電機(jī)與拖動(dòng)技術(shù)項(xiàng)目化教程 課件 2三相異步電機(jī)的轉(zhuǎn)速與轉(zhuǎn)向

三相異步電機(jī)的轉(zhuǎn)速與轉(zhuǎn)向SpeedandDirectionofThree-PhaseAsynchronousMotor旋轉(zhuǎn)磁場(chǎng)的轉(zhuǎn)向與轉(zhuǎn)速principle取決于三相電流的相序。旋轉(zhuǎn)磁場(chǎng)方向：U1V1W1

與三相電流的相序：L1→

L2→

L3一致。U1U2V1V2W2W1L1L2L3U1U2V1V2W1W2i2i1i3i1i2ImOti3旋轉(zhuǎn)磁場(chǎng)的轉(zhuǎn)向與轉(zhuǎn)速principle如何改變旋轉(zhuǎn)磁場(chǎng)的旋轉(zhuǎn)方向？L1L2L3U1U2V1V2W1W2i2i1i3L1L3L2U1U2V1V2W1W2i3i1i2U1V1W1U1V1W1U1V1W1U1V1W1交換任意兩根電源線改變電流相序旋轉(zhuǎn)磁場(chǎng)的轉(zhuǎn)向與轉(zhuǎn)速principle▲極對(duì)數(shù)（p）的概念：以Y型接法為例，當(dāng)每相繞組只有一個(gè)線圈時(shí)，按右下圖放入定子槽內(nèi)，合成的旋轉(zhuǎn)磁場(chǎng)只有一對(duì)磁極，則極對(duì)數(shù)為1。即p=1。U1U2V1V2W2W1L1L2L3U1U2V1V2W1W2i2i1i3旋轉(zhuǎn)磁場(chǎng)的轉(zhuǎn)向與轉(zhuǎn)速principle以Y型接法為例，將每相繞組都改用兩個(gè)線圈串聯(lián)組成。按下圖放入定子槽內(nèi)。形成的磁場(chǎng)則是兩對(duì)磁極。即p=2

i3W2V4U1V1W1U2V2W3U3U4V3W4i1i2U1U2U3U4V4V2V3W4W1W2W3L1L2L3V1旋轉(zhuǎn)磁場(chǎng)的轉(zhuǎn)向與轉(zhuǎn)速principleU1U2V1V2W2W1ωt=0ωt=π/2U1U2V1V2W2W1U1U2V1V2W2W1ωt=πωt=3π/2U1U2V1V2W2W1ωt=2πU1U2V1V2W2W1iuivImOωtiw2π0π/2π3π/2P=1旋轉(zhuǎn)磁場(chǎng)的轉(zhuǎn)向與轉(zhuǎn)速principle電流變化一周→旋轉(zhuǎn)磁場(chǎng)轉(zhuǎn)一圈電流每秒鐘變化50周→旋轉(zhuǎn)磁場(chǎng)轉(zhuǎn)50圈→旋轉(zhuǎn)磁場(chǎng)轉(zhuǎn)3000圈電流每分鐘變化(50×60)周p=1

時(shí)：旋轉(zhuǎn)磁場(chǎng)的轉(zhuǎn)向與轉(zhuǎn)速principleiuivImOωtiw2π0π/2π3π/2P=2ωt=

0U1U2U3U4V1V4V2V3W4W1W2W3NNSSωt=π/2U1U2U3U4V1V4V2V3W4W1W2W3NNSSωt=

3π/2U1U2U3U4W3W2W4W1V4V1V2V3NNSSωt=πU1U2U3U4V1V4V2V3W4W1W2W3NNSSωt=

2πU1U2U3U4V1V4V2V3W4W1W2W3NNSS旋轉(zhuǎn)磁場(chǎng)的轉(zhuǎn)向與轉(zhuǎn)速principle電流變化一周→旋轉(zhuǎn)磁場(chǎng)轉(zhuǎn)半圈電流每秒鐘變化50周→旋轉(zhuǎn)磁場(chǎng)轉(zhuǎn)25圈→旋轉(zhuǎn)磁場(chǎng)轉(zhuǎn)1500圈電流每分鐘變化(50×60)周p=2時(shí)：旋轉(zhuǎn)磁場(chǎng)的轉(zhuǎn)向與轉(zhuǎn)速principle600pfn=min）r/(

p123456n0/(r/min)300015001000750600500f=50Hz時(shí),不同極對(duì)數(shù)時(shí)的同步轉(zhuǎn)速如下:p為任意值時(shí)，三相異步電動(dòng)機(jī)的旋轉(zhuǎn)磁場(chǎng)的轉(zhuǎn)速（同步轉(zhuǎn)速）為：轉(zhuǎn)子的轉(zhuǎn)向與轉(zhuǎn)速principleNS轉(zhuǎn)子旋轉(zhuǎn)方向與旋轉(zhuǎn)磁場(chǎng)旋轉(zhuǎn)方向一致改變旋轉(zhuǎn)磁場(chǎng)方向就能改變電機(jī)旋轉(zhuǎn)方向任意調(diào)換三相異步電機(jī)的兩根進(jìn)線，就能改變電源相序，改變電機(jī)的旋轉(zhuǎn)方向旋轉(zhuǎn)磁場(chǎng)的轉(zhuǎn)向與轉(zhuǎn)速principle①轉(zhuǎn)子轉(zhuǎn)速n=磁場(chǎng)轉(zhuǎn)速n0②轉(zhuǎn)子轉(zhuǎn)速n>磁場(chǎng)轉(zhuǎn)速n0②轉(zhuǎn)子轉(zhuǎn)速n<磁場(chǎng)轉(zhuǎn)速n0電機(jī)降速電機(jī)降速負(fù)載適當(dāng)時(shí)，電機(jī)勻速運(yùn)行旋轉(zhuǎn)磁場(chǎng)的轉(zhuǎn)向與轉(zhuǎn)速principle轉(zhuǎn)差率（S）：同步轉(zhuǎn)速與轉(zhuǎn)子轉(zhuǎn)速之差與同步轉(zhuǎn)速的比值。轉(zhuǎn)子未轉(zhuǎn)動(dòng)時(shí)，n=0，s=1；電機(jī)理想空載時(shí)，n≈n0，s≈0。作為電動(dòng)機(jī)，轉(zhuǎn)速在0~n0范圍內(nèi)變化，轉(zhuǎn)差率在0~1范圍內(nèi)變。三相異步電機(jī)的運(yùn)行狀態(tài)principle狀態(tài)發(fā)電機(jī)電動(dòng)機(jī)電磁制動(dòng)實(shí)現(xiàn)外力使電機(jī)快速旋轉(zhuǎn)定子繞組接對(duì)稱電源外力使電機(jī)沿磁場(chǎng)反方向旋轉(zhuǎn)電磁轉(zhuǎn)矩制動(dòng)驅(qū)動(dòng)制動(dòng)能量關(guān)系機(jī)械能轉(zhuǎn)變?yōu)殡娔茈娔苻D(zhuǎn)變?yōu)闄C(jī)械能電能和機(jī)械能變成內(nèi)能旋轉(zhuǎn)磁場(chǎng)的旋轉(zhuǎn)方向取決于三相電流的相序，改變電流相序就能改變旋轉(zhuǎn)磁場(chǎng)的