【微波(bo)爐原(yuan)理】微波(bo)爐的(de)工作原(yuan)理圖解 微波(bo)爐的(de)電路圖分析

微波爐按功(gong)能分(fen)為(wei)微波(bo)加熱(re)型(xing)和微波(bo)燒烤型(xing)；按控(kong)制類型(xing)分(fen)為(wei)機械型(xing)和微電(dian)(dian)(dian)腦型(xing)。微波(bo)爐微波(bo)系統結構示(shi)意圖如(ru)右圖所示(shi)，其(qi)工作原理如(ru)下：控(kong)制電(dian)(dian)(dian)路(lu)根據用戶設(she)置的(de)(de)火(huo)力，將AC220V電(dian)(dian)(dian)壓(ya)(ya)加到高壓(ya)(ya)變(bian)(bian)壓(ya)(ya)器(qi)的(de)(de)初級，其(qi)次級輸出3V～4V和1800V～2230V兩(liang)組(zu)交(jiao)流(liu)(liu)電(dian)(dian)(dian)壓(ya)(ya)。3V～4V交(jiao)流(liu)(liu)電(dian)(dian)(dian)壓(ya)(ya)直接給磁(ci)(ci)(ci)控(kong)管(guan)燈(deng)絲供電(dian)(dian)(dian)；1800V～2230V交(jiao)流(liu)(liu)電(dian)(dian)(dian)壓(ya)(ya)經(jing)高壓(ya)(ya)電(dian)(dian)(dian)容、高壓(ya)(ya)二極(ji)管(guan)倍(bei)壓(ya)(ya)整流(liu)(liu)濾波(bo)后，變(bian)(bian)為(wei)3600V～4500V的(de)(de)負直流(liu)(liu)電(dian)(dian)(dian)壓(ya)(ya)，加到磁(ci)(ci)(ci)控(kong)管(guan)陰極(ji)。當磁(ci)(ci)(ci)控(kong)管(guan)具備燈(deng)絲電(dian)(dian)(dian)壓(ya)(ya)，且(qie)陽極(ji)（接地）與陰極(ji)之間的(de)(de)電(dian)(dian)(dian)壓(ya)(ya)差大于3500V時，就(jiu)產生(sheng)2450MHz超高頻電(dian)(dian)(dian)磁(ci)(ci)(ci)波(bo)，即微波(bo)，快(kuai)速(su)震動食品內的(de)(de)蛋白(bai)質(zhi)(zhi)、脂(zhi)類、糖類及水等(deng)物質(zhi)(zhi)的(de)(de)分(fen)子(zi)，使之相互碰撞、擠壓(ya)(ya)、摩擦(ca)，重新排列組(zu)合。簡(jian)而言之，微波(bo)爐是靠食品內部(bu)的(de)(de)摩擦(ca)生(sheng)熱(re)來進行(xing)烹調的(de)(de)。

磁(ci)控(kong)(kong)管(guan)發射(she)微(wei)波(bo)的(de)強度（即功率(lv)）與陰(yin)陽極(ji)電(dian)(dian)(dian)壓(ya)差及發射(she)時(shi)間(jian)成(cheng)正(zheng)比。實(shi)(shi)際上，工廠是通過高(gao)(gao)壓(ya)變(bian)(bian)壓(ya)器的(de)高(gao)(gao)壓(ya)輸(shu)(shu)出(chu)(chu)值來設計(ji)微(wei)波(bo)的(de)額(e)定輸(shu)(shu)出(chu)(chu)功率(lv)的(de)。用戶設置火力(li)，就是改變(bian)(bian)控(kong)(kong)制(zhi)電(dian)(dian)(dian)路(lu)(lu)給(gei)高(gao)(gao)壓(ya)變(bian)(bian)壓(ya)器提(ti)供AC220V電(dian)(dian)(dian)源的(de)時(shi)間(jian)，從而控(kong)(kong)制(zhi)了烹(peng)調時(shi)微(wei)波(bo)爐的(de)實(shi)(shi)際輸(shu)(shu)出(chu)(chu)功率(lv)。在(zai)最(zui)高(gao)(gao)火力(li)擋時(shi)，控(kong)(kong)制(zhi)電(dian)(dian)(dian)路(lu)(lu)始終給(gei)高(gao)(gao)壓(ya)變(bian)(bian)壓(ya)器初級供電(dian)(dian)(dian)，磁(ci)控(kong)(kong)管(guan)連(lian)續(xu)發射(she)微(wei)波(bo)，此時(shi)輸(shu)(shu)出(chu)(chu)功率(lv)最(zui)大；而在(zai)非(fei)最(zui)高(gao)(gao)火力(li)時(shi)，控(kong)(kong)制(zhi)電(dian)(dian)(dian)路(lu)(lu)則以30s為一個周(zhou)期，間(jian)歇性(xing)給(gei)高(gao)(gao)壓(ya)變(bian)(bian)壓(ya)器初級供電(dian)(dian)(dian)，使磁(ci)控(kong)(kong)管(guan)間(jian)歇性(xing)發射(she)微(wei)波(bo)，微(wei)波(bo)爐平均輸(shu)(shu)出(chu)(chu)功率(lv)將低于最(zui)大功率(lv)。　　電(dian)(dian)(dian)路(lu)(lu)原理(li)簡(jian)析

機械式微波爐的電(dian)控(kong)(kong)部(bu)(bu)分(fen)主要由(you)(you)四部(bu)(bu)分(fen)組(zu)成，一是(shi)(shi)(shi)市電(dian)供給部(bu)(bu)分(fen)，由(you)(you)電(dian)源插(cha)頭(tou)，市電(dian)保(bao)險(xian)絲(si)FUSE，開關(guan)和電(dian)線(xian)等組(zu)成；二(er)是(shi)(shi)(shi)升(sheng)壓(ya)(ya)部(bu)(bu)分(fen)，主要由(you)(you)升(sheng)壓(ya)(ya)變(bian)壓(ya)(ya)器T組(zu)成；三是(shi)(shi)(shi)整流部(bu)(bu)分(fen)，由(you)(you)高壓(ya)(ya)保(bao)險(xian)絲(si)H.V．FUSE，高壓(ya)(ya)二(er)極管D，高壓(ya)(ya)電(dian)容(rong)器C等組(zu)成；四是(shi)(shi)(shi)微波(bo)產生部(bu)(bu)分(fen)，主要由(you)(you)磁控(kong)(kong)管和波(bo)導(dao)裝(zhuang)置組(zu)成，如上圖(tu)所示。

在該電路(lu)中一(yi)共有以(yi)下(xia)三個電流回路(lu)：

一(yi)是市(shi)電(dian)(dian)(dian)(dian)回路(lu)，220V交(jiao)流(liu)電(dian)(dian)(dian)(dian)經保險(xian)絲、電(dian)(dian)(dian)(dian)機、升壓變壓器初級(ji)(ji)后流(liu)回插座。二是燈絲回路(lu)，升壓變壓器的一(yi)個次級(ji)(ji)繞組(zu)輸出約(yue)3V交(jiao)流(liu)電(dian)(dian)(dian)(dian)，供(gong)給磁控管燈絲。只有燈絲加熱陰(yin)極(ji)，陰(yin)極(ji)才能發射電(dian)(dian)(dian)(dian)子。上面兩個回路(lu)流(liu)的是交(jiao)流(liu)電(dian)(dian)(dian)(dian)。第(di)三(san)個回路(lu)是高(gao)壓回路(lu)，流(liu)的是高(gao)頻高(gao)壓脈(mo)動直(zhi)流(liu)電(dian)(dian)(dian)(dian)。

1、220V市電回路

當關(guan)上爐門(men)后，定(ding)時器(qi)打開(kai)。S3被(bei)下門(men)鉤推開(kai)，呈(cheng)開(kai)路(lu)(lu)狀態(tai)，在電(dian)(dian)(dian)路(lu)(lu)里不起作用，此時市電(dian)(dian)(dian)電(dian)(dian)(dian)路(lu)(lu)中的電(dian)(dian)(dian)流如(ru)下圖所示，干路(lu)(lu)電(dian)(dian)(dian)流標為I，各并(bing)聯支路(lu)(lu)里電(dian)(dian)(dian)流標為i。干路(lu)(lu)里電(dian)(dian)(dian)流I回路(lu)(lu)如(ru)下：電(dian)(dian)(dian)源L→FUSE→第(di)一閂(shuan)鎖開(kai)關(guan)Sl→定(ding)時開(kai)關(guan)S4→五個并(bing)聯支路(lu)(lu)(iL、il-i4)→第(di)二閂(shuan)鎖開(kai)關(guan)S2→熱繼電(dian)(dian)(dian)器(qi)S6→回到電(dian)(dian)(dian)源線N，則電(dian)(dian)(dian)流I=il,+il+i2+i3+i4。

【提(ti)示】（1）上述(shu)五個(ge)支(zhi)路(lu)里(li)任一個(ge)短路(lu)，總電流就會增(zeng)大，從而出現燒保險(xian)管故障(zhang)。其中(zhong)，變壓器短路(lu)尤為常見。（2）在此(ci)電路(lu)中(zhong)，干路(lu)上的元器件的連接多采用接插件，只要有一處斷開，總電流就為0，微波爐不工作(zuo)。