外文翻譯----步進電機基礎

1、<p><b>　　資料翻譯</b></p><p><b>　　英文資料</b></p><p>　　Stepper Motor Basics</p><p>　　[Tieluo Lin.Jianxun Zhang． DSP-based microstep controller of stepper motor

2、．Intelligent Control and Automation, 2004． Fifth World Congress on Volume 5, 15-19 June 2004.]</p><p>　　A stepper motor is an electromechanical device which converts electrical pulses into discrete mechanic

3、al movements. The shaft or spindle of a stepper motor rotates in discrete step increments when electrical command pulses are applied to it in the proper sequence. The motors rotation has several direct relationships to t

4、hese applied input pulses. The sequence of the applied pulses is directly related to the direction of motor shafts rotation. The speed of the motor shafts rotation is directly re</p><p>　　Stepper Motor Advan

5、tages and Disadvantages</p><p>　　Advantages</p><p>　　1. The rotation angle of the motor is proportional to the input pulse.</p><p>　　2. The motor has full torque at standstill (if t

6、he windings are energized)</p><p>　　3. Precise positioning and repeatability of movement since good stepper motors have an accuracy of 3 – 5% of a step and this error is non cumulative from one step to the n

7、ext.</p><p>　　4. Excellent response to starting/stopping/reversing.</p><p>　　5. Very reliable since there are no contact brushes in the motor. Therefore the life of the motor is simply dependant

8、 on the life of the bearing.</p><p>　　6. The motors response to digital input pulses provides open-loop control, making the motor simpler and less costly to control.</p><p>　　7. It is possible t

9、o achieve very low speed synchronous rotation with a load that is directly coupled to the shaft.</p><p>　　8. A wide range of rotational speeds can be realized as the speed is proportional to the frequency of

10、 the input pulses.</p><p>　　Disadvantages</p><p>　　1. Resonances can occur if not properly controlled.</p><p>　　2. Not easy to operate at extremely high speeds.</p><p>

11、　　Open Loop Operation</p><p>　　One of the most significant advantages of a stepper motor is its ability to be accurately controlled in an open loop system. Open loop control means no feedback information abo

12、ut position is needed. This type of control eliminates the need for expensive sensing and feedback devices such as optical encoders. Your position is known simply by keeping track of the input step pulses.</p><

13、;p>　　Stepper Motor Types</p><p>　　There are three basic stepper motor types. They are :</p><p>　　? Variable-reluctance</p><p>　　? Permanent-magnet</p><p><b>　　

14、? Hybrid</b></p><p>　　Variable-reluctance (VR)</p><p>　　This type of stepper motor has been around for a long time. It is probably the easiest to understand from a structural point of view

15、. Figure 1 shows a cross section of a typical V.R. stepper motor. This type of motor consists of a soft iron multi-toothed rotor and a wound stator. When the stator windings are energized with DC current the poles become

16、 magnetized. Rotation occurs when the rotor teeth are attracted to the energized stator poles.</p><p>　　Figure 1. Cross-section of a variablereluctance(VR) motor.</p><p>　　Permanent Magnet (PM)&

17、lt;/p><p>　　Often referred to as a “tin can” or “canstock” motor the permanent magnet step motor is a low cost and low resolution type motor with typical step angles of 7.5° to 15°. (48 – 24steps/revo

18、lution) PM motors as the name implies have permanent magnets added to the motor structure. The rotor no longer has teeth as with the VR motor. Instead the rotor is magnetized with alternating north and south poles situat

19、ed in a straight line parallel to the rotor shaft. These magnetized rotor poles provide an i</p><p>　　Hybrid (HB)</p><p>　　The hybrid stepper motor is more expensive than the PM stepper motor bu

20、t provides better performance with respect to step resolution, torque and speed. Typical step angles for the HB stepper motor range from 3.6° to 0.9° (100 – 400 steps per revolution). The hybrid stepper motor c

21、ombines the best features of both the PM and VR type stepper motors. The rotor is multi-toothed like the VR motor and contains an axially magnetized concentric magnet around its shaft. The teeth on the rotor provide an &

22、lt;/p><p>　　The two most commonly used types of stepper motors are the permanent magnet and the hybrid types. If a designer is not sure which type will best fit his applications requirements he should first eva

23、luate the PM type as it is normally several times less expensive. If not then the hybrid motor may be the right choice.</p><p>　　There also excist some special stepper motor designs. One is the disc magnet m

24、otor. Here the rotor is designed sa a disc with rare earth magnets, See fig. 5 . This motor type has some advantages such as very low inertia and a optimized magnetic flow path with no coupling between the two stator win

25、dings. These qualities are essential in some applications.</p><p>　　Size and Power</p><p>　　In addition to being classified by their step angle stepper motors are also classified according to fr

26、ame sizes which correspond to the diameter of the body of the motor. For instance a size 11 stepper motor has a body diameter of approximately 1.1 inches. Likewise a size 23 stepper motor has a body diameter of 2.3 inche

27、s (58 mm), etc. The body length may however, vary from motor to motor within the same frame size classification. As a general rule the available torque output from a motor of a p</p><p>　　Power levels for IC

28、-driven stepper motors typically range from below a watt for very small motors up to 10 –20 watts for larger motors. The maximum power dissipation level or thermal limits of the motor are seldom clearly stated in the mot

29、or manufacturers</p><p>　　data. To determine this we must apply the relationship P=V×I For example, a size 23 step motor may be rated at 6V and 1A per phase. Therefore, with two phases energized</p&g

30、t;<p>　　the motor has a rated power dissipation of 12 watts. It is normal practice to rate a stepper motor at the power dissipation level where the motor case rises 65°C above the ambient in still air. Theref

31、ore, if the motor can be mounted to a heatsink it is often possible to increase the allowable power dissipation level. This is important as the motor is designed to be and should be used at its maximum power dissipation

32、,to be efficient from</p><p>　　a size/output power/cost point of view.</p><p>　　When to Use a StepperMotor</p><p>　　A stepper motor can be a good choice henever controlled movement

33、is equired. They can be used to advantage in applications where you need to control rotation angle, speed, position and synchronism. Because of the inherent advantages listed previously, stepper motors have found their p

34、lace in many different applications. Some of these include printers, plotters, highend office equipment, hard disk drives, medical equipment, fax machines, automotive and many more.</p><p>　　The Rotating Mag

35、netic Field</p><p>　　When a phase winding of a stepper motor is energized with current a magnetic flux is developed in the stator. The d When a phase winding of a stepper motor is energized with current a ma

36、gnetic flux is developed irection of this flux is determined by the “Right Hand</p><p>　　Rule” which states: “If the coil is grasped in the right hand with the fingers pointing in the direction of the curren

37、t in the winding (the thumb is extended at a 90° angleto the fingers), then the thumb will point in the direction of the magnetic field.”</p><p>　　Figure 2 shows the magnetic flux path developed when ph

38、ase B is energized with winding current in the direction shown. The rotor then aligns itself so that the flux opposition is minimized. In this case the motor would rotate clockwise so that its south pole aligns with the

39、north pole of the stator B at position 2 and its north pole aligns with the south pole of stator B at position 6. To get the motor to rotate we can now see that we must provide a sequence of energizing the stator winding

40、s in </p><p>　　Figure 2 Magnetic flux path through a two-pole stepper motor with a lag between the rotor and stator.</p><p>　　Torque Generation</p><p>　　The torque produced by a ste

41、pper motor depends on several factors.</p><p>　　? The step rate</p><p>　　? The drive current in the windings</p><p>　　? The drive design or type</p><p>　　In a stepper m

42、otor a torque is developed when the magnetic fluxes of the rotor and stator are displaced from each other. The stator is made up of a high permeability magnetic material. The presence of this high permeability material c

43、auses the magnetic flux to be confined for the most part to the paths defined by the stator structure in the same fashion that currents are confined to the conductors of an electronic circuit. This serves to concentrate

44、the flux at the stator poles. The torque outpu</p><p>　　The basic relationship which defines the intensity of the magneticflux is defined by:</p><p>　　H = (N ×i) ÷ l where:</p

45、><p>　　N = The number of winding turns</p><p>　　i = current</p><p>　　H = Magnetic field intensity</p><p>　　l = Magnetic flux path length</p><p>　　This relatio

46、nship shows that the magnetic flux intensity and consequently the torque is proportional to the number of winding turns and the current and inversely proportional to the length of the magnetic flux path. From this basic

47、relationship one can see that the same frame size stepper motor could have very different torque output capabilities simply by changing the winding parameters. More detailed information on how the winding parameters affe

48、ct the output capability of the motor can be fou</p><p>　　Stepping Modes</p><p>　　The following are the most common drive modes.</p><p>　　? Wave Drive (1 phase on)</p><p&

49、gt;　　? Full Step Drive (2 phases on)</p><p>　　? Half Step Drive (1 & 2 phases on)</p><p>　　? Micro stepping (Continuously varying motor currents)</p><p>　　For the following disc

50、ussions please refer to the figure 3. </p><p>　　Figure 3 Unipolar and bipolar wound stepper motors.</p><p>　　In Wave Drive only one winding is energized at any given time. The stator is energiz

51、ed according to the sequence A ??B ??A ??B and the rotor steps from position 8 ??2 ??4 ??6. For unipolar and bipolar wound motors with the same winding parameters this excitation mode would result in the same mechanical

52、position. The disadvantage of this drive mode is that in the unipolar wound motor you are only using 25% and in the bipolar motor only 50% of the total motor winding at any given time. This means </p><p>　　I

53、n Full Step Drive you are energizingtwo phases at any given time.The stator is energized according to the sequence AB ??AB ??AB ? AB and the rotor steps from position 1 ??3 ??5 ??7 . Full step mode results in the same an

54、gular movement as 1 phase on drive but the mechanical position is offset by one half of a full</p><p>　　step. The torque output of the unipolar wound motor is lower than the bipolar motor (for motors with th

55、e same winding parameters) since the unipolar motor uses only 50% of the available winding while the bipolar motor uses the entire winding. </p><p>　　Half Step Drive combines both wave and full step (1&2

56、 phases on) drive modes. Every second step only</p><p>　　one phase is energized and during the other steps one phase on each stator. The stator is energized according to the sequence AB ??B ??AB ??A ??AB ??B

57、 ??AB ??A and the rotor steps from position 1 ??2 ??3 ??4 ??5 ??6 ??7 ??8. This results in angular movements that are half of those in 1- or 2-phases-on drive modes. Half stepping can reduce a phenomena referred to as re

58、sonance which can be experienced in 1- or 2-phases-on drive modes.</p><p>　　The excitation sequences for the above drive modes are summarized in Table 1.</p><p>　　Table 1. Excitation sequences f

59、or different drive modes</p><p>　　In Microstepping Drive the currents in the windings are continuously varying to be able to break up one full step into many smaller discrete steps. More information on micro

60、stepping can be found in the microstepping chapter.</p><p>　　Single Step Response and Resonances</p><p>　　The single-step response characteristics of a stepper motor is shown in figure 4. </p

61、><p>　　Figure 4 Single step response vs. time.</p><p>　　When one step pulse is applied to a stepper motor the rotor behaves in a manner as defined by the above curve.The step time t is the time it

62、 takes the motor shaft to rotate one step angle once the first step pulse is applied. This step time is highly dependent on the ratio of torque to inertia (load) as well as the type of driver used.</p><p>　　

63、Since the torque is a function of the displacement it follows that the acceleration will also be. Therefore, when moving in large step increments a high torque is developed and consequently a high acceleration. This can

64、cause over shots and ringing as shown. The settling time T is the time it takes these oscillations or ringing to cease. In certain applications this phenomena can be undesirable. It is possible to reduce or eliminate thi

65、s behaviour by microstepping the stepper motor. For more inf</p><p>　　Stepper motors can often exhibit a phenomena refered to as resonance at certain step rates. This can be seen as a sudden loss or drop in

66、torque at certain speeds which can result in missed steps or loss of synchronism. It occurs when the input step pulse rate coincides with the natural oscillation frequency of the rotor. Often there is a resonance area ar

67、ound the 100 – 200 pps region and also one in the high step pulse rate region. The resonance phenomena of a stepper motor comes from its basic </p><p><b>　　中文譯文</b></p><p><b>　

68、　步進電機基礎</b></p><p>　　[林鐵國，張建勛．基于DSP的微控制器的步進電機控制和自動化， 2004 。第五次世界代表大會第五冊15-19日， 2004年6月．]</p><p>　　步進電機是一種機電設備，它把電氣轉換成脈沖離散機械動作。當電器指揮脈沖以正確的順序應用時，軸或主軸步進電機旋轉一步離散增量。電動機轉動對這些應用輸入脈沖有幾種直接聯系。應用脈沖的序

69、列與電機軸旋轉方向直接相關。電機軸旋轉的速度與輸入脈沖的頻率直接相關，旋轉的長度與應用輸入脈沖的數字輸入直接相關。</p><p>　　步進電機的優(yōu)點和缺點:</p><p>　　優(yōu)點：1. 電機旋轉的角度與脈沖輸入成正比;</p><p>　　2. 如果繞組被加強，電機轉距會完全靜止;</p><p>　　3. 因為良好的步進電機有3

70、%-5%的準確率而且即使有錯誤，也不是從一步累計到另一步的，所以步進機能夠精確定位并且可重復性運動;</p><p>　　4.對啟動/停止/旋轉有良好的反應;</p><p>　　5. 因為電機上沒有連接點，所以它非?？煽?。電機的壽命是由軸承的壽命決定的;</p><p>　　6. 電機對數字輸入脈沖的反應提供提供開放環(huán)路的控制，這使得電機控制起來比較容易而且不那么

71、昂貴;</p><p>　　7. 在直接地結合對軸的裝載時，它是可能達到非常低速的同步自轉的;</p><p>　　8. 當速度與輸入脈沖的頻率成比例時，就可以實現大范圍的旋轉速度</p><p>　　缺點：1. 如果不恰當地控制可能會發(fā)生共鳴;</p><p>　　2. 如果速度太快就不易操縱;</p><p&g

72、t;<b>　　開環(huán)操作：</b></p><p>　　步進機的一個顯著優(yōu)勢就是它的功能能在開環(huán)系統(tǒng)中被準確控制。開環(huán)控制意味著對需要的位置是沒有反饋信息的。這類型的控制系統(tǒng)消除了對昂貴感應與反饋設置例如對光學編碼器等的需要。通過跟蹤輸入脈沖就能很容易地知曉您所處的位置。</p><p><b>　　步進機類型：</b></p>&

73、lt;p>　　有三種步進機類型，它們是：</p><p><b>　　1.可變磁阻型;</b></p><p><b>　　2.永久磁場型;</b></p><p><b>　　3.雜交復合型;</b></p><p><b>　　可變磁阻型：</b>

74、;</p><p>　　這種步進電機已存在了很長的時間.從結構的觀點來看它可能是最容易理解的。圖1顯示了典型的可變磁阻型步進機的截面。這種電機是由一個軟鐵多齒轉子和創(chuàng)傷定子構成的。當定子繞組電源被直流電強化，電機的兩極就被磁化了。當轉子齒被吸引到磁化的兩極時，電機就轉動了。</p><p>　　圖1 可變磁阻型步進機的截面</p><p><b>　　永

75、久磁場型：</b></p><p>　　這種電機通常被稱作“罐”或“傾斜”電機。這種永久磁場型電機是一種低成本和低分辨率類型的電機，它典型的分辨角度是7.5°到15°。永久磁場型步進電機顧名思義有永磁材料添加到電機結構中。與可變磁阻型電機相比，這種類型的電機轉子不再有齒，取而帶之的是轉子隨著電機南北兩極交替位于一條直線平行于轉子軸而磁化。這些磁化的轉子級為電機提供一種增加的磁性漲潮

76、強度，也因此這種類型的步進機與可變磁阻型步進機相比具有更高級的轉距特征。</p><p><b>　　雜交復合型：</b></p><p>　　混合型步進機比永久磁場型步進機要貴，但是因為考慮到了步距，轉距以及速度，它的表現要比永久磁場型步進機表現優(yōu)良。對于雜交復合型步進機而言，典型的步距角度是從3.6° 到 0.9°?；旌鲜讲竭M機中和了可變磁阻型

77、步進機和永久磁場型步進機的優(yōu)良特征。轉子像可變磁阻型步進機一樣是多齒型的，并含有磁化軸同心圓磁鐵繞其軸。轉子上的齒提供了一條更好的路徑，它有助于有助于引導磁通量為首選地點氣隙。與以上兩種類型的步進機相比，這進一步增加了定位、控股及動態(tài)轉矩特性。</p><p>　　兩種最常用類型的步進機是永久磁場型步進機和混合型步進機。如果一個設計師不知道哪種步進機是最適合其應用需求的，他應該首先評估挑選永久磁場型的，因為它通常

78、是最便宜的。如果永久磁場型步電機不行的話，那么混合型的也許會是合適的選擇。</p><p>　　同樣，還存在一些特殊類型的步進機。一種是盤式永磁步進機。這里的轉子是用稀土永磁材料制成的，設計得像一張唱片。（見圖2）這型發(fā)動機具有一些優(yōu)勢，例如很低的惰性和沒有圍繞在兩定子之間的優(yōu)化磁流路。這些品性在某些應用中是必不可少的。</p><p>　　圖2 磁通通過兩桿步進電機的轉子和定子之間&l

79、t;/p><p><b>　　尺寸和功能：</b></p><p>　　除了按自己的步距角度分類之外，步進機也按與電機直徑相關的整體尺寸來分類。例如一個尺寸為11的步進機直徑大約為1.1英寸。同樣大小為23的步進機直徑為2.3英寸( 58毫米)。整體大小相同的步進機由于屬于不同的機子在機身長度上可能會有變化，作為一般規(guī)則，某一特定尺寸電動機的可供輸出力矩隨機身長度的增加而

80、增加。</p><p>　　功率級集成電路驅動步進電機一般由對非常小電機的1瓦特到對大型電機的10-20瓦特。在汽車制造商的資料里，電機的最高功耗水平和熱量限制很少明確表示出來。為了證明這一點，我們必須運用關系式P=V×I，例如：大小為23的步進電機,每階段可在額定的6V和1A，因此,兩相電源的電動機的額定功耗為12瓦特。測量步進機的熱量揮發(fā)水平，這是通常的做法。在靜止的空氣中，步進機的熱量上升到65&

81、#176;。如果電動機可以掛載到一個散熱器也常常能夠增加允許功耗水平，這一點很重要，因為步進機的設計要求它應該從它的最高功耗、尺寸輸出功率或者尺寸輸出成本的角度來加以使用。</p><p><b>　　何時使用步進電機</b></p><p>　　當需要控制運動時，步進電機可以成為很好的選擇。當你需要控制旋轉角度,速度,位置和同步時，它們能夠在應用中發(fā)揮優(yōu)勢。因為自身

82、固有的優(yōu)勢，步進電機在多種不同的應用種都找到了它們的位置。其中一些項目包括打印機、繪圖儀、精品辦公設備、電腦硬盤、醫(yī)療設備、傳真機，汽車和更多。</p><p><b>　　旋轉磁場 </b></p><p>　　當一相繞組的步進電機電源電流與磁是發(fā)達的定子，電流的方向是由“右手定則”決定的?！坝沂侄▌t”規(guī)定：“若磁力線垂直進入右手，四指所指方向為導線中感應電流的方向

83、，則大拇指所指的方向就是磁場的方向?！?lt;/p><p>　　圖5顯示了磁通路徑發(fā)展，B階段隨著所示繞組電流的方向而加強。轉子控制自己使反向流量最低。在這種情況下將電機順時針轉動,使南極配合北極的定子B在位置2和北極配合南極定子B在位置6 ， 獲得電機輪換。為了讓步進電機轉動，我們現在可以看到，我們必須提供一組序列定子，這組定子可以提供一個旋轉磁場，由于磁吸引力，帶動定子轉動。</p><p&g

84、t;　　扭矩代轉矩控制取決于若干因素:</p><p><b>　　.步距;</b></p><p><b>　　.繞組驅動電流;</b></p><p><b>　　.驅動設計或類型;</b></p><p>　　在一個步進電機中，當定子和轉子的磁流量彼此取代時，扭距才發(fā)生變

85、化。定子是由高滲透磁性物質組成的，這種高滲透磁性物質的存在導致磁流量被部分地限定，這有助于磁流量集中在定子兩極。當繞組加強時，電機的扭力輸出與磁流量產生的強度成比例。</p><p>　　界定磁流量的基本項：</p><p>　　H = (N ×i) ÷ l</p><p><b>　　N ：匝數</b></p>

86、<p><b>　　i ：電流</b></p><p><b>　　H：磁場強度</b></p><p><b>　　L：磁流量路徑長度</b></p><p>　　這種關系表明磁場強度與扭距同匝數和電流成正比，與磁流量路徑長度成反比。從這一基本關系可以看出可以看出同樣的磁流量路徑長度，

87、不同的步進電機通過改變繞組參數可以有不同的輸出力矩。更詳細的資料關于繞組參數如何影響步進機輸出量可以在題為“驅動電流基礎”的應用說明中找到。</p><p><b>　　步進模式</b></p><p>　　下列各項是最通常的驅動模式</p><p>　　1. 波動驅動（在1 狀態(tài)）</p><p>　　2. 半步驅動（

88、在2狀態(tài)）</p><p>　　3. 全步驅動（在1和2狀態(tài)）</p><p>　　4. 細分步進（不斷地改變電機的電流）</p><p>　　對于下列的討論如圖3所示</p><p><b>　　圖3 單極步進電機</b></p><p>　　在波動驅動中只有一個線圈轉動在任何接通時間。按照A

89、??B ??A ??B的順序驅動和轉子的轉動為8 ??2 ??4 ??6。對于和相同的參數的單極和有兩極的電機，這一個脈沖模式會運行相同的機械位置。這一個驅動模式的缺點是在單極的電機只有在只有25% 被使用和在有兩極的電機中在任何的運行時間的只有 50% 的總計電機轉動。這表示你沒有在從電機運行中得到最大的轉力矩輸出。</p><p>　　在全步驅動時在任何接同時間有2個脈沖周期。按照AB ??AB ??AB ?

90、 AB 和轉子的轉動為1 ??3 ??5 ??7。全部驅動在驅動方式和1狀態(tài)相同有角動但是機械的移動位置全部被彌補一半。因為單極的電機使用，單極電機的轉力矩輸出比兩極的電機 (對于和相同的參數馬達) 低只有 50% , 有兩極的電機可以用全周期。</p><p>　　半步驅動整合了波動和全部驅動 (在1和2 脈沖)的驅動形式。每兩個脈沖逐步運行被激活并在其他運行周期在每個固定的狀態(tài)。按照AB ??B ??AB ?

91、?A ??AB ??B ??AB ??A和轉子轉動為1 ??2 ??3 ??4 ??5 ??6 ??7 ??8結果在角運動,有一半是在1或2階段--驅動方式. 半步驅動,可以減少的現象稱為共振,可以在經歷了1或2階段的驅動方式。</p><p>　　上述驅動方式激發(fā)觸發(fā)順序如表1</p><p>　　表1 驅動方式激發(fā)觸發(fā)順序</p><p>　　步進驅動電流繞組不

92、斷改變形成許多較小的離散步驟. 更多信息細分,可以發(fā)現在步進。 </p><p><b>　　單步響應</b></p><p>　　步進電機單步響應特性如圖4所示</p><p>　　如圖4 步進電機單步響應特性</p><p>　　當脈沖采用了步進電機轉子的運行方式到上述步驟曲線時間t的時候,它采取的電機軸轉動一個步

93、距角,第一步是脈沖應用. 這一步的時間是高度依賴比率轉矩慣性(負載) ,以及使用的驅動種類。由于扭矩是一個函數的位移所以接下來的加速度也將. 因此,當移動大型梯級遞增高轉矩發(fā)達,因此一個高加速度. 這可引起了長鳴所示. 沉降時間T是要花時間,因此這些振蕩或鈴聲停止. 在某些應用這一現象可不可取. 它可以減少或消除這種行為的細分步進電機. 由于扭矩是一個函數的位移所以接下來的加速度也將. 因此,當移動大型梯級遞增高轉矩發(fā)達,因此一個高加速

94、度. 沉降時間T是要花時間,因此這些振蕩或周期停止. 在某些應用這一現象. 它可以減少或消除這種行為的細分步進電機. </p><p>　　步進電機往往能表現出的現象稱為共振, 這可以看作一個突然喪失或下降時轉矩轉速一定能夠導致漏步驟或失去同步. 當它發(fā)生時,輸入階躍脈沖率剛好與自然振蕩頻率有關. 共振現象的一個步進電機來自其基礎設施建設,因此不可能消除. 這也是取決于負載的情況. 它可以減少電機驅動在半步或微步