步進電機英文資料及翻譯Stepping Motor Types

1、Stepping Motor TypesIntroductionStepping motors come in two varieties, permanent magnet and variable reluctance (there are also hybrid motors, which are indistinguishable from permanent magnet motors from the controller's point of view). Lacking a label on the motor, you can generally tell the t

2、wo apart by feel when no power is applied. Permanent magnet motors tend to "cog" as you twist the rotor with your fingers, while variable reluctance motors almost spin freely (although they may cog slightly because of residual magnetization in the rotor). You can also distinguish between t

3、he two varieties with an ohmmeter. Variable reluctance motors usually have three (sometimes four) windings, with a common return, while permanent magnet motors usually have two independent windings, with or without center taps. Center-tapped windings are used in unipolar permanent magnet motors. Ste

4、pping motors come in a wide range of angular resolution. The coarsest motors typically turn 90 degrees per step, while high resolution permanent magnet motors are commonly able to handle 1.8 or even 0.72 degrees per step. With an appropriate controller, most permanent magnet and hybrid motors can be

5、 run in half-steps, and some controllers can handle smaller fractional steps or microsteps. For both permanent magnet and variable reluctance stepping motors, if just one winding of the motor is energised, the rotor (under no load) will snap to a fixed angle and then hold that angle until the torque

6、 exceeds the holding torque of the motor, at which point, the rotor will turn, trying to hold at each successive equilibrium point. Variable Reluctance MotorsFigure 1.1 If your motor has three windings, typically connected as shown in the schematic diagram in Figure 1.1, with one terminal common to

7、all windings, it is most likely a variable reluctance stepping motor. In use, the common wire typically goes to the positive supply and the windings are energized in sequence.The cross section shown in Figure 1.1 is of 30 degree per step variable reluctance motor. The rotor in this motor has 4 teeth

8、 and the stator has 6 poles, with each winding wrapped around two opposite poles. With winding number 1 energised, the rotor teeth marked X are attracted to this winding's poles. If the current through winding 1 is turned off and winding 2 is turned on, the rotor will rotate 30 degrees clockwise

9、 so that the poles marked Y line up with the poles marked 2. To rotate this motor continuously, we just apply power to the 3 windings in sequence. Assuming positive logic, where a 1 means turning on the current through a motor winding, the following control sequence will spin the motor illustrated i

10、n Figure 1.1 clockwise 24 steps or 2 revolutions: time ->The section of this tutorial on Mid-Level Control provides details on methods for generating such sequences of control signals, while the section on Control Circuits discusses the power switching circuitry needed to drive the motor windings

11、 from such control sequences. There are also variable reluctance stepping motors with 4 and 5 windings, requiring 5 or 6 wires. The principle for driving these motors is the same as that for the three winding variety, but it becomes important to work out the correct order to energise the windings to

12、 make the motor step nicely. The motor geometry illustrated in Figure 1.1, giving 30 degrees per step, uses the fewest number of rotor teeth and stator poles that performs satisfactorily. Using more motor poles and more rotor teeth allows construction of motors with smaller step angle. Toothed faces

13、 on each pole and a correspondingly finely toothed rotor allows for step angles as small as a few degrees. Unipolar MotorsFigure 1.2 Unipolar stepping motors, both Permanent magnet and hybrid stepping motors with 5 or 6 wires are usually wired as shown in the schematic in Figure 1.2, with a center t

14、ap on each of two windings. In use, the center taps of the windings are typically wired to the positive supply, and the two ends of each winding are alternately grounded to reverse the direction of the field provided by that winding. The motor cross section shown in Figure 1.2 is of a 30 degree per

15、step permanent magnet or hybrid motor - the difference between these two motor types is not relevant at this level of abstraction. Motor winding number 1 is distributed between the top and bottom stator pole, while motor winding number 2 is distributed between the left and right motor poles. The rot

16、or is a permanent magnet with 6 poles, 3 south and 3 north, arranged around its circumfrence. For higher angular resolutions, the rotor must have proportionally more poles. The 30 degree per step motor in the figure is one of the most common permanent magnet motor designs, although 15 and 7.5 degree

17、 per step motors are widely available. Permanent magnet motors with resolutions as good as 1.8 degrees per step are made, and hybrid motors are routinely built with 3.6 and 1.8 degrees per step, with resolutions as fine as 0.72 degrees per step available. As shown in the figure, the current flowing

18、from the center tap of winding 1 to terminal a causes the top stator pole to be a north pole while the bottom stator pole is a south pole. This attracts the rotor into the position shown. If the power to winding 1 is removed and winding 2 is energised, the rotor will turn 30 degrees, or one step. To

19、 rotate the motor continuously, we just apply power to the two windings in sequence. Assuming positive logic, where a 1 means turning on the current through a motor winding, the following two control sequences will spin the motor illustrated in Figure 1.2 clockwise 24 steps or 2 revolutions: Winding

20、 1a Winding 2aWinding 1a Winding 2a time ->Note that the two halves of each winding are never energized at the same time. Both sequences shown above will rotate a permanent magnet one step at a time. The top sequence only powers one winding at a time, as illustrated in the figure above; thus, it

21、uses less power. The bottom sequence involves powering two windings at a time and generally produces a torque about 1.4 times greater than the top sequence while using twice as much power. The section of this tutorial on Mid-Level Control provides details on methods for generating such sequences of

22、control signals, while the section on Control Circuits discusses the power switching circuitry needed to drive the motor windings from such control sequences. The step positions produced by the two sequences above are not the same; as a result, combining the two sequences allows half stepping, with

23、the motor stopping alternately at the positions indicated by one or the other sequence. The combined sequence is as follows: Winding 1a Winding 2aBipolar MotorsFigure 1.3 Bipolar permanent magnet and hybrid motors are constructed with exactly the same mechanism as is used on unipolar motors, but the

24、 two windings are wired more simply, with no center taps. Thus, the motor itself is simpler but the drive circuitry needed to reverse the polarity of each pair of motor poles is more complex. The schematic in Figure 1.3 shows how such a motor is wired, while the motor cross section shown here is exa

25、ctly the same as the cross section shown in Figure 1.2. The drive circuitry for such a motor requires an H-bridge control circuit for each winding; these are discussed in more detail in the section on Control Circuits. Briefly, an H-bridge allows the polarity of the power applied to each end of each

26、 winding to be controlled independently. The control sequences for single stepping such a motor are shown below, using + and - symbols to indicate the polarity of the power applied to each motor terminal: Terminal 1a +-+-+-+- +-+-+-+- Terminal 1b -+-+-+-+- -+-+-+-+ Terminal 2a -+-+-+-+- -+-+-+-+- Te

27、rminal 2b -+-+-+-+ +-+-+-+-+ time ->Note that these sequences are identical to those for a unipolar permanent magnet motor, at an abstract level, and that above the level of the H-bridge power switching electronics, the control systems for the two types of motor can be identical. Note that many f

28、ull H-bridge driver chips have one control input to enable the output and another to control the direction. Given two such bridge chips, one per winding, the following control sequences will spin the motor identically to the control sequences given above: To distinguish a bipolar permanent magnet mo

29、tor from other 4 wire motors, measure the resistances between the different terminals. It is worth noting that some permanent magnet stepping motors have 4 independent windings, organized as two sets of two. Within each set, if the two windings are wired in series, the result can be used as a high v

30、oltage bipolar motor. If they are wired in parallel, the result can be used as a low voltage bipolar motor. If they are wired in series with a center tap, the result can be used as a low voltage unipolar motor. Bifilar MotorsBifilar windings on a stepping motor are applied to the same rotor and stat

31、or geometry as a bipolar motor, but instead of winding each coil in the stator with a single wire, two wires are wound in parallel with each other. As a result, the motor has 8 wires, not four. In practice, motors with bifilar windings are always powered as either unipolar or bipolar motors. Figure

32、1.4 shows the alternative connections to the windings of such a motor. Figure 1.4 To use a bifilar motor as a unipolar motor, the two wires of each winding are connected in series and the point of connection is used as a center-tap. Winding 1 in Figure 1.4 is shown connected this way. To use a bifil

33、ar motor as a bipolar motor, the two wires of each winding are connected either in parallel or in series. Winding 2 in Figure 1.4 is shown with a parallel connection; this allows low voltage high-current operation. Winding 1 in Figure 1.4 is shown with a series connection; if the center tap is ignor

34、ed, this allows operation at a higher voltage and lower current than would be used with the windings in parallel. It should be noted that essentially all 6-wire motors sold for bipolar use are actually wound using bifilar windings, so that the external connection that serves as a center tap is actua

35、lly connected as shown for winding 1 in Figure 1.4. Naturally, therefore, any unipolar motor may be used as a bipolar motor at twice the rated voltage and half the rated current as is given on the nameplate. The question of the correct operating voltage for a bipolar motor run as a unipolar motor, o

36、r for a bifilar motor with the motor windings in series is not as trivial as it might first appear. There are three issues: The current carrying capacity of the wire, cooling the motor, and avoiding driving the motor's magnetic circuits into saturation. Thermal considerations suggest that, if th

37、e windings are wired in series, the voltage should only be raised by the square root of 2. The magnetic field in the motor depends on the number of ampere turns; when the two half-windings are run in series, the number of turns is doubled, but because a well-designed motor has magnetic circuits that

38、 are close to saturation when the motor is run at its rated voltage and current, increasing the number of ampere-turns does not make the field any stronger. Therefore, when a motor is run with the two half-windings in series, the current should be halved in order to avoid saturation; or, in other wo

39、rds, the voltage across the motor winding should be the same as it was. For those who salvage old motors, finding an 8-wire motor poses a challenge! Which of the 8 wires is which? It is not hard to figure this out using an ohm meter, an AC volt meter, and a low voltage AC source. First, use the ohm

40、meter to identify the motor leads that are connected to each other through the motor windings. Then, connect a low-voltage AC source to one of these windings. The AC voltage should be below the advertised operating voltage of the motor; voltages under 1 volt are recommended. The geometry of the magn

41、etic circuits of the motor guarantees that the two wires of a bifilar winding will be strongly coupled for AC signals, while there should be almost no coupling to the other two wires. Therefore, probing with an AC volt meter should disclose which of the other three windings is paired to the winding

42、under power. Multiphase MotorsFigure 1.5 A less common class of permanent magnet or hybrid stepping motor is wired with all windings of the motor in a cyclic series, with one tap between each pair of windings in the cycle, or with only one end of each motor winding exposed while the other ends of ea

43、ch winding are tied together to an inaccessible internal connection. In the context of 3-phase motors, these configurations would be described as Delta and Y configurations, but they are also used with 5-phase motors, as illustrated in Figure 1.5. Some multiphase motors expose all ends of all motor

44、windings, leaving it to the user to decide between the Delta and Y configurations, or alternatively, allowing each winding to be driven independently. Control of either one of these multiphase motors in either the Delta or Y configuration requires 1/2 of an H-bridge for each motor terminal. It is no

45、teworthy that 5-phase motors have the potential of delivering more torque from a given package size because all or all but one of the motor windings are energised at every point in the drive cycle. Some 5-phase motors have high resolutions on the order of 0.72 degrees per step (500 steps per revolut

46、ion). Many automotive alternators are built using a 3-phase hybrid geometry with either a permanent magnet rotor or an electromagnet rotor powered through a pair of slip-rings. These have been successfully used as stepping motors in some heavy duty industrial applications; step angles of 10 degrees

47、per step have been reported. With a 5-phase motor, there are 10 steps per repeat in the stepping cycle, as shown below: Terminal 1 +-+-+ Terminal 2 -+-+- Terminal 3 +-+-+ Terminal 4 +-+- Terminal 5 -+-+-time ->With a 3-phase motor, there are 6 steps per repeat in the stepping cycle, as shown belo

48、w: Terminal 1 +-+- Terminal 2 -+-+- Terminal 3 +-+-+time ->Here, as in the bipolar case, each terminal is shown as being either connected to the positive or negative bus of the motor power system. Note that, at each step, only one terminal changes polarity. This change removes the power from one

49、winding attached to that terminal (because both terminals of the winding in question are of the same polarity) and applies power to one winding that was previously idle. Given the motor geometry suggested by Figure 1.5, this control sequence will drive the motor through two revolutions. To distingui

50、sh a 5-phase motor from other motors with 5 leads, note that, if the resistance between two consecutive terminals of the 5-phase motor is R, the resistance between non-consecutive terminals will be 1.5R. Note that some 5-phase motors have 5 separate motor windings, with a total of 10 leads. These ca

51、n be connected in the star configuration shown above, using 5 half-bridge driver circuits, or each winding can be driven by its own full-bridge. While the theoretical component count of half-bridge drivers is lower, the availability of integrated full-bridge chips may make the latter approach prefer

52、able. 步進電機介紹變磁阻電機單極電機雙極電機單一電機多相電機介紹步進電動機分成兩類、永磁和變磁阻(也有混合電機、永磁電機與從控制器的觀點)。缺乏一個標簽貼在電機,通常你能夠告訴這兩個分開時的感受時,沒有任何力量適用。永磁電機趨向于“差錯”,因為你扭轉子用你的手指,而變磁阻電機自由幾乎旋轉(盡管他們可能輪齒略因為轉子剩余磁化)。你也可以區(qū)分這兩個品種利用歐姆表。通常有三個變磁阻電機繞組(有時四),具有共同的回報,同時永磁電機繞組通常有兩個獨立,有或沒有中心喪葬號音。Center-tapped繞組單極永磁電機中使用。步進電動機來,在廣泛的角分辨率。每次迭代僅僅馬達的每一步轉90度,而高分辨率

53、的永磁電機通常能夠處理1.8甚至每一步0.72度。提供一個合適的控制器,大多數(shù)永磁和混合型馬達可以運行在half-steps,一些控制器可以處理步驟或microsteps較小的分數(shù)。對于永磁步進電動機和可變的不情愿,如果只是一個繞組電機被能量化,轉子在任何負載)會斷掉,然后以一個固定的角度認為,直到超過角力矩電機轉矩的舉辦,屆時,將轉子,想使在每個連續(xù)的平衡點。變磁阻電機圖 1.1如果你有三個繞組電機,通常是連接示意圖所示的圖1.1中,一個終端共同繞組,它最有可能的來源是一個變量不情愿的步進電機。在使用中,普通電線通常去積極供給和充滿活力的繞組按順序排列。橫截面如圖1.1所示的每一步30度變磁

54、阻電動機。在這個電機轉子和定子4牙齒有6個極點,每個蜿蜒纏繞在兩個相對的柱。1號激發(fā)曲折,轉子的牙齒上標記X被吸引到這條蜿蜒的極點。如果當前的曲折蜿蜒1關掉,二是打開,順時針方向旋轉的轉子將30度,兩極明顯Y上與兩極明顯2。旋轉這個汽車不斷,我們只要運用三繞組功率按順序排列。假設積極的邏輯,一個1,表示打開一個電機繞組電流流過,下面將旋轉電機控制序列圖1.1說明順時針廿四步或2革命:時間- - - - - - >這篇教程的斷面上的細節(jié)中層控制提供了方法的控制信號產生序列,而部分功率開關控制電路,討論了電路來驅動電機繞組需要從這樣的控制序列。也有變量不情愿與第四和第五步進電動機繞組,需要5

55、或6電線。這些原則驅動電機是一樣的三繞組的品種,但工作變得重要了足夠的正確順序,使電機繞組步長得很好。說明電機幾何如圖1.1,每一步給30度,用最少的轉子和定子兩極牙齒進行順利。用更電機轉子磁極牙齒和允許建設與較小的電機步距角。在每一個桿位和齒面臨相應的細碎齒轉子允許一步角為小至幾攝氏度。單極電機圖1.2單極步進電動機,其中包括長期磁體和混合式步進電動機和5或6電線通常是有線如圖原理圖1.2中,挖掘每個中心兩繞組。在使用,中心通常水龍頭的繞組、連接到積極的供給,以及兩頭各繞組接地反向交替是磁場的方向繞組提供的。電機截面如圖1.2所示的每一步30度或復合永磁電機這兩個電機類型之間的差別是沒有規(guī)定

56、在這個級別的抽象。電機繞組的1號之間分配頂部和底部的定子桿,當電機繞組2號分布左和右的電機之間的增長極。永磁轉子是6個極點,3南和3北,安排circumfrence繞著它。高等角的決心,轉子磁極一定比例較高。30度的每步進電動機,這個數(shù)字是最常見的一種永磁電機設計,盡管每一步15至7.5度電機被廣泛使用。永磁電動機和決議一樣好每一步1.8度,并提出了混合型馬達通常采用3.6和1.8度,每一步,并出臺決議一樣好每一步0.72度可用。圖中所示,從中心電流流經(jīng)龍頭1到終端一個引起繞組定子桿上一個北極而底部是定子極南極。這吸引了轉子的位置顯示。如果被權力和蜿蜒纏繞1 2被能量化,轉子將30度,或者一個

57、步驟。旋轉電機不斷,我們只是兩繞組接通電源,循序漸進。假設積極的邏輯,一個1,表示打開一個電機繞組電流流過,以下兩種控制序列將旋轉電機說明圖1.2順時針廿四步或2革命:時間- - - - - - >時間- - - - - - >注意兩個半場,每半場各繞組從不充能在同一時間內。上圖顯示兩個序列會旋轉永磁體一步一個腳印。只有力量上一個繞組序列在一段時間,就像上圖說明;因此,它使用的電力更少。序列驅動底部涉及兩個繞組、一般產生轉矩約1.4倍,而使用前序列兩倍的力量。這篇教程的斷面上的細節(jié)中層控制提供了方法的控制信號產生序列,而部分功率開關控制電路,討論了電路來驅動電機繞組需要從這樣的控制

58、序列。步驟位置所產生的兩個序列以上是不一樣的,作為一個結果,結合兩個序列允許半步進,在電機停止位置交替顯示了一個或另一個序列。組合的序列如下:時間- - - - - - >雙極電機圖1.3雙極永磁和混合型馬達由相同的機制是用在單極馬達,但是兩個繞組接線的更加簡單,沒有中心喪葬號音。因此,電機本身就是簡單但是驅動電路需要反極性的每一對電動機磁極比較復雜。圖1.3中示意圖顯示這樣的一個電機接線,而汽車截面此處顯示的是一模一樣的橫截面如圖1.2所示。驅動電路這樣的一個電機需要一個定速控制電路為每個纏繞;這些都是進行更詳細的討論在節(jié)控制電路。簡單地說,一個允許的極性定速電力的應用的每個末端上每一卷是獨立控制?？刂菩蛄袉尾竭M這樣的一個電機如下表所示,用+和-符號表示的極性每臺電機功率應用終端:終端1 + + + - - - - - - - - - - - - - - - - - - - - - - - - + + + + + + + + - - - - - - - - - - - - - - - - 終端1 b + - - - -