【微波爐原理】微波爐的(de)工作原理圖解(jie) 微波爐的(de)電路(lu)圖分(fen)析

微波爐按(an)功(gong)能(neng)分(fen)為(wei)微(wei)波(bo)(bo)(bo)(bo)加熱型(xing)和微(wei)波(bo)(bo)(bo)(bo)燒(shao)烤型(xing)；按(an)控(kong)制(zhi)類(lei)型(xing)分(fen)為(wei)機械型(xing)和微(wei)電(dian)(dian)腦型(xing)。微(wei)波(bo)(bo)(bo)(bo)爐(lu)微(wei)波(bo)(bo)(bo)(bo)系統結構示意圖如(ru)右圖所示，其工作原理如(ru)下：控(kong)制(zhi)電(dian)(dian)路根據用戶設置的(de)火力，將AC220V電(dian)(dian)壓(ya)加到(dao)(dao)高壓(ya)變壓(ya)器的(de)初級，其次級輸出3V～4V和1800V～2230V兩組交(jiao)流(liu)(liu)電(dian)(dian)壓(ya)。3V～4V交(jiao)流(liu)(liu)電(dian)(dian)壓(ya)直接(jie)給(gei)磁控(kong)管燈絲供電(dian)(dian)；1800V～2230V交(jiao)流(liu)(liu)電(dian)(dian)壓(ya)經(jing)高壓(ya)電(dian)(dian)容、高壓(ya)二極(ji)管倍(bei)壓(ya)整流(liu)(liu)濾波(bo)(bo)(bo)(bo)后，變為(wei)3600V～4500V的(de)負直流(liu)(liu)電(dian)(dian)壓(ya)，加到(dao)(dao)磁控(kong)管陰極(ji)。當磁控(kong)管具備燈絲電(dian)(dian)壓(ya)，且陽極(ji)（接(jie)地）與陰極(ji)之(zhi)間(jian)的(de)電(dian)(dian)壓(ya)差大(da)于3500V時，就產(chan)生2450MHz超高頻電(dian)(dian)磁波(bo)(bo)(bo)(bo)，即微(wei)波(bo)(bo)(bo)(bo)，快(kuai)速震動食(shi)(shi)品內(nei)的(de)蛋白質、脂類(lei)、糖類(lei)及水等物質的(de)分(fen)子，使之(zhi)相(xiang)互碰(peng)撞、擠壓(ya)、摩擦(ca)(ca)，重新排列(lie)組合。簡而言之(zhi)，微(wei)波(bo)(bo)(bo)(bo)爐(lu)是靠食(shi)(shi)品內(nei)部的(de)摩擦(ca)(ca)生熱來(lai)進行(xing)烹(peng)調(diao)的(de)。

磁控(kong)(kong)(kong)管發(fa)射(she)微(wei)波(bo)的(de)(de)強度（即功(gong)(gong)率(lv)(lv)）與陰陽極(ji)電(dian)壓(ya)(ya)(ya)差及發(fa)射(she)時(shi)(shi)(shi)間(jian)成(cheng)正(zheng)比(bi)。實(shi)際上，工廠是通過高(gao)(gao)壓(ya)(ya)(ya)變壓(ya)(ya)(ya)器(qi)的(de)(de)高(gao)(gao)壓(ya)(ya)(ya)輸(shu)出(chu)(chu)(chu)值來(lai)設計微(wei)波(bo)的(de)(de)額定(ding)輸(shu)出(chu)(chu)(chu)功(gong)(gong)率(lv)(lv)的(de)(de)。用戶設置火力(li)，就是改(gai)變控(kong)(kong)(kong)制電(dian)路給高(gao)(gao)壓(ya)(ya)(ya)變壓(ya)(ya)(ya)器(qi)提供(gong)(gong)AC220V電(dian)源的(de)(de)時(shi)(shi)(shi)間(jian)，從而控(kong)(kong)(kong)制了(le)烹調時(shi)(shi)(shi)微(wei)波(bo)爐的(de)(de)實(shi)際輸(shu)出(chu)(chu)(chu)功(gong)(gong)率(lv)(lv)。在(zai)最高(gao)(gao)火力(li)擋時(shi)(shi)(shi)，控(kong)(kong)(kong)制電(dian)路始終給高(gao)(gao)壓(ya)(ya)(ya)變壓(ya)(ya)(ya)器(qi)初級(ji)供(gong)(gong)電(dian)，磁控(kong)(kong)(kong)管連續發(fa)射(she)微(wei)波(bo)，此時(shi)(shi)(shi)輸(shu)出(chu)(chu)(chu)功(gong)(gong)率(lv)(lv)最大；而在(zai)非最高(gao)(gao)火力(li)時(shi)(shi)(shi)，控(kong)(kong)(kong)制電(dian)路則以30s為一(yi)個周期，間(jian)歇性給高(gao)(gao)壓(ya)(ya)(ya)變壓(ya)(ya)(ya)器(qi)初級(ji)供(gong)(gong)電(dian)，使磁控(kong)(kong)(kong)管間(jian)歇性發(fa)射(she)微(wei)波(bo)，微(wei)波(bo)爐平均輸(shu)出(chu)(chu)(chu)功(gong)(gong)率(lv)(lv)將低于最大功(gong)(gong)率(lv)(lv)。　　電(dian)路原理簡析(xi)

機械式微波爐的電(dian)控部(bu)(bu)分(fen)(fen)主(zhu)要(yao)由(you)四部(bu)(bu)分(fen)(fen)組成(cheng)，一(yi)是市電(dian)供給部(bu)(bu)分(fen)(fen)，由(you)電(dian)源插頭，市電(dian)保險絲FUSE，開關(guan)和電(dian)線等(deng)組成(cheng)；二是升壓(ya)(ya)部(bu)(bu)分(fen)(fen)，主(zhu)要(yao)由(you)升壓(ya)(ya)變壓(ya)(ya)器T組成(cheng)；三是整流(liu)部(bu)(bu)分(fen)(fen)，由(you)高(gao)壓(ya)(ya)保險絲H.V．FUSE，高(gao)壓(ya)(ya)二極管D，高(gao)壓(ya)(ya)電(dian)容器C等(deng)組成(cheng)；四是微波(bo)產生部(bu)(bu)分(fen)(fen)，主(zhu)要(yao)由(you)磁控管和波(bo)導裝置組成(cheng)，如上圖所示。

在該電路中(zhong)一(yi)共(gong)有以下三(san)個電流回路：

一是(shi)(shi)市電回(hui)(hui)路(lu)(lu)，220V交(jiao)流(liu)電經(jing)保(bao)險絲(si)、電機、升壓變壓器(qi)初級(ji)后(hou)流(liu)回(hui)(hui)插座(zuo)。二(er)是(shi)(shi)燈(deng)絲(si)回(hui)(hui)路(lu)(lu)，升壓變壓器(qi)的一個(ge)次級(ji)繞組(zu)輸出約(yue)3V交(jiao)流(liu)電，供給(gei)磁(ci)控管燈(deng)絲(si)。只有燈(deng)絲(si)加熱陰極，陰極才能發(fa)射電子(zi)。上面兩個(ge)回(hui)(hui)路(lu)(lu)流(liu)的是(shi)(shi)交(jiao)流(liu)電。第(di)三個(ge)回(hui)(hui)路(lu)(lu)是(shi)(shi)高(gao)壓回(hui)(hui)路(lu)(lu)，流(liu)的是(shi)(shi)高(gao)頻高(gao)壓脈動直(zhi)流(liu)電。

1、220V市電回路

當關上(shang)爐門(men)后(hou)，定(ding)時(shi)器(qi)打(da)開(kai)。S3被下(xia)門(men)鉤推開(kai)，呈開(kai)路(lu)狀態(tai)，在電(dian)(dian)路(lu)里(li)(li)不起作用(yong)，此時(shi)市電(dian)(dian)電(dian)(dian)路(lu)中的電(dian)(dian)流(liu)如(ru)下(xia)圖所示，干路(lu)電(dian)(dian)流(liu)標為(wei)I，各并聯(lian)(lian)支(zhi)路(lu)里(li)(li)電(dian)(dian)流(liu)標為(wei)i。干路(lu)里(li)(li)電(dian)(dian)流(liu)I回(hui)路(lu)如(ru)下(xia)：電(dian)(dian)源(yuan)L→FUSE→第(di)一閂鎖開(kai)關Sl→定(ding)時(shi)開(kai)關S4→五個(ge)并聯(lian)(lian)支(zhi)路(lu)(iL、il-i4)→第(di)二閂鎖開(kai)關S2→熱繼電(dian)(dian)器(qi)S6→回(hui)到電(dian)(dian)源(yuan)線N，則電(dian)(dian)流(liu)I=il,+il+i2+i3+i4。

【提示】（1）上(shang)述五個支(zhi)路里(li)任一(yi)個短路，總電流就會(hui)增(zeng)大，從而出(chu)現燒保險管(guan)故障。其中(zhong)，變(bian)壓器短路尤為常見。（2）在(zai)此(ci)電路中(zhong)，干(gan)路上(shang)的元器件的連(lian)接多(duo)采用接插件，只要(yao)有(you)一(yi)處斷(duan)開，總電流就為0，微波爐不工作。