感(gan)應(ying)電動機又稱“異步(bu)電動機(asynchronousmotor)”,即轉(zhuan)子(zi)置于旋轉(zhuan)磁場中,在旋轉(zhuan)磁場的(de)作用下,獲得一個轉(zhuan)動力矩,因(yin)而轉(zhuan)子(zi)轉(zhuan)動。
轉(zhuan)(zhuan)(zhuan)子(zi)是(shi)可轉(zhuan)(zhuan)(zhuan)動(dong)的(de)導體,通常多呈鼠籠狀。定子(zi)是(shi)電(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)中不(bu)轉(zhuan)(zhuan)(zhuan)動(dong)的(de)部分,主要任務(wu)是(shi)產(chan)生一個旋轉(zhuan)(zhuan)(zhuan)磁場。旋轉(zhuan)(zhuan)(zhuan)磁場并不(bu)是(shi)用(yong)(yong)機(ji)(ji)(ji)(ji)(ji)械方法來實現(xian)。而是(shi)以交流電(dian)(dian)通于(yu)(yu)數對電(dian)(dian)磁鐵中,使(shi)其磁極(ji)性質循環改變,故相(xiang)當于(yu)(yu)一個旋轉(zhuan)(zhuan)(zhuan)的(de)磁場。這種電(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)并不(bu)像直流電(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)有(you)(you)電(dian)(dian)刷或集電(dian)(dian)環,依據所(suo)用(yong)(yong)交流電(dian)(dian)的(de)種類有(you)(you)單(dan)相(xiang)電(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)和(he)三相(xiang)電(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji),單(dan)相(xiang)電(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)用(yong)(yong)在如洗衣機(ji)(ji)(ji)(ji)(ji),電(dian)(dian)風(feng)扇等;三相(xiang)電(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)則作為工廠的(de)動(dong)力設備(bei)。
尼(ni)古拉·特斯(si)拉(Nikola Tesla,1856年(nian)(nian)7月10日~1943年(nian)(nian)1月7日),塞爾維亞裔美籍(ji)發明(ming)家、機(ji)械工(gong)程(cheng)師、電(dian)(dian)(dian)氣工(gong)程(cheng)師。他被認為(wei)(wei)是電(dian)(dian)(dian)力商業(ye)化的(de)(de)(de)重(zhong)要(yao)推動者之(zhi)一,并因(yin)主持(chi)設計了現(xian)代(dai)交流電(dian)(dian)(dian)系(xi)統(tong)而最為(wei)(wei)人知。在(zai)邁克爾·法拉第(di)發現(xian)的(de)(de)(de)電(dian)(dian)(dian)磁(ci)場(chang)(chang)理(li)論(lun)(lun)的(de)(de)(de)基礎上,特斯(si)拉在(zai)電(dian)(dian)(dian)磁(ci)場(chang)(chang)領域(yu)有著(zhu)多(duo)項(xiang)革命性的(de)(de)(de)發明(ming)。1887年(nian)(nian)發明(ming)感應電(dian)(dian)(dian)動機(ji),他的(de)(de)(de)多(duo)項(xiang)相關專(zhuan)利以及電(dian)(dian)(dian)磁(ci)學的(de)(de)(de)理(li)論(lun)(lun)研究工(gong)作是現(xian)代(dai)的(de)(de)(de)無(wu)(wu)線通(tong)信和(he)無(wu)(wu)線電(dian)(dian)(dian)的(de)(de)(de)基石。
通過(guo)定子(zi)產(chan)(chan)生的(de)(de)旋轉(zhuan)(zhuan)(zhuan)磁場(chang)(其轉(zhuan)(zhuan)(zhuan)速(su)為同(tong)步(bu)轉(zhuan)(zhuan)(zhuan)速(su)n1)與(yu)轉(zhuan)(zhuan)(zhuan)子(zi)繞組的(de)(de)相(xiang)對運動,轉(zhuan)(zhuan)(zhuan)子(zi)繞組切割磁感(gan)線產(chan)(chan)生感(gan)應(ying)電(dian)(dian)(dian)(dian)(dian)動勢(shi),從而(er)使(shi)轉(zhuan)(zhuan)(zhuan)子(zi)繞組中產(chan)(chan)生感(gan)應(ying)電(dian)(dian)(dian)(dian)(dian)流。轉(zhuan)(zhuan)(zhuan)子(zi)繞組中的(de)(de)感(gan)應(ying)電(dian)(dian)(dian)(dian)(dian)流與(yu)磁場(chang)作用,產(chan)(chan)生電(dian)(dian)(dian)(dian)(dian)磁轉(zhuan)(zhuan)(zhuan)矩,使(shi)轉(zhuan)(zhuan)(zhuan)子(zi)旋轉(zhuan)(zhuan)(zhuan)。由于(yu)當(dang)轉(zhuan)(zhuan)(zhuan)子(zi)轉(zhuan)(zhuan)(zhuan)速(su)逐漸接(jie)近同(tong)步(bu)轉(zhuan)(zhuan)(zhuan)速(su)時,感(gan)應(ying)電(dian)(dian)(dian)(dian)(dian)流逐漸減小(xiao),所產(chan)(chan)生的(de)(de)電(dian)(dian)(dian)(dian)(dian)磁轉(zhuan)(zhuan)(zhuan)矩也相(xiang)應(ying)減小(xiao),當(dang)異步(bu)電(dian)(dian)(dian)(dian)(dian)動機工作在電(dian)(dian)(dian)(dian)(dian)動機狀態時,轉(zhuan)(zhuan)(zhuan)子(zi)轉(zhuan)(zhuan)(zhuan)速(su)小(xiao)于(yu)同(tong)步(bu)轉(zhuan)(zhuan)(zhuan)速(su)。為了描(miao)述轉(zhuan)(zhuan)(zhuan)子(zi)轉(zhuan)(zhuan)(zhuan)速(su)n與(yu)同(tong)步(bu)轉(zhuan)(zhuan)(zhuan)速(su)n1之間的(de)(de)差別,引(yin)入(ru)轉(zhuan)(zhuan)(zhuan)差率(slip)。
單(dan)相異(yi)步電機的基本結(jie)構
單相(xiang)異步電動(dong)機(ji)(ji)就是(shi)只需單相(xiang)交流電源(yuan)供(gong)電的(de)電動(dong)機(ji)(ji)。單相(xiang)異步電動(dong)機(ji)(ji)由定(ding)子(zi)、轉子(zi)、軸承、機(ji)(ji)殼、端蓋等(deng)構成。定(ding)子(zi)由機(ji)(ji)座和帶繞(rao)組(zu)的(de)鐵(tie)心組(zu)成。鐵(tie)心由硅鋼片沖(chong)槽(cao)疊(die)(die)壓(ya)(ya)而成,槽(cao)內嵌裝兩套空(kong)間互隔90°電角度的(de)主(zhu)繞(rao)組(zu)(也(ye)稱運行繞(rao)組(zu))和輔繞(rao)組(zu)(也(ye)稱起(qi)(qi)動(dong)繞(rao)組(zu)成副繞(rao)組(zu))。主(zhu)繞(rao)組(zu)接交流電源(yuan),輔繞(rao)組(zu)串接離心開關(guan)S或起(qi)(qi)動(dong)電容、運行電容等(deng)之后,再(zai)接入電源(yuan)。轉子(zi)為籠(long)型(xing)鑄(zhu)(zhu)鋁轉子(zi),它是(shi)將鐵(tie)心疊(die)(die)壓(ya)(ya)后用鋁鑄(zhu)(zhu)入鐵(tie)心的(de)槽(cao)中,并(bing)一起(qi)(qi)鑄(zhu)(zhu)出端環,使轉子(zi)導條短路成鼠籠(long)型(xing)。
單(dan)(dan)相(xiang)(xiang)異步(bu)電(dian)動(dong)機(ji)(ji)又分為單(dan)(dan)相(xiang)(xiang)電(dian)阻起動(dong)異步(bu)電(dian)動(dong)機(ji)(ji),單(dan)(dan)相(xiang)(xiang)電(dian)容起動(dong)異步(bu)電(dian)動(dong)機(ji)(ji)、單(dan)(dan)相(xiang)(xiang)電(dian)容運轉異步(bu)電(dian)動(dong)機(ji)(ji)和單(dan)(dan)相(xiang)(xiang)雙值電(dian)容異步(bu)電(dian)動(dong)機(ji)(ji)。
三相異步電機的(de)基本結構
三(san)(san)相(xiang)異步(bu)電(dian)(dian)(dian)動(dong)(dong)機(ji)(ji)主要有(you)(you)由(you)定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)和(he)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi),軸(zhou)承組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)成(cheng)。定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)主要由(you)鐵(tie)(tie)(tie)(tie)心(xin)(xin)(xin)(xin),三(san)(san)相(xiang)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu),機(ji)(ji)座(zuo),端(duan)(duan)蓋(gai)(gai)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)成(cheng)。定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)(tie)(tie)心(xin)(xin)(xin)(xin)一(yi)(yi)般(ban)由(you)0.35~0.5毫(hao)米(mi)厚(hou)表面具有(you)(you)絕(jue)緣(yuan)層(ceng)的(de)(de)(de)(de)(de)硅(gui)(gui)(gui)鋼(gang)片(pian)沖制(zhi)、疊壓(ya)(ya)而(er)(er)成(cheng),在(zai)鐵(tie)(tie)(tie)(tie)心(xin)(xin)(xin)(xin)的(de)(de)(de)(de)(de)內(nei)圓(yuan)沖有(you)(you)均(jun)(jun)勻分(fen)(fen)布(bu)的(de)(de)(de)(de)(de)槽(cao)(cao),用(yong)(yong)(yong)(yong)以(yi)(yi)嵌(qian)放(fang)定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)。三(san)(san)相(xiang)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)由(you)三(san)(san)個(ge)(ge)(ge)在(zai)空間互隔120°電(dian)(dian)(dian)角度、隊稱排(pai)列(lie)的(de)(de)(de)(de)(de)結構完全相(xiang)同繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)連接(jie)而(er)(er)成(cheng),這些繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)的(de)(de)(de)(de)(de)各(ge)個(ge)(ge)(ge)線(xian)(xian)圈按一(yi)(yi)定(ding)(ding)(ding)規律分(fen)(fen)別嵌(qian)放(fang)在(zai)定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)各(ge)槽(cao)(cao)內(nei)。其作用(yong)(yong)(yong)(yong)是通(tong)入三(san)(san)相(xiang)交流電(dian)(dian)(dian),產(chan)生旋轉(zhuan)(zhuan)(zhuan)(zhuan)磁(ci)場。機(ji)(ji)座(zuo)通(tong)常(chang)為鑄鐵(tie)(tie)(tie)(tie)件(jian),大型(xing)(xing)異步(bu)電(dian)(dian)(dian)動(dong)(dong)機(ji)(ji)機(ji)(ji)座(zuo)一(yi)(yi)般(ban)用(yong)(yong)(yong)(yong)鋼(gang)板焊(han)成(cheng),微型(xing)(xing)電(dian)(dian)(dian)動(dong)(dong)機(ji)(ji)的(de)(de)(de)(de)(de)機(ji)(ji)座(zuo)采用(yong)(yong)(yong)(yong)鑄鋁(lv)件(jian),其作用(yong)(yong)(yong)(yong)是固定(ding)(ding)(ding)定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)(tie)(tie)心(xin)(xin)(xin)(xin)與前后端(duan)(duan)蓋(gai)(gai)以(yi)(yi)支(zhi)撐轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi),并起防護(hu)、散(san)熱(re)等作用(yong)(yong)(yong)(yong)。封(feng)閉式(shi)(shi)(shi)(shi)電(dian)(dian)(dian)機(ji)(ji)的(de)(de)(de)(de)(de)機(ji)(ji)座(zuo)外(wai)面有(you)(you)散(san)熱(re)筋(jin)以(yi)(yi)增加散(san)熱(re)面積,防護(hu)式(shi)(shi)(shi)(shi)電(dian)(dian)(dian)機(ji)(ji)的(de)(de)(de)(de)(de)機(ji)(ji)座(zuo)兩(liang)端(duan)(duan)端(duan)(duan)蓋(gai)(gai)開有(you)(you)通(tong)風(feng)孔(kong),使電(dian)(dian)(dian)動(dong)(dong)機(ji)(ji)內(nei)外(wai)的(de)(de)(de)(de)(de)空氣可直接(jie)對流,以(yi)(yi)利于(yu)散(san)熱(re)。端(duan)(duan)蓋(gai)(gai)主要起固定(ding)(ding)(ding)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi),支(zhi)撐和(he)防護(hu)作用(yong)(yong)(yong)(yong)。轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)主要由(you)鐵(tie)(tie)(tie)(tie)心(xin)(xin)(xin)(xin)和(he)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)成(cheng)。轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)(tie)(tie)心(xin)(xin)(xin)(xin)所(suo)用(yong)(yong)(yong)(yong)材料與定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)一(yi)(yi)樣,由(you)0.5毫(hao)米(mi)厚(hou)的(de)(de)(de)(de)(de)硅(gui)(gui)(gui)鋼(gang)片(pian)沖制(zhi)、疊壓(ya)(ya)而(er)(er)成(cheng),硅(gui)(gui)(gui)鋼(gang)片(pian)外(wai)圓(yuan)沖有(you)(you)均(jun)(jun)勻分(fen)(fen)布(bu)的(de)(de)(de)(de)(de)孔(kong),用(yong)(yong)(yong)(yong)來安置轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)。通(tong)常(chang)用(yong)(yong)(yong)(yong)定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)(tie)(tie)心(xin)(xin)(xin)(xin)沖落后的(de)(de)(de)(de)(de)硅(gui)(gui)(gui)鋼(gang)片(pian)內(nei)圓(yuan)來沖制(zhi)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)(tie)(tie)心(xin)(xin)(xin)(xin)。一(yi)(yi)般(ban)小型(xing)(xing)異步(bu)電(dian)(dian)(dian)動(dong)(dong)機(ji)(ji)的(de)(de)(de)(de)(de)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)(tie)(tie)心(xin)(xin)(xin)(xin)直接(jie)壓(ya)(ya)裝在(zai)轉(zhuan)(zhuan)(zhuan)(zhuan)軸(zhou)上(shang),大、中型(xing)(xing)異步(bu)電(dian)(dian)(dian)動(dong)(dong)機(ji)(ji)(轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)直徑在(zai)300~400毫(hao)米(mi)以(yi)(yi)上(shang))的(de)(de)(de)(de)(de)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)(tie)(tie)心(xin)(xin)(xin)(xin)則借助與轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)支(zhi)架壓(ya)(ya)在(zai)轉(zhuan)(zhuan)(zhuan)(zhuan)軸(zhou)上(shang)。轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)分(fen)(fen)為鼠(shu)籠(long)式(shi)(shi)(shi)(shi)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)和(he)繞(rao)(rao)線(xian)(xian)式(shi)(shi)(shi)(shi)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)。 (1)鼠(shu)籠(long)式(shi)(shi)(shi)(shi)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi):轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)由(you)插入轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)槽(cao)(cao)中的(de)(de)(de)(de)(de)多根導條和(he)兩(liang)個(ge)(ge)(ge)環(huan)(huan)行的(de)(de)(de)(de)(de)端(duan)(duan)環(huan)(huan)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)成(cheng)。若去(qu)掉轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)(tie)(tie)心(xin)(xin)(xin)(xin),整(zheng)個(ge)(ge)(ge)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)的(de)(de)(de)(de)(de)外(wai)形像一(yi)(yi)個(ge)(ge)(ge)鼠(shu)籠(long),故稱籠(long)型(xing)(xing)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)。小型(xing)(xing)籠(long)型(xing)(xing)電(dian)(dian)(dian)動(dong)(dong)機(ji)(ji)采用(yong)(yong)(yong)(yong)鑄鋁(lv)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu),對于(yu)100KW以(yi)(yi)上(shang)的(de)(de)(de)(de)(de)電(dian)(dian)(dian)動(dong)(dong)機(ji)(ji)采用(yong)(yong)(yong)(yong)銅條和(he)銅端(duan)(duan)環(huan)(huan)焊(han)接(jie)而(er)(er)成(cheng)。鼠(shu)籠(long)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)分(fen)(fen)為:阻抗(kang)型(xing)(xing)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)、單鼠(shu)籠(long)型(xing)(xing)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)、雙(shuang)鼠(shu)籠(long)型(xing)(xing)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)、深槽(cao)(cao)式(shi)(shi)(shi)(shi)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)幾種,起動(dong)(dong)轉(zhuan)(zhuan)(zhuan)(zhuan)矩(ju)等特(te)性各(ge)有(you)(you)不同。 (2)繞(rao)(rao)線(xian)(xian)式(shi)(shi)(shi)(shi)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi):繞(rao)(rao)線(xian)(xian)轉(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)與定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu)相(xiang)似,也是一(yi)(yi)個(ge)(ge)(ge)對稱的(de)(de)(de)(de)(de)三(san)(san)相(xiang)繞(rao)(rao)組(zu)(zu)(zu)(zu)(zu)(zu)(zu)(zu),一(yi)(yi)般(ban)接(jie)成(cheng)星(xing)形,三(san)(san)個(ge)(ge)(ge)出線(xian)(xian)頭接(jie)到轉(zhuan)(zhuan)(zhuan)(zhuan)軸(zhou)的(de)(de)(de)(de)(de)三(san)(san)個(ge)(ge)(ge)集流環(huan)(huan)上(shang),再通(tong)過(guo)電(dian)(dian)(dian)刷與外(wai)電(dian)(dian)(dian)路(lu)聯接(jie)。
1 異步電動機起動方式
1.1 軟起動
隨著(zhu)微型計算(suan)機(ji)(ji)(ji)控(kong)(kong)制(zhi)技術的(de)迅猛(meng)發展,在(zai)相(xiang)關的(de)控(kong)(kong)制(zhi)工程(cheng)領(ling)域中(zhong)先后研(yan)制(zhi)成(cheng)功(gong)了一(yi)批電(dian)子式軟起(qi)動(dong)(dong)(dong)(dong)控(kong)(kong)制(zhi)器,廣(guang)泛應用(yong)在(zai)電(dian)動(dong)(dong)(dong)(dong)機(ji)(ji)(ji)的(de)起(qi)動(dong)(dong)(dong)(dong)過程(cheng),降壓(ya)(ya)啟動(dong)(dong)(dong)(dong)器隨之被替代(dai)。當(dang)前(qian)電(dian)子式的(de)軟起(qi)動(dong)(dong)(dong)(dong)設(she)施都使(shi)用(yong)的(de)是晶閘(zha)管的(de)調壓(ya)(ya)電(dian)路(lu),其電(dian)路(lu)構成(cheng)如下所描述(shu):晶閘(zha)管六只(zhi),兩兩反并聯(lian)后串聯(lian)至三相(xiang)電(dian)源上(shang),待(dai)系統(tong)發送(song)(song)起(qi)動(dong)(dong)(dong)(dong)信號后,微機(ji)(ji)(ji)控(kong)(kong)制(zhi)起(qi)動(dong)(dong)(dong)(dong)器系統(tong)立即進(jin)行數據(ju)(ju)計算(suan),令晶閘(zha)管輸(shu)送(song)(song)觸發信號,使(shi)晶閘(zha)管的(de)導(dao)通角得(de)到控(kong)(kong)制(zhi),根(gen)據(ju)(ju)給定的(de)輸(shu)出(chu),調節輸(shu)出(chu)電(dian)壓(ya)(ya),實現電(dian)動(dong)(dong)(dong)(dong)機(ji)(ji)(ji)的(de)控(kong)(kong)制(zhi)。該起(qi)動(dong)(dong)(dong)(dong)方(fang)式適(shi)合各種功(gong)率(lv)值的(de)三相(xiang)交流異(yi)步電(dian)動(dong)(dong)(dong)(dong)機(ji)(ji)(ji)包括(kuo)六根(gen)和三根(gen)連接(jie)方(fang)式的(de)起(qi)動(dong)(dong)(dong)(dong)控(kong)(kong)制(zhi)。
1.2 直接起(qi)動
此(ci)(ci)種起(qi)動(dong)(dong)(dong)(dong)方(fang)式(shi)(shi)是電(dian)(dian)機(ji)起(qi)動(dong)(dong)(dong)(dong)方(fang)式(shi)(shi)中(zhong)最基礎(chu)最簡單的(de),首(shou)先借助用刀開關(guan)使電(dian)(dian)動(dong)(dong)(dong)(dong)機(ji)與電(dian)(dian)網進行(xing)連接(jie),此(ci)(ci)時在(zai)額定(ding)電(dian)(dian)壓下電(dian)(dian)動(dong)(dong)(dong)(dong)機(ji)起(qi)動(dong)(dong)(dong)(dong)并運行(xing)起(qi)來,該方(fang)式(shi)(shi)特點為:投資(zi)少,設備簡單、數量少,雖(sui)然起(qi)動(dong)(dong)(dong)(dong)時間短,但起(qi)動(dong)(dong)(dong)(dong)時的(de)轉矩(ju)較小,電(dian)(dian)流較大,比較適合(he)應用在(zai)容(rong)量小的(de)電(dian)(dian)動(dong)(dong)(dong)(dong)機(ji)起(qi)動(dong)(dong)(dong)(dong)。
1.3 降(jiang)壓起動
由于直接起(qi)(qi)動(dong)(dong)存在較大的(de)缺點,降壓(ya)起(qi)(qi)動(dong)(dong)隨之(zhi)產生。這(zhe)種(zhong)起(qi)(qi)動(dong)(dong)方(fang)式(shi)適用的(de)起(qi)(qi)動(dong)(dong)環(huan)境為空(kong)載和輕載這(zhe)兩種(zhong)情況,由于降壓(ya)起(qi)(qi)動(dong)(dong)方(fang)式(shi)是在同時實現了(le)限制起(qi)(qi)動(dong)(dong)轉(zhuan)矩和起(qi)(qi)動(dong)(dong)電(dian)流的(de),因此(ci)起(qi)(qi)動(dong)(dong)工作(zuo)結(jie)束后需要(yao)使工作(zuo)的(de)電(dian)路恢復到額定狀(zhuang)態。
三(san)相感(gan)應電動機電氣制動方式有:能耗制動、反接(jie)制動、再(zai)生(sheng)制動三(san)種(zhong)。
(1)能耗(hao)制(zhi)動(dong)時(shi)切(qie)斷電動(dong)機的(de)三相交流電源,將直流電送入定子繞(rao)組。在切(qie)斷交流電源的(de)瞬間(jian),由于慣(guan)性(xing)作(zuo)用(yong),電動(dong)機仍按原來方向轉動(dong),這種方式的(de)特(te)點是制(zhi)動(dong)平穩,但需(xu)直流電源、大(da)功率電動(dong)機,所(suo)需(xu)直流設備成(cheng)本大(da),低速時(shi)制(zhi)動(dong)力小。
(2)反接制動又分負載反接制動和電源反接制動兩種。
1)負(fu)載反接制(zhi)動又稱負(fu)載倒拉反接制(zhi)動。此(ci)轉矩使(shi)(shi)重物(wu)以穩定的速度(du)緩慢(man)下降。這種(zhong)制(zhi)動的特點是(shi):電(dian)(dian)源(yuan)不用(yong)反接,不需要專用(yong)的制(zhi)動設備(bei),而(er)且還(huan)可以調節(jie)制(zhi)動速度(du),但(dan)只適用(yong)于繞線型電(dian)(dian)動機,其轉子電(dian)(dian)路需串入大(da)電(dian)(dian)阻,使(shi)(shi)轉差(cha)率大(da)于1。
2)電(dian)源(yuan)反接制(zhi)(zhi)動(dong)(dong)(dong)當(dang)(dang)電(dian)動(dong)(dong)(dong)機需制(zhi)(zhi)動(dong)(dong)(dong)時(shi)(shi),只要任意(yi)對調兩相電(dian)源(yuan)線,使旋(xuan)轉(zhuan)磁場(chang)相反就能很快制(zhi)(zhi)動(dong)(dong)(dong)。當(dang)(dang)電(dian)動(dong)(dong)(dong)機轉(zhuan)速(su)等于零(ling)時(shi)(shi),立即切(qie)斷(duan)電(dian)源(yuan)。這種制(zhi)(zhi)動(dong)(dong)(dong)的特點是:停車快,制(zhi)(zhi)動(dong)(dong)(dong)力(li)較(jiao)強,無需制(zhi)(zhi)動(dong)(dong)(dong)設備。但制(zhi)(zhi)動(dong)(dong)(dong)時(shi)(shi)由于電(dian)流大(da),沖擊力(li)也大(da),易使電(dian)動(dong)(dong)(dong)機過熱,或損傷傳(chuan)動(dong)(dong)(dong)部(bu)分的零(ling)部(bu)件。
(3)再生(sheng)制動(dong)(dong)又稱回(hui)饋制動(dong)(dong),在重物(wu)的(de)作(zuo)(zuo)用下(xia)(當起重機(ji)(ji)電動(dong)(dong)機(ji)(ji)下(xia)放重物(wu)),電動(dong)(dong)機(ji)(ji)的(de)轉(zhuan)速高于(yu)旋(xuan)轉(zhuan)磁(ci)場的(de)同步轉(zhuan)速。這時轉(zhuan)子導體(ti)產(chan)生(sheng)感應電流,在旋(xuan)轉(zhuan)磁(ci)場的(de)作(zuo)(zuo)用下(xia)產(chan)生(sheng)反旋(xuan)轉(zhuan)方向轉(zhuan)矩,但電動(dong)(dong)機(ji)(ji)轉(zhuan)速高,需用變速裝置減速。
1、一般來說,小型異步電(dian)機指的就是感應運轉型異步電(dian)機。這種(zhong)電(dian)機不只在(zai)啟(qi)動時,在(zai)運轉時也使用(yong)輔助線(xian)圈和(he)電(dian)容(rong)器。雖然(ran)啟(qi)動轉矩不是很大,但其(qi)結構簡單,信賴度高,效率也高。
2、隨(sui)負荷(he)的大小,電機(ji)的額定轉速(su)也會改變(bian)。
3、可(ke)以(yi)連續運轉。
4、使(shi)用于不(bu)需要速度制(zhi)動(dong)的應用場合(he)。
5、用(yong)E種絕緣等級,而UL型電機則(ze)用(yong)A種。
6、有(you)感應(ying)運轉型(xing)單(dan)相異步(bu)電(dian)機和三相異步(bu)電(dian)機兩種(zhong)。
7、單(dan)相電(dian)機為感應運轉型異步電(dian)機,效率高,噪(zao)聲(sheng)低。
8、單相(xiang)異(yi)步電機運轉(zhuan)時(shi),產(chan)生和旋(xuan)轉(zhuan)方(fang)(fang)向相(xiang)反的轉(zhuan)矩,因此(ci)不可能在短時(shi)間內(nei)改變方(fang)(fang)向。應在電機完全(quan)停(ting)止以后,再轉(zhuan)換其旋(xuan)轉(zhuan)方(fang)(fang)向。
9、單相電機的電源有A(110V 60Hz)、B(22V 60Hz)、C(100V 50/60Hz)、D(200V 50/60Hz)、E(115V 60Hz)、X(200-240V50Hz)等。
10、三相電機時(shi)使(shi)用U(200V 50/60Hz)、T(220V 50/60Hz)、S(380-440V 50/60Hz)電源(yuan)的異步電機。
項目
事項
絕緣阻抗
在常溫(wen)金(jin)屬(shu)阻和電(dian)動(dong)機外殼之間的絕緣電(dian)阻超過100M?
絕緣內壓
在常溫(wen)金屬繞組(zu)和電(dian)動機箱(xiang)之間的電(dian)壓
溫度上升
以1500V、50/60Hz輸(shu)入1min時沒(mei)有任何問題(ti)。
絕緣等級
E種(120℃)
過熱保護裝置
開放(120±5℃);復歸(77±5℃)
使用溫度
-10~50℃(UL CE規格電(dian)動機(ji)使(shi)用溫度為-10~40℃)
(1)電動機投入電源后不轉的原因檢查及(ji)修理
電動機投入電源后不轉,一(yi)般有下列原(yuan)因:
1)控制(zhi)設備(bei)的接(jie)線(xian)錯誤(wu);
2)過電(dian)流繼(ji)電(dian)器調整(zheng)的整(zheng)定(ding)值(zhi)偏小;
3)電源(yuan)未(wei)接(jie)通,如熔絲燒(shao)斷、開關有(you)故(gu)障或觸頭接(jie)觸不良、引線(xian)斷路(lu)等;
4)電源至電動機之間的連接有故障;
5)電動機(ji)繞組有故障,如相間短路(lu)、接地、接錯(cuo)線、斷路(lu)等;
6)繞線式轉(zhuan)子異步(bu)電(dian)動(dong)機起動(dong)誤操作或起動(dong)電(dian)阻(zu)過小;
7)電動機軸(zhou)承有故障,被(bei)卡住(zhu);
8)定、轉子鐵芯相擦(掃膛),等于增加過大(da)的負載;
9)電動機(ji)負(fu)載過大(da)或機(ji)械轉動部分(fen)被卡(ka)住等。
2)電動機過熱檢查(cha)及修理
發現正常運行的電動(dong)機過熱,一般有下列原因:
1)電(dian)源電(dian)壓突然變高,并于電(dian)動(dong)機銘牌(pai)額(e)定(ding)電(dian)壓不相符,或者三(san)相電(dian)源電(dian)壓嚴重(zhong)不平衡;
2)電動機所拖動的負載變動較大(da),電機暫時處(chu)于過載狀態;
3)由于軸(zhou)承產生(sheng)(sheng)故障或間隙磨損超(chao)限、轉軸(zhou)發生(sheng)(sheng)彎曲(qu)、鐵芯(xin)局(ju)部過熱變形、轉子軸(zhou)向串動等原因(yin),使定、轉子鐵芯(xin)掃膛;
4)環(huan)境粉塵進(jin)入(ru)電動(dong)機內(nei)部粘附(fu)在絕(jue)緣表面(mian)上和堵塞冷(leng)卻風道(dao)、冷(leng)卻風管等,使電動(dong)機通風不良(liang),冷(leng)卻效果(guo)大大降低(di),造成電機過熱;
5)電動機(ji)冷卻裝置(zhi)(zhi)失效(xiao),調節風溫裝置(zhi)(zhi)有故障(zhang),造成電機(ji)過熱;
6)三相(xiang)電動(dong)機(ji)單(dan)相(xiang)運(yun)行;
7)繞組(zu)有故障,如短路(lu)、斷路(lu)、接地(di)、接錯(cuo)等;
8)氣(qi)隙不均勻。
經(jing)重繞后(hou)的電動機發(fa)生過熱,其原因是:
1)接線錯誤;
2)線圈匝數過多或過少;
3)線圈導線過(guo)細,線圈節距過(guo)小或(huo)過(guo)大;
4)電(dian)動機(ji)(ji)裝(zhuang)配質(zhi)量不(bu)(bu)(bu)好,鐵(tie)(tie)芯(xin)未對齊,定轉子鐵(tie)(tie)芯(xin)軸(zhou)向(xiang)有(you)差(cha)距引起軸(zhou)向(xiang)磁(ci)拉力(li),氣隙裝(zhuang)配和調整不(bu)(bu)(bu)均勻。由于(yu)電(dian)動機(ji)(ji)絕緣水(shui)平不(bu)(bu)(bu)斷提(ti)高(gao)(gao)(gao),允許(xu)(xu)溫(wen)升(sheng)限度也提(ti)高(gao)(gao)(gao),所(suo)以電(dian)機(ji)(ji)外殼溫(wen)升(sheng)較高(gao)(gao)(gao)可能屬正常。但(dan)要用酒精(jing)溫(wen)度計測試部門(men)的外殼溫(wen)升(sheng)和軸(zhou)承溫(wen)升(sheng),并和電(dian)動機(ji)(ji)的絕緣等級所(suo)允許(xu)(xu)的溫(wen)升(sheng)相對照比(bi)較后,確認電(dian)動機(ji)(ji)是過熱,那么可按以下(xia)步驟進(jin)行檢查 [9] 。
1)首(shou)先檢(jian)查三相(xiang)電(dian)源(yuan)的電(dian)壓(ya)是否平衡(heng)(heng),電(dian)壓(ya)波(bo)動(dong)的程度是否大(da)(da)(da)于(yu)制造場廠(chang)的保證值(±10[%])。由于(yu)電(dian)壓(ya)不平衡(heng)(heng),產生(sheng)三相(xiang)不平衡(heng)(heng)電(dian)流,引起電(dian)機損耗增大(da)(da)(da)和電(dian)機發熱,所(suo)以要及時糾正。電(dian)源(yuan)頻率變動(dong)對(±5[%])電(dian)機發熱也有影響,但實(shi)際變化不大(da)(da)(da),所(suo)以在分析時一般(ban)可不考慮。
2)檢查(cha)電機(ji)是(shi)(shi)否單相(xiang)運轉,三相(xiang)接(jie)(jie)觸(chu)器的觸(chu)頭是(shi)(shi)否接(jie)(jie)觸(chu)好,開關的熔絲是(shi)(shi)否有(you)一(yi)相(xiang)燒斷(duan),接(jie)(jie)線有(you)否(單相(xiang))斷(duan)開。故(gu)障(zhang)檢查(cha)出(chu)后進(jin)行處理。
3)檢查(cha)(cha)三相電流是否超(chao)過額定(ding)(ding)值(zhi)。若(ruo)超(chao)過額定(ding)(ding)值(zhi)時(shi)(shi),要檢查(cha)(cha)其(qi)原因。處(chu)理這類故障時(shi)(shi),要查(cha)(cha)清(qing)造成掃(sao)膛的(de)原因:①轉軸(zhou)彎曲;②軸(zhou)承故障。輕(qing)微的(de)鐵芯掃(sao)膛不影(ying)響(xiang)電機(ji)正常運(yun)行(xing),掃(sao)膛嚴重時(shi)(shi),可(ke)用車(che)刀將轉子表面輕(qing)輕(qing)切削一層(一般車(che)削直徑為(wei)0.2mm左右為(wei)宜)。
4)粉(fen)塵(chen)敷滿絕緣(yuan)影響電機散熱(re),過濾網堵塞,通風道和通風管(guan)堵塞等(deng),都會(hui)引起電機過熱(re)。因此(ci)可采取(qu)吹風清掃(sao)措(cuo)施(shi)了消除(chu)粉(fen)塵(chen),必(bi)要時電機要解體進行清洗處(chu)理。
5)如(ru)認為繞組(zu)有故障時(shi),可進(jin)行繞組(zu)短(duan)路(lu)和(he)接地試驗檢(jian)查。根據進(jin)行經驗表(biao)明,電(dian)機繞組(zu)如(ru)有匝間(jian)短(duan)路(lu),電(dian)機則會(hui)振動,動轉時(shi)間(jian)不少(shao)就會(hui)時(shi)間(jian)不長就會(hui)冒煙。但是匝間(jian)短(duan)路(lu)引起電(dian)機發熱,并且持續(xu)長時(shi)期的(de)(de)機會(hui),是很少(shao)的(de)(de)。
重(zhong)繞大修后的(de)電機溫(wen)升超限,可(ke)能是絕緣處(chu)理(li)工(gong)藝不(bu)好(hao),線(xian)圈數(shu)(shu)據(ju)不(bu)對,接線(xian)錯誤以及(ji)裝配質量等問題引起(qi)。這時電機應(ying)解體對照(zhao)原始記錄檢查,以及(ji)查明繞組數(shu)(shu)據(ju)的(de)正確性。