電容分壓器定義

  電容分壓器因為相對普通電阻式(shi)分壓(ya)器的(de)(de)耐(nai)壓(ya)強(qiang)度(du)大(da)(da)，不易擊(ji)穿，一般用(yong)來測(ce)量(liang)交(jiao)流(liu)高壓(ya)。但由于其(qi)頻響效應(ying)的(de)(de)響應(ying)時間值比電(dian)阻(zu)(zu)分壓(ya)器大(da)(da)，所(suo)以在沖擊(ji)電(dian)壓(ya)的(de)(de)測(ce)量(liang)中比電(dian)阻(zu)(zu)分壓(ya)器用(yong)的(de)(de)少，對于特高沖擊(ji)電(dian)壓(ya)的(de)(de)測(ce)量(liang)經常用(yong)阻(zu)(zu)容分壓(ya)器。用(yong)于測(ce)量(liang)沖擊(ji)電(dian)壓(ya)。

電容分壓器工作原理

  電(dian)(dian)(dian)容分(fen)(fen)(fen)壓(ya)(ya)(ya)器由高(gao)(gao)壓(ya)(ya)(ya)臂電(dian)(dian)(dian)容C1和低壓(ya)(ya)(ya)臂電(dian)(dian)(dian)容C2組成。電(dian)(dian)(dian)容分(fen)(fen)(fen)壓(ya)(ya)(ya)器利用電(dian)(dian)(dian)容分(fen)(fen)(fen)壓(ya)(ya)(ya)原理(li)(li)實現電(dian)(dian)(dian)壓(ya)(ya)(ya)變換(huan)(huan)，將高(gao)(gao)壓(ya)(ya)(ya)分(fen)(fen)(fen)為低壓(ya)(ya)(ya)并進行A/D 變換(huan)(huan)，經電(dian)(dian)(dian)/光轉換(huan)(huan)耦合(he)進行光纖(xian)傳輸， 傳至信號處(chu)理(li)(li)單(dan)元進行光/電(dian)(dian)(dian)轉換(huan)(huan)，經微機(ji)系統處(chu)理(li)(li)輸出(chu)數(shu)字信號或進行D/A 轉換(huan)(huan)輸出(chu)模擬信號。其工作原理(li)(li)如圖所示：

電容分壓器電路詳解

  實用(yong)電(dian)路(lu)中不只是(shi)電(dian)阻器(qi)可以構(gou)(gou)成分壓電(dian)路(lu)，其他許多元器(qi)件都可構(gou)(gou)成分壓電(dian)路(lu)，在交流電(dian)路(lu)中也(ye)有用(yong)電(dian)容構(gou)(gou)成的分壓電(dian)路(lu)。

  如(ru)上(shang)圖所示是(shi)電(dian)容(rong)分壓電(dian)路(lu)。電(dian)路(lu)中，Cl和C2構成電(dian)容(rong)分壓電(dian)路(lu)，Ui是(shi)交流輸(shu)入信號電(dian)壓，Uo是(shi)輸(shu)出信號電(dian)壓，輸(shu)出信號電(dian)壓取出電(dian)容(rong)C2上(shang)。

  電(dian)阻(zu)分(fen)壓電(dian)路是(shi)各種分(fen)壓電(dian)路中最(zui)基本(ben)的(de)電(dian)路，分(fen)析電(dian)容分(fen)壓電(dian)路等時可以運用(yong)分(fen)析電(dian)阻(zu)分(fen)壓電(dian)路的(de)基本(ben)思路和方法(fa)，再借助(zhu)電(dian)容器的(de)具(ju)體(ti)特性(xing)進行個性(xing)分(fen)析。

關于電容分壓電路的分析思路和方法說明下列幾點：

（1）由于(yu)電(dian)容的(de)隔直特性(xing)，所以這一分(fen)壓電(dian)路不適合于(yu)直流電(dian)路。

（2）電容分(fen)(fen)壓電路(lu)(lu)的(de)信號輸(shu)入(ru)、輸(shu)出(chu)方(fang)(fang)式與電阻(zu)分(fen)(fen)壓電路(lu)(lu)一樣，電路(lu)(lu)分(fen)(fen)析的(de)方(fang)(fang)法相同，電阻(zu)分(fen)(fen)壓電路(lu)(lu)的(de)分(fen)(fen)析方(fang)(fang)法是各種形式分(fen)(fen)壓電路(lu)(lu)分(fen)(fen)析方(fang)(fang)法的(de)基礎。

（3）進行輸出電(dian)(dian)壓(ya)(ya)大小分(fen)(fen)(fen)析(xi)時，運用(yong)等(deng)效(xiao)(xiao)理解方法最簡單(dan)，見電(dian)(dian)路(lu)(lu)(lu)右(you)側的等(deng)效(xiao)(xiao)電(dian)(dian)路(lu)(lu)(lu)，電(dian)(dian)容Cl和C2的容抗分(fen)(fen)(fen)析(xi)用(yong)兩只電(dian)(dian)阻(zu)來等(deng)效(xiao)(xiao)，這(zhe)樣電(dian)(dian)容分(fen)(fen)(fen)壓(ya)(ya)電(dian)(dian)路(lu)(lu)(lu)就(jiu)等(deng)效(xiao)(xiao)成電(dian)(dian)阻(zu)分(fen)(fen)(fen)壓(ya)(ya)電(dian)(dian)路(lu)(lu)(lu)，可以用(yong)電(dian)(dian)阻(zu)分(fen)(fen)(fen)壓(ya)(ya)電(dian)(dian)路(lu)(lu)(lu)中分(fen)(fen)(fen)析(xi)輸出電(dian)(dian)壓(ya)(ya)大小的方法來分(fen)(fen)(fen)析(xi)。

（4）等效電(dian)路的分(fen)(fen)析(xi)中(zhong)關(guan)鍵(jian)是容(rong)抗(kang)(kang)大(da)小的理解，這里需要了解電(dian)容(rong)容(rong)抗(kang)(kang)的有關(guan)特(te)性，容(rong)抗(kang)(kang)與(yu)頻率成(cheng)反(fan)比(bi)，容(rong)抗(kang)(kang)與(yu)容(rong)量(liang)成(cheng)反(fan)比(bi)。不了解容(rong)抗(kang)(kang)與(yu)頻率、容(rong)量(liang)之間的關(guan)系就無法(fa)進(jin)行這種等效分(fen)(fen)析(xi)，許多初學者電(dian)路分(fen)(fen)析(xi)中(zhong)遇到困難也是出(chu)于對這些(xie)基本知識和(he)概念的掌握不全 面、不扎實(shi)。

（5）流過電(dian)(dian)容(rong)(rong)(rong)(rong)分壓(ya)電(dian)(dian)路各電(dian)(dian)容(rong)(rong)(rong)(rong)的(de)信號頻率相(xiang)同，這樣進行等(deng)效(xiao)電(dian)(dian)路分析時(shi)只需要(yao)考慮C1、C2的(de)容(rong)(rong)(rong)(rong)量(liang)大小對容(rong)(rong)(rong)(rong)抗的(de)影(ying)響(xiang)。如果C1的(de)容(rong)(rong)(rong)(rong)量(liang)等(deng)于(yu)(yu)C2的(de)容(rong)(rong)(rong)(rong)量(liang)，那么(me)C1和C2的(de)容(rong)(rong)(rong)(rong)抗相(xiang)等(deng)，即等(deng)效(xiao)電(dian)(dian)路中的(de)R C1、R C2相(xiang)等(deng)，由前面(mian)電(dian)(dian)阻分壓(ya)電(dian)(dian)路特性(xing)可知，此(ci)時(shi)輸出(chu)電(dian)(dian)壓(ya)Uo等(deng)于(yu)(yu)輸入電(dian)(dian)壓(ya)Ui的(de)一半；當電(dian)(dian)容(rong)(rong)(rong)(rong)C1的(de)容(rong)(rong)(rong)(rong)量(liang)大于(yu)(yu)C2的(de)容(rong)(rong)(rong)(rong)量(liang)時(shi)，C1的(de)容(rong)(rong)(rong)(rong)抗R C1小于(yu)(yu)C2的(de)容(rong)(rong)(rong)(rong)抗RC2，此(ci)時(shi)輸出(chu)電(dian)(dian)壓(ya)Uo大于(yu)(yu)輸入電(dian)(dian)壓(ya)Ui的(de)一半。

（6）分壓(ya)(ya)電(dian)(dian)(dian)路(lu)(lu)其實質是(shi)為(wei)(wei)了將(jiang)較大的(de)輸入信號(hao)(hao)電(dian)(dian)(dian)壓(ya)(ya)適當(dang)衰減，得到一個比輸入電(dian)(dian)(dian)壓(ya)(ya)小(xiao)的(de)輸出電(dian)(dian)(dian)壓(ya)(ya)。在(zai)(zai)(zai)(zai)交(jiao)(jiao)流電(dian)(dian)(dian)路(lu)(lu)中，分壓(ya)(ya)電(dian)(dian)(dian)路(lu)(lu)是(shi)用來將(jiang)輸入的(de)交(jiao)(jiao)流信號(hao)(hao)進行適當(dang)的(de)衰減，可以(yi)(yi)采(cai)用電(dian)(dian)(dian)阻分壓(ya)(ya)電(dian)(dian)(dian)路(lu)(lu)實現這一電(dian)(dian)(dian)路(lu)(lu)功(gong)能(neng)，為(wei)(wei)何又要(yao)采(cai)用電(dian)(dian)(dian)容分壓(ya)(ya)電(dian)(dian)(dian)路(lu)(lu)？因為(wei)(wei)電(dian)(dian)(dian)阻對信號(hao)(hao)存在(zai)(zai)(zai)(zai)損(sun)耗(hao)，而電(dian)(dian)(dian)容在(zai)(zai)(zai)(zai)理(li)論(lun)上對信號(hao)(hao)能(neng)量不(bu)存在(zai)(zai)(zai)(zai)損(sun)耗(hao)，所以(yi)(yi)在(zai)(zai)(zai)(zai)一些交(jiao)(jiao)流信號(hao)(hao)電(dian)(dian)(dian)路(lu)(lu)中，特別是(shi)高(gao)頻信號(hao)(hao)電(dian)(dian)(dian)路(lu)(lu)中采(cai)用電(dian)(dian)(dian)容分壓(ya)(ya)電(dian)(dian)(dian)路(lu)(lu)而不(bu)用電(dian)(dian)(dian)阻分壓(ya)(ya)電(dian)(dian)(dian)路(lu)(lu)。