外文文獻及翻譯--三相異步電動機的幾種調速方式

1、<p><b>　　畢 業(yè) 論 文</b></p><p>　　外 文 文 獻 譯 文 及 原 文</p><p>　　學 生： </p><p>　　學 號： </p><p>　　院 （系）：

2、電氣與信息工程學院 </p><p>　　專 業(yè)： 電氣工程及其自動化 </p><p>　　指導教師： </p><p>　　2014 年 6 月 10 日</p><p><b>　　中文2340字</b></p><p>　

3、　三相異步電動機的幾種調速方式</p><p>　　三相異步電動機轉速公式為： n=60f/p(1-s)</p><p>　　從上式可見，改變供電頻率f、電動機的極對數(shù)p及轉差率s均可太到改變轉速的目的。從調速的本質來看，不同的調速方式無非是改變交流電動機的同步轉速或不改變同步轉兩種。</p><p>　　在生產(chǎn)機械中廣泛使用不改變同步轉速的調速方法有繞線式電動機的

4、轉子串電阻調速、斬波調速、串級調速以及應用電磁轉差離合器、液力偶合器、油膜離合器等調速。改變同步轉速的有改變定子極對數(shù)的多速電動機，改變定子電壓、頻率的變頻調速有能無換向電動機調速等。</p><p>　　從調速時的能耗觀點來看，有高效調速方法與低效調速方法兩種：高效調速指時轉差率不變，因此無轉差損耗，如多速電動機、變頻調速以及能將轉差損耗回收的調速方法（如串級調速等）。有轉差損耗的調速方法屬低效調速，如轉子串電

5、阻調速方法，能量就損耗在轉子回路中；電磁離合器的調速方法，能量損耗在離合器線圈中；液力偶合器調速，能量損耗在液力偶合器的油中。一般來說轉差損耗隨調速范圍擴大而增加，如果調速范圍不大，能量損耗是很小的。</p><p>　　一、變極對數(shù)調速方法</p><p>　　這種調速方法是用改變定子繞組的接紅方式來改變籠型電動機定子極對數(shù)達到調速目的，特點如下：</p><p>

6、;　　1、具有較硬的機械特性，穩(wěn)定性良好；</p><p>　　2、無轉差損耗，效率高；</p><p>　　3、接線簡單、控制方便、價格低；</p><p>　　4、有級調速，級差較大，不能獲得平滑調速；</p><p>　　5、可以與調壓調速、電磁轉差離合器配合使用，獲得較高效率的平滑調速特性。</p><p>　

7、　本方法適用于不需要無級調速的生產(chǎn)機械，如金屬切削機床、升降機、起重設備、風機、水泵等。</p><p><b>　　二、變頻調速方法</b></p><p>　　變頻調速是改變電動機定子電源的頻率，從而改變其同步轉速的調速方法。變頻調速系統(tǒng)主要設備是提供變頻電源的變頻器，變頻器可分成交流－直流－交流變頻器和交流－交流變頻器兩大類，目前國內大都使用交－直－交變頻器。其

8、特點：</p><p>　　1、效率高，調速過程中沒有附加損耗</p><p>　　2、應用范圍廣，可用于籠型異步電動機</p><p>　　3、調速范圍大，特性硬，精度高</p><p>　　4、技術復雜，造價高，維護檢修困難。</p><p>　　本方法適用于要求精度高、調速性能較好場合。</p>&

9、lt;p><b>　　三、串級調速方法</b></p><p>　　串級調速是指繞線式電動機轉子回路中串入可調節(jié)的附加電勢來改變電動機的轉差，達到調速的目的。大部分轉差功率被串入的附加電勢所吸收，再利用產(chǎn)生附加的裝置，把吸收的轉差功率返回電網(wǎng)或轉換能量加以利用。根據(jù)轉差功率吸收利用方式，串級調速可分為電機串級調速、機械串級調速及晶閘管串級調速形式，多采用晶閘管串級調速，其特點為：<

10、;/p><p>　　1、可將調速過程中的轉差損耗回饋到電網(wǎng)或生產(chǎn)機械上，效率較高；</p><p>　　2、裝置容量與調速范圍成正比，投資省，適用于調速范圍在額定轉速７０％－９０％的生產(chǎn)機械上；</p><p>　　3、調速裝置故障時可以切換至全速運行，避免停產(chǎn)；</p><p>　　4、晶閘管串級調速功率因數(shù)偏低，諧波影響較大；</p&g

11、t;<p>　　本方法適合于風機、水泵及軋鋼機、礦井提升機、擠壓機上使用。</p><p>　　四、繞線式電動機轉子串電阻調速方法</p><p>　　繞線式異步電動機轉子串入附加電阻，使電動機的轉差率加大，電動機在較低的轉速下運行。串入的電阻越大，電動機的轉速越低。此方法設備簡單，控制方便，但轉差功率以發(fā)熱的形式消耗在電阻上。屬有級調速，機械特性較軟。</p>

12、<p>　　五、定子調壓調速方法</p><p>　　當改變電動機的定子電壓時，可以得到一組不同的機械特性曲線，從而獲得不同轉速。由于電動機的轉矩與電壓平方成正比，因此最大轉矩下降很多，其調速范圍較小，使一般籠型電動機難以應用。為了擴大調速范圍，調壓調速應采用轉子電阻值大的籠型電動機，如專供調壓調速用的力矩電動機，或者在繞線式電動機上串聯(lián)頻敏電阻。為了擴大穩(wěn)定運行范圍，當調速在2：1以上的場合應采用反

13、饋控制以達到自動調節(jié)轉速目的。</p><p>　　調壓調速的主要裝置是一個能提供電壓變化的電源，目前常用的調壓方式有串聯(lián)飽和電抗器、自耦變壓器以及晶閘管調壓等幾種。晶閘管調壓方式為最佳。調壓調速的特點：</p><p>　　1、調壓調速線路簡單，易實現(xiàn)自動控制。</p><p>　　2、調壓過程中轉差功率以發(fā)熱形式消耗在轉子電阻中，效率較低。</p>

14、<p>　　調壓調速一般適用于100KW以下的生產(chǎn)機械。</p><p>　　六、電磁調速電動機調速方法</p><p>　　電磁調速電動機由籠型電動機、電磁轉差離合器和直流勵磁電源（控制器）三部分組成。直流勵磁電源功率較小，通常由單相半波或全波晶閘管整流器組成，改變晶閘管的導通角，可以改變勵磁電流的大小。</p><p>　　電磁轉差離合器由電樞、磁極

15、和勵磁繞組三部分組成。電樞和后者沒有機械聯(lián)系，都能自由轉動。電樞與電動機轉子同軸聯(lián)接稱主動部分，由電動機帶動；磁極用聯(lián)軸節(jié)與負載軸對接稱從動部分。當電樞與磁極均為靜止時，如勵磁繞組通以直流，則沿氣隙圓周表面將形成若干對N、S極性交替的磁極，其磁通經(jīng)過電樞。當電樞隨拖動電動機旋轉時，由于電樞與磁極間相對運動，因而使電樞感應產(chǎn)生渦流，此渦流與磁通相互作用產(chǎn)生轉矩，帶動有磁極的轉子按同一方向旋轉，但其轉速恒低于電樞的轉速N1，這是一種轉差調速

16、方式，變動轉差離合器的直流勵磁電流，便可改變離合器的輸出轉矩和轉速。電磁調速電動機的調速特點：</p><p>　　1、裝置結構及控制線路簡單、運行可靠、維修方便；</p><p>　　2、調速平滑、無級調速</p><p>　　3、對電網(wǎng)無諧影響；</p><p>　　4、速度失大、效率低。</p><p>　　本方

17、法適用于中、小功率，要求平滑動、短時低速運行的生產(chǎn)機械。</p><p>　　七、液力耦合器調速方法</p><p>　　液力耦合器是一種液力傳動裝置，一般由泵輪和渦輪組成，它們統(tǒng)稱工作輪，放在密封殼體中。殼中充入一定量的工作液體，當泵輪在原動機帶動下旋轉時，處于其中的液體受葉片推動而旋轉，在離心力作用下沿著泵輪外環(huán)進入渦輪時，就在同一轉向上給渦輪葉片以推力，使其帶動生產(chǎn)機械運轉。液力耦合

18、器的動力轉輸能力與殼內相對充液量的大小是一致的。在工作過程中，改變充液率就可以改變耦合器的渦輪轉速，作到無級調速，其特點為：</p><p>　　1、功率適應范圍大，可滿足從幾十千瓦至數(shù)千千瓦不同功率的需要；</p><p>　　2、結構簡單，工作可靠，使用及維修方便，且造價低；</p><p>　　3、尺寸小，能容大；</p><p>　　

19、4、控制調節(jié)方便，容易實現(xiàn)自動控制。</p><p>　　本方法適用于風機、水泵的調速。</p><p>　　The three-phase induction motor speed control method</p><p>　　Three-phase asynchronous motor speed formula: N = 60f / p (1-s) &l

20、t;/p><p>　　Can be seen from the above formula, change the power supply frequency f, motor pole number p and the slip s may be too much to change the speed of purpose. From the speed of the essence of view, is s

21、imply a different way to change speed synchronous AC motor does not change the sync transfer speed or two.</p><p>　　Widespread use in production machines without changing the synchronous speed of motor speed

22、 control method Wound Rotor Series Resistance Speed, chopper speed control, cascade control, and application of electromagnetic slip clutch, fluid couplings, clutches and other film speed. Change the synchronous speed of

23、 change on the number of stator pole multi-speed motor to change the stator voltage and frequency to frequency conversion with no change to the motor speed and so on.</p><p>　　Energy from the speed point of

24、view when, with high speed method and inefficient methods of two kinds of speed: high speed when the slip refers to the same, so no slip losses, such as multi-speed motors, Slip frequency control and loss can speed recov

25、ery methods (such as cascade control, etc.). A deteriorating loss of speed control methods are inefficient speed, such as series resistance of the rotor speed method, the energy loss in the rotor circuit on; Electromagne

26、tic Clutch The speed method, </p><p>　　1.Variable Speed Control Method of Pole PairsThis speed is then used to change the stator winding way to change the red cage motor stator pole pairs to achieve speed c

27、ontrol purposes, the following featuresWith hard mechanical properties, good stability:</p><p>　　No slip loss, high efficiency; Wiring simple, easy to control, low price;A level speed, differential large, c

28、an not get smooth speed control;With pressure and speed adjustment, with the use of electromagnetic slip clutch, smooth and efficient access to high speed characteristics.</p><p>　　This method is suitable f

29、or the production does not require variable speed machinery, such as metal cutting machine Bed , Lift , Lifting equipment, Fans Water Pump And so on.</p><p>　　2.the Frequency Control Method</p><p&

30、gt;　　Frequency Control Method Frequency control is to change the motor stator Power supply Frequency, thus changing the speed of its synchronous speed method. Frequency control system main equipment is to provide variabl

31、e frequency power supply Inverter , Inverter can be divided into AC - DC - AC inverter and AC - AC converter two categories, most of the current domestic use of AC - DC - AC inverter. Its characteristics High efficiency,

32、 speed the process without additional loss; Wide range of ap</p><p>　　This method is suitable for the high accuracy, good speed performance occasions. </p><p>　　3. Cascade Speed Regulation

33、 Method </p><p>　　Cascade control method Cascade control is wound into the rotor circuit in the series of additional potential can be adjusted to change the motor's slip, to achieve speed control purp

34、oses. Most of the deterioration in power to be in series with the added potential absorbed, re-use generate additional devices to absorb the deterioration in power to return power to use or conversion of energy. Slip-pow

35、er absorption under way, cascade control can be divided into Motor Cascade control, mechanical and</p><p>　　4. Wound Rotor Motor Speed Control Method of Series ResistanceWound Rotor Motor additional resista

36、nce in series, so that the motor slip up, motor running at low speed. The greater the resistance in series, the motor speed is lower. This method is simple, easy to control, but deteriorate the power consumption in the f

37、orm of heat in the resistor. Is a class speed, soft mechanical properties.</p><p>　　5. the Stator Pressure and Speed Adjustment MethodStator voltage when changing the motor, you can get a different set of m

38、echanical properties of curves, which were different speeds. Since the motor torque and voltage proportional to the square, the largest decline in a lot of torque, speed range of its small cage motors in general and diff

39、icult to apply. In order to expand the speed range, pressure and speed adjustment should be larger rotor resistance value cage motors, such as dedicated volt</p><p>　　Pressure and speed adjustment is a key d

40、evice to provide power supply voltage, the current way of a tandem common saturation voltage regulator Reactor , Auto Transformer And several other Thyristor Surge. Thyristor Surge is the best way. Adjusting Speed featur

41、esPressure and speed adjustment circuit is simple, easy to realize automatic control; Poor power surge process to heat transfer in the rotor resistance in the form of consumption, low efficiency.</p><p>

42、;　　Pressure and speed adjustment generally applies to 100KW below production machinery.</p><p>　　Rlectromagnetic speed regulating motor speed control method of electromagnetic </p><p>　　Speed re

43、gulating electric motor squirrel cage motor, electric slip clutch and DC excitation power supply (Controller) consists of three parts. DC excitation power small, usually consisting of single phase half-wave or full wave

44、rectifiers thyristors composition, change thyristor conduction angle, you can change the magnetizing current size. </p><p>　　6. Electromagnetic speed regulating motor sp

45、eed control method</p><p>　　Electromagnetic slip clutch armature, poles and excitation windings composed of three parts. Armature and the latter has no mechanical contact, are free to rotate. Armature motor

46、coaxial connection active part, driven by motors; docking with the load axis magnetic pole coupling from the moving parts. When the armature poles are at rest, such as excitation windings for DC, along the circumferentia

47、l surface will form a number of air gap on the n, s, of alternating polarity poles, the magnetic flux</p><p>　　Appliances, structure and control circuit is simple, reliable operation, easy maintenance; spee

48、d and smooth, stepless speed regulation</p><p>　　The power network harmonic effects; </p><p>　　Lost speed, low efficiency. </p><p>　　This method applies to medium and small power, r

49、equires low speed when the smooth, short run production machinery.</p><p>　　7. Hydraulic Coupler Speed Regulation Method</p><p>　　The hydraulic coupler speed regulating hydraulic Coupler is a de

50、vice for hydraulic drive, is made up of the pump and turbine, they collectively work wheels, placed in a sealed case. Shell filled with a certain amount of working fluid, when pump is impulse driven by rotation, in which

51、 liquid propelled by blades which rotate, and under the action of centrifugal force along the outer wheels when entering the turbine pump, to thrust to the turbine blades on the same turn, make it drive production ma<

52、/p><p>　　Power scope, can meet the needs of from a couple of different power 10-kilowatt to shuqianqian; </p><p>　　Simple structure, reliable performance, easy to operation and maintenance, and low