感應電(dian)動(dong)(dong)機又稱“異步電(dian)動(dong)(dong)機(asynchronousmotor)”,即轉(zhuan)子置(zhi)于旋轉(zhuan)磁場中,在(zai)旋轉(zhuan)磁場的(de)作用(yong)下,獲得一個轉(zhuan)動(dong)(dong)力(li)矩,因而轉(zhuan)子轉(zhuan)動(dong)(dong)。
轉(zhuan)子(zi)是(shi)可轉(zhuan)動(dong)(dong)的(de)導(dao)體,通常多呈鼠籠狀。定子(zi)是(shi)電(dian)動(dong)(dong)機(ji)中不(bu)轉(zhuan)動(dong)(dong)的(de)部分,主要任務是(shi)產生一(yi)個旋轉(zhuan)磁(ci)場(chang)。旋轉(zhuan)磁(ci)場(chang)并不(bu)是(shi)用(yong)機(ji)械方法來實現。而是(shi)以交流(liu)電(dian)通于數對電(dian)磁(ci)鐵中,使其磁(ci)極性(xing)質(zhi)循(xun)環改(gai)變,故相(xiang)當(dang)于一(yi)個旋轉(zhuan)的(de)磁(ci)場(chang)。這種電(dian)動(dong)(dong)機(ji)并不(bu)像直流(liu)電(dian)動(dong)(dong)機(ji)有電(dian)刷(shua)或集電(dian)環,依據所用(yong)交流(liu)電(dian)的(de)種類(lei)有單相(xiang)電(dian)動(dong)(dong)機(ji)和三(san)相(xiang)電(dian)動(dong)(dong)機(ji),單相(xiang)電(dian)動(dong)(dong)機(ji)用(yong)在如洗衣機(ji),電(dian)風扇等;三(san)相(xiang)電(dian)動(dong)(dong)機(ji)則(ze)作為工(gong)廠的(de)動(dong)(dong)力設備。
尼古拉(la)·特斯(si)拉(la)(Nikola Tesla,1856年7月10日(ri)~1943年1月7日(ri)),塞(sai)爾維(wei)亞裔美籍發(fa)明家(jia)、機械(xie)工程師、電(dian)(dian)氣工程師。他被認為是電(dian)(dian)力商業化(hua)的(de)(de)(de)重(zhong)要推動者之(zhi)一(yi),并(bing)因主持設計(ji)了現(xian)代交流電(dian)(dian)系統而(er)最為人知。在邁(mai)克爾·法(fa)拉(la)第(di)發(fa)現(xian)的(de)(de)(de)電(dian)(dian)磁場理論的(de)(de)(de)基(ji)礎上,特斯(si)拉(la)在電(dian)(dian)磁場領域有著多項革命性的(de)(de)(de)發(fa)明。1887年發(fa)明感(gan)應電(dian)(dian)動機,他的(de)(de)(de)多項相(xiang)關專利以及(ji)電(dian)(dian)磁學的(de)(de)(de)理論研(yan)究工作是現(xian)代的(de)(de)(de)無(wu)線通信和無(wu)線電(dian)(dian)的(de)(de)(de)基(ji)石。
通過定(ding)子(zi)(zi)(zi)產生(sheng)(sheng)的(de)旋轉磁(ci)(ci)場(chang)(其(qi)轉速為同(tong)(tong)步(bu)(bu)轉速n1)與(yu)轉子(zi)(zi)(zi)繞(rao)組的(de)相對運(yun)動,轉子(zi)(zi)(zi)繞(rao)組切割磁(ci)(ci)感(gan)線產生(sheng)(sheng)感(gan)應(ying)(ying)電(dian)動勢(shi),從而使轉子(zi)(zi)(zi)繞(rao)組中產生(sheng)(sheng)感(gan)應(ying)(ying)電(dian)流(liu)。轉子(zi)(zi)(zi)繞(rao)組中的(de)感(gan)應(ying)(ying)電(dian)流(liu)與(yu)磁(ci)(ci)場(chang)作用,產生(sheng)(sheng)電(dian)磁(ci)(ci)轉矩,使轉子(zi)(zi)(zi)旋轉。由于當轉子(zi)(zi)(zi)轉速逐(zhu)漸(jian)(jian)接近同(tong)(tong)步(bu)(bu)轉速時,感(gan)應(ying)(ying)電(dian)流(liu)逐(zhu)漸(jian)(jian)減(jian)小(xiao),所(suo)產生(sheng)(sheng)的(de)電(dian)磁(ci)(ci)轉矩也相應(ying)(ying)減(jian)小(xiao),當異(yi)步(bu)(bu)電(dian)動機工作在電(dian)動機狀態時,轉子(zi)(zi)(zi)轉速小(xiao)于同(tong)(tong)步(bu)(bu)轉速。為了描述轉子(zi)(zi)(zi)轉速n與(yu)同(tong)(tong)步(bu)(bu)轉速n1之間的(de)差別,引入轉差率(slip)。
單相異步電機的基本結(jie)構
單相異步電(dian)(dian)(dian)動機(ji)就是只需(xu)單相交流電(dian)(dian)(dian)源供電(dian)(dian)(dian)的(de)電(dian)(dian)(dian)動機(ji)。單相異步電(dian)(dian)(dian)動機(ji)由(you)定(ding)子(zi)、轉(zhuan)子(zi)、軸(zhou)承(cheng)、機(ji)殼、端(duan)蓋等(deng)構成(cheng)。定(ding)子(zi)由(you)機(ji)座和(he)帶繞(rao)組(zu)(zu)(zu)的(de)鐵(tie)心組(zu)(zu)(zu)成(cheng)。鐵(tie)心由(you)硅鋼片沖槽(cao)疊(die)壓(ya)而成(cheng),槽(cao)內嵌裝(zhuang)兩套(tao)空間互隔90°電(dian)(dian)(dian)角度的(de)主繞(rao)組(zu)(zu)(zu)(也稱(cheng)運行繞(rao)組(zu)(zu)(zu))和(he)輔(fu)繞(rao)組(zu)(zu)(zu)(也稱(cheng)起動繞(rao)組(zu)(zu)(zu)成(cheng)副繞(rao)組(zu)(zu)(zu))。主繞(rao)組(zu)(zu)(zu)接交流電(dian)(dian)(dian)源,輔(fu)繞(rao)組(zu)(zu)(zu)串接離(li)心開關S或起動電(dian)(dian)(dian)容、運行電(dian)(dian)(dian)容等(deng)之后,再接入電(dian)(dian)(dian)源。轉(zhuan)子(zi)為籠型鑄(zhu)鋁轉(zhuan)子(zi),它是將鐵(tie)心疊(die)壓(ya)后用鋁鑄(zhu)入鐵(tie)心的(de)槽(cao)中,并一起鑄(zhu)出端(duan)環,使轉(zhuan)子(zi)導(dao)條短路(lu)成(cheng)鼠籠型。
單相(xiang)(xiang)異(yi)(yi)步(bu)(bu)電(dian)動機又(you)分為單相(xiang)(xiang)電(dian)阻起動異(yi)(yi)步(bu)(bu)電(dian)動機,單相(xiang)(xiang)電(dian)容起動異(yi)(yi)步(bu)(bu)電(dian)動機、單相(xiang)(xiang)電(dian)容運轉(zhuan)異(yi)(yi)步(bu)(bu)電(dian)動機和單相(xiang)(xiang)雙(shuang)值電(dian)容異(yi)(yi)步(bu)(bu)電(dian)動機。
三(san)相異(yi)步電機(ji)的基(ji)本結構
三(san)相(xiang)異(yi)(yi)步(bu)電(dian)動(dong)(dong)(dong)機(ji)主要有由(you)(you)(you)(you)(you)定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)和(he)(he)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi),軸(zhou)(zhou)(zhou)承組(zu)(zu)(zu)成(cheng)。定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)主要由(you)(you)(you)(you)(you)鐵(tie)(tie)心(xin),三(san)相(xiang)繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu),機(ji)座(zuo),端(duan)蓋(gai)組(zu)(zu)(zu)成(cheng)。定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)心(xin)一(yi)(yi)(yi)(yi)般(ban)由(you)(you)(you)(you)(you)0.35~0.5毫(hao)米厚(hou)表面具有絕緣(yuan)層(ceng)的(de)(de)(de)(de)(de)(de)(de)硅(gui)鋼(gang)片沖(chong)制、疊壓而成(cheng),在(zai)(zai)鐵(tie)(tie)心(xin)的(de)(de)(de)(de)(de)(de)(de)內(nei)圓沖(chong)有均勻(yun)分(fen)(fen)布的(de)(de)(de)(de)(de)(de)(de)槽(cao),用(yong)以嵌放定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu)。三(san)相(xiang)繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu)由(you)(you)(you)(you)(you)三(san)個在(zai)(zai)空間互隔120°電(dian)角度、隊(dui)稱(cheng)排列的(de)(de)(de)(de)(de)(de)(de)結構完全相(xiang)同繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu)連接(jie)而成(cheng),這些繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu)的(de)(de)(de)(de)(de)(de)(de)各(ge)個線(xian)圈按(an)一(yi)(yi)(yi)(yi)定(ding)(ding)(ding)規律分(fen)(fen)別嵌放在(zai)(zai)定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)各(ge)槽(cao)內(nei)。其作用(yong)是通入(ru)三(san)相(xiang)交流電(dian),產生旋轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)磁(ci)場(chang)。機(ji)座(zuo)通常為鑄(zhu)鐵(tie)(tie)件,大型(xing)(xing)異(yi)(yi)步(bu)電(dian)動(dong)(dong)(dong)機(ji)機(ji)座(zuo)一(yi)(yi)(yi)(yi)般(ban)用(yong)鋼(gang)板焊成(cheng),微型(xing)(xing)電(dian)動(dong)(dong)(dong)機(ji)的(de)(de)(de)(de)(de)(de)(de)機(ji)座(zuo)采(cai)用(yong)鑄(zhu)鋁件,其作用(yong)是固定(ding)(ding)(ding)定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)心(xin)與(yu)前后端(duan)蓋(gai)以支撐(cheng)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi),并起防護(hu)(hu)、散熱等(deng)作用(yong)。封閉(bi)式(shi)(shi)電(dian)機(ji)的(de)(de)(de)(de)(de)(de)(de)機(ji)座(zuo)外(wai)(wai)面有散熱筋以增加散熱面積,防護(hu)(hu)式(shi)(shi)電(dian)機(ji)的(de)(de)(de)(de)(de)(de)(de)機(ji)座(zuo)兩(liang)端(duan)端(duan)蓋(gai)開有通風孔,使電(dian)動(dong)(dong)(dong)機(ji)內(nei)外(wai)(wai)的(de)(de)(de)(de)(de)(de)(de)空氣可(ke)直接(jie)對流,以利于散熱。端(duan)蓋(gai)主要起固定(ding)(ding)(ding)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi),支撐(cheng)和(he)(he)防護(hu)(hu)作用(yong)。轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)主要由(you)(you)(you)(you)(you)鐵(tie)(tie)心(xin)和(he)(he)繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu)組(zu)(zu)(zu)成(cheng)。轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)心(xin)所用(yong)材料(liao)與(yu)定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)一(yi)(yi)(yi)(yi)樣(yang),由(you)(you)(you)(you)(you)0.5毫(hao)米厚(hou)的(de)(de)(de)(de)(de)(de)(de)硅(gui)鋼(gang)片沖(chong)制、疊壓而成(cheng),硅(gui)鋼(gang)片外(wai)(wai)圓沖(chong)有均勻(yun)分(fen)(fen)布的(de)(de)(de)(de)(de)(de)(de)孔,用(yong)來安置轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu)。通常用(yong)定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)心(xin)沖(chong)落后的(de)(de)(de)(de)(de)(de)(de)硅(gui)鋼(gang)片內(nei)圓來沖(chong)制轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)心(xin)。一(yi)(yi)(yi)(yi)般(ban)小型(xing)(xing)異(yi)(yi)步(bu)電(dian)動(dong)(dong)(dong)機(ji)的(de)(de)(de)(de)(de)(de)(de)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)心(xin)直接(jie)壓裝在(zai)(zai)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)軸(zhou)(zhou)(zhou)上,大、中型(xing)(xing)異(yi)(yi)步(bu)電(dian)動(dong)(dong)(dong)機(ji)(轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)直徑在(zai)(zai)300~400毫(hao)米以上)的(de)(de)(de)(de)(de)(de)(de)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)心(xin)則借助與(yu)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)支架壓在(zai)(zai)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)軸(zhou)(zhou)(zhou)上。轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu)分(fen)(fen)為鼠(shu)籠(long)(long)式(shi)(shi)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)和(he)(he)繞(rao)(rao)(rao)(rao)(rao)(rao)線(xian)式(shi)(shi)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)。 (1)鼠(shu)籠(long)(long)式(shi)(shi)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi):轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu)由(you)(you)(you)(you)(you)插入(ru)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)槽(cao)中的(de)(de)(de)(de)(de)(de)(de)多(duo)根(gen)導條和(he)(he)兩(liang)個環行的(de)(de)(de)(de)(de)(de)(de)端(duan)環組(zu)(zu)(zu)成(cheng)。若去掉(diao)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)鐵(tie)(tie)心(xin),整個繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu)的(de)(de)(de)(de)(de)(de)(de)外(wai)(wai)形像一(yi)(yi)(yi)(yi)個鼠(shu)籠(long)(long),故(gu)稱(cheng)籠(long)(long)型(xing)(xing)繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu)。小型(xing)(xing)籠(long)(long)型(xing)(xing)電(dian)動(dong)(dong)(dong)機(ji)采(cai)用(yong)鑄(zhu)鋁轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu),對于100KW以上的(de)(de)(de)(de)(de)(de)(de)電(dian)動(dong)(dong)(dong)機(ji)采(cai)用(yong)銅(tong)條和(he)(he)銅(tong)端(duan)環焊接(jie)而成(cheng)。鼠(shu)籠(long)(long)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)分(fen)(fen)為:阻(zu)抗(kang)型(xing)(xing)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)、單鼠(shu)籠(long)(long)型(xing)(xing)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)、雙鼠(shu)籠(long)(long)型(xing)(xing)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)、深槽(cao)式(shi)(shi)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)幾(ji)種(zhong),起動(dong)(dong)(dong)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)矩等(deng)特性各(ge)有不同。 (2)繞(rao)(rao)(rao)(rao)(rao)(rao)線(xian)式(shi)(shi)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi):繞(rao)(rao)(rao)(rao)(rao)(rao)線(xian)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu)與(yu)定(ding)(ding)(ding)子(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)(zi)繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu)相(xiang)似,也是一(yi)(yi)(yi)(yi)個對稱(cheng)的(de)(de)(de)(de)(de)(de)(de)三(san)相(xiang)繞(rao)(rao)(rao)(rao)(rao)(rao)組(zu)(zu)(zu),一(yi)(yi)(yi)(yi)般(ban)接(jie)成(cheng)星(xing)形,三(san)個出線(xian)頭接(jie)到(dao)轉(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)(zhuan)軸(zhou)(zhou)(zhou)的(de)(de)(de)(de)(de)(de)(de)三(san)個集流環上,再通過電(dian)刷與(yu)外(wai)(wai)電(dian)路聯(lian)接(jie)。
1 異步(bu)電動(dong)機起動(dong)方式(shi)
1.1 軟起動
隨著微(wei)型(xing)計算機(ji)(ji)控(kong)制(zhi)技(ji)術(shu)的迅猛(meng)發展,在(zai)相(xiang)(xiang)關的控(kong)制(zhi)工程領域中先后(hou)研制(zhi)成功了一批電(dian)(dian)子式(shi)(shi)軟起動(dong)(dong)控(kong)制(zhi)器(qi)(qi),廣(guang)泛應(ying)用(yong)在(zai)電(dian)(dian)動(dong)(dong)機(ji)(ji)的起動(dong)(dong)過(guo)程,降壓(ya)啟(qi)動(dong)(dong)器(qi)(qi)隨之被替代。當(dang)前電(dian)(dian)子式(shi)(shi)的軟起動(dong)(dong)設施(shi)都(dou)使(shi)用(yong)的是(shi)晶(jing)(jing)閘(zha)管的調壓(ya)電(dian)(dian)路(lu),其電(dian)(dian)路(lu)構(gou)成如(ru)下所描述(shu):晶(jing)(jing)閘(zha)管六只,兩兩反(fan)并聯(lian)后(hou)串聯(lian)至三(san)(san)相(xiang)(xiang)電(dian)(dian)源上,待系(xi)(xi)統發送(song)起動(dong)(dong)信(xin)號(hao)后(hou),微(wei)機(ji)(ji)控(kong)制(zhi)起動(dong)(dong)器(qi)(qi)系(xi)(xi)統立即進(jin)行數據(ju)計算,令晶(jing)(jing)閘(zha)管輸(shu)送(song)觸發信(xin)號(hao),使(shi)晶(jing)(jing)閘(zha)管的導通角得(de)到(dao)控(kong)制(zhi),根(gen)據(ju)給定的輸(shu)出,調節輸(shu)出電(dian)(dian)壓(ya),實現電(dian)(dian)動(dong)(dong)機(ji)(ji)的控(kong)制(zhi)。該起動(dong)(dong)方式(shi)(shi)適合(he)各種(zhong)功率值的三(san)(san)相(xiang)(xiang)交流異步電(dian)(dian)動(dong)(dong)機(ji)(ji)包括(kuo)六根(gen)和三(san)(san)根(gen)連(lian)接方式(shi)(shi)的起動(dong)(dong)控(kong)制(zhi)。
1.2 直接(jie)起動
此種(zhong)起動(dong)(dong)(dong)方式是電(dian)(dian)機起動(dong)(dong)(dong)方式中最基礎最簡單的,首(shou)先借助用刀開關使電(dian)(dian)動(dong)(dong)(dong)機與(yu)電(dian)(dian)網(wang)進行連(lian)接(jie),此時在額定(ding)電(dian)(dian)壓(ya)下電(dian)(dian)動(dong)(dong)(dong)機起動(dong)(dong)(dong)并運(yun)行起來,該方式特點為:投資少,設備簡單、數量(liang)(liang)少,雖然起動(dong)(dong)(dong)時間短,但起動(dong)(dong)(dong)時的轉(zhuan)矩(ju)較(jiao)(jiao)(jiao)小,電(dian)(dian)流(liu)較(jiao)(jiao)(jiao)大,比較(jiao)(jiao)(jiao)適合應用在容量(liang)(liang)小的電(dian)(dian)動(dong)(dong)(dong)機起動(dong)(dong)(dong)。
1.3 降(jiang)壓起動(dong)
由于直接起動(dong)(dong)(dong)存在較大的缺點,降壓起動(dong)(dong)(dong)隨之(zhi)產(chan)生。這種(zhong)起動(dong)(dong)(dong)方式適用的起動(dong)(dong)(dong)環(huan)境為空載和(he)輕載這兩(liang)種(zhong)情(qing)況(kuang),由于降壓起動(dong)(dong)(dong)方式是在同時實現(xian)了限(xian)制起動(dong)(dong)(dong)轉矩和(he)起動(dong)(dong)(dong)電(dian)流的,因(yin)此起動(dong)(dong)(dong)工作(zuo)結束后(hou)需要使(shi)工作(zuo)的電(dian)路恢復到額定狀態。
三(san)相感應電動(dong)機電氣(qi)制(zhi)(zhi)動(dong)方式有(you):能耗(hao)制(zhi)(zhi)動(dong)、反接制(zhi)(zhi)動(dong)、再生(sheng)制(zhi)(zhi)動(dong)三(san)種。
(1)能耗制(zhi)(zhi)動(dong)時(shi)切斷電動(dong)機的三相交流電源,將直(zhi)流電送(song)入(ru)定子(zi)繞組。在切斷交流電源的瞬間(jian),由于慣性作用,電動(dong)機仍按原來方(fang)向(xiang)轉動(dong),這種方(fang)式的特點是制(zhi)(zhi)動(dong)平(ping)穩(wen),但需直(zhi)流電源、大(da)功(gong)率電動(dong)機,所需直(zhi)流設備成本大(da),低速時(shi)制(zhi)(zhi)動(dong)力小。
(2)反(fan)(fan)接制(zhi)動又分負載反(fan)(fan)接制(zhi)動和電源反(fan)(fan)接制(zhi)動兩(liang)種。
1)負載反(fan)接制動(dong)(dong)又稱負載倒拉反(fan)接制動(dong)(dong)。此轉矩使(shi)重物以(yi)(yi)穩定的速度(du)緩(huan)慢下降(jiang)。這種制動(dong)(dong)的特(te)點(dian)是:電(dian)源(yuan)不(bu)用反(fan)接,不(bu)需(xu)要(yao)專(zhuan)用的制動(dong)(dong)設(she)備,而且還可以(yi)(yi)調節(jie)制動(dong)(dong)速度(du),但只適(shi)用于繞線(xian)型電(dian)動(dong)(dong)機,其轉子電(dian)路需(xu)串入大電(dian)阻,使(shi)轉差率大于1。
2)電(dian)(dian)(dian)源(yuan)反接制(zhi)(zhi)動(dong)(dong)當電(dian)(dian)(dian)動(dong)(dong)機需制(zhi)(zhi)動(dong)(dong)時,只要任意對調(diao)兩(liang)相電(dian)(dian)(dian)源(yuan)線,使旋轉(zhuan)磁場相反就能很快制(zhi)(zhi)動(dong)(dong)。當電(dian)(dian)(dian)動(dong)(dong)機轉(zhuan)速等于零時,立即切斷電(dian)(dian)(dian)源(yuan)。這種(zhong)制(zhi)(zhi)動(dong)(dong)的(de)(de)特(te)點(dian)是:停車快,制(zhi)(zhi)動(dong)(dong)力(li)較(jiao)強,無需制(zhi)(zhi)動(dong)(dong)設備。但制(zhi)(zhi)動(dong)(dong)時由(you)于電(dian)(dian)(dian)流(liu)大,沖擊力(li)也大,易使電(dian)(dian)(dian)動(dong)(dong)機過(guo)熱(re),或(huo)損傷傳動(dong)(dong)部(bu)分的(de)(de)零部(bu)件。
(3)再生(sheng)(sheng)制(zhi)動(dong)(dong)又稱回(hui)饋制(zhi)動(dong)(dong),在重(zhong)物(wu)(wu)的(de)作(zuo)用下(當起重(zhong)機電(dian)動(dong)(dong)機下放重(zhong)物(wu)(wu)),電(dian)動(dong)(dong)機的(de)轉(zhuan)速(su)高于旋轉(zhuan)磁場(chang)的(de)同(tong)步轉(zhuan)速(su)。這(zhe)時轉(zhuan)子導體產生(sheng)(sheng)感應電(dian)流(liu),在旋轉(zhuan)磁場(chang)的(de)作(zuo)用下產生(sheng)(sheng)反(fan)旋轉(zhuan)方向轉(zhuan)矩,但電(dian)動(dong)(dong)機轉(zhuan)速(su)高,需用變速(su)裝置減(jian)速(su)。
1、一般(ban)來(lai)說,小型(xing)異(yi)步電機指的就是(shi)(shi)感應運轉型(xing)異(yi)步電機。這種電機不只在啟(qi)動時,在運轉時也使用輔助線圈(quan)和電容器。雖然啟(qi)動轉矩(ju)不是(shi)(shi)很大,但(dan)其結構(gou)簡單,信(xin)賴度高,效(xiao)率(lv)也高。
2、隨負荷的大小,電機的額定轉(zhuan)速也會(hui)改變。
3、可以連續運轉。
4、使用于不(bu)需要速(su)度制動的應用場(chang)合。
5、用E種絕緣等(deng)級,而UL型電機則用A種。
6、有感應運轉型單相(xiang)異步電(dian)機(ji)和三(san)相(xiang)異步電(dian)機(ji)兩種(zhong)。
7、單(dan)相電機(ji)為感應運轉型異(yi)步電機(ji),效率高,噪聲低。
8、單相異步電(dian)(dian)機運轉(zhuan)(zhuan)時(shi),產生(sheng)和旋(xuan)轉(zhuan)(zhuan)方(fang)(fang)向(xiang)相反的轉(zhuan)(zhuan)矩,因此(ci)不(bu)可能在(zai)短(duan)時(shi)間內(nei)改變方(fang)(fang)向(xiang)。應在(zai)電(dian)(dian)機完全停止(zhi)以后,再轉(zhuan)(zhuan)換其旋(xuan)轉(zhuan)(zhuan)方(fang)(fang)向(xiang)。
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、三相電機時使(shi)用U(200V 50/60Hz)、T(220V 50/60Hz)、S(380-440V 50/60Hz)電源的(de)異(yi)步電機。
項目
事項
絕緣阻抗
在常(chang)溫金(jin)屬阻和電動機外殼(ke)之間的絕(jue)緣電阻超過100M?
絕緣內壓
在常(chang)溫金屬(shu)繞(rao)組(zu)和電(dian)動機(ji)箱之間(jian)的電(dian)壓
溫度上升
以1500V、50/60Hz輸入1min時沒有任(ren)何問題。
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(gui)格電動(dong)機使用溫度(du)為-10~40℃)
(1)電動機投(tou)入電源后不(bu)轉(zhuan)的原(yuan)因檢(jian)查及修理
電(dian)(dian)動機投入電(dian)(dian)源后不轉,一般(ban)有下列原(yuan)因:
1)控制設備的接(jie)線錯誤;
2)過電流(liu)繼電器調整(zheng)的整(zheng)定值偏小(xiao);
3)電源(yuan)未(wei)接(jie)(jie)通,如熔(rong)絲燒斷(duan)、開關(guan)有故(gu)障或觸(chu)頭接(jie)(jie)觸(chu)不良、引(yin)線斷(duan)路等;
4)電源至電動機之間的(de)連接有(you)故障(zhang);
5)電動機繞組(zu)有(you)故(gu)障,如相間(jian)短路(lu)、接(jie)(jie)地、接(jie)(jie)錯線、斷路(lu)等;
6)繞線式轉子異步電(dian)動機起(qi)動誤操作或起(qi)動電(dian)阻過小;
7)電動機軸(zhou)承有(you)故障(zhang),被(bei)卡住;
8)定、轉子鐵芯相擦(掃膛),等于增加過大的負載(zai);
9)電(dian)動(dong)機負載過(guo)大或機械轉動(dong)部分被卡(ka)住等。
2)電動機過熱(re)檢(jian)查(cha)及修理
發現正常運行的(de)電動(dong)機過(guo)熱,一(yi)般(ban)有下列原因:
1)電源(yuan)電壓(ya)突然(ran)變高,并于電動機銘牌(pai)額(e)定電壓(ya)不相符,或(huo)者(zhe)三相電源(yuan)電壓(ya)嚴(yan)重不平衡;
2)電(dian)動機所拖動的負載(zai)變動較大,電(dian)機暫時處于過載(zai)狀態;
3)由(you)于軸承產生故(gu)障或間隙磨損超限、轉軸發(fa)生彎曲、鐵(tie)(tie)芯(xin)局(ju)部過熱變形、轉子(zi)軸向串動等原因,使定、轉子(zi)鐵(tie)(tie)芯(xin)掃膛;
4)環境粉塵進入電動(dong)機內(nei)部粘附在絕緣表面(mian)上和堵塞冷(leng)(leng)卻(que)風(feng)道、冷(leng)(leng)卻(que)風(feng)管等,使電動(dong)機通風(feng)不良,冷(leng)(leng)卻(que)效(xiao)果大大降低,造(zao)成電機過(guo)熱;
5)電動機冷(leng)卻(que)裝(zhuang)置失效(xiao),調節風(feng)溫裝(zhuang)置有故障(zhang),造成電機過(guo)熱;
6)三相電(dian)動機(ji)單相運行;
7)繞(rao)組有(you)故障(zhang),如短路、斷路、接地、接錯等;
8)氣(qi)隙不(bu)均勻。
經重繞后的電(dian)動機發(fa)生過熱(re),其(qi)原因是:
1)接線錯誤;
2)線圈匝數過(guo)多或過(guo)少;
3)線(xian)圈導線(xian)過細,線(xian)圈節(jie)距過小(xiao)或過大;
4)電(dian)動(dong)機裝配質量不好,鐵(tie)芯(xin)未對(dui)齊,定轉子鐵(tie)芯(xin)軸向有差(cha)距引起軸向磁拉力(li),氣隙裝配和(he)調整不均勻(yun)。由于(yu)電(dian)動(dong)機絕緣水平不斷(duan)提(ti)高,允(yun)許溫(wen)(wen)(wen)升(sheng)限(xian)度也提(ti)高,所(suo)以電(dian)機外殼溫(wen)(wen)(wen)升(sheng)較高可能屬(shu)正常。但要用(yong)酒精溫(wen)(wen)(wen)度計(ji)測試部門的(de)外殼溫(wen)(wen)(wen)升(sheng)和(he)軸承溫(wen)(wen)(wen)升(sheng),并和(he)電(dian)動(dong)機的(de)絕緣等級(ji)所(suo)允(yun)許的(de)溫(wen)(wen)(wen)升(sheng)相對(dui)照比較后,確認電(dian)動(dong)機是過熱,那么可按以下步驟進(jin)行(xing)檢查(cha) [9] 。
1)首先檢查三相(xiang)(xiang)電(dian)(dian)(dian)源的(de)電(dian)(dian)(dian)壓(ya)是否平(ping)(ping)衡(heng),電(dian)(dian)(dian)壓(ya)波(bo)動的(de)程度(du)是否大(da)(da)于制(zhi)造場廠的(de)保證(zheng)值(zhi)(±10[%])。由于電(dian)(dian)(dian)壓(ya)不平(ping)(ping)衡(heng),產生(sheng)三相(xiang)(xiang)不平(ping)(ping)衡(heng)電(dian)(dian)(dian)流,引起電(dian)(dian)(dian)機(ji)損耗增大(da)(da)和(he)電(dian)(dian)(dian)機(ji)發熱,所以要及時(shi)糾(jiu)正。電(dian)(dian)(dian)源頻率變(bian)動對(±5[%])電(dian)(dian)(dian)機(ji)發熱也有影響,但實際變(bian)化不大(da)(da),所以在分析時(shi)一般可不考慮(lv)。
2)檢查電機是(shi)否(fou)單相(xiang)運(yun)轉,三相(xiang)接觸器的觸頭是(shi)否(fou)接觸好,開關(guan)的熔絲是(shi)否(fou)有一相(xiang)燒斷(duan),接線有否(fou)(單相(xiang))斷(duan)開。故(gu)障檢查出(chu)后進行處理。
3)檢查三(san)相電流是否超過(guo)額(e)定(ding)值。若超過(guo)額(e)定(ding)值時(shi),要檢查其原(yuan)因(yin)。處理(li)這類(lei)故障時(shi),要查清造成掃(sao)膛的(de)原(yuan)因(yin):①轉軸彎曲(qu);②軸承(cheng)故障。輕微(wei)的(de)鐵芯掃(sao)膛不影(ying)響電機正(zheng)常運行(xing),掃(sao)膛嚴重時(shi),可用車(che)刀將轉子表面輕輕切(qie)削一層(一般車(che)削直徑為0.2mm左(zuo)右為宜)。
4)粉(fen)塵敷滿絕緣影(ying)響電(dian)機(ji)散熱(re),過濾網(wang)堵塞(sai),通(tong)風(feng)(feng)道和通(tong)風(feng)(feng)管(guan)堵塞(sai)等,都會引(yin)起電(dian)機(ji)過熱(re)。因此可采(cai)取吹風(feng)(feng)清(qing)掃(sao)措施了消(xiao)除粉(fen)塵,必要時電(dian)機(ji)要解體進行(xing)清(qing)洗處(chu)理(li)。
5)如(ru)(ru)認為(wei)繞(rao)組有故障時,可進(jin)行繞(rao)組短(duan)路(lu)(lu)和接(jie)地試驗檢查(cha)。根據進(jin)行經驗表(biao)明,電機繞(rao)組如(ru)(ru)有匝(za)間(jian)(jian)短(duan)路(lu)(lu),電機則(ze)會(hui)振(zhen)動(dong),動(dong)轉時間(jian)(jian)不(bu)少(shao)就會(hui)時間(jian)(jian)不(bu)長(chang)就會(hui)冒(mao)煙(yan)。但是匝(za)間(jian)(jian)短(duan)路(lu)(lu)引(yin)起電機發熱,并且持續長(chang)時期的(de)機會(hui),是很(hen)少(shao)的(de)。
重(zhong)繞(rao)大(da)修(xiu)后的電(dian)機溫升超(chao)限(xian),可(ke)能是絕緣處理工藝不好,線圈數據(ju)不對,接線錯誤以及(ji)裝配質(zhi)量(liang)等問題(ti)引起。這時電(dian)機應解體(ti)對照原(yuan)始(shi)記錄檢查,以及(ji)查明(ming)繞(rao)組(zu)數據(ju)的正確性。