【微波爐(lu)原理】微波爐(lu)的(de)工作原理圖解 微波爐(lu)的(de)電路圖分析

微波爐按功(gong)能分為微(wei)(wei)波(bo)加(jia)熱(re)型(xing)和微(wei)(wei)波(bo)燒烤型(xing)；按控(kong)(kong)制類(lei)型(xing)分為機械(xie)型(xing)和微(wei)(wei)電(dian)(dian)(dian)腦型(xing)。微(wei)(wei)波(bo)爐(lu)微(wei)(wei)波(bo)系統結構示意圖如(ru)右(you)圖所示，其工作原理如(ru)下：控(kong)(kong)制電(dian)(dian)(dian)路根據用戶設置的(de)火力，將AC220V電(dian)(dian)(dian)壓(ya)(ya)(ya)加(jia)到高壓(ya)(ya)(ya)變(bian)壓(ya)(ya)(ya)器(qi)的(de)初級(ji)，其次(ci)級(ji)輸出3V～4V和1800V～2230V兩組(zu)交(jiao)流(liu)(liu)電(dian)(dian)(dian)壓(ya)(ya)(ya)。3V～4V交(jiao)流(liu)(liu)電(dian)(dian)(dian)壓(ya)(ya)(ya)直(zhi)接給磁控(kong)(kong)管(guan)燈絲供電(dian)(dian)(dian)；1800V～2230V交(jiao)流(liu)(liu)電(dian)(dian)(dian)壓(ya)(ya)(ya)經高壓(ya)(ya)(ya)電(dian)(dian)(dian)容、高壓(ya)(ya)(ya)二極(ji)(ji)管(guan)倍(bei)壓(ya)(ya)(ya)整流(liu)(liu)濾波(bo)后，變(bian)為3600V～4500V的(de)負直(zhi)流(liu)(liu)電(dian)(dian)(dian)壓(ya)(ya)(ya)，加(jia)到磁控(kong)(kong)管(guan)陰極(ji)(ji)。當(dang)磁控(kong)(kong)管(guan)具備(bei)燈絲電(dian)(dian)(dian)壓(ya)(ya)(ya)，且陽極(ji)(ji)（接地）與陰極(ji)(ji)之(zhi)間的(de)電(dian)(dian)(dian)壓(ya)(ya)(ya)差大于3500V時，就產生(sheng)2450MHz超高頻電(dian)(dian)(dian)磁波(bo)，即(ji)微(wei)(wei)波(bo)，快速震動食品內的(de)蛋白質、脂類(lei)、糖類(lei)及水等(deng)物(wu)質的(de)分子，使(shi)之(zhi)相互碰撞、擠壓(ya)(ya)(ya)、摩(mo)擦，重新排列(lie)組(zu)合。簡而言之(zhi)，微(wei)(wei)波(bo)爐(lu)是靠(kao)食品內部的(de)摩(mo)擦生(sheng)熱(re)來進行烹調的(de)。

磁控(kong)(kong)(kong)管(guan)發(fa)射(she)微波的(de)強度（即功(gong)(gong)(gong)率(lv)(lv)）與陰陽極電(dian)(dian)壓差及發(fa)射(she)時間(jian)成正比(bi)。實際(ji)上，工(gong)廠(chang)是通(tong)過高(gao)壓變(bian)(bian)壓器(qi)(qi)的(de)高(gao)壓輸(shu)(shu)(shu)出(chu)值來設(she)計微波的(de)額(e)定(ding)輸(shu)(shu)(shu)出(chu)功(gong)(gong)(gong)率(lv)(lv)的(de)。用戶設(she)置火力(li)，就(jiu)是改(gai)變(bian)(bian)控(kong)(kong)(kong)制(zhi)電(dian)(dian)路(lu)(lu)給(gei)高(gao)壓變(bian)(bian)壓器(qi)(qi)提供AC220V電(dian)(dian)源(yuan)的(de)時間(jian)，從而控(kong)(kong)(kong)制(zhi)了烹調時微波爐的(de)實際(ji)輸(shu)(shu)(shu)出(chu)功(gong)(gong)(gong)率(lv)(lv)。在最(zui)高(gao)火力(li)擋(dang)時，控(kong)(kong)(kong)制(zhi)電(dian)(dian)路(lu)(lu)始終(zhong)給(gei)高(gao)壓變(bian)(bian)壓器(qi)(qi)初級供電(dian)(dian)，磁控(kong)(kong)(kong)管(guan)連續發(fa)射(she)微波，此時輸(shu)(shu)(shu)出(chu)功(gong)(gong)(gong)率(lv)(lv)最(zui)大(da)；而在非最(zui)高(gao)火力(li)時，控(kong)(kong)(kong)制(zhi)電(dian)(dian)路(lu)(lu)則以30s為一個周期，間(jian)歇性給(gei)高(gao)壓變(bian)(bian)壓器(qi)(qi)初級供電(dian)(dian)，使磁控(kong)(kong)(kong)管(guan)間(jian)歇性發(fa)射(she)微波，微波爐平(ping)均(jun)輸(shu)(shu)(shu)出(chu)功(gong)(gong)(gong)率(lv)(lv)將低于最(zui)大(da)功(gong)(gong)(gong)率(lv)(lv)。　　電(dian)(dian)路(lu)(lu)原(yuan)理簡析

機械式微波爐的(de)電(dian)(dian)(dian)控部分主(zhu)(zhu)(zhu)要(yao)由(you)(you)四(si)(si)部分組(zu)(zu)成，一是市(shi)電(dian)(dian)(dian)供給部分，由(you)(you)電(dian)(dian)(dian)源(yuan)插頭，市(shi)電(dian)(dian)(dian)保(bao)險絲FUSE，開(kai)關(guan)和電(dian)(dian)(dian)線等組(zu)(zu)成；二(er)是升壓部分，主(zhu)(zhu)(zhu)要(yao)由(you)(you)升壓變壓器T組(zu)(zu)成；三是整流部分，由(you)(you)高(gao)(gao)壓保(bao)險絲H.V．FUSE，高(gao)(gao)壓二(er)極管D，高(gao)(gao)壓電(dian)(dian)(dian)容器C等組(zu)(zu)成；四(si)(si)是微波產生部分，主(zhu)(zhu)(zhu)要(yao)由(you)(you)磁控管和波導裝(zhuang)置組(zu)(zu)成，如上圖所示。

在該電路(lu)中一共有以下三(san)個電流回路(lu)：

一是市電(dian)(dian)回(hui)路，220V交流電(dian)(dian)經保險絲(si)(si)、電(dian)(dian)機、升(sheng)壓(ya)(ya)變(bian)壓(ya)(ya)器(qi)初(chu)級后流回(hui)插座。二(er)是燈(deng)絲(si)(si)回(hui)路，升(sheng)壓(ya)(ya)變(bian)壓(ya)(ya)器(qi)的一個(ge)次級繞組輸出約3V交流電(dian)(dian)，供給磁(ci)控管(guan)燈(deng)絲(si)(si)。只(zhi)有(you)燈(deng)絲(si)(si)加熱陰(yin)極，陰(yin)極才能發射電(dian)(dian)子。上面兩(liang)個(ge)回(hui)路流的是交流電(dian)(dian)。第三個(ge)回(hui)路是高壓(ya)(ya)回(hui)路，流的是高頻高壓(ya)(ya)脈(mo)動直流電(dian)(dian)。

1、220V市電回路

當關上(shang)爐門(men)后，定(ding)時器打(da)開(kai)。S3被下(xia)門(men)鉤推(tui)開(kai)，呈開(kai)路(lu)狀態(tai)，在電(dian)(dian)路(lu)里(li)不起(qi)作用(yong)，此時市電(dian)(dian)電(dian)(dian)路(lu)中(zhong)的電(dian)(dian)流(liu)(liu)(liu)(liu)如下(xia)圖所示，干路(lu)電(dian)(dian)流(liu)(liu)(liu)(liu)標(biao)為I，各并聯(lian)支路(lu)里(li)電(dian)(dian)流(liu)(liu)(liu)(liu)標(biao)為i。干路(lu)里(li)電(dian)(dian)流(liu)(liu)(liu)(liu)I回路(lu)如下(xia)：電(dian)(dian)源(yuan)L→FUSE→第一(yi)閂鎖開(kai)關Sl→定(ding)時開(kai)關S4→五個并聯(lian)支路(lu)(iL、il-i4)→第二閂鎖開(kai)關S2→熱繼電(dian)(dian)器S6→回到電(dian)(dian)源(yuan)線N，則電(dian)(dian)流(liu)(liu)(liu)(liu)I=il,+il+i2+i3+i4。

【提示】（1）上述(shu)五個支路(lu)(lu)(lu)(lu)里任一個短(duan)路(lu)(lu)(lu)(lu)，總電流就會(hui)增大(da)，從(cong)而出(chu)現(xian)燒保(bao)險管故障。其中(zhong)，變壓器(qi)短(duan)路(lu)(lu)(lu)(lu)尤為(wei)常(chang)見。（2）在此(ci)電路(lu)(lu)(lu)(lu)中(zhong)，干路(lu)(lu)(lu)(lu)上的(de)元器(qi)件的(de)連接(jie)多采(cai)用接(jie)插件，只(zhi)要有一處斷開，總電流就為(wei)0，微波爐(lu)不工(gong)作(zuo)。