专外考前复习重点.docx

1、专外考前复习重点P1U1A1 passive network 无源网络 2 active network 有源网络3 passive circuit elements 无源电路元件4 the rate of change with time of the current 电流随时间的变化率5 proportionality constant 比例常数 6 differential equation 微分方程7 voltage source 电压源 current source 电流源8 the second-order differential equation 二阶微分方程9. loop a

2、nalysis 回路分析法 10. voltage drop 电压降 11. loop current 回路电流12 Note that conventional current flow is used ; hence the current in each element is shown in the direction of direction of decreasing voltage. 注意，图中电流的参考方向为惯用的参考方向，因此流过每一个元件的电流方向与电压降的方向一致。13 In their ideal form, voltage sources generate a con

3、stant voltage independent of the current drawn from the source. The aforementioned battery and generator are regarded as voltage sources since their voltage is essentially constant with load. On the other hand, current sources produce a current whose magnitude is independent of the load connected to

4、 the source. 在理想状态下：电压源产生恒定的电压，它与从电压源中流出的电流无关。因为负载变化时电压基本恒定，所以上述电池和发电机被认为是电压源。另一方面，电流源产生电流，电流的大小与电源连接的负载无关。14. An electrical circuit or network is composed of elements such as resistors, inductors, and capacitors connected together in some manner. If the network contains no energy sources, such as b

5、atteries or electrical generators, it is known as a passive network. On the other hand, if one or more energy sources are present, the resultant combination is an active network.15. In the case of a resistor, the voltage-current relationship is given by Ohms law, which states that the voltage across

6、 the resistor is equal to the current through the resistor multiplied by the value of the resistance.16. The voltage across a pure inductor is defined by Faradays law, which states that the voltage across the inductor is proportional to the rate of change with time of the current through the inducto

7、r.17. Active electrical devices involve the conversion of energy to electrical form. From its stored chemical energy. The electrical energy of a generator is a result of the mechanical energy of the rotating armature.18. Active electrical elements occur in two basic forms: voltage sources and curren

8、t source.19. On the other hand, current sources produce a current whose magnitude is independent of the load connected to the source.20. A common method of analyzing an electrical network is mesh or loop analysis. The fundamental law that is applied in this method is kirchhoffs first law, which stat

9、es that the algebraic sum of the voltages around a closed loop is 0,or,in any closed loop, the sum of the voltage rises must equal the sum of the voltage drops.分析电气网络的一般方法是网孔分析法或回路分析法。应用于此方法的基本定律是基尔霍夫第一定律，基尔霍夫第一定律指出：一个闭合回路中的电压代数和为0，换句话说，任一闭合回路中的电压升等于电压降。P1U1B1 positive half-cycle 正半周 2 phase sequenc

10、e 相序3 line voltage 线电压4 armature coil 电枢绕组5 three-wire or four-wire three-phase system 三线或四线三相系统6 wye-connection 星（Y）形联结7 delta-connection 三角形（）联结8 phasor diagram 相量图9 power factor 功率因数10 A three-phase electric circuit is energized by three alternating emfs of the same frequency and differing in tim

11、e phase by 120 electrical degrees. 三相电路可由三个频率相同、在时间相位上相差120电角度的电动势供电。11 Three-phase machinery and control equipment are smaller, lighter in weight, and more efficient than single-phase equipment of the same rated capacity. In addition to the above-mentioned advantages offered by a three-phase system

12、, the distribution of three-phase power requires only three fourths as much line copper as does the single-phase distribution of the same amount of power. 三相供电的机械和控制设备与相同额定容量的单相供电的设备相比：体积小，重量轻，效率高。三相系统除了具有上述优点，三相电的传输所需要的铜线仅仅是单相电传输同样功率所需铜线的3/4。13. At unity power factor, the power in a single-phase ci

13、rcuit is zero twice each cycle 在功率因数为1时，单相电路里的功率值每个周波有两次为零。14. Viewed in this light, it will be found that the analysis of three-phase circuits is little more difficult than that of single-phase circuits. 这样看来，三相电路的分析比单相电路的分析难不了多少。15. These windings are so spaced on the armature surface that the emf

14、s generated in them are 120 apart in time phase. 这些绕组在电枢表面上是按它们产生的电动势在时间相位上相差120分布的。16 It is helpful when drawing circuit diagrams of wye connection to arrange the three phases in the shape of a Y as shown in Fig. 将三相绕组排列成如图所示的Y形有助于Y形联接电路图的绘制。17 It should be noted that if the polarity of point A wit

15、h respect to N ( ) is assumed for the positive half-cycle, then when used in the same phasor diagram should be drawn opposite to, or 180 out of phase with, .应该注意，如果把A点相对于N点的极性（ ）定为正半周，那么 在用于同一相量图中时就应该画得同 相反，即相位差为180。18 The current flowing out to the line wires from the generator terminals A, B and C

16、 must flow from the neutral point N, out through the generator coils.从发电机接线端A、B和C (图 1-1B-2)流到线路导线的电流必定从中性点N中流出，并流过发电机线圈。19. three-phase circuit 三相电路 20. single-phase circuits 单相电路21. In a single-phase circuit, the power is of a pulsating nature22. power factor 功率因数23. Although the power supplied to

17、 each of the three phases of a three-phase circuit is pulsating, it may be proved that the total three-phase power supplied a balanced three-phase circuit is constant. Because of this, the characteristics of three-phase apparatus, in general, are superior to those of similar single-phase apparatus.

18、24. The coil ends may all be brought out of the generator to form three separate single-phase circuits. However, the coils are ordinarily interconnected either internally or externally to form a three-wire or four-wire three-phase system.25. There are two ways of connecting the coils of three-phase

19、generators, and in general, there are two ways of connecting devices of any sort to a three-phase circuit. These are the wye-connection and delta-connection. Most generators are wye-connected, but loads may be either wye-connected or delta-connected.26. The voltages generated in each phase of an AC

20、generator are called the phase voltages (symbol Ep).27. The voltage between any two of the three line terminals A, B, or C is called line-to-line voltage or, simply, a line voltage(symbol EL).28. It should be noted in Fig. 1-1B-2 that each phasor is lettered with two subscripts.29. The two letters i

21、ndicate the two points between which the voltage exists, and the order of the letters indicates the relative polarity of the voltage during its positive half-cycle.30. For example, the symbol EAN indicates a voltage between the points A and N with the point A being positive with respect to point N d

22、uring its positive half-cycle.31. Therefore, in a balanced wye-connection EL = 1.73EP 因此，用平衡星型连接: EL = 1.73EP32. In a wye connection IL = IP 用星型连接: IL = IPP1U2A1 two-port system 双端口系统2 output resistance 输出阻抗3 integrated circuit (IC) 集成电路4 inner workings 工作原理 6 gain factor 增益系数5 filter circuit 滤波电路 7

23、 gathering terms 综合上述等式8 the connection of the circuitry inside the Op-Amp.运算放大器的内部电路结构。9 This makes design difficult since these parameters usually vary from device to device, as well as with temperature.器件之间参数的分散性和温度漂移特性给设计工作增加了难度。10 Various currents are defined in part b of the figure. 各个电流定义如b图所

24、示。11 Each is measured with respect to ground potential. 每一个电压均指的是相对于接地管脚的电位。12 Not shown are other connections necessary to run the Op-Amp such as its attachments to power supplies and to ground potential. 让运算放大器正常运行所必需的其它一些管脚，诸如电源管脚、接地管脚等并未画出。13 This is one of the key features of Op-Amp design-the

25、action of the circuit on signals depends only upon the external elements which can be easily varied by the designer and which do not depend upon the detailed character of the Op-Amp itself. 这是运算放大器设计的重要特征之一在信号作用下，电路的动作仅取决于能够容易被设计者改变的外部元件，而不取决于运算放大器本身的细节特性。14 In some sense, by using an Op-Amp we trad

26、e off “power” for “control”.从某种意义上说，使用运算放大器是以“能量”为代价来换取“控制”。15 Integrated circuit technology as construction of many amplifier circuits on a single composite “chip” of semiconductor material. 集成电路技术使得在非常小的一块半导体材料构成的复合 “芯片”上可以安装许多放大器电路。16. The operational amplifier 运算放大器17. Operational amplifiers are

27、 differential devices. By this we mean that the output voltage with respect to ground is given by the expression UO = A(U+-U-) where A is the gain of the Op-Amp and U+ and U- the voltages at inputs. In other words, the output voltage is A times the difference in potential between the two inputs.18.

28、First, we note that the voltage at the positive input, U+ , is equal to the source voltage, U+ = Us.19. This shows that if A is very large, then the gain of the circuit is independent of the exact value of A and can be controlled by the choice of R1 and R2.20. The first law states that in normal Op-

29、Amp circuits we may assume that the voltage difference between the input terminals is zero, that is, U+ = U-21. The second law states that in normal Op-Amp circuits both of the input currents may be assumed to be zero: I+ = I- = 022. The first law is due to the large value of the intrinsic gain A. F

30、or example, if the output of an Op-Amp is 1V and A = 100,000, then (U+-U-) = 10-5V. This is such a small number that it can often be ignored, and we set U+ = U-. The second law comes from the construction of the circuitry inside the Op-Amp which is such that almost no current flows into either of th

31、e two inputs.P1U2B1. electrons or mobile negative charges(N-type)：自由电子2. “holes” or positive charges(P-type)：正电荷 3. bipolar transistor :双向晶体管4. forward bias :正偏 5. the emitter :发射极 6. the collector :集电极7. the base :基极 8. common emitter configuration :共射极连接9. The particular advantage offered by this

32、circuit is that a relatively small base current can control and instigate a very much larger collector current (or, more correctly, a small input power is capable of producing a much larger output power).In other words, the transistor works as an amplifier.电路特性就是一个相对小的基极电流能够控制和激发一个非常大的集电极电流（或者更准确地说，一个小的输入功率能够产生一个大的输出功率）。换句话说，晶体管起放大器的作用。10. reverse biased :反向偏置 11. working principles :工作原理12. three leads :三根引线 13. integrated circuits :集成电路14. power transistors :功率晶体管