1、三相異步電動機的結構及工作原理一 結構 三相異步電動機的種類很多，但各類三相異步電動機的基本結構是相同的 它們都由定子和轉子這兩大基本部分組成，在定子和轉子之間具有一定的氣隙 此外，還有端蓋、軸承、接線盒、吊環等其他附件，如圖 1.1 所示。圖 1.1 封閉式三相籠型異步電動機結構圖1軸承；2前端蓋；3轉軸；4接線盒；5吊環；6定子鐵心；7轉子；8定子繞組；9機座；10后端蓋；11風罩；12風扇1定子部分定子是用來產生旋轉磁場的。三相電動機的定子一般由外殼、定子鐵心、定 子繞組等部分組成。（1）外殼三相電動機外殼包括機座、端蓋、軸承蓋、接線盒及吊環等部件。 機座：鑄鐵或鑄鋼澆鑄成型，它的作用是

2、保護和固定三相電動機的定子繞 組。中、小型三相電動機的機座還有兩個端蓋支承著轉子，它是三相電動機機械 結構的重要組成部分。通常，機座的外表要求散熱性能好，所以一般都鑄有散熱 片。端蓋：用鑄鐵或鑄鋼澆鑄成型，它的作用是把轉子固定在定子內腔中心，使 轉子能夠在定子中均勻地旋轉。軸承蓋：也是鑄鐵或鑄鋼澆鑄成型的，它的作用是固定轉子，使轉子不能軸 向移動，另外起存放潤滑油和保護軸承的作用。接線盒：一般是用鑄鐵澆鑄，其作用是保護和固定繞組的引出線端子。 吊環：一般是用鑄鋼制造，安裝在機座的上端，用來起吊、搬抬三相電動機（2）定子鐵心異步電動機定子鐵心是電動機磁路的一部分，由0.35mm0.5mm厚表面涂

3、有絕緣漆的薄硅鋼片疊壓而成，如圖 1.2 所示。由于硅鋼片較薄而且片與片之間是 絕緣的，所以減少了由于交變磁通通過而引起的鐵心渦流損耗。鐵心內圓有均勻 分布的槽口，用來嵌放定子繞圈。（a） 定子鐵心 （b） 定子沖片 圖 1.2 定子鐵心及沖片示意圖（3）定子繞組定子繞組是三相電動機的電路部分，三相電動機有三相繞組，通入三相對 稱電流時，就會產生旋轉磁場。三相繞組由三個彼此獨立的繞組組成，且每個繞 組又由若干線圈連接而成。每個繞組即為一相，每個繞組在空間相差 120電角 度。線圈由絕緣銅導線或絕緣鋁導線繞制。中、小型三相電動機多采用圓漆包線， 大、中型三相電動機的定子線圈則用較大截面的絕緣扁銅

4、線或扁鋁線繞制后，再 按一定規律嵌入定子鐵心槽內。定子三相繞組的六個出線端都引至接線盒上，首 端分別標為U1, V1, W1，末端分別標為U2, V2, W2。這六個出線端在接線盒 里的排列如圖1.3所示，可以接成星形或三角形。圖1.3 定子繞組的聯結(a)星形連接(b)三角形連接2轉子部分( 1 )轉子鐵心是用 0.5mm 厚的硅鋼片疊壓而成，套在轉軸上，作用和定子鐵心相同，一 方面作為電動機磁路的一部分，一方面用來安放轉子繞組。( 2)轉子繞組 異步電動機的轉子繞組分為繞線形與籠形兩種，由此分為繞線轉子異步電 動機與籠形異步電動機。 繞線形繞組 與定子繞組一樣也是一個三相繞組，一般接成星形

5、，三相引出線分別接到 轉軸上的三個與轉軸絕緣的集電環上，通過電刷裝置與外電路相連，這就有可能 在轉子電路中串接電阻或電動勢以改善電動機的運行性能，見圖1.4。圖 1.4 繞線形轉子與外加變阻器的連接1集電環；2電刷；3變阻器 籠形繞組 在轉子鐵心的每一個槽中插入一根銅條，在銅條兩端各用一個銅環（稱為 端環）把導條連接起來，稱為銅排轉子，如圖1.5 （a）所示。也可用鑄鋁的方 法，把轉子導條和端環風扇葉片用鋁液一次澆鑄而成，稱為鑄鋁轉子，如圖 1.5（b）所示。100kW以下的異步電動機一般采用鑄鋁轉子。（a）銅排轉子 （b）鑄鋁轉子 圖 1.5 籠形轉子繞組3其他部分 其他部分包括端蓋、風扇等

6、。端蓋除了起防護作用外，在端蓋上還裝有軸承， 用以支撐轉子軸。風扇則用來通風冷卻電動機。三相異步電動機的定子與轉子之 間的空氣隙，一般僅為0.2mm1.5mm。氣隙太大，電動機運行時的功率因數 降低；氣隙太小，使裝配困難，運行不可靠，高次諧波磁場增強，從而使附加損 耗增加以及使啟動性能變差。二.三相異步電動機原理當向三相定子繞組中通過入對稱的三相交流電時，就產生了一個以同步轉速 n1 沿定子和轉子內圓空間作順時針方向旋轉的旋轉磁場。由于旋轉磁場以 n1 轉 速旋轉，轉子導體開始時是靜止的，故轉子導體將切割定子旋轉磁場而產生感應 電動勢（感應電動勢的方向用右手定則判定）。由于導子導體兩端被短路環

7、短接， 在感應電動勢的作用下，轉子導體中將產生與感應電動勢方向基本一致的感生電 流。轉子的載流導體在定子磁場中受到電磁力的作用（力的方向用左手定則判 定）。電磁力對轉子軸產生電磁轉矩，驅動轉子沿著旋轉磁場方向旋轉。 通過上述分析可以總結出電動機工作原理為：當電動機的三相定子繞組（各相差 120 度電角度），通入三相對稱交流電后，將產生一個旋轉磁場，該旋轉磁場切 割轉子繞組，從而在轉子繞組中產生感應電流（轉子繞組是閉合通路），載流的 轉子導體在定子旋轉磁場作用下將產生電磁力，從而在電機轉軸上形成電磁轉 矩，驅動電動機旋轉，并且電機旋轉方向與旋轉磁場方向相同The three-phase asyn

8、chronous motor structure and working principleThe structure of three-phase asynchronous motor:Types of three-phase asynchronous motor, but all kinds of three-phase asynchronous motor is the same basic structure, they are the stator and rotor of these two basic components, the stator and rotor has a

9、certain air gap between. In addition, end caps, bearings, cable boxes, rings and other accessories, As shown in Figure 1.1.Figure 1.1 Closed-end three-phase cage induction motor structure 1 - bearing; 2 - the front cover; 3 - axis; 4 - Junction Box; 5 - rings; 6 - stator core;7 - rotor; 8 - stator w

10、indings; 9 - base; 10 - after the end caps; 11 - wind shield; 12 - Fan1. Stator partStator is used to generate the rotating magnetic field. Stator three-phase motors generally shell, stator core, stator windings and other parts.shellThree-phase motor casing including base, end caps, bearing caps, ri

11、ngs, such as junction boxes and components.Machine Block: cast iron or steel casting molding, and its role is to protect and fixed three-phase motor stator windings. Small and medium-sized three-phase motor base and two end caps supporting the rotor, which is three-phase electrical machinery an impo

12、rtant part of the structure. Typically, the base looks good thermal performance requirements, so there are generally cast heat sink.Cover: The casting of cast iron or cast steel molding, which is fixed to the rotor center in the stator cavity, the rotor in the stator in the rotating evenly.Bearing C

13、aps: Cast iron or steel casting is formed, its role is a fixed rotor, the rotor can not move axially, and lubricants storage and protection from the role of bearing.Junction Box: Cast iron casting in general is that its role is to protect and fixed pinout terminals of the windings.Rings: steel manuf

14、acturing in general is installed in the upper base for lifting, moving, carrying three-phase motor.Stator Core Induction motor stator core is part of the motor circuit from 0.35mm 0.5mm thick coated with a thin insulating paint from silicon, as shown in Figure 1.2. And as a result of silicon thin fi

15、lm and between the insulation film, so reduced as a result of alternating magnetic flux through the core caused by eddy current loss. Core inner circle are uniformly distributed the slot to put the stator cruising inlay.(A) stator core (b) stator laminationFigure 1.2 Stator Core and red-chip diagram

16、The stator windingsThree-phase motor stator windings are part of the circuit, there are three-phase three-phase motor windings, symmetrical three-phase current access, it will have a rotating magnetic field. Three-phase winding consists of three separate components of the winding, and each has a num

17、ber of coil windings connected. Is a phase of each winding, each winding in the space angle difference between the 120 electrical. Coil of copper wire from the insulation or insulated aluminum wire around the system. Small and medium-sized three-phase motors use a round wire, large and medium-sized

18、three-phase motor stator windings are insulated with a larger cross-section aluminum flat wound copper wire or flat system, and then embedded in a certain law of stator core slots. Three-phase stator windings of the six round side are directed to the junction box on the first side, respectively, mar

19、ked U1, V1, W1, respectively, marked as the end of U2, V2, W2. The six round side of the box with the wiring as shown in Figure 1.3, you can access into a star or triangle.Figure 1.3 links the stator windings(A) star connection (b) triangle connectingRotor part (1) Rotor CoreWith 0.5mm thick steel f

20、rom, set in the shaft, the role and the same stator core, on the one hand, as part of the motor magnetic circuit, on the one hand to place the rotor windings.(2) rotor windingsThe rotor winding induction motor winding is divided into two kinds of cage-shaped and which is divided into winding rotor a

21、synchronous motor with cage induction motor. shaped winding windingLike with the stator windings is also a three-phase winding, the general access into astrocytes, respectively, received a three-phase pinout on the three axes and axes of the collector ring insulation, and through the brush device co

22、nnected with the external circuit, which may circuit in the rotor resistance or electromotive force in series in order to improve the operation of motor performance, see Figure 1.4.Figure 1.4 Rotor winding-shaped connection with the plus rheostat 1 - collecting ring; 2 - Brush; 3 - Varistors cage wi

23、ndingRotor core in each slot a copper insert in the ends of the copper with a 銅環(known as side Wan) to conn ect the lead article, called copper rotor, Figure 1.5 (a) as shown in . Aluminum methods can also be used to guide the rotor end ring and fan blades made of aluminum casting a liquid, known as

24、 cast aluminum rotor, Figure 1.5 (b) below. Following the induction motor 100kW generally cast aluminum rotor.(a) copper rotor (b) cast aluminum rotorFigure 1.5 Rotor cageOther parts ofOther parts including the cover, fans, etc. In addition to the role of end caps to protect, in the end caps is also

25、 fitted with bearings to support the rotor shaft. Cooling fan motor is used for ventilation. Three-phase asynchronous motor stator and rotor of the air gap between the general is only 0.2mm 1.5mm. Air gap too large, the motor run-time to reduce the power factor; air-gap is too small to make the asse

26、mbly difficult, does not run a reliable, high-harmonic magnetic field increased, thus increasing wear and tear as well as additional start-up performance to deteriorateII. The principle of three-phase asynchronous motor : When the three-phase stator windings through the three-phase alternating curre

27、nt into symmetric, they have had a n1 synchronous speed along the stator and rotor space for inner circle clockwise rotation of the rotating magnetic field. As the rotation speed of rotating magnetic field to n1, the beginning of the rotor conductors is static, it will be cutting the rotor conductor

28、s in the stator rotating magnetic field induction electromotive force generated(electromotive force induced by the direction of right-hand rule to determine). Since the derivation conductor ring at both ends by a short circuit shorted, the role of EMF in the sensor, the rotor conductors and inductive electromotive force will produce basically the same as the direction of the induced current. Rotor stator cu