【正文】 1 畢業(yè)設(shè)計（論文） 外文翻譯 題 目 ： 直流電機(jī)控制系統(tǒng) 專 業(yè) ： 電子信息工程 班 級 ： 08 級 學(xué) 生 ： 辛國鵬 指導(dǎo)教師 ： 湯曉方 西安理工大學(xué)高科學(xué)院 2020 年 2 說 明 英文翻譯 是畢業(yè)設(shè)計（論文）答辯委員會對 學(xué)生答辯資格審查的依據(jù)材料之一。學(xué)生應(yīng)當(dāng)在畢業(yè)設(shè)計（論文）工作 期內(nèi)完成， 英文翻譯 不合格者不得參加答辯。 英文翻譯包括英文全文和翻譯兩部分 （ 中文 翻譯不少于 2020字） 。 所選英文 資料 內(nèi)容應(yīng)與本 人 專業(yè)或本人論文題目有關(guān)。 從網(wǎng)上下載的中英文對照文章按不合格論。 3 英文全文 Introduction to . Machines . machines are characterized by their versatility. By means of various binations of shunt, series, and separately excited field windings they can be designed to display a wide variety of voltampere or speedtorque characteristics for both dynamic and steady state operation. Because of the ease with which they can be controlled, systems of . machines are often used in applications requiring a wide range of motor speeds or precise control of motor output. The essential features of a . machine are shown schematically. The stator has salient poles and is excited by one or more field coils. The airgap flux distribution created by the field winding is symmetrical about the centerline of the field poles. This is called the field axis or direct axis. As we know, the . voltage generated in each rotating armature coil is converted to . in the external armature terminals by means of a rotating mutator and stationary brushes to which the armature leads are connected. The mutatorbrush bination forms a mechanical rectifier, resulting in a . armature voltage as well as an armature . Wave then is 90 electrical degrees from the axis of the field poles, . in the quadrature axis. In the schematic representation the brushes are shown in quadrature axis because this is the position of the coils to which they are connected. The armature . Wave then is along the brush axis as shown. (The geometrical position of the brushes in an actual machine is approximately 90 electrical degrees from their position in the schematic diagram because of the shape of the end connections to the mutator.) The magic torque and the speed voltage appearing at the brushes are independent of the spatial waveform of the flux distribution。 for convenience we shall continue to assume a sinusoidal fluxdensity wave in the air gap. The torque can then be found from the magic field viewpoint. The torque can be expressed in terms of the interaction of the directaxis airgap flux 4 per pole d? and spacefundamental ponent 1Fa of the armature . With the brushes in the quadrature axis the angle between these fields is 90 electrical degrees, and its sine equals unity. For a P pole machine 2122 dPT Fa? ???? ???? （ 11） In which the minus sign gas been dropped because the positive direction of the torque can be determined from physical reasoning. The space fundamental 1Fa of the sawtooth armature is 28? times its peak. Substitution in above equation then gives ()2 a aaPCT i N mm ???? （ 12） Where, aI =current in external armature circuit。 aC =total number of conductors in armature winding。 m=number of parallel paths through winding. And 2 aa PCK m?? （ 13） is a constant fixed by the design of the winding. The rectified voltage generated in the armature has already been discussed before for an elementary singlecoil armature. The effect of distributing the winding in several slots is shown in figure. In which each of the rectified sine wave is the voltage generated in one of the coils, mutation taking place at the moment when the coil sides are in the neutral zone. The generated voltage as observed from the brushes and is the sum of the rectified voltages of all the coils in series between brushes and is shown by the rippling line labeled ae in figure. With a dozen or so mutator segments per pole, the ripple bees very small and the average generated voltage observed from the brushes equals the sum of the average values of the rectified coil 5 voltages. The rectified voltage ae between brushes, Known also as the speed voltage, is 2 aa d m a d mPCeKm ? ? ? ???? （ 14） where aK is the design constant. The rectified voltage of a distributed winding has the same average value as that of a concentrated coil. The difference is that the ripple is greatly reduced. From the above equations, with all variable expressed