一、調頻串聯諧振試驗裝置原理

　　發生串聯諧振的基本(ben)原(yuan)理是：在R-L-C電路中

　　由電(dian)(dian)(dian)工知識得到(dao)：Uc=I/ωC,UL=I*ωL，UR=I*R，U=Uc+UL+UR，當LRC串聯回路(lu)(lu)中(zhong)的(de)(de)(de)感(gan)抗(kang)(kang)與試(shi)品(pin)容(rong)抗(kang)(kang)相(xiang)等時，電(dian)(dian)(dian)感(gan)中(zhong)的(de)(de)(de)磁(ci)(ci)場能(neng)(neng)量(liang)與試(shi)品(pin)電(dian)(dian)(dian)容(rong)中(zhong)的(de)(de)(de)電(dian)(dian)(dian)場能(neng)(neng)量(liang)相(xiang)互補償，試(shi)品(pin)所(suo)需的(de)(de)(de)無功功率全部由電(dian)(dian)(dian)抗(kang)(kang)器供給(gei)，電(dian)(dian)(dian)源(yuan)只提(ti)供回路(lu)(lu)的(de)(de)(de)有(you)功損耗。電(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)壓(ya)與諧(xie)(xie)振(zhen)回路(lu)(lu)電(dian)(dian)(dian)流同(tong)相(xiang)位(wei)(wei)，電(dian)(dian)(dian)感(gan)上的(de)(de)(de)電(dian)(dian)(dian)壓(ya)降與電(dian)(dian)(dian)容(rong)上的(de)(de)(de)壓(ya)降大小相(xiang)等，相(xiang)位(wei)(wei)相(xiang)反。由圖1 可知，當 ωL=1/ωc，回路(lu)(lu)的(de)(de)(de)諧(xie)(xie)振(zhen)頻率 f=1/2π√LC，也就是說(shuo)，電(dian)(dian)(dian)路(lu)(lu)發生(sheng)串聯諧(xie)(xie)振(zhen)，電(dian)(dian)(dian)源(yuan)提(ti)供很小的(de)(de)(de)勵磁(ci)(ci)電(dian)(dian)(dian)壓(ya)，試(shi)品(pin)上就能(neng)(neng)得到(dao)很高的(de)(de)(de)電(dian)(dian)(dian)壓(ya),電(dian)(dian)(dian)源(yuan)頻率為諧(xie)(xie)振(zhen)頻率。

    二、調頻串聯諧振試驗裝置的特點

　　利(li)用串聯諧(xie)振原理在回路中產(chan)生(sheng)(sheng)高(gao)電壓,一般(ban)頻(pin)率為30~300Hz。串聯諧(xie)振高(gao)壓發(fa)生(sheng)(sheng)器(qi)原理如(ru)下圖2表(biao)示：

　　當(dang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源頻(pin)率(lv)（f）、電(dian)(dian)(dian)(dian)(dian)(dian)(dian)感(gan)（L）及被試(shi)(shi)(shi)(shi)設(she)備(bei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容（C）滿(man)足下(xia)式時(shi)(shi)(shi)回(hui)(hui)(hui)路(lu)(lu)(lu)處于串聯諧(xie)(xie)(xie)振(zhen)狀態(tai)此時(shi)(shi)(shi)：f=1/2π√LC，回(hui)(hui)(hui)路(lu)(lu)(lu)中電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)為I=Ulx/R,被試(shi)(shi)(shi)(shi)設(she)備(bei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)為Ucx=I/ωCx輸出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)與勵磁電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)之比為試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)回(hui)(hui)(hui)路(lu)(lu)(lu)的(de)(de)品質因數：Q=Ucx/Ulx=（ωL）/R，由(you)于試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)回(hui)(hui)(hui)路(lu)(lu)(lu)中電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻R很(hen)(hen)小，故試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)回(hui)(hui)(hui)路(lu)(lu)(lu)品質因數很(hen)(hen)大。一(yi)般正(zheng)常時(shi)(shi)(shi)可達(da)50以上(shang)，既輸出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)是勵磁電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)50倍(bei)，因此用(yong)較低容量的(de)(de)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)變壓(ya)(ya)(ya)(ya)器就(jiu)能(neng)(neng)得(de)到(dao)(dao)較高的(de)(de)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)。這(zhe)樣就(jiu)解(jie)決了在一(yi)般的(de)(de)交流(liu)(liu)(liu)耐壓(ya)(ya)(ya)(ya)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)中試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)變壓(ya)(ya)(ya)(ya)器容量不能(neng)(neng)滿(man)足試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)要(yao)求的(de)(de)問題。而(er)(er)此時(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容量與電(dian)(dian)(dian)(dian)(dian)(dian)(dian)感(gan)的(de)(de)關系為ωL=1/ωc，因為對某個試(shi)(shi)(shi)(shi)品而(er)(er)言(yan)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容量是固有的(de)(de)，試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)用(yong)可調電(dian)(dian)(dian)(dian)(dian)(dian)(dian)感(gan)的(de)(de)價格也(ye)非常昂貴(gui)，因此解(jie)決問題的(de)(de)途徑就(jiu)引到(dao)(dao)了改變電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源頻(pin)率(lv)回(hui)(hui)(hui)路(lu)(lu)(lu)的(de)(de)諧(xie)(xie)(xie)振(zhen)頻(pin)率(lv)，在初始(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)下(xia)調節回(hui)(hui)(hui)路(lu)(lu)(lu)的(de)(de)頻(pin)率(lv)，觀察Uc的(de)(de)變化達(da)大值時(shi)(shi)(shi)，增加或減小頻(pin)率(lv)時(shi)(shi)(shi)諧(xie)(xie)(xie)振(zhen)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)都(dou)要(yao)下(xia)降，這(zhe)時(shi)(shi)(shi)的(de)(de)頻(pin)率(lv)為諧(xie)(xie)(xie)振(zhen)頻(pin)率(lv)，這(zhe)時(shi)(shi)(shi)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)為諧(xie)(xie)(xie)振(zhen)點電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)，增加勵磁電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)就(jiu)能(neng)(neng)升高諧(xie)(xie)(xie)振(zhen)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)，從(cong)而(er)(er)達(da)到(dao)(dao)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)目的(de)(de)。另外，由(you)于試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)回(hui)(hui)(hui)路(lu)(lu)(lu)是處于諧(xie)(xie)(xie)振(zhen)狀態(tai)，回(hui)(hui)(hui)路(lu)(lu)(lu)本身具有良(liang)好的(de)(de)濾波(bo)(bo)作用(yong)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源波(bo)(bo)形(xing)(xing)中的(de)(de)諧(xie)(xie)(xie)波(bo)(bo)分量在設(she)備(bei)兩端大為減小，從(cong)而(er)(er)輸出(chu)良(liang)好的(de)(de)正(zheng)弦(xian)波(bo)(bo)形(xing)(xing)。當(dang)試(shi)(shi)(shi)(shi)品放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)或擊穿時(shi)(shi)(shi)，即回(hui)(hui)(hui)路(lu)(lu)(lu)中等(deng)值電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容被短路(lu)(lu)(lu)，諧(xie)(xie)(xie)振(zhen)條件被破(po)壞，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)明顯下(xia)降，恢復(fu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)上(shang)升緩慢，試(shi)(shi)(shi)(shi)品上(shang)不發(fa)生暫態(tai)過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)，且電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源供給的(de)(de)短路(lu)(lu)(lu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)受到(dao)(dao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)抗的(de)(de)限(xian)(xian)制而(er)(er)減少，從(cong)而(er)(er)限(xian)(xian)制被試(shi)(shi)(shi)(shi)設(she)備(bei)的(de)(de)損壞程度。