導語：測試電(dian)源研究論文(wen)一(yi)文(wen)來源于(yu)網友上(shang)傳(chuan)，不(bu)代表(biao)本(ben)站觀點，若(ruo)需要(yao)原創文(wen)章可咨詢客服老(lao)師，歡迎參考。

一、自激(ji)和失(shi)真度大(da)問題

自(zi)激(ji)和失(shi)真(zhen)度是(shi)(shi)關聯的(de)(de),自(zi)激(ji)時失(shi)真(zhen)度隨之變(bian)壞,帶非線性負(fu)(fu)載時,由于電(dian)流的(de)(de)非正(zheng)弦變(bian)化,在線路上產生(sheng)壓降,也產生(sheng)電(dian)壓的(de)(de)失(shi)真(zhen)。自(zi)激(ji)是(shi)(shi)由于放大的(de)(de)閉(bi)環(huan)增益大于1時,某(mou)一(yi)個頻率會移(yi)相,使之正(zheng)好反(fan)向形成了正(zheng)反(fan)饋,還有一(yi)種是(shi)(shi)布線上寄生(sheng)電(dian)容電(dian)感形成小幅(fu)自(zi)激(ji),減(jian)小失(shi)真(zhen)度可(ke)以通(tong)過提(ti)高負(fu)(fu)反(fan)饋量來改善。

直流負反饋不存在相位(wei)問題(ti),是解(jie)決(jue)自(zi)激問題(ti)的一種辦法。直流負反饋放大(da)器的數學模型和數學算(suan)式如下。

由(you)圖和(he)數(shu)學(xue)算式可(ke)以看出(chu)(chu)(chu),輸(shu)出(chu)(chu)(chu)Uout主要由(you)K和(he)F決定,前饋(kui)(kui)信(xin)(xin)號(hao)(hao)(hao)(hao)uq和(he)反(fan)饋(kui)(kui)信(xin)(xin)號(hao)(hao)(hao)(hao)uf是反(fan)相(xiang)(xiang)的(de)(de)(de)(de),經比(bi)較求(qiu)(qiu)(qiu)和(he),決定輸(shu)入電(dian)(dian)(dian)(dian)壓ui相(xiang)(xiang)乘的(de)(de)(de)(de)系數(shu)(F+uq+uf),此(ci)系數(shu)變(bian)化反(fan)映了輸(shu)出(chu)(chu)(chu)電(dian)(dian)(dian)(dian)壓誤差量的(de)(de)(de)(de)大(da)小,由(you)此(ci)補償輸(shu)出(chu)(chu)(chu)電(dian)(dian)(dian)(dian)壓的(de)(de)(de)(de)誤差。以上(shang)是放(fang)大(da)器的(de)(de)(de)(de)數(shu)學(xue)模型,要用(yong)(yong)物理器件(jian)來(lai)實現(xian)(xian),擬定出(chu)(chu)(chu)以下電(dian)(dian)(dian)(dian)路(lu)(lu),前饋(kui)(kui)電(dian)(dian)(dian)(dian)路(lu)(lu)和(he)反(fan)饋(kui)(kui)電(dian)(dian)(dian)(dian)路(lu)(lu)仍保(bao)持(chi)原電(dian)(dian)(dian)(dian)路(lu)(lu),整(zheng)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)路(lu)(lu)用(yong)(yong)運放(fang)精密整(zheng)流(liu)(liu)(liu),比(bi)較求(qiu)(qiu)(qiu)和(he)電(dian)(dian)(dian)(dian)路(lu)(lu)用(yong)(yong)運放(fang)求(qiu)(qiu)(qiu)和(he)電(dian)(dian)(dian)(dian)路(lu)(lu),如果前饋(kui)(kui)信(xin)(xin)號(hao)(hao)(hao)(hao)uq取(qu)自CPU板(ban)上(shang)的(de)(de)(de)(de)0832的(de)(de)(de)(de)基準,可(ke)直(zhi)接將(jiang)前饋(kui)(kui)信(xin)(xin)號(hao)(hao)(hao)(hao)uq接求(qiu)(qiu)(qiu)和(he)運放(fang)的(de)(de)(de)(de)正相(xiang)(xiang)端,求(qiu)(qiu)(qiu)和(he)電(dian)(dian)(dian)(dian)路(lu)(lu)兼有濾波作用(yong)(yong),輸(shu)出(chu)(chu)(chu)反(fan)映輸(shu)出(chu)(chu)(chu)電(dian)(dian)(dian)(dian)壓誤差的(de)(de)(de)(de)直(zhi)流(liu)(liu)(liu),此(ci)直(zhi)流(liu)(liu)(liu)要與輸(shu)入信(xin)(xin)號(hao)(hao)(hao)(hao)ui相(xiang)(xiang)乘,乘法(fa)可(ke)通過兩種途徑來(lai)實現(xian)(xian),一種是用(yong)(yong)專用(yong)(yong)乘法(fa)器AD633;另一種是用(yong)(yong)分立(li)元件(jian),做一個帶恒(heng)流(liu)(liu)(liu)源的(de)(de)(de)(de)差分放(fang)大(da)器,用(yong)(yong)直(zhi)流(liu)(liu)(liu)去控制差分電(dian)(dian)(dian)(dian)路(lu)(lu)的(de)(de)(de)(de)恒(heng)流(liu)(liu)(liu)源大(da)小,也可(ke)以實現(xian)(xian)乘法(fa)作用(yong)(yong),最后視(shi)情況而定。

二、功放效率的問題

乙類功放最(zui)大輸出功率Pom=1/2Vcem*Icm

電(dian)源(yuan)輸出功率Pem=2/πEc*Icm

其(qi)效率η=Pom/Pem=π/4*Vcem/Ec

由式(shi)子可得:當輸出電壓(ya)的最(zui)大(da)值與供電電壓(ya)Ec相等時,Vcem/Ec=1(忽略管子的飽和壓(ya)降),其效率(lv)最(zui)大(da)是:π/4=78.5%。

所以,功(gong)放(fang)(fang)(fang)供(gong)電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)根據(ju)負載(zai)大(da)小(xiao)調整是(shi)提高(gao)功(gong)放(fang)(fang)(fang)效率的(de)一種(zhong)方法。現擬(ni)定(ding)一個檢(jian)測(ce)(ce)功(gong)放(fang)(fang)(fang)輸(shu)出(chu)電(dian)(dian)(dian)壓(ya)大(da)小(xiao)區間電(dian)(dian)(dian)路,將功(gong)放(fang)(fang)(fang)輸(shu)出(chu)電(dian)(dian)(dian)壓(ya)整流(liu)濾波,送(song)去電(dian)(dian)(dian)壓(ya)大(da)小(xiao)區間比較電(dian)(dian)(dian)路,判(pan)斷(duan)功(gong)放(fang)(fang)(fang)輸(shu)出(chu)電(dian)(dian)(dian)壓(ya)的(de)大(da)小(xiao),確定(ding)功(gong)放(fang)(fang)(fang)供(gong)電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)的(de)切(qie)換(huan),從而實現根據(ju)功(gong)放(fang)(fang)(fang)輸(shu)出(chu)電(dian)(dian)(dian)壓(ya)大(da)小(xiao)來分(fen)檔調整功(gong)放(fang)(fang)(fang)供(gong)電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)。檢(jian)測(ce)(ce)功(gong)放(fang)(fang)(fang)輸(shu)出(chu)電(dian)(dian)(dian)壓(ya)大(da)小(xiao)區間分(fen)8檔(視試(shi)驗(yan)情況而增減),去切(qie)換(huan)供(gong)電(dian)(dian)(dian)變壓(ya)器交流(liu)電(dian)(dian)(dian)壓(ya)檔位。

三(san)、過(guo)壓過(guo)流及過(guo)熱的保護問題(ti)

電(dian)壓(ya)(ya)源(yuan)(yuan)采用過(guo)流(liu)檢(jian)測(ce)保(bao)護(hu),因為電(dian)壓(ya)(ya)源(yuan)(yuan)恒(heng)壓(ya)(ya)不恒(heng)流(liu),過(guo)載時(shi)以過(guo)流(liu)表(biao)現(xian)(xian),從功(gong)放(fang)電(dian)流(liu)反饋電(dian)阻(zu)上檢(jian)出過(guo)流(liu)信(xin)號時(shi),切(qie)斷(duan)(duan)功(gong)放(fang)供電(dian)。電(dian)流(liu)源(yuan)(yuan)采用過(guo)壓(ya)(ya)檢(jian)測(ce)保(bao)護(hu),因為電(dian)流(liu)源(yuan)(yuan)恒(heng)流(liu)不恒(heng)壓(ya)(ya),過(guo)載時(shi)以過(guo)壓(ya)(ya)表(biao)現(xian)(xian),通過(guo)分(fen)壓(ya)(ya)電(dian)阻(zu)檢(jian)出過(guo)壓(ya)(ya)信(xin)號時(shi),切(qie)斷(duan)(duan)功(gong)放(fang)供電(dian)。過(guo)熱(re)(re)的保(bao)護(hu)可用溫(wen)控開關(guan)測(ce)量(liang)散(san)熱(re)(re)塊的溫(wen)度(du),當溫(wen)度(du)過(guo)高(gao)時(shi)切(qie)斷(duan)(duan)功(gong)放(fang)供電(dian)或(huo)開啟散(san)熱(re)(re)風扇。

四、功放管的保(bao)護問題

功放管(guan)(guan)(guan)的(de)(de)(de)(de)燒(shao)壞(huai)因(yin)素很多,二(er)(er)次擊穿(chuan)(chuan)是較(jiao)多的(de)(de)(de)(de)原(yuan)因(yin),二(er)(er)次擊穿(chuan)(chuan)是雙極(ji)(ji)型三(san)極(ji)(ji)管(guan)(guan)(guan)特有的(de)(de)(de)(de)現(xian)象,是指三(san)極(ji)(ji)管(guan)(guan)(guan)的(de)(de)(de)(de)Uce電壓(ya)大到一(yi)(yi)定程(cheng)(cheng)度,首先雪(xue)崩擊穿(chuan)(chuan)(一(yi)(yi)次擊穿(chuan)(chuan)),此時(shi)如不(bu)超(chao)過功放管(guan)(guan)(guan)的(de)(de)(de)(de)功耗,管(guan)(guan)(guan)子(zi)仍然是安全的(de)(de)(de)(de),如電流(liu)再增大,三(san)極(ji)(ji)管(guan)(guan)(guan)會出現(xian)電壓(ya)Uce突然驟降和電流(liu)Ic驟升的(de)(de)(de)(de)負(fu)阻(zu)性現(xian)象,管(guan)(guan)(guan)子(zi)立即燒(shao)壞(huai),即為二(er)(er)次擊穿(chuan)(chuan),這一(yi)(yi)過程(cheng)(cheng)極(ji)(ji)快。二(er)(er)次擊穿(chuan)(chuan)的(de)(de)(de)(de)電壓(ya)與(yu)三(san)極(ji)(ji)管(guan)(guan)(guan)的(de)(de)(de)(de)電流(liu)有關,三(san)極(ji)(ji)管(guan)(guan)(guan)的(de)(de)(de)(de)電流(liu)大,二(er)(er)次擊穿(chuan)(chuan)的(de)(de)(de)(de)電壓(ya)就(jiu)低,還(huan)與(yu)散熱有關。

采用(yong)每(mei)個(ge)功(gong)放管加(jia)保險,這(zhe)種加(jia)保險方式的相應是(shi)否快,能否起(qi)到保護作用(yong)還有(you)待(dai)驗(yan)證。還有(you)一種方法是(shi)在功(gong)放管和(he)推動管的基極與集電極加(jia)個(ge)嵌位(wei)穩(wen)壓(ya)管,起(qi)到抑制浪涌電壓(ya)引起(qi)的二次擊穿(chuan)。

綜上所述,采取上述方法之后相信可以對測試電源的性能有極(ji)大的提高(gao),但(dan)具體應用(yong)情況及詳細(xi)數據有待進行試驗并完善。

參考文獻:

[1]童詩(shi)白,華成英.模擬電子技術(shu)基礎(第三(san)版(ban))[M].高(gao)等教育出版(ban)社.

[2]張(zhang)有順(shun),馮井崗.電能計(ji)(ji)量基礎(chu)[M].中國計(ji)(ji)量出版社,2002.

[3]曲學基等.穩定電源電路設計手冊[M].電子(zi)工(gong)業出版社,2003.

【摘要】本(ben)文針(zhen)對(dui)(dui)目前(qian)測試電源存在的(de)幾種常見問(wen)題(ti)提出了(le)針(zhen)對(dui)(dui)性的(de)解決(jue)方案(an)。

【關鍵詞】測試電源自激失真度功(gong)放