外文翻譯--伺服電機(jī)原理及應(yīng)用

1、<p><b>　　原文說明</b></p><p>　　原文說明的內(nèi)容是：文章闡述了電機(jī)的工作原理、發(fā)展過程、以及伺服電機(jī)的工作控制原理。并且舉例說明了伺服電機(jī)所適用的場(chǎng)合。</p><p>　　題名Servomotor’s Elements and Applications</p><p>　　作者 NEWMARKER</p

2、><p><b>　　來源 佳工機(jī)電網(wǎng)</b></p><p>　　How Does a Motor Work?</p><p>　　An electric motor converts electricity into mechanical motion. Electric motors are used in household applian

3、ces, electric fans, remote-controlled toys, and in thousands of other applications. </p><p>　　The electric motor grew out of one of the earliest discoveries in electric science—Arago’s rotations. In 1824, Fr

4、ancois Arago discovered that a magnetic needle suspended over a copper disk would rotate when the disc was spun. The next year, computer pioneer Charles Babbage and astronomer John Herschel showed that the action could b

5、e reversed: spinning a more powerful magnet above the copper disk would spin the copper disc. Then, in 1831, Michael Faraday conducted experiments that helped explain </p><p>　　Over the next few decades many

6、 inventors made improved devices for turning electricity into motion. One of these was Hippolyte Pixii’s 1832 improvement called the commutator, which switched the flow of current between two or more sets of stationary e

7、lectromagnets to keep a motor continuously rotating. Thomas Davenport was the first to build an electric motor large enough to be used in industry, and he was also the first to seek a patent on a motor. Soon electric mot

8、ors were being used for such t</p><p>　　An important change came in the later 1880s and 1890s, when electric power companies began considering the switch to alternating current. Alternating current was perfe

9、ct for the distribution of electric power over long distances, and it worked well with the Edison electric lamp, but no practical AC motor existed until the works of Galileo Ferraris in Italy and Nikola Tesla in the Unit

10、ed States. Tesla’s contributions are remembered today more than Ferraris’ in part because Tesla was subsequently </p><p>　　Servomotor</p><p>　　Servomotors are available as AC or DC motors. Early

11、 servomotors were generally DC motors because the only type of control for large currents was through SCRs for many years. As transistors became capable of controlling larger currents and switching the large currents at

12、higher frequencies, the AC servomotor became used more often. Early servomotors were specifically designed for servo amplifiers. Today a class of motors is designed for applications that may use a servo amplifier or a va

13、riable-fr</p><p>　　Some changes that must be made to any motor that is designed as a servomotor includes the ability to operate at a range of speeds without overheating, the ability to operate at zero speed

14、and retain sufficient torque to hold a load in position, and the ability to operate at very low speeds for long periods of time without overheating. Older-type motors have cooling fans that are connected directly to the

15、motor shaft. When the motor runs at slow speed, the fan does not move enough air to cool the</p><p>　　FIGURE 1-1 Typical PM servomotors</p><p>　　FIGURE 1-2 Cutaway picture of a permanent magnet

16、servomotor</p><p>　　Brushless Servomotors</p><p>　　The brushless servomotor is designed to operate without brushes. This means that the commutation that the brushes provided must now be provided

17、 electronically. Electronic commutation is provided by switching transistors on and off at appropriate times. Figure 1-3 shows three examples of the voltage and current waveforms that are sent to the brushless servomotor

18、. Figure 1-4 shows an example of the three windings of the brushless servomotor. The main point about the brushless servomotor is that it</p><p>　　FIGURE 1-3 (a) Trapezoidal input voltage and square wave cur

19、rent waveforms. (b) Sinusoidal input voltage and sinusoidal voltage and square wave output voltage waveforms. (c) Sinusoidal input voltage and sinusoidal current waveforms. This has become the most popular type of brushl

20、ess servomotor control.</p><p>　　Figure 1-4 shows three sets of transistors that are similar to the transistors in the output stage of the variable-frequency drive. In Fig. l-4a the transistors are connected

21、 to the three windings of the motor in a similar manner as in the variable-frequency drive. In Fig. l-4b the diagram of the waveforms for the output of the transistors is shown as three separate sinusoidal waves. The wav

22、eforms for the control circuit for the base of each transistor are shown in Fig. l-4c. Figure l-4d shows t</p><p>　　FIGURE 11-86 (a) Transistors connected to the three windings of the brushless servomotor. (

23、b) Waveforms of the three separate voltages that are used to power the three motor windings. (c) Waveforms of the signals used to control the transistor sequence that provides the waveforms for the previous diagram, (d)

24、Waveform of the overall back EMF</p><p>　　Servomotor Controllers </p><p>　　Servomotor controllers have become more than just amplifiers for a servomotor. Today servomotor controllers must be abl

25、e to make a number of decisions and provide a means to receive signals from external sensors and controls in the system, and send signals to host controllers and PLCs that may interface with the servo system. Figure 1-5

26、shows a picture of several servomotors and their amplifiers. The components in this picture look similar to a variety of other types of motors and controllers. </p><p>　　FIGURE 1-5 Example servomotors and am

27、plifiers</p><p>　　Figure 1-6 shows a diagram of the servomotor controller so that you can see some of the differences from other types of motor controllers. The controller in this diagram is for a DC servomo

28、tor. The controller has three ports that bring signals in or send signals out of the controller. The power supply, servomotor, and tachometer are connected to port P3 at the bottom of the controller. You can see that the

29、 supply voltage is 115-volt AC single phase. A main disconnect is connected in series with </p><p>　　The servomotor is connected to the controller at terminals 4 and 5. Terminal 5 is + and terminal 4 is - .

30、Terminal 3 provides a ground for the shield of the wires that connect the motor and the controller. The tachometer is connected to terminals 1 and 2. Terminal 2 is + and terminal 1 is - . The shield for this cable is gro

31、unded to the motor case. The wires connected to this port will be larger than wires connected to the other ports, since they must be capable of carrying the larger motor curr</p><p>　　FIGURE 1-6 Diagram of a

32、 servo controller. This diagram shows the digital (on-off) signals and the analog signals that are sent to the controller, and the signals the controller sends back to the host controller or PLC.</p><p>　　Th

33、e command signal is sent to the controller through port PI. The terminals for the command signal are 1 and 2. Terminal 1 is + and terminal 2 is - . This signal is a type signal, which means that it is not grounded or doe

34、s not share a ground potential with any other part of the circuit. Several additional auxiliary signals are also connected through port 1. These signals include inhibit (INH), which is used to disable the drive from an e

35、xternal controller, and forward and reverse commands (FAC </p><p>　　Port PI also provides several digital output signals that can be used to send fault signals or other information such as "drive runnin

36、g" back to a host controller or PLC. Port PI basically is the interface for all digital (on-off) signals. </p><p>　　Port P2 is the interface for analog (0-max) signals. Typical signals on this bus inclu

37、de motor current and motor velocity signals that are sent from the servo controller back to the host or PLC where they can be used in verification logic to ensure the controller is sending the correct information to the

38、motor. Input signals from the host or PLC can also be sent to the controller to set maximum current and velocity for the drive. In newer digital drives, these values are controlled by drive para</p><p>　　PWM

39、 Servo Amplifier </p><p>　　The PWM servo amplifier is used on small-size servo applications that use DC brush-type servomotors. Figure 1-7 shows a diagram for this type of amplifier. From the diagram you can

40、 see that single-phase AC power is provided to the amplifier as the supply at the lower left part of the diagram. The AC voltage is rectified and sent to the output section of the drive that is shown in the top right com

41、er of the diagram. The output section of the drive uses four IGBTs to create the pulse-width modulat</p><p>　　The remaining circuits show a variety of fault circuits in the middle of the diagram that origina

42、te from the fault logic board and provide an output signal at the bottom of the diagram. You should notice that the fault output signals include overvoltage, overtemperature, and overcurrent. A fourth signal is identifie

43、d as SSO (system status output), which indicates the status of the system as faulted anytime a fault has occurred. A jumper is used to set the SSO signal as an open collector output w</p><p>　　The input term

44、inals at the bottom right part of the diagram are used to enable or inhibit the drive, and to select forward amplifier clamp (FAC) or reverse amplifier clamp (RAC). The inhibit signal is used as a control signal, since i

45、t inhibits the output stage of the amplifier if it is high. The FAC and RAC signals limit the current in the opposite direction to 5%. </p><p>　　The input signals are shown in the diagram at the upper left s

46、ide. The VCS (velocity command signal) requires a +VCS and a -VCS signal to provide the differential signal. </p><p>　　FIGURE 1-7 Diagram of a pulse-width modulator (PWM) amplifier with a brush-type DC servo

47、motor</p><p>　　Applications for Servo Amplifiers and Motors </p><p>　　You will get a better idea of how servomotors and amplifiers operate if you see some typical applications. Figure 1-8 shows

48、an example of a servomotor used to control a press feed. In this application sheet material is fed into a press where it is cut off to length with a knife blade or sheer. The sheet material may have a logo or other adver

49、tisement that must line up registration marks with the cut-off point. In this application the speed and position of the sheet material must be synchronized </p><p>　　FIGURE 1-8 Application of a servomotor co

50、ntrolling the speed of material as it enters a press for cutting pieces to size.</p><p>　　An Example of a Servo Controlled In-Line Bottle-Filling Application</p><p>　　A second application is sho

51、wn in Fig. 1-9. In this application multiple filling heads line up with bottles as they move along a continuous line. Each of the filling heads must match up with a bottle and track the bottle while it is moving. Product

52、 is dispensed as the nozzles move with the bottles. In this application 10 nozzles are mounted on a carriage that is driven by a ball-screw mechanism. The ball-screw mechanism is also called a lead screw. When the motor

53、turns the shaft of the ball screw</p><p>　　The servo drive system utilizes a positioning drive controller with software that allows the position and velocity to be tracked as the conveyor line moves the bott

54、les. A master encoder tracks the bottles as they move along the conveyor line. An auger feed system is also used just prior to the point where the bottles enter the filling station. The auger causes a specific amount of

55、space to be set between each bottle as it enters the filling station. The bottles may be packed tightly as they appr</p><p>　　FIGURE 1-9 Application of a beverage-filling station controlled by a servomotor&l

56、t;/p><p>　　The servo drive system compares the position of the bottles from the master encoder to the feedback signal that indicates the position of the filling carriage that is mounted to the ball screw. The s

57、ervo drive amplifier will increase or decrease the speed of the ball-screw mechanism so that the nozzles will match the speed of the bottles exactly. </p><p>　　An Example of a Servo Controlled Precision Auge

58、r Filling System </p><p>　　A third application for a servo system is provided in Fig. 1-10. In this application a large filling tank is used to fill containers as they pass along a conveyor line. The materia

59、l that is dispensed into the containers can be a single material fill or it can be one of several materials added to a container that is dumped into a mixer for a blending operation. Since the amount of material that is

60、dispensed into the container must be accurately weighed and metered into the box, an auger that is c</p><p>　　FIGURE 1-10 Application of a precision auger filling station controlled by a servomotor.</p>

61、;<p>　　The speed of the auger can be adjusted so that it runs at high speed when the container is first being filled, and the speed can be slowed to a point where the final grams of material can be metered precise

62、ly as the container is filled to the proper point. As the price of material increases, precision filling equipment can provide savings as well as quality in the amount of product used in the recipe. </p><p>

63、　　An Example of a Label Application Using Servomotors </p><p>　　The fourth application has a servomotor controlling the speed of a label-feed mechanism that pulls preprinted labels from a roll and applies th

64、em to packages as they move on a continuous conveyor system past the labeling mechanism. The feedback signals are provided by an encoder that indicates the location of the conveyor, tach generator that indicates the spee

65、d of the conveyor, and a sensor that indicates the registration mark on each label. The servo positioning system is controlled by a micro</p><p>　　FIGURE 1-11 Example of a labeling application controlled by

66、a servomotor</p><p>　　An Example of a Random Timing Infeed System Controlled by a Servomotor </p><p>　　The fifth application is presented in Fig. 1-12, and it shows a series of packaging equipme

67、nt that operates as three separate machines. The timing cycle of each station of the packaging system is independent from the others. The packaging system consists of an infeed conveyor, a positioning conveyor, and a wra

68、pping station. The infeed conveyor and the wrapping station are mechanically connected so that they run at the same speed. The position of the packages on the wrapping station must be stric</p><p>　　FIGURE 1

69、-12 Example of a packaging system with random timing functions controlled by a servo-motor.</p><p><b>　　譯 文</b></p><p><b>　　伺服電機(jī)原理及應(yīng)用</b></p><p><b>　　電

70、機(jī)是如何工作的？</b></p><p>　　電動(dòng)機(jī)是將電能轉(zhuǎn)換成機(jī)械運(yùn)動(dòng),電機(jī)用在家用電器,電動(dòng)風(fēng)扇,遙控玩具等各種使用場(chǎng)合</p><p>　　電機(jī)起源于早期電學(xué)上的一個(gè)發(fā)現(xiàn)- Arago轉(zhuǎn)動(dòng).在1824年, Francois Arago發(fā)現(xiàn)懸浮在銅盤上的磁針,在銅盤轉(zhuǎn)動(dòng)時(shí)也跟著轉(zhuǎn)動(dòng).第二年,計(jì)算機(jī)先驅(qū)Charles Babbage和天文學(xué)家John Herschel向人們

71、展示上述運(yùn)動(dòng)可以相逆的:轉(zhuǎn)動(dòng)一塊位于銅盤上方較強(qiáng)的磁鐵時(shí),銅盤也轉(zhuǎn)動(dòng).在1831年, Michael Faraday通過試驗(yàn)來解釋這一現(xiàn)象發(fā)生的原因.在電機(jī)實(shí)際運(yùn)用前,半個(gè)多世紀(jì)來做這些電機(jī)些基礎(chǔ)研究</p><p>　　過了幾十年后,許多發(fā)明家不斷改進(jìn)發(fā)明將電能轉(zhuǎn)換成機(jī)械能.其中一個(gè)就是1832 Hippolyte Pixii改進(jìn)了之后稱為換向器的發(fā)明.它通過改變位于兩個(gè)或更多的固定電磁石電流方向,以維持一臺(tái)電

72、機(jī)連續(xù)運(yùn)轉(zhuǎn). Thomas Davenport是第一個(gè)制造出在工業(yè)中使用的電機(jī).并是第一個(gè)對(duì)電機(jī)申請(qǐng)專利的.不久電機(jī)被用作諸如交通運(yùn)輸?shù)葓?chǎng)合. Moritz-Hermann De Jacobi將一臺(tái)電機(jī)安裝在涅瓦河上的一條船上. Charles G. Page用電機(jī)做了一臺(tái)小型機(jī)車.伴隨著19世紀(jì)80年代商業(yè)性電力供應(yīng)系統(tǒng)出現(xiàn),制造出更大的電機(jī)也變得有可能. Edison鼓勵(lì)在工業(yè)中便用電機(jī),并且設(shè)計(jì)了幾一些為工業(yè)使用兵新型電機(jī)<

73、/p><p>　　在19世紀(jì)80年代到90年代發(fā)生了一個(gè)重大變化,電力公司開始考慮轉(zhuǎn)成交流電.交流適合于長距離傳輸.并且在Edison的電燈上工作的很好,但是沒有實(shí)際的交流電機(jī)存在,直到意大利的Galileo Ferraris和美國的Nikola Tesla. 在今天人們認(rèn)為Tesla的貢獻(xiàn)比Ferraris大部分原因是前者后來受雇于西屋公司,這家公司應(yīng)用了他自己的及其他人的專利,成了為電氣設(shè)備一個(gè)主要的生產(chǎn)者.隨著

74、交流電機(jī)成為可能,交流電力的發(fā)展,交流電機(jī)一直使用到現(xiàn)在。</p><p><b>　　伺服電機(jī)</b></p><p>　　伺服電機(jī)包括交流電機(jī)和直流電機(jī)。早期的伺服電機(jī)通常是直流電機(jī)，因?yàn)槟菚r(shí)只有通過可控硅才能控制大電流。由于晶體管能夠控制大電流,并在更高的頻率轉(zhuǎn)換大電流，交流電機(jī)使用越來越廣泛。早期的伺服電機(jī)是特別為伺服放大器設(shè)計(jì)的。如今電機(jī)設(shè)計(jì)則可應(yīng)用于伺服放

75、大器或變頻控制器。這意味著，電機(jī)一方面可以用于伺服系統(tǒng)，另一方面可以用于變頻驅(qū)動(dòng)。一些公司把不使用步進(jìn)電機(jī)的環(huán)閉系統(tǒng)稱為伺服系統(tǒng)，因此與調(diào)速器相連接的交流異步電機(jī)也可以被稱作為伺服電機(jī)。</p><p>　　伺服電機(jī)還有些地方需要改進(jìn)，包括在額定轉(zhuǎn)速內(nèi)運(yùn)行不過熱，電機(jī)靜止時(shí)仍能保證足夠的扭矩去承受負(fù)載在規(guī)定的位置，以及超低速長時(shí)間轉(zhuǎn)動(dòng)不過熱。舊型電機(jī)冷卻風(fēng)扇是直接連在接電機(jī)主軸上。當(dāng)電機(jī)工作在低速時(shí)，風(fēng)扇不能產(chǎn)生

76、足夠的氣流來冷卻電機(jī)。新一代的電機(jī)擁有獨(dú)立的風(fēng)扇安裝在電機(jī)上，所以能提供足夠的冷卻氣流。這個(gè)風(fēng)扇動(dòng)力來自一個(gè)恒壓源所以可以使風(fēng)扇能始終運(yùn)行在最高轉(zhuǎn)速下，而不管伺服電機(jī)的轉(zhuǎn)速如何。在所有伺服電機(jī)中，最實(shí)用的是永磁電動(dòng)機(jī)。永磁電機(jī)的繞組電壓可以是交流也可以是直流.這類永磁電機(jī)同以前的永磁電機(jī)類似。圖1-1顯示的是一臺(tái)普通永磁電機(jī)的剖示圖。圖1-2展示的是伺服永磁電機(jī)的剖示圖。從圖中可以看出，新的電機(jī)在軸承室，轉(zhuǎn)子，定子上同以前的電機(jī)類似。主

77、要的區(qū)別只在于這種新類型的電機(jī)可以較大的負(fù)載從靜止?fàn)顟B(tài)動(dòng)作。這類永磁電機(jī)同樣有一個(gè)編碼器或變壓器被放置在電機(jī)內(nèi)部。這個(gè)可以確保設(shè)備能更精確的顯示電機(jī)軸的位置或速度。</p><p>　　圖1-1 典型永磁電機(jī)</p><p>　　圖1-2剖視圖 永磁伺服電機(jī)</p><p><b>　　無刷伺服電機(jī)</b></p><p&g

78、t;　　無刷伺服電機(jī)可以無碳刷運(yùn)行，這就意味著它的換向現(xiàn)在需要由電子完成而不是由機(jī)械碳刷來完成。電子換向由晶體管以某種周期方式開關(guān)來實(shí)現(xiàn)的。圖1-3顯示三條輸入到無刷伺服電機(jī)的電壓和電流波形。圖1-4顯示一臺(tái)三相繞組的無刷伺服電機(jī)，這種無刷伺服電機(jī)的主要特點(diǎn)是可以交流或直流電源驅(qū)動(dòng)。</p><p>　　圖1-3(a)輸入電壓、電流方波梯形波表(b)正弦電壓和正弦輸入電壓和方波輸出電壓波型(c)正玄輸入電壓和正弦

79、電流波形 這已經(jīng)成為最流行的無刷式伺服控制</p><p>　　圖1-3展示三種電壓波形來驅(qū)動(dòng)無刷伺服電機(jī)。圖1-3a展示梯形反電動(dòng)勢(shì)電壓，方波電流輸入，圖1-3b顯示為一正弦波輸入電壓和一方波電流波形，圖-3c顯示一正弦波辦公設(shè)備電壓放一正弦波電流波形,正弦波電壓和正弦波電流波形是無刷伺服電機(jī)最常用的驅(qū)動(dòng)。</p><p>　　圖1-4（a）晶體管三相繞阻無刷伺服電機(jī)。（b）三相繞阻電機(jī)

80、使用三個(gè)獨(dú)立的電壓波形。（c）波形信號(hào)用來控制晶體管的波形序列。（d）反電勢(shì)波形。</p><p>　　圖1-4展示三組晶體管,它同變頻驅(qū)動(dòng)的輸出端很相似.在圖1-4a，連接到電機(jī)三相繞阻的晶體管同變頻驅(qū)動(dòng)基本相同。圖1-4b晶體管輸出波形圖，它是由三組獨(dú)立的正弦波形組成。圖1-4c是輸入到每個(gè)晶體管的控制端的波形。圖1-4d顯示驅(qū)動(dòng)波形的反電勢(shì)。</p><p><b>　　伺

81、服電機(jī)控制器</b></p><p>　　伺服電機(jī)控制器使一臺(tái)伺服電機(jī)不只是用于放大器功能。今天的伺服電機(jī)控制器既要能做一定量的判斷，也要提供一種方法能接受外部傳感器和內(nèi)部控制的信號(hào)，同時(shí)也可以在主控制器，PLCS和伺服系統(tǒng)數(shù)據(jù)交換。圖1-5展示一些伺服電機(jī)與放大器。從圖中看,這些同其它類型的電機(jī)和控制器比較相似。</p><p>　　圖1-5 伺服電機(jī)與放大器</p&g

82、t;<p>　　圖1-6顯示一張伺服電機(jī)控制器的圖,你可以從中看出與其它類型電機(jī)的不同之處。圖中的控制器用于直流伺服電機(jī)。輸入電源，伺服電機(jī)及轉(zhuǎn)速計(jì)連接到控制器底部的P3端口?？梢钥闯鲚斎腚娫礊?15V單相交流電。一個(gè)主斷路器串聯(lián)在L1線上。由L1和N經(jīng)過的電源經(jīng)過一個(gè)隔離的降壓變壓器.變壓器的次級(jí)電壓可是介于20到85伏的之間的任意電壓。控制器通過引腳8接地.你應(yīng)該記得在這點(diǎn)接地只是用來對(duì)系統(tǒng)的金屬部份提供短路保護(hù)。&l

83、t;/p><p>　　圖1-6 伺服控制圖 （此圖顯示將數(shù)字信號(hào)和模擬信號(hào)送到控制器，再由信號(hào)控制器將信號(hào)送回給所在的主控制器或可編程控制器）</p><p>　　伺服電機(jī)邊接控制器的4腳和5腳。其中5腳是+，4腳是-。3腳是對(duì)電機(jī)和控制器提供一種屏蔽接地保護(hù)。轉(zhuǎn)速計(jì)連接到引腳1和引腳2，其中腳2是+，腳1是-。屏蔽線纜同電機(jī)外殼連接.連接到這個(gè)端口的引線應(yīng)該比同其它端口的引線要粗，因?yàn)樗麄兂?/p>

84、受更大的電機(jī)電流。如果電機(jī)使用額外的散熱風(fēng)扇，它也應(yīng)該連接到這個(gè)端口上，在絕大部分場(chǎng)合，散熱風(fēng)扇由一常規(guī)的110V或240V的單相或三相交流電供電。</p><p>　　控制信號(hào)通過P1端口送到控制器.控制信號(hào)的引腳是1和2,其中1是+,2是-.這是一種非接地常規(guī)的信號(hào),同電路中其它部分不共享接地,一些附加的輔助信號(hào)也連接到P1。這些信號(hào)包括約束，如可以通過外部控制器來使驅(qū)動(dòng)失效。正反轉(zhuǎn)命令，如要求控制器給電機(jī)通

85、電，使電機(jī)按順時(shí)針方向或逆時(shí)針方向轉(zhuǎn)動(dòng)。在某些場(chǎng)合，最大正轉(zhuǎn)行程極限開關(guān)和最大反轉(zhuǎn)行程開關(guān)連接到一起，以便當(dāng)機(jī)器運(yùn)行到極限位置時(shí)觸發(fā)另一狀態(tài)的開關(guān)。這時(shí)將自動(dòng)的以反方向重新驅(qū)動(dòng)。</p><p>　　P1端品也提供一些數(shù)字輸出信號(hào),一通常用于送出一些故障信號(hào)或其它信息,諸如正在運(yùn)轉(zhuǎn),到主控制器或PLC.P1端口主要是數(shù)字(1-0)信號(hào)的端口。</p><p>　　P2端口是邏輯信口的窗口，

86、總線上的典型信號(hào)包括電機(jī)電流和電機(jī)轉(zhuǎn)速信號(hào)由伺服控制器送出，送入主機(jī)或PLC，以便做出正確邏輯判斷以確保控制器能出正確信息到電機(jī)上。從主機(jī)或PLC上的輸入信號(hào)也被送到控制器上來設(shè)置驅(qū)動(dòng)的最大電流和轉(zhuǎn)速。在更新的數(shù)字驅(qū)動(dòng)中，這些值由編好程序的驅(qū)動(dòng)參數(shù)來控制的。</p><p><b>　　脈寬調(diào)制伺服放大器</b></p><p>　　脈寬伺服放大器被用作小尺寸的伺服場(chǎng)

87、合，如使用直流有刷伺服電機(jī)。圖1-7展示這一類型放大器的圖。從左下圖中可以看到單相交流電源供電給放大器。右上圖中交流電經(jīng)整流后，被送到驅(qū)動(dòng)的輸出單元，動(dòng)輸出單元用四個(gè)IGBT來產(chǎn)生脈寬調(diào)制波形。IGBT連接后以便他們提供30-120V直流電壓，高達(dá)30A的電流到直流有刷伺服電機(jī)。電機(jī)的極性由圖中顯示。在這張圖的中間的保留電路顯示一些從故障邏輯板上的故障電路，在圖的下方提供一路輸出信號(hào)。可以看到故障輸出信號(hào)包括過壓,過溫及過電流。第四個(gè)信

88、號(hào)作為SSO(系統(tǒng)狀態(tài)輸出)。它顯示當(dāng)故障發(fā)生時(shí)的系統(tǒng)狀態(tài)。一個(gè)跳線用來設(shè)置SSO信號(hào)。 </p><p>　　在這張圖的右下角的輸入腳用來顯示驅(qū)動(dòng)的的使能控制或抑止，選擇是前過放大控制還是向后放大控制。抑制信號(hào)作為控制信號(hào)。當(dāng)放大器過高的時(shí)抑制輸出過程。FAC和RAC信號(hào)限制電流到放大或縮小5%。</p><p>　　左上方顯示的是輸入信號(hào)。VCS(速度控制信號(hào))要求一個(gè)+VCS和一個(gè)-

89、VCS信號(hào)來提供不同的信號(hào)。</p><p>　　伺服放大器和電機(jī)的應(yīng)用場(chǎng)合</p><p>　　可以從伺服電機(jī)和放大器一些典型的應(yīng)用場(chǎng)合延升到其它更好的使用場(chǎng)合。圖-8顯示的是一臺(tái)伺服電機(jī)被用作控制一個(gè)壓力切割器。在這個(gè)應(yīng)用表中，薄片材料被送入一個(gè)卷壓器中，在那兒它被用一把刀刃切長一定長度。薄片材料可以是一個(gè)帶有切斷點(diǎn)標(biāo)記的商標(biāo)或是廣告紙。帶有切斷點(diǎn)標(biāo)記的。在這個(gè)場(chǎng)合中，薄片材料的速度和

90、位置司切斷點(diǎn)保持同步。反饋傳感器可以是一個(gè)編碼器或是解碼器,它同一個(gè)光電傳感器連接在一起，用來判斷標(biāo)記的位置。所提供的操作面板用來使操作者能減慢系統(tǒng)動(dòng)作，以維護(hù)刀刃或是換一卷新的材料。面板上可以進(jìn)行參數(shù)調(diào)整以適應(yīng)每一種原料。系統(tǒng)也可以同一個(gè)可編程的控制器或其它類型的控制器連接，以便操作面板上可以用來選擇每一種材料或產(chǎn)品在運(yùn)行時(shí)的正確的切斷點(diǎn)。</p><p>　　圖1-7圖示 脈寬調(diào)制放大器直流有刷伺服電機(jī)<

91、;/p><p>　　圖1-8 由伺服電機(jī)控制材料壓入的速度來確保尺寸</p><p>　　灌裝流水線伺服控制應(yīng)用實(shí)例</p><p>　　第二個(gè)應(yīng)用如圖1-9所示。在這個(gè)應(yīng)用中若干個(gè)填充頭和瓶子一樣排列成一直線向前移動(dòng)。每個(gè)填充頭必須與每個(gè)瓶子以及瓶子運(yùn)行的軌道相配合。噴嘴跟著瓶子移動(dòng)并且填充物料。這里使用把10個(gè)噴嘴安裝在機(jī)架上并通過滾珠絲杠裝置來傳動(dòng)。滾珠絲桿也叫做

92、螺桿。當(dāng)電機(jī)轉(zhuǎn)動(dòng)絲桿軸，機(jī)架會(huì)水平地沿著絲桿軸長度移動(dòng)。這個(gè)平穩(wěn)的運(yùn)動(dòng)能夠使每個(gè)噴嘴將物料裝入憑中，而且?guī)缀醪粫?huì)有溢出。</p><p>　　伺服驅(qū)動(dòng)系統(tǒng)利用一個(gè)定位控制器驅(qū)動(dòng)軟件來確定的傳送帶的位置和速度實(shí)現(xiàn)瓶子的移動(dòng)。主編程軌跡是瓶子沿著傳送線向前移動(dòng)。螺旋流入的方式是利用在進(jìn)入灌注區(qū)域的前點(diǎn)。螺旋流入方式是根據(jù)每個(gè)瓶子進(jìn)入灌注區(qū)域所保持的間距精確數(shù)據(jù)計(jì)算所得。瓶子都在接近螺旋灌注點(diǎn)被緊緊的固定，但是當(dāng)瓶子通

93、過螺旋灌注點(diǎn)時(shí)位置間距是十分精確的，所以噴嘴和瓶子頸部有足夠的空間相配合。傳感器聯(lián)合檢測(cè)系統(tǒng)確保在瓶子錯(cuò)位，或者瓶子與瓶子之間出現(xiàn)過大距離時(shí)，噴嘴不會(huì)再噴出物料。</p><p>　　伺服驅(qū)動(dòng)系統(tǒng)對(duì)來自主編程器的瓶子位置與顯示了安裝在螺旋絲桿上的填充機(jī)架位置的反饋信號(hào)進(jìn)行比較。伺服驅(qū)動(dòng)放大器會(huì)增加或減少滾珠絲杠裝置的速度,使噴嘴與瓶子的速度準(zhǔn)確的匹配。</p><p>　　圖1-9 應(yīng)用伺

94、服電機(jī)控制的飲料灌裝機(jī)</p><p>　　精確螺旋伺服控制系統(tǒng)應(yīng)用實(shí)例</p><p>　　伺服系統(tǒng)第三方面的應(yīng)用如圖1－10所示。這個(gè)應(yīng)用中使用一個(gè)巨大的供應(yīng)槽來給沿著轉(zhuǎn)送帶運(yùn)動(dòng)的容器填料。材料被灌入到容器內(nèi)，可以僅僅放入一種材料也可以是將某一種材料傾倒在攪拌器進(jìn)行混合攪拌操作后再灌入到容器中。因此，所有灌入到容器內(nèi)的材料必須被準(zhǔn)確的稱量過才能裝入。伺服系統(tǒng)通過一個(gè)絲桿進(jìn)行控制。反饋傳

95、感器在這個(gè)系統(tǒng)中是一個(gè)稱量系統(tǒng)，例如測(cè)壓元件在前面的章節(jié)已經(jīng)討論過。命令信號(hào)來自一個(gè)可編程控制器或者工作人員可以選擇手動(dòng)控制，在操作終端上進(jìn)行控制。命令信號(hào)來自一個(gè)可編程控制器或者工作人員可以從操作終端上手動(dòng)選擇一個(gè)配方。材料的數(shù)量多少是根據(jù)不同的配方?jīng)Q定。</p><p>　　圖1－10 實(shí)施精確數(shù)字螺旋伺服控制的灌注機(jī)</p><p>　　螺旋桿的速度是可以調(diào)整的，當(dāng)容器剛開始灌注時(shí)，

96、螺旋桿是高速運(yùn)轉(zhuǎn)的，當(dāng)達(dá)到經(jīng)過準(zhǔn)確計(jì)量出容器在最后罐滿前適當(dāng)?shù)目潭葧r(shí)，螺旋桿以額定的低速運(yùn)轉(zhuǎn)。由于材料價(jià)格的增長，精密的灌注設(shè)備在使用規(guī)定的配方下在相同產(chǎn)品數(shù)量下即可以提高節(jié)約材料又能保證質(zhì)量。</p><p>　　利用伺服電機(jī)打印標(biāo)簽應(yīng)用實(shí)例</p><p>　　第四個(gè)應(yīng)用是由伺服電機(jī)控制標(biāo)簽打印機(jī)的預(yù)印標(biāo)簽牽引滾筒的速度，當(dāng)盒子穿過標(biāo)簽打印機(jī)構(gòu)時(shí)把標(biāo)簽印在隨著連續(xù)傳送帶系統(tǒng)移動(dòng)的盒子上

97、。反饋信號(hào)由三個(gè)裝置共同提供，一個(gè)能指示傳送帶位置的 編碼器，一個(gè)能指示傳送帶速度的技術(shù)發(fā)生器，還有個(gè)能顯示每個(gè)標(biāo)簽的注冊(cè)記號(hào)的傳感器。由一個(gè)微型處理器來控制伺服位置系統(tǒng)設(shè)定誤差信號(hào)， 并由伺服放大器提供功率信號(hào)給伺服電機(jī)。如圖1－11所示。</p><p>　　圖1－11 由伺服電機(jī)控制標(biāo)簽打印機(jī)的應(yīng)用</p><p>　　伺服電機(jī)控制隨機(jī)定時(shí)橫切系統(tǒng)應(yīng)用實(shí)例</p>&l

98、t;p>　　第5中運(yùn)用在11-94中出現(xiàn)。同時(shí)，那頁還展示了一個(gè)系列的組件設(shè)備。這個(gè)設(shè)備可以分為3個(gè)獨(dú)立的機(jī)器使用。每個(gè)組件系統(tǒng)所在的站點(diǎn)的定時(shí)循環(huán)周期是與外界相獨(dú)立的。組件系統(tǒng)由infeed傳送帶，一個(gè)定位傳送帶和一個(gè)纏繞站點(diǎn)。infeed傳送帶和纏繞站點(diǎn)是相互機(jī)械連接的，所以它們等速運(yùn)轉(zhuǎn)。纏繞站點(diǎn)上的組件的位置是被嚴(yán)格控制的，這使得各組件不至于相互過于緊密。一塊被稱為 飛行的金屬 與纏繞站點(diǎn)傳送帶在某個(gè)特定接點(diǎn)連接以保證每個(gè)組

99、件各就各位。一個(gè)傳感器被安裝在定位傳送帶的開始端使得能在組件開始移向定位傳送帶時(shí)確定組件的前邊界。另一個(gè)傳感器被安裝在了組件傳送帶的底部以觀察金屬的 運(yùn)行。 所以這些從傳感器發(fā)出的信號(hào)都被發(fā)送到辭賦電機(jī)以提供信息數(shù)據(jù)，所以辭賦器可以調(diào)節(jié)定位傳送帶的速度。這樣可以使每個(gè)組件當(dāng)它移向組件傳送帶時(shí)都能和某個(gè) 運(yùn)行 器排列成一條直線。這種運(yùn)用說明了辭賦定位控制器可以應(yīng)對(duì)從2個(gè)以上傳感器發(fā)出的各種不同的信號(hào)，原因是它使用了微處理器 。</p