)(de)(de)占(zhan)空比(bi)越(yue)大(da)；反之越(yue)小(xiao)。根據(ju)這(zhe)一(yi)規律來(lai)(lai)實現(xian)該控制器(qi)(qi)(qi)的(de)(de)(de)(de)調壓、軟(ruan)啟動及保護(hu)功能。另(ling)外，可(ke)(ke)以(yi)通過改(gai)變5腳和(he)7腳之間的(de)(de)(de)(de)外接電阻的(de)(de)(de)(de)大(da)小(xiao)，使時(shi)鐘脈(mo)沖(chong)寬度變化(hua)來(lai)(lai)實現(xian)死區大(da)小(xiao)的(de)(de)(de)(de)調節(jie)[2]。

　　4 充電器的控制與保護策略

　　航(hang)空(kong)蓄電(dian)池(chi)充電(dian)器的(de)(de)控制(zhi)(zhi)原理框(kuang)圖如(ru)圖4所(suo)示。芯片SG3525產(chan)生的(de)(de)兩路 PWM波經過(guo)光(guang)耦隔離以后，被送入(ru)IR2130從而(er)驅動(dong)開關管(guan)工作(zuo)，由于(yu)充電(dian)器的(de)(de)負載為(wei)電(dian)壓時刻變化的(de)(de)航(hang)空(kong)蓄電(dian)池(chi)，因此(ci)在(zai)控制(zhi)(zhi)電(dian)路中還采用了電(dian)壓電(dian)流雙(shuang)閉環控制(zhi)(zhi)、過(guo)流及(ji)過(guo)溫(wen)保護電(dian)路，從而(er)能保證(zheng)充電(dian)器高效、可靠的(de)(de)完成整個充電(dian)過(guo)程。     

   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入恒流充電狀態，此時由外部的電壓傳感器和電流傳感器采集來的電壓、電流信號傳送到控制電路進行電壓、電流雙閉環調節，保持充電電流恒定；當充電電壓達到另一定值（第二定值）電壓時，蓄電池充電器進入涓流充電狀態，當蓄電池充電器檢測到(dao)蓄電(dian)池兩(liang)端(duan)電(dian)壓不再發生明顯變化時，充電(dian)過程(cheng)結(jie)束。

　 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。
  使用(yong)該(gai)蓄電(dian)(dian)(dian)(dian)池(chi)充(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)對(dui)(dui)某型號航空蓄電(dian)(dian)(dian)(dian)池(chi)進(jin)(jin)行了充(chong)(chong)電(dian)(dian)(dian)(dian)試驗，最(zui)大充(chong)(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流(liu)限制為(wei)30A，溫度限制值定為(wei)350C。蓄電(dian)(dian)(dian)(dian)池(chi)的初始電(dian)(dian)(dian)(dian)壓(ya)為(wei)20V，充(chong)(chong)電(dian)(dian)(dian)(dian)開始時(shi)，充(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)以20A的電(dian)(dian)(dian)(dian)流(liu)對(dui)(dui)蓄電(dian)(dian)(dian)(dian)池(chi)持(chi)續充(chong)(chong)電(dian)(dian)(dian)(dian)約58分鐘，然(ran)后(hou)以較小的電(dian)(dian)(dian)(dian)流(liu)3A對(dui)(dui)蓄電(dian)(dian)(dian)(dian)池(chi)進(jin)(jin)行涓流(liu)充(chong)(chong)電(dian)(dian)(dian)(dian)，直至蓄電(dian)(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)(dian)壓(ya)上(shang)升到(dao)32.45V時(shi)，蓄電(dian)(dian)(dian)(dian)池(chi)兩端的電(dian)(dian)(dian)(dian)壓(ya)不(bu)再(zai)發生(sheng)明顯的上(shang)升現象(xiang)，此時(shi)充(chong)(chong)電(dian)(dian)(dian)(dian)器(qi)停止充(chong)(chong)電(dian)(dian)(dian)(dian)，歷時(shi)150分鐘。

　　本文提出了一種鎘鎳航空蓄電池充電器的設(she)計(ji)方案(an)和控制原(yuan)理，精確實現(xian)(xian)了(le)(le)(le)恒流充(chong)電和涓流充(chong)電功能，該充(chong)電器(qi)實現(xian)(xian)了(le)(le)(le)輸(shu)出與電網的高(gao)頻電氣(qi)隔離，充(chong)電效率高(gao)，使(shi)用方便(bian)，工作(zuo)穩(wen)定，有效地縮短了(le)(le)(le)充(chong)電時間，提高(gao)了(le)(le)(le)充(chong)電質量，便(bian)于現(xian)(xian)場應(ying)用，滿足航空蓄電池的使(shi)用要求(qiu)，現(xian)(xian)已經裝備(bei)使(shi)用，效果(guo)良好(hao)。