電容分壓器定義

  電容分壓器因為相對普通電阻式分(fen)(fen)(fen)壓(ya)(ya)器的耐壓(ya)(ya)強(qiang)度大(da)，不(bu)易(yi)擊穿，一(yi)般(ban)用(yong)(yong)來測量交流高(gao)(gao)壓(ya)(ya)。但由(you)于(yu)其(qi)頻響(xiang)效應的響(xiang)應時間值比電阻(zu)分(fen)(fen)(fen)壓(ya)(ya)器大(da)，所以在沖擊電壓(ya)(ya)的測量中比電阻(zu)分(fen)(fen)(fen)壓(ya)(ya)器用(yong)(yong)的少(shao)，對于(yu)特高(gao)(gao)沖擊電壓(ya)(ya)的測量經常用(yong)(yong)阻(zu)容分(fen)(fen)(fen)壓(ya)(ya)器。用(yong)(yong)于(yu)測量沖擊電壓(ya)(ya)。

電容分壓器工作原理

  電容(rong)(rong)分(fen)壓(ya)器(qi)由高(gao)壓(ya)臂電容(rong)(rong)C1和低壓(ya)臂電容(rong)(rong)C2組(zu)成。電容(rong)(rong)分(fen)壓(ya)器(qi)利用電容(rong)(rong)分(fen)壓(ya)原理實現電壓(ya)變換(huan)(huan)，將(jiang)高(gao)壓(ya)分(fen)為低壓(ya)并(bing)進(jin)行A/D 變換(huan)(huan)，經電/光轉(zhuan)換(huan)(huan)耦合進(jin)行光纖傳(chuan)輸(shu)， 傳(chuan)至信號處理單元(yuan)進(jin)行光/電轉(zhuan)換(huan)(huan)，經微機系統處理輸(shu)出數字信號或進(jin)行D/A 轉(zhuan)換(huan)(huan)輸(shu)出模擬信號。其工作原理如圖所示：

電容分壓器電路詳解

  實用電(dian)路中不只是電(dian)阻器(qi)可以(yi)構成(cheng)分壓電(dian)路，其(qi)他許多元器(qi)件(jian)都可構成(cheng)分壓電(dian)路，在交流電(dian)路中也有用電(dian)容構成(cheng)的分壓電(dian)路。

  如上圖所示是(shi)電(dian)容(rong)(rong)分(fen)壓(ya)電(dian)路(lu)。電(dian)路(lu)中，Cl和C2構成(cheng)電(dian)容(rong)(rong)分(fen)壓(ya)電(dian)路(lu)，Ui是(shi)交流輸入信號(hao)電(dian)壓(ya)，Uo是(shi)輸出信號(hao)電(dian)壓(ya)，輸出信號(hao)電(dian)壓(ya)取出電(dian)容(rong)(rong)C2上。

  電(dian)(dian)阻分(fen)(fen)壓(ya)(ya)電(dian)(dian)路(lu)是各種(zhong)分(fen)(fen)壓(ya)(ya)電(dian)(dian)路(lu)中(zhong)最基本(ben)的(de)電(dian)(dian)路(lu)，分(fen)(fen)析電(dian)(dian)容(rong)分(fen)(fen)壓(ya)(ya)電(dian)(dian)路(lu)等(deng)時可以運用分(fen)(fen)析電(dian)(dian)阻分(fen)(fen)壓(ya)(ya)電(dian)(dian)路(lu)的(de)基本(ben)思路(lu)和方法，再借助(zhu)電(dian)(dian)容(rong)器的(de)具(ju)體特性(xing)進行個性(xing)分(fen)(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)容的隔(ge)直(zhi)特性，所以這一分(fen)壓電(dian)路不適合(he)于(yu)直(zhi)流電(dian)路。

（2）電(dian)容(rong)分(fen)(fen)(fen)壓(ya)電(dian)路(lu)的(de)(de)信號輸入、輸出方式與電(dian)阻分(fen)(fen)(fen)壓(ya)電(dian)路(lu)一樣(yang)，電(dian)路(lu)分(fen)(fen)(fen)析的(de)(de)方法相同，電(dian)阻分(fen)(fen)(fen)壓(ya)電(dian)路(lu)的(de)(de)分(fen)(fen)(fen)析方法是各(ge)種形式分(fen)(fen)(fen)壓(ya)電(dian)路(lu)分(fen)(fen)(fen)析方法的(de)(de)基礎(chu)。

（3）進行輸出電(dian)(dian)(dian)壓(ya)(ya)大小分析(xi)時(shi)，運(yun)用等效(xiao)理(li)解方法最簡(jian)單，見電(dian)(dian)(dian)路右側的等效(xiao)電(dian)(dian)(dian)路，電(dian)(dian)(dian)容(rong)Cl和(he)C2的容(rong)抗分析(xi)用兩(liang)只電(dian)(dian)(dian)阻(zu)來(lai)等效(xiao)，這樣電(dian)(dian)(dian)容(rong)分壓(ya)(ya)電(dian)(dian)(dian)路就等效(xiao)成電(dian)(dian)(dian)阻(zu)分壓(ya)(ya)電(dian)(dian)(dian)路，可以(yi)用電(dian)(dian)(dian)阻(zu)分壓(ya)(ya)電(dian)(dian)(dian)路中(zhong)分析(xi)輸出電(dian)(dian)(dian)壓(ya)(ya)大小的方法來(lai)分析(xi)。

（4）等效電路(lu)的分(fen)析(xi)中關鍵是(shi)容(rong)(rong)抗(kang)大小的理解，這(zhe)里需(xu)要了(le)(le)解電容(rong)(rong)容(rong)(rong)抗(kang)的有(you)關特性，容(rong)(rong)抗(kang)與頻率(lv)成(cheng)(cheng)反比(bi)，容(rong)(rong)抗(kang)與容(rong)(rong)量成(cheng)(cheng)反比(bi)。不了(le)(le)解容(rong)(rong)抗(kang)與頻率(lv)、容(rong)(rong)量之間的關系就無法進行這(zhe)種等效分(fen)析(xi)，許多初學者電路(lu)分(fen)析(xi)中遇到困(kun)難(nan)也是(shi)出(chu)于(yu)對這(zhe)些基本知(zhi)識和概念的掌握不全 面(mian)、不扎實(shi)。

（5）流過(guo)電容(rong)(rong)(rong)分壓(ya)電路各(ge)電容(rong)(rong)(rong)的(de)信號頻(pin)率(lv)相(xiang)(xiang)同，這樣進(jin)行等(deng)(deng)效(xiao)電路分析時(shi)(shi)只需(xu)要考(kao)慮(lv)C1、C2的(de)容(rong)(rong)(rong)量(liang)大(da)小對容(rong)(rong)(rong)抗的(de)影響。如果(guo)C1的(de)容(rong)(rong)(rong)量(liang)等(deng)(deng)于C2的(de)容(rong)(rong)(rong)量(liang)，那么C1和C2的(de)容(rong)(rong)(rong)抗相(xiang)(xiang)等(deng)(deng)，即等(deng)(deng)效(xiao)電路中的(de)R C1、R C2相(xiang)(xiang)等(deng)(deng)，由(you)前面電阻(zu)分壓(ya)電路特性可知，此時(shi)(shi)輸(shu)(shu)出電壓(ya)Uo等(deng)(deng)于輸(shu)(shu)入電壓(ya)Ui的(de)一半；當電容(rong)(rong)(rong)C1的(de)容(rong)(rong)(rong)量(liang)大(da)于C2的(de)容(rong)(rong)(rong)量(liang)時(shi)(shi)，C1的(de)容(rong)(rong)(rong)抗R C1小于C2的(de)容(rong)(rong)(rong)抗RC2，此時(shi)(shi)輸(shu)(shu)出電壓(ya)Uo大(da)于輸(shu)(shu)入電壓(ya)Ui的(de)一半。

（6）分(fen)壓(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)其(qi)實質是(shi)為(wei)了將(jiang)較大的(de)輸入(ru)信(xin)(xin)(xin)(xin)號(hao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)適(shi)當衰減(jian)，得(de)到一個比(bi)輸入(ru)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)小的(de)輸出電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)。在(zai)交(jiao)(jiao)流電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)中，分(fen)壓(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)是(shi)用(yong)來將(jiang)輸入(ru)的(de)交(jiao)(jiao)流信(xin)(xin)(xin)(xin)號(hao)進行適(shi)當的(de)衰減(jian)，可以采(cai)用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)分(fen)壓(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)實現(xian)這(zhe)一電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)功能，為(wei)何又(you)要采(cai)用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)分(fen)壓(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)？因為(wei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)對信(xin)(xin)(xin)(xin)號(hao)存在(zai)損耗，而電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)在(zai)理論上對信(xin)(xin)(xin)(xin)號(hao)能量(liang)不(bu)存在(zai)損耗，所(suo)以在(zai)一些交(jiao)(jiao)流信(xin)(xin)(xin)(xin)號(hao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)中，特別是(shi)高(gao)頻信(xin)(xin)(xin)(xin)號(hao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)中采(cai)用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)分(fen)壓(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)而不(bu)用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)分(fen)壓(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)。