有關(guān)感應(yīng)電動(dòng)機(jī)的中英對(duì)照

1、感應(yīng)電動(dòng)機(jī)的基本工作原理可以旋轉(zhuǎn)馬蹄形磁鐵和銅圓盤(pán)的實(shí)驗(yàn)來(lái)說(shuō)明。當(dāng)馬蹄鐵磁鐵旋轉(zhuǎn)時(shí)，穿過(guò)銅圓盤(pán)的移動(dòng)磁場(chǎng)在盤(pán)中感應(yīng)出渦旋電流。這些渦旋電流的方向能夠引起圓盤(pán)跟隨馬蹄形磁鐵旋轉(zhuǎn)。根據(jù)右手定則將會(huì)產(chǎn)生渦旋電流。右手定則指出：伸出右手的大拇指、食指、中指，并讓他們互相垂直，這樣實(shí)質(zhì)的方向?yàn)榇艌?chǎng)方向，大拇指指向?yàn)閷?dǎo)體運(yùn)動(dòng)方向，中指的方向?yàn)楦袘?yīng)電壓的方向。注意，導(dǎo)體的相對(duì)運(yùn)動(dòng)方向和磁場(chǎng)旋轉(zhuǎn)的方向相反。運(yùn)用左手定責(zé)得出銅盤(pán)受到得力與磁鐵旋轉(zhuǎn)方向一致。左手定則指出：伸出左手的大拇指、食指、中指，并令他們互相垂直，讓食指指向磁場(chǎng)方向，中指指向電流的方向，則大拇指的方向即為作用力的方向。盡管銅盤(pán)將按照旋轉(zhuǎn)磁場(chǎng)的

2、方向運(yùn)動(dòng)，但它決不會(huì)與磁場(chǎng)的速度相同。因?yàn)槿缍咚俣认嗤?，它們之間將不存在相對(duì)運(yùn)動(dòng)，從而銅盤(pán)中也就沒(méi)有感應(yīng)電流產(chǎn)生。旋轉(zhuǎn)磁場(chǎng)和銅盤(pán)間的速度之差稱為轉(zhuǎn)差率。轉(zhuǎn)差率對(duì)于感應(yīng)式電動(dòng)機(jī)的工作至關(guān)重要。在感應(yīng)電動(dòng)機(jī)中，旋轉(zhuǎn)磁場(chǎng)是由定子中的繞組激發(fā)的，感應(yīng)電流是在轉(zhuǎn)子中流動(dòng)的，旋轉(zhuǎn)馬蹄磁鐵和銅圓盤(pán)在結(jié)構(gòu)上與當(dāng)今的感應(yīng)式電動(dòng)機(jī)有很大區(qū)別，但是它們基本原理上是相同的。旋轉(zhuǎn)磁場(chǎng)對(duì)感應(yīng)式電動(dòng)機(jī)是至關(guān)重要的。實(shí)際電機(jī)中，它是通過(guò)空間上交替布置繞組和時(shí)間相位上相互交替的激勵(lì)電壓實(shí)現(xiàn)的。轉(zhuǎn)子是采用層疊的鋼片沖壓而成的，轉(zhuǎn)子繞組有疊片上沖槽內(nèi)嵌入的導(dǎo)體條構(gòu)成。這寫(xiě)導(dǎo)體條在兩端通過(guò)短路環(huán)構(gòu)成短路。不包括層疊片式鐵心中鑄入鋁

3、的方式構(gòu)成轉(zhuǎn)子。在較大功率的交流電機(jī)中，鑄鋁轉(zhuǎn)子不實(shí)用，采用的是在轉(zhuǎn)子槽中插入鋼條的作法。這些鋼條在兩端通過(guò)銅短路環(huán)短路，短路環(huán)是采用纖接或焊接的方式與銅條相連的。有時(shí)采用青銅或其他合金代替銅來(lái)制作鼠籠和短路環(huán)。到底在多大功率上，以銅轉(zhuǎn)子代替鑄鋁轉(zhuǎn)子因不同的制造商而不同名的是幾千馬力以上的電動(dòng)機(jī)轉(zhuǎn)子一般都采用條形工藝。另一個(gè)與電動(dòng)機(jī)容量有關(guān)的結(jié)構(gòu)特性是所采用的線圈組的類型。在中小型交流電動(dòng)機(jī)中，大多數(shù)線圈是散繞的。這些線圈采用的是圓截面導(dǎo)線，這些導(dǎo)線繞置在定子槽中，并將其端部繞置成菱形。只不過(guò)雜給定繞組中導(dǎo)線是隨即分布的，因此得名“散繞”。對(duì)于大型交流電動(dòng)機(jī)尤其是高壓電動(dòng)機(jī)，如2300v以上的

4、電動(dòng)機(jī)，則采用模繞線圈。這些線圈采用截面為矩形的導(dǎo)線構(gòu)成，將它們彎曲成型后纏上絕緣帶。在制作定子繞組時(shí)，線圈被做成適當(dāng)?shù)某叽纾员銓⒄麄€(gè)線圈置于定子槽中。模繞式線圈可用作高壓線圈，因?yàn)樗^容易在將繞組置于定子之前為每個(gè)線圈采用額外的絕緣措施。.motorthe basic principe of operation of an induction machine in illustrated by the revolving horsesshou-magnet and copper-disk experiment pictured in fig 1-1.when the horseshou m

5、agnet is rotated，the moving magnetic field passing across the copper disk induces eddy currents in the disk.these eddy currents are in such a direction as to cause the disk to follow the rotation of the horseshoe magnet.with the direction of rotation shown in the figure，the eddy cyrrents will be as

6、displayed to flemings right-hand rule.flemings right-hand rule：place the thumb and the first and second fingers of the right hand so that all three are mutually perpendicular.with the hand in this position，the first finger in pointed in the direction of the field，the thumb is in the direction of mot

7、ion of the conductor， and the second finger is in the direction of the induced voltage.note that the relative motion of the conductor is opposite to the direction of rotation of the magnetic field.by applying flemings left-hand rule，the force on the copper disk is determined to be in the direction o

8、f rotation of the magnet.flemings left-hand rule：place the thumb and the first and second fingers of the left hand so that all three are mutually perpendicular to each other.with the first finger in the direction of the field and the second finger in the direction of the current，the thumb indicates

9、the direction of the force.whereas the copper disk will rotate in the same direction as the rotating magnetic field，it will never reach the same speed ad the rotating magnet，because if it did，there would be no relative motion between the two and therefore no current induced in the copper disk.the di

10、fference in speed between the rotartng magnetic field and the copper disk is known as slip，which is essential to the operation of an induction motor.in induction motors the rotating magnetic field is set up by windings in the stator，and the induced currents are carried by conductors in the rotor.the

11、 rotating horseshoe magnet and copper disk are considerably different in structure from todays induction motor，but the basic principles of operation are the same.the rotating magnetic field is essential to the functioning of an induction motor.in practical machines this rotating magnetic field is ac

12、hered by a combination of a space displacement of the winding and a time-phase displacement of the exciting voltage.the rotor is formed from laminated electrical steel punching，and the rotor winding consists of bars contained in slots punched in the laminations.these bars are short-circuited at both

13、 ends by a short-circuiting ring.a bar-end ring structure，without the laminated core，is called a squirrel cage.in small-and medium-horsepower sizes，rotors are made by casting aluminum into the rotou core，in the larger sizes of ac motors，cast-aluminum rotors are not pratical，and copper bars are inser

14、ted into rotor slots.these copper bars are short circuited at both ends by a copper end ring，and the end ring is brazed or soldered onto the bars，sometimes bronze or other alloys are used ti replace copper in making the cage and end ring.the size at which the transition between cast-aluminum and cop

15、per rotors takes place varies among motor manyfacturers，but virtually all rotors in motor sizes of several thousand horsepower and above are built with bar-type rotors.another construction feature dependent in motor size is the type of coil winding used.in small and medium-size ac motors，most coils

16、are random-wound.these coils are made with round wire，which is wound into the stator slots and assumes a diamond shapr in the end turns； however， the wires are randomly located within a given coil，and hence the name “random-wound.” for large ac motors and particularly for high-voltagemotors，2300v and above，form-would coils are used.these coils are construted from rectangular wire，which is bent into shape around forms and them taped.the coil is formed to the proper size so