江北電機的(de)(de)原理:電機(ji)的(de)(de)原理很簡單,簡單的(de)(de)說就是利用電能在線(xian)圈上(shang)產生旋轉(zhuan)(zhuan)(zhuan)磁場,并推動(dong)(dong)轉(zhuan)(zhuan)(zhuan)子轉(zhuan)(zhuan)(zhuan)動(dong)(dong)的(de)(de)裝置。學過(guo)電磁感應(ying)定(ding)律的(de)(de)都知道(dao),通電的(de)(de)線(xian)圈在磁場中會受力轉(zhuan)(zhuan)(zhuan)動(dong)(dong),電機(ji)的(de)(de)基本(ben)原理就是如(ru)此,這是初中物理的(de)(de)知識。電機(ji)結構:拆開過(guo)電機(ji)的(de)(de)人都知道(dao),電機(ji)主要是兩部(bu)分組成,固定(ding)不動(dong)(dong)的(de)(de)定(ding)子部(bu)分以及轉(zhuan)(zhuan)(zhuan)動(dong)(dong)的(de)(de)轉(zhuan)(zhuan)(zhuan)子部(bu)分,具體如(ru)下:
1、定子(靜止部(bu)分)
定(ding)子(zi)鐵(tie)心:電機磁路重要部分,并在其上(shang)放置定(ding)子(zi)繞組;
定(ding)子繞(rao)組:就是線(xian)圈,電動機的電路部分,接電源,用于(yu)產生(sheng)旋轉磁場;
機座:固定(ding)定(ding)子鐵心(xin)及電機端蓋,并起防護、散熱等作用;
2、轉子(旋轉部分)
轉(zhuan)子鐵心:電機磁路的(de)重要部分,在(zai)鐵心槽內放置轉(zhuan)子繞組(zu);
轉(zhuan)子繞(rao)組:切(qie)割定子旋轉(zhuan)磁(ci)場產生(sheng)感應(ying)電動勢及電流,并形成電磁(ci)轉(zhuan)矩從而使(shi)電動機旋轉(zhuan);
電機的幾個計(ji)算公式(shi):
1、電磁相關的
1)電(dian)動機的感應電(dian)動勢(shi)公式:E=4.44*f*N*Φ,E為(wei)(wei)線圈電(dian)動勢(shi)、 f為(wei)(wei)頻率 、 S為(wei)(wei)環繞出的導體(ti)(比(bi)如鐵芯)橫截面積(ji)、 N為(wei)(wei)匝(za)數、Φ是磁通。
公式(shi)是(shi)怎(zen)么推導來的(de)(de),這些事情我們(men)就不去(qu)鉆研(yan)了,我們(men)主(zhu)要(yao)是(shi)看(kan)看(kan)怎(zen)么利用它。感應(ying)電(dian)(dian)動(dong)勢(shi)是(shi)電(dian)(dian)磁感應(ying)的(de)(de)本質(zhi),有感應(ying)電(dian)(dian)動(dong)勢(shi)的(de)(de)導體(ti)閉合后(hou),就會產(chan)生(sheng)感應(ying)電(dian)(dian)流。感應(ying)電(dian)(dian)流在磁場中就會受到(dao)安(an)培(pei)力,產(chan)生(sheng)磁矩,從而推動(dong)線圈(quan)轉(zhuan)動(dong)。
從(cong)上面公式知道,電動勢大(da)小與(yu)電源頻率(lv)、線圈匝數(shu)及磁(ci)通量成正比。
磁(ci)通量計算公式Φ=B*S*COSθ,當面積為S的平(ping)面與(yu)磁(ci)場方(fang)向垂直的時候,角θ為0,COSθ就等于(yu)1,公式就變(bian)成Φ=B*S。
將上面兩個(ge)公式(shi)結合(he)一下(xia),就(jiu)可以得到電(dian)機磁(ci)通強度計算公式(shi)為:B=E/(4.44*f*N*S)。
2)另外一個(ge)是(shi)安培力公式(shi)(shi),我們要知道線圈(quan)受到的(de)(de)力是(shi)多少,就(jiu)需要這(zhe)個(ge)公式(shi)(shi)F=I*L*B*sinα,其(qi)中I為電(dian)流強(qiang)度(du),L為導(dao)體長度(du),B為磁(ci)場強(qiang)度(du),α是(shi)電(dian)流方向與磁(ci)場方向間的(de)(de)夾角。當導(dao)線垂直于磁(ci)場時候(hou),公式(shi)(shi)就(jiu)變(bian)成F=I*L*B了(如果(guo)是(shi)N匝線圈(quan)的(de)(de)話,磁(ci)通B就(jiu)是(shi)N匝線圈(quan)的(de)(de)總磁(ci)通,而不(bu)需要再乘N了)。
知道了受(shou)力(li),就知道轉矩(ju),轉矩(ju)等于扭(niu)力(li)乘以作(zuo)用(yong)(yong)半徑,T=r*F=r*I*B*L(向量(liang)乘積)。通過功(gong)率=力(li)*速(su)度(du)(P=F*V)以及(ji)線速(su)度(du)V=2πR*每秒轉速(su)(n秒)兩個公(gong)式 ,可(ke)以與功(gong)率建立上關(guan)系,得到下面序(xu)號3的(de)公(gong)式。不過要注意,這時候(hou)使用(yong)(yong)實際輸出(chu)扭(niu)矩(ju),所以計(ji)算出(chu)的(de)功(gong)率是輸出(chu)功(gong)率。
2、交流異步(bu)電(dian)機(ji)(ji)的轉(zhuan)(zhuan)速(su)(su)(su)(su)計算公式:n=60f/P,這個很簡單,轉(zhuan)(zhuan)速(su)(su)(su)(su)與電(dian)源頻率成正比,與電(dian)機(ji)(ji)極(ji)對子(記(ji)住是一對)數成反比,直接(jie)套(tao)用(yong)公式就好。不(bu)(bu)過(guo)這個公式實(shi)際計算出是同步(bu)轉(zhuan)(zhuan)速(su)(su)(su)(su)(旋轉(zhuan)(zhuan)磁(ci)場速(su)(su)(su)(su)度),異步(bu)電(dian)機(ji)(ji)實(shi)際轉(zhuan)(zhuan)速(su)(su)(su)(su)會略低(di)于(yu)同步(bu)轉(zhuan)(zhuan)速(su)(su)(su)(su),所以我(wo)們往往會看到4極(ji)電(dian)機(ji)(ji)一般是1400多轉(zhuan)(zhuan),達不(bu)(bu)到1500轉(zhuan)(zhuan)。
3、電(dian)機(ji)(ji)轉(zhuan)矩、功(gong)(gong)(gong)(gong)(gong)(gong)率(lv)計轉(zhuan)速的關(guan)系:T=9550P/n(P是(shi)(shi)電(dian)機(ji)(ji)功(gong)(gong)(gong)(gong)(gong)(gong)率(lv)、n是(shi)(shi)電(dian)機(ji)(ji)轉(zhuan)速),可以從上面序號1內(nei)容中(zhong)推導(dao)出(chu)來,不(bu)過我們(men)沒必要學(xue)會推導(dao),記住(zhu)這個(ge)計算公(gong)式就可以。不(bu)過再次提(ti)醒,公(gong)式中(zhong)功(gong)(gong)(gong)(gong)(gong)(gong)率(lv)P不(bu)是(shi)(shi)輸(shu)入(ru)功(gong)(gong)(gong)(gong)(gong)(gong)率(lv),而是(shi)(shi)輸(shu)出(chu)功(gong)(gong)(gong)(gong)(gong)(gong)率(lv),由于電(dian)機(ji)(ji)有損耗,輸(shu)入(ru)功(gong)(gong)(gong)(gong)(gong)(gong)率(lv)不(bu)等(deng)于輸(shu)出(chu)功(gong)(gong)(gong)(gong)(gong)(gong)率(lv)。但是(shi)(shi)書本上往往理想化,將輸(shu)入(ru)功(gong)(gong)(gong)(gong)(gong)(gong)率(lv)等(deng)于輸(shu)出(chu)功(gong)(gong)(gong)(gong)(gong)(gong)率(lv)了。
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