電動(dòng)機(jī)轉(zhuǎn)速測定系統(tǒng)的設(shè)計(jì)外文翻譯

1、外文文獻(xiàn)譯文設(shè)計(jì)（論文）題目：電動(dòng)機(jī)轉(zhuǎn)速測定系統(tǒng)的設(shè)計(jì)專業(yè)與班級(jí)：測控技術(shù)與儀器0601班學(xué)生姓名：楊紅偉指導(dǎo)教師：周彬2010年3月18日Synchronous motorAbstract ：In recent decades, with the power electronics, microelectronics technology and the development of modern control theory, medium and small power motors in the industrial and agricultural production and pe

2、ople's daily lives are very broad application. Particularly in the township enterprises and household electrical appliances, need a large number of medium and small-power motors. Because of this motor development and wide application, its use, maintenance and repair work has become increasingly

3、important，Here are just on the knowledge of synchronous motor1. Principle of operationIn order to understand the principle of operation of a synchronous motor, let us examine what happens if we connect the armature winding (laid out in the stator) of a 3-phase synchronous machine to a suitable balan

4、ced 3-phase source and the field winding to a D.C source of appropriate voltage. The current flowing through the field coils will set up stationary magnetic poles of alternate North and South.(for convenience let us assume as alient pole rotor, as shown in Fig. 50). On the other hand, the 3-phase cu

5、rrents flowing in the armature winding produce a rotating magnetic field rotating at synchronous speed. In other words there will be moving North and South poles established in the stator due to the 3-phase currents i.e at any location in the stator there will be a North pole at some instant of time

6、 and it will become a South pole after a time period corresponding to half a cycle. (after a time = 1/2f , where f = frequency of the supply). Let us assume that the stationary South pole in the rotor is aligned with the North pole in the stator moving in clockwise direction at a particular instant

7、of time, as shown in Fig50. These two poles get attracted andFigure 50: Force of attraction between stator poles and rotor poles - resulting in production of torque in clockwise direction try to maintain this alignment ( as per Lenz' s law) and hence the rotor pole tries to follow the stator pol

8、e as the conditions are suitable for the production of torque in the clockwise direction. However the rotor can not move instantaneously due to its mechanical inertia, and so it needs sometime to move. In the mean time, the stator pole would quickly (a time duration corresponding to half a cycle) ch

9、a nge its polarity and becomes a South poleSo the force of attractio n will no longer be present and instead the like poles experience a force of repulsion as shown in Fig. 51. In other words, the conditions are now suitable for the Figure 51: Force of repulsion between stator poles and rotor poles

10、- resulting in production of torque in anticlockwise direction production of torque in the anticlockwise direction. Even this condition will not last longer as the stator pole would again change to North pole after a time of 1/ 2f .Thus the rotor will experience an alternating force which tries to m

11、ove it clockwise and anticlockwise at twice the frequency of the supply, i.e. at intervals corresponding to 1/ 2f seconds. As this duration is quite small compared to the mechanical time constant of the rotor, the rotor cannot respond and move in any direction. The rotor continues to be stationary o

12、nly.On the contrary if the rotor is brought to near synchronous speed by some external means say a small motor (known as pony motor-which could be a D.C or AC induction rotor) mounted on the same shaft as that of the rotor, the rotor poles get locked to the unlike poles in the stator and the rotor c

13、ontinues to run at the synchronous speed even if the supply to the pony motor is disconnected.Thus the synchronous rotor cannot start rotating on its own or usually we say that the synchronous rotor has no starting torque. So, some special provision has to be made either inside the machine or outsid

14、e of the machine so that the rotor is brought to near about its synchronous speed. At that time, if the armature is supplied with electrical power, the rotor can pull into step and continue to operate at its synchronous speed. Some of the commonly used methods for starting synchronous rotor are desc

15、ribed in the following section.2. Methods of starting synchronous motorBasically there are three methods that are used to start a synchronous motor:? To reduce the speed of the rotating magnetic field of the stator to a low eonugh value that the rotor can easily accelerate and lock in with it during

16、 one half-cycle of the rotating magnetic field' s rotation. This is done by reducing the frequency of theapplied electric power. This method is usually followed in the case of inverter-fed synchronous motor operating under variable speed drive applications.? To use an external prime mover to acc

17、elerate the rotor of synchronous motor near to its synchronous speed and then supply the rotor as well as stator. Of course care should be taken to ensure that the direction of rotation of the rotor as well as that of the rotating magnetic field of the stator are the same. This method is usually fol

18、lowed in the laboratory- the synchronous machine is started as a generator and is then connected to the supply mains by following the synchronization or paralleling procedure. Then the power supply to the prime mover is disconnected so that the synchronous machine will continue to operate as a motor

19、.? To use damper windings or amortisseur windings if these are provided in the machine. The damper windings or amortisseur windings are provided in most of the large synchronous motors in order to nullify the oscillations of the rotor whenever the synchronous machine is subjected to a periodically v

20、arying load.Each of these methods of starting a synchronous motor are described below in detail.2.1Motor starting by reducing the supply FrequencyIf the rotating magnetic field of the stator in a synchronous motor rotates at a low enough speed, there will be no problem for the rotor to accelerate an

21、d to lock in with the stator 'msagnetic field. The speed of the stator magnetic field can then be increased to its rated operating speed by gradually increasing the supply frequency f up to its normal 50or60Hz value.This approach to starting of synchronous motors makes a lot of sense, but there

22、is a big problem: Where from can we get the variable frequency supply? The usual power supply systems generally regulate the frequency to be 50 or 60 Hz as the case may be. However, variable-frequency voltage source can be obtained from a dedicated generator only in the olden days and such a situati

23、on was obviously impractical except for very unusual or special drive applications.But the present day solid state power converters offer an easy solution to this. We now have the rectifier-inverter and cycloconverters, which can be used to convert a constant frequency AC supply to a variable freque

24、ncy AC supply. With the development of such modern solid-state variable-frequency drive packages, it is thus possible to continuously control the frequency of the supply connected to the synchronous motor all the way from a fraction of a hertz up to and even above the normal rated frequency. If such

25、 a variable-frequency drive unit is included in a motor-control circuit to achieve speed control, then starting the synchronous motor is very easy-simply adjust the frequency to a very low value for starting, and then raise it up to the desired operating frequency for normal running.When a synchrono

26、us motor is operated at a speed lower than the rated speed, its internal generated voltage (usually called the counter EMF) EA = K-will be smaller than normal. As such the terminal voltage applied to the motor must be reduced proportionally with the frequency in order to keep the stator current with

27、in the rated value. Generally, the voltage in any variable-frequency power supply varies roughly linearly with the output frequency.2.2 Motor Starting with an External MotorThe second method of starting a synchronous motor is to attach an external starting motor (pony motor) to it and bring the sync

28、hronous machine to near about its rated speed (but not exactly equal to it, as the synchronization process may fail to indicate the point of closure of the main switch connecting the synchronous machine to the supply system) with the pony motor. Then the output of the synchronous machine can be sync

29、hronized or paralleled with its power supply system as a generator, and the pony motor can be detached from the shaft of the machine or the supply to the pony motor can be disconnected. Once the pony motor is turned OFF, the shaft of the machine slows down, the speed of the rotor magnetic field B R

30、falls behind Bnet, momentarily and the synchronous machine continues to operate as a motor. As soon as it begins to operates as a motor the synchronous motor can be loaded in the usual manner just like any motor.This whole procedure is not as cumbersome as it sounds, since many synchronous motors ar

31、e parts of motor-generator sets, and the synchronous machine in the motor-generator set may be started with the other machine serving as the starting motor. More over, the starting motor is required to overcome only the mechanical inertia of the synchronous machine without any mechanical load (load

32、isattached only after the synchronous machine is paralleled to the power supply system).Since only the motors inertia must be overtchoemseta, rting motor can have a muchsmaller rating than the synchronous motor it is going to start. Generally most of the large synchronous motors have brushless excit

33、ation systems mounted on their shafts. It is then possible to use these exciters as the starting motors. For many medium-size to large synchronous motors, an external starting motor or starting by using the exciter may be the only possible solution, because the power systems they are tied to may not

34、 be able to handle the starting currents needed to use the damper winding.Motor from the development since the advent of generations of products are all around the basic principle of the development, how to run and maintain the main motor is the most important task we are. Motor in China's econo

35、mic development play a vital role in, along with China's accession to WTO, the industry faced National Motors enormous international competitive pressures and challenges are becoming more intensified. To save energy and protect the local environment, high efficiency motor is the international de

36、velopment trend. It would appear, is to promote the high-efficiency motor is necessary.From：Corps from 2005 Sichuan synchronous motor works5 / 10同步電動(dòng)機(jī)摘要：近幾十年來，隨著電力電子技術(shù)、 微電子技術(shù)及現(xiàn)代控制理論的發(fā)展， 中、 小功率電動(dòng)機(jī)在工農(nóng)業(yè)生產(chǎn)及人們的日常生活中都有極其廣泛的的應(yīng)用。 特別是 在鄉(xiāng)鎮(zhèn)企業(yè)及家用電器中， 更需要有大量的中、 小功率電動(dòng)機(jī)。 由于這種電動(dòng)機(jī) 的發(fā)展及廣泛的應(yīng)用， 它的使用、 保養(yǎng)和維護(hù)工作也越來越重要， 下面就

37、介紹關(guān) 于同步電動(dòng)機(jī)的相關(guān)知識(shí)。為了了解一個(gè)同步電動(dòng)機(jī)的工作原理， 讓我們研究這是如何發(fā)生的， 如果我 們連接的電樞繞組 （在定子里闡述） 是3相同步機(jī)合適的平衡 3相電源和勵(lì)磁繞組 的D. C適當(dāng)?shù)碾妷?。目前，通過場線圈流動(dòng)將替代固定南北磁極，另一方面，3相電流在電樞繞組產(chǎn)生旋轉(zhuǎn)磁場的同步轉(zhuǎn)速旋轉(zhuǎn)流動(dòng)。 換言之在移動(dòng)中的任何位 置定子由于有三相電流， 建立南北兩極將在一定的時(shí)間并即時(shí)北極將成為一段時(shí) 間后1南極期間相應(yīng)的半周期（經(jīng)過一段時(shí)間=1/2f，其中f =頻率的供應(yīng)）讓我 們假設(shè)，固定南極轉(zhuǎn)子與定子在北極順時(shí)針方向排列正以特定時(shí)刻的時(shí)間， 部隊(duì) 之間定子，轉(zhuǎn)子極 - 在生產(chǎn)中的吸引力造

38、成的扭矩順時(shí)針方向努力維持這個(gè)路 線（根據(jù)楞次定律）因此轉(zhuǎn)子極試圖按定子極作為條件的扭矩順時(shí)針方向生產(chǎn)。 不過，轉(zhuǎn)子不能即時(shí)移動(dòng)，由于它的機(jī)械慣性，因此需要某個(gè)移動(dòng)來執(zhí)行。與此 同時(shí)，定子極會(huì)很快（持續(xù)時(shí)間相應(yīng)的半周期）改變其極性，成為南極。因此， 引力將不再存在，而是像極經(jīng)歷一個(gè)斥力，與定子磁極，轉(zhuǎn)子磁極斥力 - 生產(chǎn) 中產(chǎn)生的扭矩在逆時(shí)針的方向。生產(chǎn)的扭矩在逆時(shí)針的方向。 即使是這種情況不會(huì)持續(xù)作為定子極長將再次 改變北極后時(shí)間。因此，轉(zhuǎn)子將體驗(yàn)交替的力量，試圖提出相應(yīng)的時(shí)間間隔為 1 秒，順時(shí)針和逆時(shí)針的兩倍供應(yīng)，即頻率。隨著這一期限是非常小的機(jī)械相比， 轉(zhuǎn)子時(shí)間常數(shù)，轉(zhuǎn)子無法響應(yīng)和向任

39、何方向移動(dòng)。轉(zhuǎn)子繼續(xù)平穩(wěn)。相反，如果轉(zhuǎn)子所帶來的一些外部手段來接近同步轉(zhuǎn)速說， 小馬達(dá)（稱為小 馬電機(jī)可在轉(zhuǎn)導(dǎo)轉(zhuǎn)子） 一直流或交流上作為轉(zhuǎn)子， 同一軸上的轉(zhuǎn)子磁極被鎖定在 不同的定子和轉(zhuǎn)子磁極繼續(xù)運(yùn)行在同步轉(zhuǎn)速，即使到小馬汽車供應(yīng)中斷。因此， 同步轉(zhuǎn)子無法啟動(dòng)自身旋轉(zhuǎn)或通常我們說， 沒有同步轉(zhuǎn)子起動(dòng)轉(zhuǎn)矩。 因此， 一些 特殊的規(guī)定， 必須內(nèi)作出任何機(jī)器或機(jī)器的外面， 使轉(zhuǎn)子提請(qǐng)有關(guān)其同步轉(zhuǎn)速附 近。當(dāng)時(shí)，如果電樞與電力供應(yīng)的轉(zhuǎn)子拉入一步，將要繼續(xù)運(yùn)轉(zhuǎn)其同步的速度。 常用下面描述的方法啟動(dòng)同步電動(dòng)機(jī)。2. 同步電動(dòng)機(jī)啟動(dòng)方法基本上有三個(gè)用來同步電動(dòng)機(jī)啟動(dòng)方法 要減少定子旋轉(zhuǎn)磁場速度足夠低的價(jià)值，

40、 轉(zhuǎn)子可以輕松地加速并鎖定在與 它在1個(gè)半的旋轉(zhuǎn)磁場的旋轉(zhuǎn)周期。這是通過減少電力的使用頻率。這種方法通 常遵循的逆變器的情況饋?zhàn)兯衮?qū)動(dòng)下的同步電動(dòng)機(jī)運(yùn)行的應(yīng)用程序。要使用一個(gè)外部的主要驅(qū)動(dòng)者， 加快同步電機(jī)轉(zhuǎn)子附近的同步速度， 然后 在供應(yīng)的轉(zhuǎn)子和定子。 當(dāng)然， 應(yīng)采取確保轉(zhuǎn)子的旋轉(zhuǎn)方向， 以及這對(duì)定子旋轉(zhuǎn)磁 場是相同的。這種方法通常是遵循該實(shí)驗(yàn)室的同步電機(jī)啟動(dòng)發(fā)生器和一個(gè)連接的 應(yīng)用程序，然后按照同步或平行的程序供應(yīng)電源。 那么電源的主要驅(qū)動(dòng)者被斷開， 使同步電機(jī)將繼續(xù)作為一個(gè)發(fā)動(dòng)機(jī)。要使用阻尼繞組的繞組如果這些是在馬提供的燒瓷。 阻尼繞組的繞組中提 供的最大型同步電動(dòng)機(jī)， 以抵銷了轉(zhuǎn)子的振動(dòng)， 每當(dāng)同步機(jī)是受到周期性變化的 負(fù)載。對(duì)同步電動(dòng)機(jī)的啟動(dòng)，這些方法如下描述。2.