機(jī)械專業(yè)外文翻譯--伺服系統(tǒng)-資料下載頁(yè)
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【導(dǎo)讀】設(shè)計(jì)的要求，基本達(dá)到了預(yù)期的目的。由輸入軸隨意運(yùn)動(dòng)引起輸出軸運(yùn)動(dòng)的一種形式是同步發(fā)送接收系統(tǒng)。式是伺服機(jī)構(gòu)或伺服系統(tǒng)同步系統(tǒng)可在相當(dāng)大的距離內(nèi)在兩個(gè)分開(kāi)的軸之間工作，但不提供力矩放大—傳送到負(fù)載的力矩不能超過(guò)輸入力矩。由于這個(gè)原因，并且在。需給輸入軸加上很小的力矩。遙控運(yùn)行不是伺服系統(tǒng)的固有特性，但可以通過(guò)數(shù)據(jù)。傳送裝置實(shí)現(xiàn)，通常同步器作為系統(tǒng)的一部分。c．伺服系統(tǒng)要能夠把存在條件與期望結(jié)果相比較得出差值或偏差信號(hào)。這種功率放大器通常稱作伺服放大器。換器產(chǎn)生并送到伺服放大器的偏差電壓的相位和幅值。依次引起伺服放大器或控制器轉(zhuǎn)。平衡電位計(jì)產(chǎn)生的偏差信號(hào)與控制變換器產(chǎn)生的偏。而平衡電位計(jì)轉(zhuǎn)軸指令則可加到一個(gè)電位計(jì)滑動(dòng)觸點(diǎn)的轉(zhuǎn)子上。圖4給出了表示雙極、雙相感應(yīng)電動(dòng)機(jī)的轉(zhuǎn)于、剖面和電路圖。在轉(zhuǎn)子導(dǎo)體中產(chǎn)生電勢(shì)，因此有電流流過(guò)轉(zhuǎn)子
【正文】 on Motor. At any instant of time the flux shown in the diagrams is the resultant flux produced by currents flowing in both coils. When the phase angle is 0186。, only coil A carries current, and the flux is directed upward along the axis of coil A. At 90186。, only coil B carries current, and the flux is directed to the right. At 180186。, the flux is directed downward because coil A carries current in the negative direction. The patterns in the top row show that the flux rotates one revolution for each cycle of the supply current. Flux patterns obtained at intermediate values of phase angle, when current flows in both coils, are given in the second row of Fig. 5. Because the turns of the stator coils are distributed in the slots in such a way that the air gap flux density varies sinusoid ally with angle around the rotor, the flux remains constant in magnitude throughout its rotation, and the speed of rotation is constant. For example, at a phase angle of 45 coil A carries a current whose magnitude is of maximum producing a. flux in the upward direction which is of maximum value. Coil B also carries a current whose magnitude is of maximum producing a flux to the right whose magnitude is of maximum. The vector sum of these two flux ponents at right angles to each other falls at an angle of 45 and has a magnitude equal to the maximum magnitude of either individual ponents, Figure 5 Rotating Field in TwoPhase Induction Motor Figure 6 Relation of Rotating Flux to Rotor Currents and Torque in a TwoPhase Induction Motor The speed at which the flux rotates is called the synchronous speed and depends upon the frequency of the coil currents. For a twopole motor operated from 40U cps power, the synchronous speed is rpm. Trip direction of rotation of the flux in a twophase induction motor is reversed if the terminals of either stator coil are interchanged. In other words, a 180186。 phase shift in either stator current will reverse the direction of the rotation of the motor. With the current IA reversed in polarity it can be seen that the direction of rotation of the magic flux is counterclockwise rather than clockwise as before. Rotation of the magic flux past the conductors of the rotor induces voltages in these conductors, and currents therefore flow in the shortcircuited rotor winding. The direction of rotor currents are indicated by dots and crosses in Fig. 6 for a particular instant during the rotation of the flux. (In the figure, rotor currents are assumed to be in phase with the rotor induced voltage. This assumption is correct only when the rotor speed nearly equals the synchronous speed. ) The letters N and S indicating the rotating north and south poles of the stator, and N39。 and S39。 represent the north and south poles of the rotor produced by the rotor currents. The rotor is thus a mag that tends to align itself with the stator field. A torque is produced in a direction to make the rotor follow the rotating magic field of the stator.
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