電磁灶常見調試功率方法
一、間隙加熱法
間(jian)隙施(shi)加(jia)激(ji)勵脈(mo)沖(chong),使(shi)電(dian)(dian)磁(ci)灶(zao)斷(duan)續加(jia)熱(re)(re),控制斷(duan)續加(jia)熱(re)(re)時間(jian)間(jian)隔來調(diao)節電(dian)(dian)磁(ci)灶(zao)的(de)功率(lv)。該(gai)方式電(dian)(dian)路簡(jian)單,但是有通斷(duan)時的(de)電(dian)(dian)磁(ci)噪(zao)聲出現并且對供電(dian)(dian)電(dian)(dian)源有電(dian)(dian)流沖(chong)擊(ji)。采用(yong)該(gai)調(diao)功方式要注意激(ji)勵脈(mo)沖(chong)的(de)關斷(duan)必須(xu)在電(dian)(dian)流過零時刻,否則(ze)關斷(duan)時鍋底的(de)電(dian)(dian)磁(ci)噪(zao)音(yin)較(jiao)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(chu)級(ji)抽頭,以分別獲得大、中、小、三擋功率(lv)(lv)。這種調功方(fang)式因(yin)為有接觸器的(de)存在,機(ji)芯體積較大,但(dan)是在大、中、小三擋功率(lv)(lv)時都可以用頻率(lv)(lv)跟蹤的(de)方(fang)法使功率(lv)(lv)管工(gong)作(zuo)在零電(dian)(dian)壓開關和零電(dian)(dian)流(liu)開關狀態(tai)。在所有調功方(fang)式中該(gai)方(fang)式的(de)功率(lv)(lv)管的(de)溫升最低,電(dian)(dian)磁灶的(de)熱效率(lv)(lv)高達(da)95%以上。
接觸(chu)器的接通與釋(shi)放必(bi)須先關斷激勵(li)脈沖,使之(zhi)在功(gong)率輸出級無電流的狀態下進行切換(huan)。
三、移相調脈寬法
電(dian)路中,若(ruo)變壓(ya)器(qi)沒有(you)(you)(you)抽頭,僅起到感應線圈(quan)與主電(dian)源的(de)(de)(de)隔離、與負(fu)載的(de)(de)(de)匹配作(zuo)用(yong)。T1、T2為(wei)左邊(bian)橋(qiao)(qiao)(qiao)臂(bei)(bei),T3、T4為(wei)右(you)邊(bian)橋(qiao)(qiao)(qiao)臂(bei)(bei)。T1、T2的(de)(de)(de)激勵脈沖(chong)反相并留有(you)(you)(you)足(zu)夠(gou)的(de)(de)(de)死(si)區時(shi)(shi)間,保證T1、T2不致(zhi)產生(sheng)共態導通。同(tong)理(li),T3、T4的(de)(de)(de)激勵脈沖(chong)反相并且也留有(you)(you)(you)足(zu)夠(gou)的(de)(de)(de)死(si)區時(shi)(shi)間。當左右(you)橋(qiao)(qiao)(qiao)臂(bei)(bei)的(de)(de)(de)激勵脈沖(chong)相位(wei)差(cha)從180°~0°變化時(shi)(shi),電(dian)磁(ci)灶(zao)的(de)(de)(de)功(gong)(gong)率(lv)從最大至(zhi)最小(xiao)連(lian)續平(ping)滑地變化,半邊(bian)橋(qiao)(qiao)(qiao)臂(bei)(bei)的(de)(de)(de)功(gong)(gong)率(lv)管實(shi)現(xian)零電(dian)壓(ya)開關;另外半邊(bian)橋(qiao)(qiao)(qiao)臂(bei)(bei)的(de)(de)(de)功(gong)(gong)率(lv)管實(shi)現(xian)零電(dian)流開關。實(shi)際使用(yong)移相調脈寬(kuan)法(fa)(fa)時(shi)(shi),因省(sheng)去了補償電(dian)感,當電(dian)磁(ci)灶(zao)功(gong)(gong)率(lv)較小(xiao)時(shi)(shi)超(chao)前橋(qiao)(qiao)(qiao)臂(bei)(bei)的(de)(de)(de)零電(dian)壓(ya)開關將會失準,因此在小(xiao)功(gong)(gong)率(lv)時(shi)(shi)宜(yi)改用(yong)間隙加熱的(de)(de)(de)方法(fa)(fa)來調節功(gong)(gong)率(lv)。
移相調脈寬法的缺點(dian)是(shi)IGBT管子中(zhong)的續流(liu)二(er)極管中(zhong)有(you)較大(da)的電流(liu)通(tong)過,功率管的工作狀態不如上述變壓器(qi)抽頭法來(lai)得好,其優點(dian)是(shi)可連續調節功率,省去了三只交流(liu)接觸器(qi)。
四、改變整流電壓法
三相整(zheng)(zheng)(zheng)流(liu)模塊(kuai)改(gai)用可(ke)控(kong)整(zheng)(zheng)(zheng)流(liu)模塊(kuai),用0-10V的(de)控(kong)制電(dian)壓(ya)(ya)(ya)改(gai)變(bian)可(ke)控(kong)整(zheng)(zheng)(zheng)流(liu)模塊(kuai)整(zheng)(zheng)(zheng)流(liu)后的(de)直流(liu)輸(shu)(shu)出(chu)電(dian)壓(ya)(ya)(ya)來改(gai)變(bian)電(dian)磁灶的(de)輸(shu)(shu)出(chu)功(gong)(gong)(gong)率。在額定(ding)(ding)輸(shu)(shu)入電(dian)壓(ya)(ya)(ya)下,整(zheng)(zheng)(zheng)流(liu)模塊(kuai)全(quan)導通(tong)(tong),獲得額定(ding)(ding)最大功(gong)(gong)(gong)率,在非額定(ding)(ding)最大功(gong)(gong)(gong)率下由于整(zheng)(zheng)(zheng)流(liu)輸(shu)(shu)出(chu)的(de)直流(liu)電(dian)壓(ya)(ya)(ya)下降(jiang),功(gong)(gong)(gong)率呈現出(chu)與電(dian)壓(ya)(ya)(ya)的(de)平方(fang)關系下降(jiang)。該調功(gong)(gong)(gong)方(fang)式的(de)優點(dian)是電(dian)路簡單,可(ke)連(lian)續調功(gong)(gong)(gong),在整(zheng)(zheng)(zheng)個調功(gong)(gong)(gong)范圍內(nei)均可(ke)實現頻率跟蹤。該電(dian)路缺點(dian)是調功(gong)(gong)(gong)時可(ke)控(kong)整(zheng)(zheng)(zheng)流(liu)模塊(kuai)沒有全(quan)導通(tong)(tong),有斬波(bo)(bo)缺口,對(dui)電(dian)磁兼容性(xing)指標(biao)影響較大。要使電(dian)磁兼容性(xing)指標(biao)過關,對(dui)電(dian)源濾(lv)波(bo)(bo)器和整(zheng)(zheng)(zheng)流(liu)濾(lv)波(bo)(bo)電(dian)路要求(qiu)較高,該部分的(de)元件數相對(dui)較多,整(zheng)(zheng)(zheng)機體(ti)積和成本增加。
五、調頻法
在(zai)(zai)最大功(gong)(gong)率(lv)時使電(dian)路(lu)(lu)工作(zuo)在(zai)(zai)近諧(xie)振狀(zhuang)態下,提高激勵脈沖頻率(lv),電(dian)路(lu)(lu)工作(zuo)在(zai)(zai)失諧(xie)狀(zhuang)態下,功(gong)(gong)率(lv)減小(xiao)。該方(fang)法(fa)的(de)(de)優(you)點是(shi)電(dian)路(lu)(lu)簡單,但是(shi)當電(dian)磁灶輸出功(gong)(gong)率(lv)較(jiao)大時若(ruo)發生調功(gong)(gong),電(dian)流(liu)(liu)相位(wei)(wei)滯(zhi)后電(dian)壓相位(wei)(wei)較(jiao)大,在(zai)(zai)較(jiao)大電(dian)流(liu)(liu)的(de)(de)狀(zhuang)態下關(guan)斷,功(gong)(gong)率(lv)管管耗較(jiao)大,這樣,即使散熱器上的(de)(de)溫升并沒有(you)明顯(xian)升高,也有(you)可(ke)能(neng)管芯(xin)已過熱而(er)損壞ICBT功(gong)(gong)率(lv)模塊,因此在(zai)(zai)8kW以上的(de)(de)功(gong)(gong)率(lv)時不(bu)宜采用該方(fang)法(fa)調功(gong)(gong)。
六、變壓器初級抽頭切換、調頻、調壓法
通過變壓器初級(ji)抽頭的(de)切換來(lai)獲得大、中(zhong)、小(xiao)三(san)擋(dang)功(gong)(gong)(gong)(gong)率(lv),由于脈(mo)沖功(gong)(gong)(gong)(gong)率(lv)輸(shu)出(chu)(chu)變壓器的(de)使(shi)(shi)用(yong),使(shi)(shi)得功(gong)(gong)(gong)(gong)率(lv)輸(shu)出(chu)(chu)級(ji)與(yu)負載匹配良好,功(gong)(gong)(gong)(gong)率(lv)級(ji)能工作(zuo)在(zai)(zai)最(zui)佳狀(zhuang)(zhuang)態(tai)。在(zai)(zai)大、中(zhong)、小(xiao)三(san)擋(dang)功(gong)(gong)(gong)(gong)率(lv)處用(yong)頻 率(lv)跟蹤的(de)方(fang)(fang)(fang)法(fa)(fa)使(shi)(shi)功(gong)(gong)(gong)(gong)率(lv)管(guan)工作(zuo)在(zai)(zai)零(ling)(ling)電壓開關和(he)(he)零(ling)(ling)電流(liu)(liu)開關狀(zhuang)(zhuang)態(tai)下(xia)。在(zai)(zai)小(xiao)擋(dang)到中(zhong)擋(dang)、中(zhong)擋(dang)到大擋(dang)調(diao)功(gong)(gong)(gong)(gong)范(fan)圍內再(zai)用(yong)微(wei)調(diao)激勵脈(mo)沖頻率(lv)的(de)方(fang)(fang)(fang)法(fa)(fa)來(lai)連(lian)續調(diao)節功(gong)(gong)(gong)(gong)率(lv),此時功(gong)(gong)(gong)(gong)率(lv)管(guan)工作(zuo)在(zai)(zai)零(ling)(ling)電壓開關和(he)(he) 零(ling)(ling)電流(liu)(liu)開通,近似(si)零(ling)(ling)電流(liu)(liu)關斷狀(zhuang)(zhuang)態(tai)下(xia)。在(zai)(zai)小(xiao)擋(dang)到零(ling)(ling)功(gong)(gong)(gong)(gong)率(lv)范(fan)圍內用(yong)調(diao)頻的(de)方(fang)(fang)(fang)法(fa)(fa)會(hui)破壞功(gong)(gong)(gong)(gong)率(lv)管(guan)零(ling)(ling)電壓開關的(de)狀(zhuang)(zhuang)態(tai),則采用(yong)調(diao)節輸(shu)出(chu)(chu)整流(liu)(liu)電壓的(de)方(fang)(fang)(fang)法(fa)(fa)來(lai)調(diao)節功(gong)(gong)(gong)(gong)率(lv)。
這種調功(gong)方式相對較為復雜,成本也高(gao),其突出優點是調功(gong)范圍大、功(gong)率(lv)輸出級與(yu)負載匹配良好(hao)、電磁灶在(zai)8kW功(gong)率(lv)時(shi)散熱器溫升不(bu)超過6℃(在(zai)25℃的環(huan)境溫度下(xia)測試)。
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