電磁灶常見調試功率方法
一、間隙加熱法
間(jian)隙施加(jia)激(ji)勵(li)脈(mo)沖,使電(dian)(dian)磁灶斷(duan)續加(jia)熱,控制斷(duan)續加(jia)熱時(shi)間(jian)間(jian)隔來調節電(dian)(dian)磁灶的(de)(de)功(gong)率(lv)。該方(fang)式(shi)電(dian)(dian)路簡單(dan),但是(shi)有(you)(you)通斷(duan)時(shi)的(de)(de)電(dian)(dian)磁噪聲出(chu)現(xian)并且對(dui)供電(dian)(dian)電(dian)(dian)源(yuan)有(you)(you)電(dian)(dian)流沖擊。采用該調功(gong)方(fang)式(shi)要注意激(ji)勵(li)脈(mo)沖的(de)(de)關斷(duan)必須在(zai)電(dian)(dian)流過(guo)零時(shi)刻,否則關斷(duan)時(shi)鍋底的(de)(de)電(dian)(dian)磁噪音(yin)較大。
二、脈沖功率輸出變壓器初級抽頭切換法
可通過控制電路分別接通三只交流接觸器的常開觸點J1-1、J2-1、J3-1,來接通脈沖功率輸出變壓器初級抽頭,以分別(bie)獲得(de)大、中(zhong)、小、三擋功(gong)(gong)(gong)率(lv)(lv)。這種調功(gong)(gong)(gong)方式(shi)因為有接觸器(qi)的存(cun)在(zai),機芯體積較大,但是在(zai)大、中(zhong)、小三擋功(gong)(gong)(gong)率(lv)(lv)時都可以用(yong)頻率(lv)(lv)跟蹤的方法使功(gong)(gong)(gong)率(lv)(lv)管工作在(zai)零電壓開(kai)關和零電流開(kai)關狀態。在(zai)所有調功(gong)(gong)(gong)方式(shi)中(zhong)該方式(shi)的功(gong)(gong)(gong)率(lv)(lv)管的溫升最低(di),電磁(ci)灶的熱效率(lv)(lv)高達95%以上。
接觸器(qi)的接通與釋(shi)放必須(xu)先關(guan)斷激勵脈(mo)沖,使之在功率(lv)輸出級無電流(liu)的狀態下進行切換(huan)。
三、移相調脈寬法
電(dian)(dian)路中,若(ruo)變(bian)壓器沒有(you)抽頭(tou),僅起到感(gan)應(ying)線圈與(yu)主電(dian)(dian)源(yuan)的(de)(de)(de)隔離(li)、與(yu)負載(zai)的(de)(de)(de)匹配作用。T1、T2為左邊(bian)橋(qiao)臂,T3、T4為右邊(bian)橋(qiao)臂。T1、T2的(de)(de)(de)激勵脈沖(chong)反相(xiang)并(bing)留(liu)(liu)有(you)足(zu)夠(gou)的(de)(de)(de)死區(qu)時(shi)間(jian),保證T1、T2不致產生共態導通。同理,T3、T4的(de)(de)(de)激勵脈沖(chong)反相(xiang)并(bing)且也(ye)留(liu)(liu)有(you)足(zu)夠(gou)的(de)(de)(de)死區(qu)時(shi)間(jian)。當左右橋(qiao)臂的(de)(de)(de)激勵脈沖(chong)相(xiang)位差從(cong)180°~0°變(bian)化時(shi),電(dian)(dian)磁灶(zao)的(de)(de)(de)功(gong)(gong)率從(cong)最大至最小(xiao)連續平滑地變(bian)化,半邊(bian)橋(qiao)臂的(de)(de)(de)功(gong)(gong)率管實現零電(dian)(dian)壓開(kai)關;另外半邊(bian)橋(qiao)臂的(de)(de)(de)功(gong)(gong)率管實現零電(dian)(dian)流開(kai)關。實際使用移相(xiang)調(diao)脈寬法(fa)時(shi),因省(sheng)去了補(bu)償電(dian)(dian)感(gan),當電(dian)(dian)磁灶(zao)功(gong)(gong)率較小(xiao)時(shi)超前橋(qiao)臂的(de)(de)(de)零電(dian)(dian)壓開(kai)關將會失(shi)準,因此在小(xiao)功(gong)(gong)率時(shi)宜改用間(jian)隙加熱(re)的(de)(de)(de)方法(fa)來調(diao)節功(gong)(gong)率。
移(yi)相調脈寬法的(de)(de)缺點(dian)是IGBT管子(zi)中的(de)(de)續流二極管中有較大的(de)(de)電流通過,功率管的(de)(de)工(gong)作狀態不如上(shang)述(shu)變(bian)壓器抽頭法來得好,其優點(dian)是可連續調節功率,省去了三只交(jiao)流接觸器。
四、改變整流電壓法
三相(xiang)整流(liu)(liu)模塊改(gai)(gai)用可(ke)控整流(liu)(liu)模塊,用0-10V的(de)(de)控制電(dian)壓(ya)改(gai)(gai)變(bian)(bian)可(ke)控整流(liu)(liu)模塊整流(liu)(liu)后的(de)(de)直(zhi)流(liu)(liu)輸出(chu)電(dian)壓(ya)來改(gai)(gai)變(bian)(bian)電(dian)磁灶的(de)(de)輸出(chu)功(gong)(gong)率(lv)(lv)。在額定(ding)(ding)輸入(ru)電(dian)壓(ya)下(xia)(xia),整流(liu)(liu)模塊全導通,獲得(de)額定(ding)(ding)最(zui)大功(gong)(gong)率(lv)(lv),在非額定(ding)(ding)最(zui)大功(gong)(gong)率(lv)(lv)下(xia)(xia)由于整流(liu)(liu)輸出(chu)的(de)(de)直(zhi)流(liu)(liu)電(dian)壓(ya)下(xia)(xia)降,功(gong)(gong)率(lv)(lv)呈現出(chu)與電(dian)壓(ya)的(de)(de)平方關系(xi)下(xia)(xia)降。該調(diao)功(gong)(gong)方式的(de)(de)優(you)點是電(dian)路(lu)簡單,可(ke)連續調(diao)功(gong)(gong),在整個調(diao)功(gong)(gong)范(fan)圍內均可(ke)實現頻率(lv)(lv)跟(gen)蹤。該電(dian)路(lu)缺點是調(diao)功(gong)(gong)時可(ke)控整流(liu)(liu)模塊沒(mei)有全導通,有斬(zhan)波缺口,對電(dian)磁兼容性指(zhi)標(biao)影響較(jiao)大。要使電(dian)磁兼容性指(zhi)標(biao)過關,對電(dian)源濾波器和(he)整流(liu)(liu)濾波電(dian)路(lu)要求較(jiao)高,該部分(fen)的(de)(de)元件數相(xiang)對較(jiao)多,整機體積和(he)成本增加。
五、調頻法
在(zai)(zai)最(zui)大功(gong)率(lv)(lv)時(shi)使(shi)(shi)電(dian)路(lu)工作(zuo)(zuo)在(zai)(zai)近諧振狀態(tai)下(xia)(xia),提高激勵脈沖頻(pin)率(lv)(lv),電(dian)路(lu)工作(zuo)(zuo)在(zai)(zai)失(shi)諧狀態(tai)下(xia)(xia),功(gong)率(lv)(lv)減(jian)小。該方法的(de)(de)優點是(shi)電(dian)路(lu)簡單(dan),但是(shi)當電(dian)磁灶輸出功(gong)率(lv)(lv)較(jiao)大時(shi)若發生(sheng)調(diao)(diao)功(gong),電(dian)流(liu)相(xiang)位(wei)滯后(hou)電(dian)壓相(xiang)位(wei)較(jiao)大,在(zai)(zai)較(jiao)大電(dian)流(liu)的(de)(de)狀態(tai)下(xia)(xia)關斷,功(gong)率(lv)(lv)管管耗較(jiao)大,這(zhe)樣,即使(shi)(shi)散(san)熱器上(shang)的(de)(de)溫升(sheng)并沒有明(ming)顯升(sheng)高,也(ye)有可(ke)能管芯(xin)已過熱而損(sun)壞ICBT功(gong)率(lv)(lv)模塊,因此在(zai)(zai)8kW以上(shang)的(de)(de)功(gong)率(lv)(lv)時(shi)不宜采用該方法調(diao)(diao)功(gong)。
六、變壓器初級抽頭切換、調頻、調壓法
通過變壓器初(chu)級(ji)(ji)抽頭的(de)(de)切換來獲(huo)得(de)大(da)、中(zhong)、小三(san)(san)擋功(gong)(gong)(gong)(gong)率(lv),由于(yu)脈沖功(gong)(gong)(gong)(gong)率(lv)輸(shu)出(chu)變壓(ya)(ya)器的(de)(de)使(shi)(shi)用(yong),使(shi)(shi)得(de)功(gong)(gong)(gong)(gong)率(lv)輸(shu)出(chu)級(ji)(ji)與(yu)負載匹配良好,功(gong)(gong)(gong)(gong)率(lv)級(ji)(ji)能工作在(zai)(zai)最佳狀(zhuang)態。在(zai)(zai)大(da)、中(zhong)、小三(san)(san)擋功(gong)(gong)(gong)(gong)率(lv)處用(yong)頻 率(lv)跟蹤的(de)(de)方法使(shi)(shi)功(gong)(gong)(gong)(gong)率(lv)管工作在(zai)(zai)零(ling)電(dian)壓(ya)(ya)開(kai)(kai)關和(he)(he)零(ling)電(dian)流開(kai)(kai)關狀(zhuang)態下。在(zai)(zai)小擋到(dao)中(zhong)擋、中(zhong)擋到(dao)大(da)擋調(diao)功(gong)(gong)(gong)(gong)范圍內再(zai)用(yong)微調(diao)激勵脈沖頻率(lv)的(de)(de)方法來連續調(diao)節功(gong)(gong)(gong)(gong)率(lv),此時功(gong)(gong)(gong)(gong)率(lv)管工作在(zai)(zai)零(ling)電(dian)壓(ya)(ya)開(kai)(kai)關和(he)(he) 零(ling)電(dian)流開(kai)(kai)通,近似(si)零(ling)電(dian)流關斷狀(zhuang)態下。在(zai)(zai)小擋到(dao)零(ling)功(gong)(gong)(gong)(gong)率(lv)范圍內用(yong)調(diao)頻的(de)(de)方法會破壞(huai)功(gong)(gong)(gong)(gong)率(lv)管零(ling)電(dian)壓(ya)(ya)開(kai)(kai)關的(de)(de)狀(zhuang)態,則采用(yong)調(diao)節輸(shu)出(chu)整流電(dian)壓(ya)(ya)的(de)(de)方法來調(diao)節功(gong)(gong)(gong)(gong)率(lv)。
這種調功(gong)方式(shi)相對較為復雜(za),成本也高(gao),其突出優點(dian)是調功(gong)范圍大、功(gong)率(lv)(lv)輸出級與負(fu)載匹(pi)配(pei)良好、電磁灶在(zai)8kW功(gong)率(lv)(lv)時散熱器溫升不超過6℃(在(zai)25℃的環境溫度(du)下測試)。
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