电气工程及其自动化专业英语第三章section_3-1
电气工程及自动化专业英语考试翻译课文Electric Power Systems 电力系统3.1
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Section 1 Introduction 第一节介绍The modern society depends on the electricity supply more heavily than ever before.现代社会比以往任何时候对电力供应的依赖更多。
It can not be imagined what the world should be if the electricity supply were interrupted all over the world. 如果中断了世界各地的电力供应,无法想像世界会变成什么样子Electric power systems (or electric energy systems), providing electricity to the modern society, have become indispensable components of the industrial world. 电力系统(或电力能源系统),提供电力到现代社会,已成为产业界的不可缺少的组成部分。
The first complete electric power system (comprising a generator, cable, fuse, meter, and loads) was built by Thomas Edison –the historic Pearl Street Station in New York City which began operation in September 1882. 托马斯爱迪生建立了世界上第一个完整的电力系统(包括发电机,电缆,熔断器,计量,并加载)它就是位于纽约市具有历史意义的珍珠街的发电厂始于1882年9月运作。
This was a DC system consisting of a steam-engine-driven DC generator supplying power to 59 customers within an area roughly 1.5 km in radius. The load, which consisted entirely of incandescent lamps, was supplied at 110 V through an underground cable system. 这是一个直流系统,由一个蒸汽发动机驱动的直流发电机其供电面积约1.5公里至59范围内的客户。
电气工程及其自动化专业英语答案
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第一章⚫Section1习题答案一.Choose the best answer into the blank1.B2.D3.C4.A5.B二.Answer the following questions according to the text1.No. The current need not be a constant-valued function because charge can vary with2.Time.2.The current increases when the time rate of charges is greater.3.The uab=-1V can be interpreted in two ways:①point b is 1 V higher than point a;②the Potential at point a with respect to point b is -1V.4.w=∫pdt5.Because by the passive sign convention,current enters through the positive polarity ofThe voltage,p=ui>0 implies that the element is absorbing power and p=ui<0 impliesThat the element is releasing or supplying power.⚫Section2习题答案一.Choose the best answer into the blank1.B2.A3.B4.C5.B二.Answer the following questions according to the text1.The difference between an independent source and a dependent source is: the source2.Quantity of a dependent source is controlled by another voltage or current,but the source Quantity of an independent source maintains a specified value.3.An ideal independent source is an active element that provides a specified voltage or4.Current that is completely independent of other circuit variables.3.No.The current through an independent voltage source can be calculated by the4.External circuit.4.A voltage-controlled voltage source(VCVS),A current-controlled voltage source (CCVS),A voltage-controlled current source (VCCS), A current-controlled current source (CCCS)5.No,it isn’t.三.Translate the following into Chinese(译文)在随后内容中提及的所有简单电路元件,根据通过它的电流和其两端电压之间的关系进行分类。
电气工程与自动化专业英语翻译(第三章)
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晶体管和电子管在大多数电器和电子设备,晶体管几乎完全取代电子管。
晶体管作为电子管执行相同的功能。
但是,它们也有几个重要的优点。
大公较小,从而使更紧凑的产品成为可能。
晶体管也比电子管更坚固耐用。
它通常会提供更好的性能,在一段较长的时间。
最重要的是,晶体管通常需要少得多的电流和电压下正常工作。
这样可以节省能源。
例如,12V汽车收音机使用管吸引约2.5A。
一个类似的晶体管汽车收音机提请只有一小部分的安培。
低功耗晶体管电路的需求尽可能小,重量轻,随身便携产品的工作很长一段时间,小,低小的电池。
各种各样的晶体管最常见的两种类型的晶体管是NPN型晶体管和PNP晶体管。
它们通常被称为双极型晶体管,因为他们的操作取决于被布置为二极管连接在一个“背背”的方式这两种材料的移动。
这样的安排形成三个区域的发射极,基极和集电极。
这些地区被确定由符号E,B,和C。
的一晶体管的区域接合引线或标签,它连接在晶体管电路。
晶体管封装在金属外壳经常有第四铅被称为盾铅的。
将此导线安装在壳体内部,并连接到电路中的一个公共点。
金属外壳的屏蔽层附近晶体管表格的静电和磁场。
符号解释: 有一个方便的方式来记住的符号是否代表了一个结晶体管NPN 或PNP型。
注意代表发射器的箭头指向什么方向。
如果箭头指向相差形成的基,它可以被认为是“不指向N”,因此,该符号代表一个NPN晶体管。
如果箭头指向底座,它可以被认为是的“指向N”。
因此,这个符号代表的P-N-P晶体管。
鉴定: 大多数晶体管标识由一些字母代码,例如2N,然后通过一系列的数字,例如,2N104,2N337,2N556。
其它晶体管都确定了一系列的数字或数字和字母,例如40050,40404,和4D20的组合。
晶体上手册: 设备是否是NPN或PNP型的晶体管的识别码不表示。
晶体管手册或规格表中发现这样的技术数据。
这些手册也给各种不同的电路中使用的晶体管的信息。
晶体管外形图提供了详细的信息,它们的大小,形状和连接。
电气工程及其自动化专业英语第三章课文翻译
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Semiconductor switches are very important and crucial components in power electronic systems.these switches are meant to be the substitutions of the mechanical switches,but they are severely limited by the properties of the semiconductor materials and process of manufacturing. 在电力电子系统,中半导体开关是非常重要和关键部件。
半导体开关将要替换机械开关,但半导体材料的性质和生产过程严重限制了他们。
Switching losses开关损耗Power losses in the power eletronic converters are comprised of the Switching losses and parasitic losses. 电力电子转换器的功率损耗分为开关损耗和寄生损耗the parasitic losses account for the losses due to the winding resistances of the inductors and transformers,the dielectric losses of capacitors,the eddy and the hysteresis losses. 寄生损失的绕组电感器、变压器的阻力、介电损耗的电容器,涡流和磁滞损耗the switching losses are significant and can be managed. 这个开关损耗是非常重要的,可以被处理。
they can be further divided into three components:(a)the on-state losses,(b)the off-state losses and the losses in the transition states. 他们可以分为三个部分: 通态损耗,断态损耗和转换过程中产生的损耗。
电气自动化专业英语3
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System Design Methodology
The control system design should include appropriate feedback control loops to ensure stable and accurate system performance
Power electronic device selection
The selection of appropriate power electronic devices is critical for the performance and reliability of the power electronic system
Definition
Electrical automation has a wide range of application fields, which can achieve efficient, safe, reliable, and economical automation control, improve production efficiency, improve labor conditions, and provide strong technical support for the rapid development of modern industry.
Semiconductor technology
This involves the basic knowledge of semiconductors, including their properties and the operation of transformers and diodes
电气自动化专业英语第三单元
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电气自动化专业英语第三单元专业英语第三单元3 Analog Electronics3.1 INTRODUCTION3.1.1 The Contrast between Analog and Digital ElectronicsWe have already explored how transistors and diodes are used as switching devices to process information which is represented in digital form. Digital electronics uses transistors as electrically controlled switches: transistors are either saturated or cut off. The active region is used only in transition from one state to the other.By contrast, analog electronics depends on the active region of tran sistors and other types of amplifiers. The Greek roots of “analog” mean “in due ratio”, signifying in this usage that information is encoded into an electrical signal which is proportional to the quantity being represented.713宿舍In Fig.3.1 our information is some sort of music, originating physically in the excitation and resonance’s of a musical instrument. The radiated sound consists in the ordered movement of air molecules and is best understood ad acoustic waves. These produce motion in the diaphragm of a microphone, which in turn produces an electrical signal. The variation in the electrical signal are a proportional representation of the sound waves. The electrical signal is amplifiedelectronically, with an increase in signal power occurring at the expense of the input AC power to the amplifier. The amplifier output drives a recording head and produces a wavy groove on a disk. If the entire system is good, every acoustic variation of the air will be recorded on the disk and, when the record is playedback through a similar system and the signal reradiated ad sound energy be a loudspeaker, the resulting sound should faithfully reproduce the original music.Electronic systems based on analog principles form an important class of electronic devices. Radio and TV broadcasting are common examples of analog systems, as are many electrical instruments used in monitoring deflection(strain gages, for example), motion (tachometers), and temperature (thermocouples).Many electrical instruments-voltmeters, ohmmeters, ammeters, and oscilloscopes-utilize analog techniques, at least in part.Analog computers existed before digital computers were developed. In an analog computer, the unknowns in a differential equation are modeled with electrical signals. Such signals are integrated, scaled, and summed electrically to yield solutions with modes effort compared with analytical or numerical techniques.3.1.2 The Contents Of This ChapterAnalog techniques employ the frequency-domain viewpoint extensively. We begin by expanding our concept of the frequency domain to include periodic, nonperiodic, and random signals. We will see that most analog signals and processes can be represented in the frequency domain. We shall introduce the concept of a spectrum, that is, the representation of a signal as the simultaneous existence of many frequencies. Bandwidth (the width of a spectrum) in the frequency domain will be related to information rate in the time domain.714宿舍This expanded concept of the frequency domain also helps us distinguish the effects of linear and nonlinear analog devices. Linear circuits are shown to be capable of“filtering” out unwanted frequency components. By contrast, new frequencies can be created by nonlinear devices such as diodes and transistors. This property allows us to shift analog signals in the frequency domain through AM and FM modulation techniques, which are widely used in public and private communication systems. As an example we shall describe the operation of an AM radio.Next we study the concept of feedback, a technique by which gain in analog systems is exchanged for other desirable qualities such as audio amplifiers or TV receivers would at best offer poor performance. Understanding of the benefits of feedback provides the foundation for appreciating the many uses of operational amplifiers in analog electronics.Operational amplifiers (op amps, for short) provide basic building blocks for analog circuits in the same way that NOR and NAND gates are basic building blocks for digital circuits. We will present some of the more common applications of op amps, concluding with their use in analog computers.3.3.2 OPERATIONAL-AMPLIFIER CIRCUITS3.2.1 Introduction(1) The Importance of OP Amps. An operational amplifier isa high-gain electronic amplifier which is controlled by negative feedback to accomplish many functions or “operations” in analog circuits. Such amplifiers were developed originally to accomplish operations such as integration and summation in analog computers for the solving of differential equations. Applications of op amps have increased until, at the present time, most analog electronic circuits are based on op amp techniques. If, for example, you required an amplifier with of 10, convenience, reliability, and cost considerations would dictate the use of an opamp. Thus op amp from the basic building blocks of analog circuits much as NAND and NOR gates provide the basic building blocks of digital circuits.(2) An OP-Amp Model Typical Properties. The typical op amp is a sophisticated transistor amplifier utilizing a dozen or more transistors,several diodes, and many resistors. Such amplifiers are mass produced on semiconductor chips and sell for less than $1 each. These parts are reliable, rugged, and approach the ideal in their electronic properties.Fig.3.2 shows the symbol and the basic properties of op amp. The two input voltages, u+and u-, are subtracted and amplified with a large voltage gain, A, typically 105~106. The input resistance, Ri, is large, 100KΩ~100MΩ. The output resistance, Ro, is small, 10~100Ω. The amplifier is often supplied with DC power from positive (+Ucc)and negative(﹣Ucc) power supplies. For this case, the output voltage lies between the power supply voltages, ﹣Ucc﹤Uo﹤+Ucc. Sometimes one power connection is grounded (i.e., “﹣Ucc”=0). In this case the output lies in the range, 0﹤Uo﹤+Ucc. The power connections are seldom drawn in circuit diagrams; it is assumed that one connects the op amp to the appropriate power source. Thus the op amp approximates an ideal voltage amplifier, having high input resistance, low output resistance, and high gain.The high gain is converted to other useful features through the use of strong negative feedback.All the benefits of negative feedback are utilized by op-amp circuits. To those listed earlier in this chapter, we would for op-amp circuits add three more: low expanse, ease of design, and simple construction.(3)The Contents of This Section. We begin by analyzing twocommonop-amp applications, the inverting and uninverting amplifiers. We derive the gain of these amplifiers by a method that may be applied simple and effectively to any op-amp circuit. We then discuss active filters, which are op amp amplifiers with capacitors added to shape their frequency response. We then deal briefly with analog computers and conclude by discussing some nonlinear application of op-amp.3.2.2 Op-amp Amplifiers712宿舍(1) The Inverting Amplifier. The inverting amplifier, show in Fig.3.3, use an op-amp plus two resistors. The positive (+)input to the op-amp is grounded (zero signal); the negative (﹣)input is)and to the feedback signal from the connected to the input signal (via R1output (via R). One potential source of confusion in the followingFdiscussion is that we must speak of two amplifiers simultaneously. The op amp is an amplifier which forms the amplifying element in a feedback amplifier which contains the op amp plus associated resistors. To lessen confusion, we shall reserve the term “amplifier”to apply only to the overall, feedback amplifier. The op-amp will never be call ed an amplifier; it will be called the op-amp. For example, if we refer to the input current to the amplifier, we are referring to the current through Ri, not the current into the op-amp.We could solve for the gain of the inverting amplifier in Fig.3.3 either by solving the basic circuit laws (KCL and KVL) or byattempting to divide the circuit into main amplifier and feedback system blocks. We shall, however, present another approach based on the assumption that the op-amp gain is very high, effectively infinite. In the following, we shall give a general assumption, which may be applied to any op-amp circuit; then we will apply this assumption specifically to the present circuit. As a result, we will establish and input resistance of the inverting amplifier.We assume that the output is well behaved and does not try to go to infinity. Thus we assume that the negative feedback stabilizes the amplifier such that moderate input voltages produce moderate output voltages. If the power supplies are +10 and﹣10V, for example, the output would have to lie between these limits.Therefore, the input voltage to the op-amp is very small, essentially zero, because it is the output voltage divided by the large voltage gain of the op-ampu+﹣u_≈0?u+≈u_For example, if ∣Uo∣﹤10V and A=105, then ∣u+﹣u_∣﹤10\105=1+and u_ are equal with 100μV or less,for any op-amp circuit. For the inverting amplifier in Fig.3.3, u+is ground;therefore, u_≈0. Consequently, the current at the input to the amplifierwould bei 1= 1_R u Ui - ≈1R Ui (3.1) Because u +≈u_ and Ri is large, the current into the + and – op-ampinputs will be very small, essentially zero∣i +∣=∣i -∣=||RiU U +--≈0 (3.2) For example, for Ri =100KΩ, |i_|﹤104-/105=109-A.For the inverting amplifier, Eq. (3.2) implies that the current at the input, i i , flows through R f , as shown in Fig.3.4. This allows us to compute the output voltage. The voltage across R F would be i i R F and, because one end of R F is connected to u_≈0 Uo=-i i R F =-1R U i R F Thus the voltage gain would beA u =Ui Uo =1R R F - (3.3) The minus sign in the gain expression means that the output will be inverted relative to the input: a positive signal at the input: a positive signal at the input will produce a negative signal at the output, Eq. (3.3) shows the gain to depend o the ratio R F to R 1. This would imply that onlythe ratio and not the individual values of R F to R 1 matter. This would betrue if the input resistance to the amplifier were unimportant, but the input resistance to an amplifier is often critical. The input resistance to the inverting amplifier would follow from Eq. (3.1);R i =i i i U ≈R 1 (3.4)For a voltage amplifier, the input resistance is an importantfactor, for if R i were too low the signal source (of U i ) could be loaded down by R i . Thus in a design, R 1 must be sufficiently high to avoid his loadingproblem. Once R 1 is fixed, R F may be selected to achieve the requiredgain. Thus the values of individual resistors become important because they affect the input resistance to the amplifier.Let us design an inverting amplifier to have a gain of ﹣8. The input signal is to come from a voltage source having an output resistance of 100Ω. To reduce loading, the input resistor, R 1, must be much larger than100Ω. For a 5﹪loading reduction, we would set R 1=2000Ω. To achievea gain of -8(actually 95﹪of -8, considering loading ), we require that R F =8×2000=16KΩ.Feedback effects dominate the characteristics of the amplifier. When an input voltage is applied, the value of u_ will increase. This will cause U 0 to increase rapidly in the negative direction . This negative voltagewill increase to the value where the effect of U 0 on the –input via R F cancels the effect of U i through R 1. Put another way, the output willadjust itself to withdraw through R F any current that U i injects through R 1, since the input current to the op-amp is extremely small. In this waythe output depends only R F and R 1.711宿舍 The Noninverting Amplifier. For thenoninverting amplifier show in Fig.3.5 the input is connected to the +input. The feedback from the output connects still to the– op amp input, as required for negative feedback. T o determine the gain, we apply the assumptions outlined above.①Because u +≈u_, it follows thatu_ ≈U i (3.5)②Because i ≈0, R F and R 1 carry the same current. Hence U0 is related to u_ through a voltage-divider relationshipu i =U 0 FR R R +11(3.6) Combining Eqs. (3.5) and (3.6), we establish the gain to beU i =U 0F R R R +11=A u =+(1+1R R F ) (3.7) The + sign before the gain expression emphasize that the output of the amplifier has the same polarity as the input: a positive input signal produces a positive output signal. Again we see that the ratio of R F and R 1 determines the gain of the amplifier.When a voltage is applied to the amplifier, the output voltage increase rapidly and will continue to rise until the voltage across R 1 reaches theinput voltage. Thus little input current will flow into the amplifier, and the gain depends only on R F and R 1. The input resistance to the noninvertingamplifier will be very high because the input current to the amplifier is also the input current to the op-amp, i +, which must be extremely small.Input resistance values exceeding 1 000 MΩ are easily achieved with this circuit. This feature of high input resistance is an important virtue of the noninverting amplifier.3.2.3 Active Filters(1)What Are Active Filters? An active filter combines amplification with filtering. The RC filters we investigated earlierare called passive filters because they provide only filtering. An active filter uses an op-amp to furnish gain but has capacitors added to the input and feedback circuits to shape the filter characteristics.We derived earlier the gain characteristics of an inverting amplifier in the time domain. In Fig.3.6 we show the frequency-do-main version. We may easily translate the earlier derivation into the frequency domainU i ?U i (ω) U 0?U 0(ω)A u =﹣1R R F ?F u (ω)=﹣)()(1ωωZ Z F The filter function, F u (ω), is thus the ratio of the two impedances,and in general with give gain as well as filtering. We could have written the minus sign a s 180°, for in the frequency domain the inversion is equivalent to a phase shift of 180°.(2) Low-pass Filter. Placing a capacitor in parallel with R F (seeFig.3.7) will at high frequencies tend to lower Z and hence the gain of the amplifier; consequently, this capacitor an inverting amplifier into a low-pass filter with gain. We may writeF Z (ω)=R F ∣∣F C j ω1=F F C j R ω+)/1(1=FF F C R j R ω+1(3.8) Thus the gain would be)/(11111c u F F F u j A C R j R R F ωωω+=+-=(3.9) Where 1/R R Au F -=, the gain without the capacitor, andF C C R R /1=ωwould be the cutoff frequency. The gain of the amplifier isapproximately constant until the frequency exceeds C ω, after which thegain decreases with increasing ω. The Bode plot of this filter function is shown in Fig.3.8 for the case where R F =10K ωΩ, R1=1KΩ, and C F =1μF.(3) High-pass filter. The high-pass filter show in Fig.3.9 usesa capacitor in series with R 1 to reduce the gain at low frequencies. Thedetails of the analysis will be left to a problem. The gain of this filter isu c c F u A j j R R F =+-=)/(1)/()(1ωωωωω)/(1)/(c c j j ωωωω+ Where 1/R R Au F -= is the gain without the capacitor and 11/1C R c =ω is the cutoff frequency, below which the amplifier gain is reduced. The Bode plot of this filter characteristic is show in Fig.3.10.(4) Other Active Filter. By using more advanced techniques, one can simulate RLC narrowband filters and, by using additional op-amps, many sophisticated filter characteristics can be achieved. Discussion of such applications lies beyond the scope of this text, but there exist many handbooks showing circuits and giving design information about active filters.3. 2. 4 Analog ComputerOften a differential equation is Fig.3.10 solved by integration. The integration may be accomplished by analytical methods or by numerical methods on a digital computer. Integration may also be performed electronically with an op-amp circuit. Indeed, op-amps were developed initially for electronic integration of differential equations.⑴ An Integ rator . The op-amp circuit in Fig.3.11 uses negative feedback through a capacitor to perform integration.We have charge the capacitor in the feedback path to an initial value of U 1, and then removed this prebias(预偏置)voltage at t=0. Let usexamine the initial state of the circuit before investigatingwhat will happen after the switch is opened. Since +u is approximately zero, sowill be _u , and hence the output voltage is fixed at ﹣1U . The inputcurrent to amplifier, R U i /, will flow through the 1U voltage will remainat ﹣1U until the switch is opened.After the switch is opened at t=0, the input current will flow through the capacitor and hence the U C will be,0,0)()0()(dt RC t U U t Uc ti ?+= Thus the output voltage of the circuit is0)(1)()(,,010≥--=-=?t dt t U RC U t U t U ti c (3.10)Except for the minus sign, the output is the integral of U i scaled by1/RC, which may be made equal to any value we wish by proper choiceof R and C.⑵ Scaling and Summing . We need two other circuits to solve simple differential equations by analog computer methods. Scaling refers to multiplication by a constant, such as 12KU U ±=Where K is a constant. This is the equation of an amplifier, and hence we would use the inverting amplifier in Fig.3.5 for the – sign or the noninverting amplifier in Fig.3.5 for the + sign.A summer produces the weighted sum of two or more signals.Fig.3.12 shows a summer with two inputs. We may understand the operation of the circuit by applying the same reasoning we used earlier to understand the inverting amplifier. Since 0≈-u , the sum of the currents through 1R and 2R is22111R U R U i +=(3.11) The output voltage will adjust itself to draw this current through RF, and hence the output voltage will be)(221110R R U R R U R i U F F F ?+?-=-= The output will thus be sum of 1U and 2U , weighted by the gainfactors, 1/F R R and 2F R R , respectively. If the inversion produced by thesummer is unwanted, the summer can followed by an inverted, a scalier with a gain of -1. Clearly, we could add other inputs in parallel withR R and 21. In the example to follow, we shall sum three signals to solve a second order differential equation.(3) Solving a DE. Let us design an analog computer circuit tosolve the differential equation t u dt du dtu d 10cos 65222=++ t>0 U(0)=﹣2 and at dtdu 3+= t=0 (3.12) Moving everything except the highest-order derivative to the right side yields t u dt du dtu d 10cos 32222+--=(3.13)女生宿舍The circuit which solves Eq. (3.12) is shown in Fig.3.13. The circuit consists of two integrators to integrate the left side of Eq. (3.13), a summer to represent the right side, and two inverts to correct the signs. The noninverting inputs are grounded, and the inputs and feedback are connected to the inverting input of the op-amps. Hence we have shown only the inverting inputs. With 22/dt u d the input to the integrators, the output of the first integrator will be-du/dt [with the battery giving the initial condition of 3V , as in Eq. (3.13)], and hence the output of the second integrator will be +u (withan initial condition of -2 V ). This output is fed into the summer, along with du/dt after inversion, and the driving function cos10 t, which must also be inverted to cancel the inversion in the summer. The input resistors connecting the three signals into the summer produce the weighting factors in Eq. (3.13), and hence the output of the summer represents the right side of Eq. ( 3.13 ). Wetherefor e connect that output to our “input” of 22/dtd to satisfy Eq.u(3.12 ). To observe the solution to Eq. (3.12 ), we merely open the switches at t=0.Clearly, these techniques can be applied to higher-order equations. Sophisticated use of analog computer requires a variety of refinements. Often, the equations being solved are scaled in time (time is sped up or slowed down on the computer) to accommodate realistic resistor and capacitor values. Also, voltage and current values can be scaled to bring the unknowns within the allowable range of the computer. In the next section we show how nonlinear operations can be introduced to solve nonlinear differential equations by analog methods.3. 2. 5 Nonlinear Applications of Op-ampsOp-amps can be combined with nonlinear circuit elements such as diodes and transistors to produce a variety of useful circuits. Below we discuss a few such applications. Many more circuits are detailed in standard handbooks and manufacturers’ application literature for their products.An Improved Half-Wave Rectifier. The op-amp in Fig 3.14 drives a half-wave rectifier. When the input voltage is negativethe output of the op-amp will be OFF; hence the output will be zero. When the output is positive the diode will turn ON and the output will be identical to the input, because the circuit will perform as a non-inverting amplifier shownin Fig.3.5 with R F=0. Use of the op-amp effectively reduces the diode turn-on voltage. If the input voltage is greater than 0.7/A, where A is the voltage gain of the op-amp, the output voltage exceed 0.7V and turn on the diode. Hence the turn-on voltage is effectively reduced from 0.7~0.7/A.This circuit would not be used in a power supply circuit; rather, it would be used in a detector or other circuit processing small signals, where the turn-on voltage of the diode would be a problem.。
电气工程及其自动化专业英语第三章section_3-1
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Section 1 Semiconductor Switches
give rise to power losses in the switching devices. We will examine these switching losses in two cases separately: the inductive and capacitive loads. Switching with Inductive Load The inductor is assumed to be large so that the current through it in steady state is nearly constant Io. Assume that initially the switch is off. The inductor current is +Io and freewheels through diode V1. When the switch is turned on, the current through the switch begins to build up linearly (an assumption) to +Io while the diode V1 is still on.
Poff usoff ir
(3-2)
Section 1 Semiconductor Switches
The usoff and ir are respectively the reverse bias voltage in the off-state and the reverse current through the switch. For example, the typical power diodes and the power transistors have high reverse voltages in hundreds to thousands of volts and microamps to milliamps through them in the off state. Transition-State Losses The practical switching devices have limited capabilities of rate of voltage transition and the rate of current steering. These nonabrupt transition rates
电气工程及其自动化专业英语
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time-invariant 时不变的
self-(or mutual-)induction 自(互)感
displacement current 位移电流 conductance 电导
voltage drop 电压降 volt-ampere characteristics 伏安特性
metal-filament lamp 金属丝灯泡
seen, increase of current from zero to
I≈I1 causes the terminal voltage of the source to decrease linearly
V12=V=E-VS=E-RSI
Fig.1.3
In other words, the voltage drop VS across the source resistance rises in proportion to the current. This goes on until
电气工程及其自动化专业英语第三章section_3-2
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Section 2 The DC-DC Converters
Text New Words and Expressions Transition of part of speech Exercises End
Section 2 The DC-DC Converters
Section 2 The DC-DC Converters
If the duty ratio D is made a linear function of uC, a control voltage
D = ku C
U o = (kU S )u C
(3-6)
The output voltage is then a linear function of the control voltage. This is also the principle of switchmode linear amplifier. The gain of this amplifier is determined by the input dc source voltage. Neglecting the power losses in the circuit elements, we could use the equation of the balance of power
Section 2 The DC-DC Converters
US I S = Uo Io
− −
(3-7)
where IS is the average current from the DC source. Hence,
Io
−
=
电气工程及其自动化专业英语
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电气工程及其自动化专业英语Section I basic electric circuitChapter 1 Introduction to electric circuitsNew Words and Expressions1. electrical circuit n. 电路2. voltage n. 电压,伏特3. curre nt n. 电流,通用的,流通的,现在的4. curre nt flow n. 电流5. resistor n. 电阻,电阻器6. battery n. 电池7. load n. 负载,负荷8. performa nee n. 性能9. circuit diagram n. 电路图10. idealized model n. 理想模型Introduction*A simple circuit and its components.idealized model of the circuit*Model can be cha nged if n ecessary.*summarizeIn elementary physics classes you undoubtedly have been introduced to the fun dame ntal con cepts of electricity and how real comp onen ts can be put together to form an electrical circuit. A very simple circuit, for example, might consist of a battery, some wire, a switch, and an incandescent light bulb as shown in Fig.1-1. The battery supplies the en ergy required to force electro ns around the loop, heati ng the filame nt of the bulb and caus ing the bulb to radiate a lot of heat and some light.Energy is transferred from a source, the battery, to a load, the bulb———You probably already know that the voltage of the battery and the electrical resista nee of the bulb have something to do with the amount of curre nt that will flowin the circuit. From your own practical experienee you also know that no current will flow until the switch is closed. That is, for a circuit to do anything, the loop has to be completed so that electro ns can flow from the battery to the bulb and the n back aga in to the battery. And fin ally, you probably realize that it doesn t much matter, whether there is on e foot or two feet of wire connecting the battery to the bulb, but that it probably would matter if there is a mile of wire between it and the bulb.Also shown in Fig. 1-1 is a model made up of idealized components. The batteryis modeled as an ideal source that puts out a constant voltage, VB, no matter what amount of curre nt, i, is draw n. The wires are con sidered to be perfect con ductors that offer no resista nee to curre nt flow. The switch is assumed to be ope n or closed. There is no arcing of curre nt across the gap whe n the switch is ope ned, nor is there any bounce to the switch as it makes con tact on closure. The light bulb is modeled as a simple resistor, R, that never changes its value, no matter how hot it becomes or how much curre nt is flow ing through it.Fig. 1-1 (a) A simple circuit(b) An idealized represe ntati on of thecircuitFor most purposes, the idealized model shown in Fig. 1-1b is an adequate represe ntati on of the circuit; that is, our prediction of the current that will flow through the bulb whenever the switch is closed will be sufficiently accurate that we can consider the problem solved. There may be times, however, when the model is in adequate. The battery voltage, for example, may drop as more and more curre nt is drawn, or as the battery ages. --------------------------------- T he light bulb' s resistance may change as it heats up, and the filame nt may have a bit of inductance and capacitance associated with it as well as resistance so that when the switch is closed, the current may not jump in sta ntan eously from zero to some fin al, steady state value. The wires may beundersized, and some of the power delivered by the battery may be lost in the wires before it reaches the load. These subtle effects may or may not be important, depending on what we are trying to find out and how accurately we must be able to predict the performa nee of the circuit. If we decide they are importa nt, we can always cha nge the model as n ecessary and then proceed with the an alysis. The point here is simple. The comb in ati ons of resistors, capacitors, in ductors, voltage sources, curre nt sources, and so forth, that you see in a circuit diagram are merely models of real comp onents that comprise a real circuit, and a certa in amount of judgme nt is required to decide how complicated the model must be before sufficie ntly accurate results can be obta in ed. For our purposes, we will be using very simple models in general, leav ing many of the complicati ons to more adva need textbooks.Chapter 2Definitions of key electrical quantitiesNew Words and Expressionscharge n. vt.电荷;充电nu cleus n.原子核(pl.); nuclear adj.n egative n.否定,负数,底片adj.否定的,消极的,负的,阴性的positive adj.[数]正的adj.[电]阳的in gen eral 通常,大体上,一般而言,总的说来algebraic adj.代数的,关于代数学的soluti on to the circuit problem n.关于电路问题的解法the un its of power n.功率的单位direct curre nt (dc) n 直流电alter nat ing curre nt(ac) n.交流电sinu soidally adv.正弦地tran sistor n.晶体管Part 1 Charge and CurrentAn atom con sists of a positively charged nu cleus surro un ded by a swarm of n egativelycharged electr ons. The charge associated with one electr on has bee n found to be 1.602 x 10- 19 coulombs; or, stated the other way around, one coulomb can be defined as the charge on 6.242 x 1018 electro ns. While most of the electr ons associated with an atom are tightly bound to the nu cleus, good con ductors, like copper, have free electrons that are sufficie ntly dista nt from their nu clei that their attract ion to any particular n ucleus is easily overcome. These con ducti on electr ons are free to wan der from atom to atom, and their moveme nt con stitutes an electric curre nt.In a wire, when one coulomb ' s worth of charge passes a given spot in one second, the current is defined to be one ampere (abbreviated A), named after the nineteenth-century physicist Andr ' e Marie Amp'ere. That is, curre nt i is the net rate of flow of charge q past a point, or through an area:i=d q/d t (1.1)In general, charges can be negative or positive. For example, in a neon light, positive ions move in one direct ion and n egative electr ons move in the other. Each con tributes to curre nt, and the total curre nt is their sum. By conven ti on, the direct ion of curre nt flow is take n to be the direct ion that positive charges would move, whether or not positive charges happen to be in the picture. Thus, in a wire, electrons moving to the right constitute a current that flows to the left, as shown in Fig.1-2.(〉)dq--- / =—dtFig. 1-2 By conven tio n, n egative charges movi ng in one direct ion con stitute a positive curre ntflow in the opposite direct ionW/hen charge flows at a steady rate in one direction only, the current is said to be direct current, or 血A battery, for example, supplies direct curre nt. When charge flows back and forth sinusoidally, it is said to be alternating current, or ac. In the United States the ac electricity delivered by tes of ac and dc are show n in Fig.1-3.Time ―(a)Fig. 1-3 (a) Steady-state direct curre nt (de) (b) Alter nat ing curre nt(ac)Part 2 Kirchhoff' s Current LawTwo of the most fun dame ntal properties of circuits were established experime ntally a cen tury and a half ago by a Germa n professor, Gustav Robert Kirchhoff (1824 - 1887). The first property, known as Kirchhoff ' s current law (abbreviated KCL), states that at every instant of time the sum of the curre nts flow ing into any node of a circuit must equal the sum of the curre nts leavi ng the no de, where a node is any spot where two or more wires are join ed. This is a very simple, but powerful con cept. It is in tuitively obvious once you assert that curre nt is the flow of charge, and that charge is con servative—n either being created nor destroyed as it en ters a no de. Uni ess charge somehow builds up at a no de, which it does not, the n the rate at which charge en ters a node must equal the rate at which charge leaves the no de.There are several alter native ways to state Kirchhoff ' s curre nt law. The most com monly used stateme nt says that the sum of the curre nts flow ing into a node is zero as show n in Fig. 1-4a, in which case some of those curre nts must have n egative values while some have positive values. Equally valid would be the stateme nt that the sum of the curre nts leav ing a node must be zero as show n in Fig. 1-4b(aga in some of these curre nts n eed to have positive values and some n egative). Fin ally, we could say that the sum of the curre nts en teri ng a node equals the sum of the curre nts leav ing a node (Fig. 1-4c). These are all equivale nt as long as we un dersta nd what is meant about the directi on of curre nt flow whe n we in dicate it with an arrow on a circuit diagram. Curre nt that actually flows in the directi on show n by the arrow is give n a positive sig n. Curre nts that actuallyflow in the opposite direct ion have n egative values.(a) The sum of the curre nts into a node equals zero(b) The sum of the curre nts leav ing the node is zero(c) The sum of the curre nts en teri ng a node equals the sum of the curre nts leavi ng the node Note that you can draw curre nt arrows in any directio n that you want — that much is arbitrary — but once havi ng draw n the arrows, you must the n write Kirchhoff ' s curre nt law in a manner that is con siste nt with your arrows, as has bee n done in Fig.1-4. The algebraic soluti on to the circuit problem will automatically determ ine whether or not your arbitrarily determ ined direct ions for curre nts were correct.Example 1.1 Using Kirchhoff ' s Current LawA node of a circuit is shown with current direction arrows chosen arbitrarily. Havingpicked those directi on s, i1 = - 5 A, i2 = 3 A, and i3 = - 1 A. Write an expressi on for Kirchhoff ' s current law and solve for i4.Solution. By Kirchhoff ' s current law,i1 + i2 = i3 + i4 so thatThat is, i4is actually 1 A flowi ng into the no de. Note that i2, i3, and i4 are all en teri ng the no de, and i1 is the only curre nt that is leavi ng the no de.Part 3 Kirchhoff ' s Voltage LawElectr ons won ' t flow through a circuit uni ess they are give n some en ergy to help send them on their way. That “ push ” is measured in volts, where voltage is defi ned to be the amount nodenodenode1 + i4 i4 = - 1 AFig. 1-4 lllustrating various ways that Kirchhoff ' s current law can be statedof en ergy (w, joules) give n to a un it of charge,v=dw/dq A 12-V battery therefore gives 12 joules of en ergy to each coulomb of charge that it stores. Note that the charge does not actually have to move for voltage to have meaning. Voltage describes the potential for charge to do work.While curre nts are measured through a circuit comp onent, voltages are measured across componen ts. Thus, for example, it is correct to say that curre nt through a battery is 10 A, while the voltage across that battery is 12 V. Other ways to describe the voltage across a comp onent in clude whether the voltage rises across the comp onent or drops. Thus, for example, for the simple circuit in Fig. 1-1, there is a voltage rise across the battery and voltage drop across the light bulb. Voltages are always measured with respect to someth ing. That is, the voltage of the positive terminal of the battery is“ so many volts ” with respect to the negative terminal; or, the voltage at a point in a circuit is some amount with respect to some other poin t. In Fig. 1-5, curre nt through a resistor results in a voltage drop from point A to point B of VAB volts. V A and VB arethe voltages at each end of the resistor, measured with respect to some other point.The reference point for voltages in a circuit is usually desig nated with a ground symbol. While many circuits are actually groun ded — that is, there is a path for curre nt to flow directly into the earth —some are not (such as the battery, wires, switch, and bulb in a flashlight). When a ground symbol is show n on a circuit diagram, you should con sider it to be merely a reference point at which thevoltage is defi ned to be zero. Fig.1-6 points out how cha nging the node labeled as ground cha nges the voltages at each node in the circuit, but does not cha nge the voltage drop across each comp onent.(1-2)Fig. 1-5 The voltage drop from point A to point B is V AB, where VAB = VA - VBThe sec ond of Kirchhoff ' s fun dame ntal laws states that the sum of the voltages around any loop of a circuit at any instant is zero. This is known as Kirchhoff ' s voltage law (KVL). Just as was the case for Kirchhoff ' s curre nt law, there are alter native, but equivale nt, ways of stat ing KVL. We can, for example, say that the sum of the voltage rises in any loop equals the sum of the voltagedrops around the loop. Thus in Fig. 1-6, there is a voltage rise of 12 V across the battery and avoltage drop of 3 V across R1 and a drop of 9 V across R2. ------------- Notice that it doesn' t matterwhich node was labeled ground for this to be true. Just as was the case with Kirchhoff ' s current law, we must be careful about labeli ng and in terpret ing the sig ns of voltages in a circuit diagram in order to write the proper vers ion of KVL. A plus (+) sig n on a circuit comp onent in dicates a reference direct ion un der the assumpti on that the pote ntial at that end of the comp onent is higher than the voltage at the other end. Aga in, as long as we are con siste nt in writi ng Kirchhoff ' s voltage law, the algebraic soluti on for the circuit will automatically take care of sig ns.Part 5 Summary of Principal Electrical QuantitiesThe key electrical qua ntities already in troduced and the releva nt relati on ships betwee n these quantities are summarized in Table 1-1.Since electrical quantities vary over such a large range of magnitudes, you will often find yourself work ing with very small qua ntities or very large qua ntities. For example, the voltage created by your TV antenna may be measured in millionths of a volt (microvolts, 卩V), while the power gen erated by a large power stati on may be measured in billi ons of watts, or gigawatts (GW). To describe quantities that may take on such extreme values, it is useful to have a system of prefixes that accompany the units. The most commonly used prefixes in electrical engineering are give n in Table 1-2.Part 6 Ideal Voltage Source and Ideal Current SourceElectric circuits are made up of a relatively small nu mber of differe nt kinds of circuiteleme nts, or comp onen ts, which can be in terc onn ected in an extraord in arily large nu mber of ways.At this point in our discussion, we will concentrate on idealized characteristics of these circuit eleme nts, realiz ing that real comp onents resemble, but do not exactly duplicate, the characteristics that we describe here.An ideal voltage source is one that provides a give n, known voltage vs, no matter what sort ofload it is conn ected to. That is, regardless of the curre nt draw n from the ideal voltage source, it will always provide the same voltage. Note that an ideal voltage source does not have to deliver a con sta nt voltage; for example, it may produce a sinu soidally vary ing voltage —the key is that voltage is not a fun ctio n of the amount of curre nt draw n. A symbol for an ideal voltage source is show n in Fig. 1-7.A special case of an ideal voltage source is an ideal battery that provides a con sta nt dc output, as show n in Fig. 1-8. A real battery approximates the ideal source; but as curre nt in creases, the output drops somewhat. To acco unt for that drop, quite ofte n the model used for a real battery is an ideal voltage source in series with the internal resista nee of the battery.An ideal curre nt source produces a give n amount of curre nt is no matter what load it sees. As show n in Fig. 1-9, a commo nly used symbol for such a device is circle with an arrow in dicati ng the directi on of curre nt flow. While a battery is a good approximati on to an ideal voltage source, there is nothing quite so familiar that approximates an ideal curre nt source. Some tran sistor circuits come close to this ideal and are ofte n modeled with idealized curre nt sources.Section II The electric power systemChapter 1 Brief Introduction to The Electric Power SystemNew Words and ExpressionsMinimum a 最小prime mover n 原动机gen erator n 发电机load n 负载furn ace n 炉膛boiler n 锅炉fissi on able n 可裂变的fissi on able material 核燃料Part 1 Minimum Power systemelevatio n n 高度,海拔internal combusti on engine 内燃机 steam-drive n turbi ne 汽轮机hydraulic turbi ne 水轮机convert v 变换,转换 shaft n 传动轴,轴 torquen 力矩servomecha nism n 伺服机构* Elements of a minimum electric power system *Types of energy source *Types of prime mover *Types of electrical load*Functions of the control systemA minimum electric power system is shown in Fig.1-1, the system consists of an energy source, a prime mover, a generator, and a load.The en ergy source may be coal, gas, or oil burned in a furnace to heat water and gen erate steam in a boiler; it may be fissi on able material which, in a nu clear reactor, will heat water to produce steam; it may be water in a pond at an elevatio n above the gen erat ing stati on; or it may be oil or gas burned in an internal combusti on engine.The prime mover may be a steam-driven turbine, a hydraulic turbine or water wheel, or aninternal combustion engine. Each one of these prime movers has the ability to convert energy in the form of heat, falling water, or fuel into rotation of a shaft, which in turn will drive theEnergy source Prime nioverGenerator Lx>adContjolFig* 1-1 The tninfnmm electric power systemgen erator.The electrical load on the gen erator may be lights, motors, heaters, or other devices, alone or in comb in ati on. Probably the load will vary from mi nute to min ute as differe nt dema nds occur. The control system functions (are ) to keep the speed of the machines substantially constant and the voltage within prescribed limits, even though the load may cha nge. To meet these load con diti on s, it is n ecessary for fuel in put to cha nge, for the prime mover in put to vary, and for the torque on the shaft from the prime mover to cha nge in order that the gen erator may be kept at con sta nt speed. In additi on, the field curre nt to the gen erator must be adjusted to maintain con sta nt output voltage. The con trol system may in clude a man stati oned in the power pla nt who watches a set of meters on the gen erator output term in als and makes the n ecessary adjustme nts manu ally .In a moder n stati on, the con trol system is a servomecha nism that sen ses gen erator-output con diti ons and automatically makes the n ecessary cha nges in en ergy in put and field curre nt to hold the electrical output with in certa in specificati ons.Part 2 More Complicated Systems*Foreword*Cases of power system with out circuit breaker *Power system with circuit breakerNew Words and Expressions1. associated2. circuit3. circuit breaker4. dee nergize5. dee nergized6. outage n7. diagram8. switch out of9. switch offIn most situati ons the load is not directly conn ected to the gen erator term in als. More com monlya 联接的 n 电路n 断路器 vt 切断,断电 adj 不带电的停电 n 简图退出来,断开 v 切断,关闭the load is some distanee from the generator, requiring a power line connecting them. It is desirable to keep the electric power supply at the load with in specificati ons. However, the con trols are near the generator, which may be in another building, perhaps several miles away.If the dista nce from the gen erator to the load is con siderable, it may be desirable to in stall transformers at the generator and at the load end, and to transmit the power over a high-voltage line (Fig.1-2). For the same power, the higher-voltage line carries less current, has lower losses for the same wire size, and provides more stable voltage., TransformerTransformerPrime 〔Mover Generator f C High-voltage line—Fig- 1-2 A generator connected through transformers anda high-voltage line to a distant loadIn some cases an overhead line may be un acceptable. In stead it may be adva ntageous to use an un dergro und cable. With the power systems talked above, the power supply to the load must be in terrupted if, for any reas on, any comp onent of the system must be moved from service for maintenance or repair.Additi onal system load may require more power tha n the gen erator can supply. Ano ther gen erator with its associated tran sformers and high-voltage line might be added.It can be shown that there are some advantages in making ties between the generators (1) and at the end of the high-voltage lines (2 and 3), as shown in Fig.1-3. This system will operate satisfactorily as long as no trouble develops or no equipment needs to be taken out of service.Kig. 1-3 A system with para)lei operation or the generators t of the transformers andof the transmission lintsThe above system may be vastly improved by the in troducti on of circuit breakers, which may be ope ned and closed as n eeded. Circuit breakers added to the system, Fig.1-4, permit selected piece of equipme nt to switch out of service without disturb ing the rema in der of system. With this arran geme nt any eleme nt of the system may be dee nergized for maintenance or repair by operati on of circuit breakers. Of course, if any piece of equipme nt is take n out of service, the n the total load must be carried by the remaining equipment. Attention must be given to avoid overloads duri ng such circumsta nces. If possible, outages of equipme nt are scheduled at times when load requireme nts are below no rmal.Low-voltageo=^GeneratorsFig.1-5 shows a system in which three gen erators and three loads are tied together by threeFig* 1-4 A system with necessary circuit breakerstran smissi on lin es. No circuit breakers are show n in this diagram, although many would berequired in such a system.Fis- 1-S Three generators supplying threeloads over hlgh-voltnge trAnsmlsston linesChapter 2 Faults on Power SystemNew Words and Expressions1. fault2. in terfere neen 干扰,防碍6. feed (fed)给。
电气工程及其自动化专业英语第三章section_3-2分析解析
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Power Electronic Technology
Section 2 The DC-DC Converters
Text
New Words and Expressions Transition of part of speech
Exercises
End
Section 2 The DC-DC Converters
Section 2 The DC-DC Converters
Buck Converter The Buck converter is a voltage step-down and current step-up converter. The topology is shown in Fig.3-2. The two-position switch is synthesized from a switch and a diode. The switch is turned on for a time τ periodically at a rate 1/Ts.
Fig.3-3 Circuit modes in steady-state operation
Section 2 The DC-DC Converters
As the switch is turned on in mode l, the diode is reverse biased and the current flows through inductor into the voltage sink. After a time τ, the switch is turned off. The inductor current then freewheels through the diode as shown in the circuit of mode 2. The second mode is terminated at TS when the switch is turned on again. The current and voltage waveforms are shown in Fig.3-4. The average output voltage is
电气工程专业英语-3 Analog Electronics
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strain [ strein ] gage: [ geidʒ ] 应变计
digital electronics [ 'didʒitl ] [ ilek'trɔniks ] 量器
数字电子学
swith [ 'swiθ ] n.开关
saturate [ 'sætʃəreit ] v.使饱和;
active region [ 'ri:dʒən ] 动态区域
模拟技术广泛地使用了频域的观点,我们以将频域的概 念扩展到周期性的、非周期性的、和随机信号作为开始,我 们将看到大多数模拟信号和过程都可以在频域中表示。
We shall introduce the concept of a spectrum, that is, the representation of a signal as the simultaneous existence of many frequencies. Bandwidth (the width of a spectrum) in the frequency domain will be related to information rate in the time domain.
microphone [ ‘maikrəfəʊn ] 扩音器,麦克 风
tachometer [ tæ'kɔmitə ] 转速器 thermocouple [ 'θə:məu.kʌpl ]. 热电偶 oscilloscope [ ɔ'siləskəup ] 示波器 analytical解析的 numerical [ nju(:)'merikəl ] 数值的 integrate [ 'intigreit ] 求……的积分 scale [ skeil ] 改变比例
电气工程及其自动化专业英语介绍
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电气工程及其自动化专业英语介绍Introduction to Electrical Engineering and its Automation Major1. IntroductionElectrical Engineering and its Automation is a specialized field that combines electrical engineering principles with automation technologies to design, develop, and control electrical systems and processes. This major focuses on the application of electrical engineering principles in various industries such as power generation, telecommunications, manufacturing, and transportation.2. CurriculumThe curriculum of the Electrical Engineering and its Automation major is designed to provide students with a strong foundation in electrical engineering principles, as well as specialized knowledge in automation technologies. The coursework includes both theoretical and practical components, allowing students to gain hands-on experience in designing and implementing electrical systems.Some of the core courses offered in this major include:- Circuit Analysis- Digital Electronics- Control Systems- Power Systems- Microprocessors and Microcontrollers- Industrial Automation- Robotics and Artificial Intelligence- Instrumentation and Measurements- Electrical Machines and Drives- Communication Systems3. Skills and CompetenciesUpon completion of the Electrical Engineering and its Automation major, graduates will possess a diverse set of skills and competencies. These include:3.1 Technical Skills:- Proficiency in electrical circuit analysis and design.- Knowledge of automation technologies and their application in various industries.- Ability to design and implement control systems for electrical processes.- Familiarity with power generation and distribution systems.- Understanding of digital electronics and microprocessors.- Competence in programming languages used in automation systems.3.2 Analytical and Problem-Solving Skills:- Ability to analyze complex electrical systems and identify potential issues.- Proficiency in troubleshooting and problem-solving in electrical and automation systems.- Capacity to design innovative solutions to improve efficiency and productivity.- Strong mathematical and analytical skills to model and simulate electrical systems.3.3 Communication and Teamwork Skills:- Effective communication skills to collaborate with colleagues and clients.- Ability to work in multidisciplinary teams to solve complex problems.- Strong presentation skills to convey technical information to non-technical stakeholders.4. Career ProspectsGraduates of the Electrical Engineering and its Automation major have a wide range of career opportunities in various industries. Some potential career paths include:4.1 Electrical Engineer:- Designing and developing electrical systems for power generation, transmission, and distribution.- Conducting research and development in electrical engineering.- Troubleshooting and maintaining electrical systems in industrial settings.- Ensuring compliance with safety regulations and industry standards.4.2 Automation Engineer:- Designing and implementing automation systems for manufacturing processes.- Programming and configuring control systems for industrial automation.- Optimizing process efficiency and productivity through automation technologies.- Conducting system integration and testing for automation projects.4.3 Control Systems Engineer:- Designing and implementing control systems for various applications.- Developing algorithms and software for control systems.- Conducting system analysis and optimization for improved performance.- Collaborating with multidisciplinary teams to integrate control systems into complex processes.5. Research and InnovationThe field of Electrical Engineering and its Automation is constantly evolving, with new technologies and innovations emerging. Graduates of this major can pursue research and development opportunities in academia, government agencies, or private industries. They can contribute to advancements in renewable energy systems, smart grid technologies, robotics, artificial intelligence, and more.Conclusion:The Electrical Engineering and its Automation major provides students with a comprehensive understanding of electrical engineering principles and their application in automation technologies. Graduates of this major are equipped with the skills and knowledge necessary to pursue successful careers in various industries. With the increasing demand for automation and control systems, the prospects for professionals in this field are promising.。
电气工程及其自动化专业英语期末复习资料整理(单词)
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circuit components 电路元件the dielectric 电解质circuit parameters 电路参数storage battery 蓄电池electrical device 电气设备wire导线electric energy 电能 e.m.f.=electromotive force 电动势energy source 电源unidirectional current 单方向电流primary cell 原生电池circuit diagram 电路图secondary cell 再生电池load characteristic 负载特性energy converter 电能转换器terminal voltage 端电压conductor 导体external characteristic 外特性generator 发电机load resistance 负载电阻heating appliance电热器voltage drop 电压降direct-current (D.C.)circuit 直流电路conductance电导magnetic and electric field 电磁场volt-ampere characteristic 伏-安特性time-invariant时不变的metal-filament lamp 金属丝灯泡self-(or mutual-)induction 自(互)感carbon-filament lamp 碳丝灯泡displacement current位移电流non-linear characteristic非线性特性part 1-unit 2ideal source理想电源ideal current source 理想电流源series and parallel equivalent circuit串并联等值电路active circuit elements 有源电路元件internal resistance 内阻passive circuit elements 无源电路元件sending end 发送端power transmission line 输电线double subscript 双下标receiving end 接收端ideal voltage source理想电压源lackage current漏电流part 1-unit 3Ohm’s law 欧姆定律active branch有源支路circuit branch 支路positive reference direction 正(参考)方向reference point 参考点potential distribution电位分布passive element 无源元件single-loop network (circuit )单回路网络(电路)complex circuit 复杂电路 D.C. machine直流电机P.D.=potential drop电压降part 1-unit 4r.m.s values=root of mean sguare 均方根complex number 复数effective values 有效值Cartesian coordinates 笛卡尔坐标系steady direct current 恒稳直流电counter-clockwise 逆时针方向sinusoidal time function 正弦时间函数vector diagrams 矢量图clockwise顺时针方向complex plane复平面trigonometric transformations 三角转换vector of voltages (currents ,magnetic ,fluxes )电压(电流,磁通等)矢量Argand 阿尔冈,法国数学家analytical solution 解析法absolute value 绝对值Argand diagram 阿尔冈图modulus复数模origin of coordinates 坐标原点complex time function 复数的幅值rotating vector 旋转矢量real part 复数实部instantaneous values 瞬时值imaginary part复数虚部epoch angle初相角301&302吐血整理男生版专业英语单词part 1-unit 1complex-number method=method复数法phase displacement相位差of complex numbersvector矢量constant angular velocity恒定角速度Part 1-unit 5small signal amplifier小信号放大器isolation隔离。
电气工程及其自动化专业英语介绍
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电气工程及其自动化专业英语介绍第一篇:电气工程及其自动化专业英语介绍Electrical Engineering and AutomationElectrical Engineering and Automation was created at forty years ago.AS a new subject, it is relating to many walks of life, small to a switch designed to study aerospace aircraft, has its shadow.Electrical Engineering and Automation of electrical information professional is an emerging field of science, but because of people's daily lives and industrial production is closely related to the extraordinarily rapid development of relatively more mature now.High-tech industry has become an important component of the widely used in industry, agriculture, national defense and other fields, in the national economy is playing an increasingly important role.Worse more, Electrical Engineering and Automation is very hard to learn.The graduate should obtain much knowledge and ability.Such as natural science foundations include more sturdy mathematics, physics, etc, better Humanity, social science basic for sum foreign language for integration capability.Besides the essential technological basic theory knowledge of the originally professional field, mainly include circuit, electric magnetic field theory, electronic technology, information place in system Paying attention to, control theory, computer software andhardware basic theories.And so on.Control theory and electrical network theory is a professional electrical engineering and automation of the base, power electronics technology, computer technology is its main technical means, but also includes a system analysis, system design, system development and system management and decision-making research.Thereare some characteristics of the profession, that is, combining the strength of power, electrical and electronic technology, software and hardware combined with a cross-disciplinary nature, electricity, electronics, control, computer integrated multi-disciplinary, so that graduates with strong adaptation capacity.电气10-3班魏学军25号第二篇:电气工程及其自动化专业英语induction machine 感应式电机 horseshoe magnet 马蹄形磁铁magnetic field 磁场eddy current 涡流right-hand rule 右手定则left-hand rule 左手定则slip 转差率induction motor 感应电动机rotating magnetic field 旋转磁场 winding 绕组 stator 定子 rotor 转子 induced current 感生电流 time-phase 时间相位 exciting voltage 励磁电压 solt 槽 lamination 叠片 laminated core 叠片铁芯 short-circuiting ring 短路环 squirrel cage 鼠笼 rotor core 转子铁芯 cast-aluminum rotor 铸铝转子 bronze 青铜 horsepower 马力 random-wound 散绕 insulation 绝缘 ac motor 交流环电动机 end ring 端环alloy 合金 coil winding 线圈绕组 form-wound 模绕 performance characteristic 工作特性 frequency 频率revolutions per minute 转/分分motoring 电动机驱动generating 发电 per-unit value 标么值 breakdown torque 极限转矩breakaway force 起步阻力overhauling 检修wind-driven generator 风动发电机 revolutions per second 转/秒秒 number of poles 极数 speed-torque curve 转速力矩特性曲线 plugging 反向制动 synchronous speed 同步转速 percentage 百分数 locked-rotor torque 锁定转子转矩 full-load torque 满载转矩 prime mover 原动机inrush current 涌流magnetizing reacance 磁化电抗line-to-neutral 线与中性点间的 staor winding 定子绕组 leakage reactance 漏磁电抗no-load 空载full load 满载多相(的Polyphase 多相的)iron-loss 铁损 complex impedance 复数阻抗 rotor resistance 转子电阻 leakage flux 漏磁通 locked-rotor 锁定转子 chopper circuit 斩波电路 separately excited 他励的 compounded 复励 dc motor 直流电动机 de machine 直流电机 speed regulation 速度调节 shunt 并励series 串励armature circuit 电枢电路optical fiber 光纤interoffice 局间的wave guide 波导波导管bandwidth 带宽light emitting diode 发光二极管silica 硅石二氧化硅 regeneration 再生后反馈放大再生, coaxial 共轴的同轴的共轴的,同轴的 high-performance 高性能的 carrier 载波 mature 成熟的 Single Side Band(SSB)单边带 coupling capacitor 结合电容 propagate 传导传播 modulator 调制器 demodulator 解调器 line trap 限波器 shunt 分路器 Amplitude Modulation(AM 调幅 Frequency Shift Keying(FSK)移频键控 tuner 调谐器 attenuate 衰减incident 入射的two-way configuration 二线制generator voltage 发电机电压 dc generator 直流发电机 polyphase rectifier 多相整流器boost 增压time constant 时间常数forward transfer function 正向传递函数error signal 误差信号regulator 调节器stabilizing transformer 稳定变压器time delay 延时direct axis transient time constant 直轴瞬变时间常数 transient response 瞬态响应 solid state 固体 buck 补偿 operational calculus 算符演算 gain 增益 pole 极点 feedback signal 反馈信号 dynamic response 动态响应voltage control system 电压控制系统mismatch 失配error detector 误差检测器 excitation system 励磁系统 field current 励磁电流transistor 晶体管high-gain 高增益boost-buck 升压去磁feedback system 反馈系统 reactive power 无功功率 feedback loop 反馈回路 automatic Voltage regulator(AVR)自动电压调整器自动电压调整器 reference Voltage 基准电压 magnetic amplifier 磁放大器amplidyne 微场扩流发电机self-exciting 自励的limiter 限幅器manual control 手动控制 block diagram 方框图 linear zone 线性区potential transformer 电压互感器stabilization network 稳定网络stabilizer 稳定器 air-gap flux 气隙磁通 saturation effect 饱和效应saturation curve 饱和曲线 flux linkage 磁链 per unit value 标么值shunt field 并励磁场 magnetic circuit 磁路 load-saturation curve 负载饱和曲线 air-gap line 气隙磁化线 polyphase rectifier 多相整流器circuit components 电路元件circuit parameters 电路参数electrical device 电气设备 electric energy 电能 primary cell 原生电池电能转换器energy converter 电能转换器conductor 导体heating appliance 电热器 direct-current 直流 time invariant 时不变的 self-inductor 自感 mutual-inductor 互感 the dielectric 电介质storage battery 蓄电池 e.m.f = electromotive force电动势 generator 发电机 gas insulated substation GIS 气体绝缘变电站气体绝缘变电站 turbogenerator 汽轮发电机 neutral point 中性点hydrogenerator 水轮发电机 moving contact 动触头 hydraulic turbine 水轮机fixed contact 静触头steam turbine 汽轮机arc-extinguishing chamber 灭弧室dynamo 直流发电机stray capacitance 杂散电容motor 电动机stray inductance 杂散电感stator 定子sphere gap 球隙rotor 转子bushing tap grounding wire 套管末屏接地线power transformer 电力变压器electrostatic voltmeter 静电电压表 variable transformer 调压变压器 ammeter 电流表 taped transformer 多级变压器 grounding capacitance 对地电容 step up(down)transformer 升(降)压变压器 voltage divider 分压器降压变压器 circuit breaker CB 断路器 surge impedance 波阻抗dead tank oil circuit breaker 多油断路器 Schering bridge 西林电桥live tank oil circuit breaker 少油断路器 Rogowski coil 罗可夫斯基线圈 vacuum circuit breaker 真空断路器 oscilloscope 示波器 sulphur hexafluoride breaker SF6 断路器 peak voltmeter 峰值电压表峰值电压表potential transformer PT 电压互感器conductor 导线current transformer CT 电流互感器 cascade transformer 串级变压器disconnector 隔离开关coupling capacitor 耦合电容earthingswitch 接地开关 test object 被试品 synchronous generator 同步发电机 detection impedance 检测阻抗 asynchronous machine 异步电机 substation 变电站 Insulator 绝缘子 hydro power station 水力发电站 lightning arrester 避雷器 thermal power station 火力发电站metal oxide arrester MOA 氧化锌避雷器 nuclear power station 核电站bus bar 母线oil-filled power cable 充油电力电缆overhead line 架空线mixed divider(阻容混合分压器阻容)混合分压器阻容transmission line 传输线XLPE cable 交链聚乙烯电缆(coaxial)cable(同轴电缆 relay 继电器同轴)电缆同轴 iron core 铁芯tuned circuit 调谐电路 winding 绕组 suspension insulator 悬式绝缘子bushing 套管porcelain insulator 陶瓷绝缘子波头(尾电阻front(tail)resistance 波头尾)电阻glass insulator 玻璃绝缘子inverter station 换流站 flash counter 雷电计数器 steel-reinforced aluminum conductor 充电(阻尼阻尼)电阻钢芯铝绞线charging(damping)resistor 充电阻尼电阻 tank 箱体 point plane gap 针板间隙 earth(ground)wire 接地线 exciting winding 激磁绕组grading ring 均压环trigger electrode 触发电极highvoltage engineering 高电压工程glow discharge 辉光放电highvoltage testing technology 高电压试验技术harmonic 谐波Power electronics 电力电子Automatic control 自动控制Principles of electric circuits 电路原理 Digital signal processing 数字信号处理电气工程专业英语词汇表2 power system 电力系统impulse current 冲击电流 power network 电力网络 impulse flashover 冲击闪络 insulation 绝缘 inhomogenous field 不均匀场 overvoltage 过电压insulation coordination 绝缘配合aging 老化internal discharge 内部放电 alternating current 交流电 lightning stroke 雷电波 AC transmission system 交流输电系统 lightning overvoltage 雷电过电压介质)损耗角 arc discharge 电弧放电 loss angle(介质损耗角介质attachment coefficient 附着系数magnetic field 磁场attenuation factor 衰减系数mean free path 平均自由行程anode(cathode)阳极阴极 mean molecular velocity 平均分子速度阳极(阴极阴极)breakdown(电)击穿negative ions 负离子电击穿bubble breakdown 气泡击穿 non-destructive testing 非破坏性试验cathode ray oscilloscope 阴极射线示波器 non-uniform field 不均匀场 cavity 空穴腔 partial discharge 局部放电空穴,腔 corona 电晕peak reverse voltage 反向峰值电压 composite insulation 组合绝缘photoelectric emission 光电发射 critical breakdown voltage 临界击穿电压 photon 光子 Discharge 放电 phase-to-phase voltage 线电压 Dielectric 电介质绝缘体 polarity effect 极性效应电介质,绝缘体 dielectric constant 介质常数 power capacitor 电力电容 dielectric loss 介质损耗quasi-uniform field 稍不均匀场direct current 直流电radio interference 无线干扰divider ratio 分压器分压比rating of equipment 设备额定值grounding 接地routing testing 常规试验electric field 电场 residual capacitance 残余电容 electrochemical deterioration 电化学腐蚀 shielding 屏蔽 electron avalanche 电子崩short circuit testing 短路试验electronegative gas 电负性气体space charge 空间电荷 epoxy resin 环氧树脂 streamer breakdown 流注击穿expulsion gap 灭弧间隙surface breakdown 表面击穿field strength 场强 sustained discharge 自持放电 field stress 电场力switching overvoltage 操作过电压field distortion 场畸变thermal breakdown 热击穿 field gradient 场梯度 treeing 树枝放电field emission 场致发射 uniform field 均匀场 flashover 闪络 wave front(tail)波头尾)波头(尾gaseous insulation 气体绝缘withstand voltage 耐受电压Prime mover 原动机Power factor 功率因数Torque 力矩Distribution automation system 配电网自动化系统Servomechanism 伺服系统Automatic meter reading 自动抄表Boiler 锅炉Armature 电枢Internal combustion engine 内燃机Brush 电刷Deenergize 断电 Commutator 换向器 Underground cable 地下电缆Counter emf 反电势电气工程专业英语词汇表3 退磁,去磁Loop system 环网系统Demagnetization 退磁去磁Distribution system 配电系统 Relay panel 继电器屏 Trip circuit 跳闸电路 Tertiary winding 第三绕组 Switchboard 配电盘开关屏 Eddy current 涡流配电盘,开关屏Instrument transducer 测量互感器Copper loss 铜损Oil-impregnated paper 油浸纸绝缘 Iron loss 铁损 Bare conductor 裸导线 Leakage flux 漏磁通 Reclosing 重合闸 Autotransformer 自耦变压器 Distribution dispatch center 配电调度中心 Zero sequence current 零序电流 Pulverizer 磨煤机 Series(shunt)compensation 串(并)联补偿并联补偿汽包,炉筒 Drum 汽包炉筒 Restriking 电弧重燃Superheater 过热器 Automatic oscillograph 自动录波仪 Peak-load 峰荷 Tidal current 潮流 Prime grid substation 主网变电站 Trip coil 跳闸线圈 Reactive power` 无功功率 Synchronous condenser 同步调相机 Active power 有功功率 Main and transfer busbar 单母线带旁路 Shunt reactor 并联电抗器 Feeder 馈电线 Blackout 断电、停电Skin effect 集肤效应断电、Extra-high voltage(EHV)超高压Potential stress 电位应力电场强度电位应力(电场强度电场强度)Ultra-high voltage(UHV)特高压Capacitor bank 电容器组Domestic load 民用电crusher 碎煤机Reserve capacity 备用容量pulverizer 磨煤机 Fossil-fired power plant 火电厂 baghouse 集尘室 Combustion turbine 燃气轮机 Stationary(moving)blade 固定可动叶片固定(可动可动)叶片Right-of-way 线路走廊Shaft 转轴Rectifier 整流器Kinetic(potential)energy 动(势)能Inductive(Capacitive)电势能感的(电容的电容的)感的电容的Pumped storage power station 抽水蓄能电站Reactance(impedance)电抗阻抗Synchronous condenser 同步调相机电抗(阻抗阻抗)Reactor 电抗器 Light(boiling)-water reactor 轻(沸)水反应堆沸水反应堆电抗的,无功的Reactive 电抗的无功的Stator(rotor)定(转)子Phase displacement(shift)相移转子Armature 电枢Surge 冲击过电压Salient-pole 凸极冲击,过电压Retaining ring 护环Slip ring 滑环Carbon brush 炭刷Arc suppression coil 消弧线圈Short-circuit ratio 短路比Primary(backup)relaying 主(后备继电保护后备)继电保护后备Induction 感应 Phase shifter 移相器 Autotransformer 自藕变压器Power line carrier(PLC)电力线载波器)电力线载波(器 Bushing 套管Line trap 线路限波器 Turn(turn ratio)匝(匝比变比 Uninterruptible power supply 不间断电源匝比,变比匝比变比)Power factor 功率因数 Spot power price 实时电价分时(电价电价)Tap 分接头 Time-of-use(tariff)分时电价Recovery voltage 恢复电压 XLPE(Cross Linked Polyethylene)交联聚乙烯(电缆电缆)交联聚乙烯电缆Arc reignition 电弧重燃Rms(root mean square)均方根值 Operationmechanism 操动机构 RF(radio frequency)射频电气工程专业英语词汇表4 Pneumatic(hydraulic)气动(液压)Rpm(revolution per minute)转/ 分Nameplate 铭牌LAN(local area network)局域网Independent pole operation 分相操作 LED(light emitting diode)发光二极管 Malfunction 失灵 Single(dual, ring)bus 单(双,环形母线环形)母线双环形 Shield wire 避雷线 IC(integrated circuit)集成电路Creep distance 爬电距离 FFT(fast Fourier transform)快速傅立叶变换 Silicon rubber 硅橡胶 Telemeter 遥测 Composite insulator 合成绝缘子Load shedding 甩负荷Converter(inverter)换流器逆变器Lateral 支线换流器(逆变器逆变器)Bus tie breaker 母联断路器Power-flow current 工频续流Protective relaying 继电保护sparkover 放电 Transfer switching 倒闸操作 Silicon carbide 碳化硅Outgoing(incoming)line 出(进)线 Zinc oxide 氧化锌进线相位超前(滞后滞后)Phase Lead(lag)相位超前滞后 Withstand test 耐压试验Static var compensation(SVC)静止无功补偿Dispatcher 调度员Flexible AC transmission system(FACTS)灵活交流输电系统Supervisory control and data acquisition(SCADA)监控与数据采集EMC(electromagnetic compatibility)电磁兼容ISO(internationalstandardization organization)国际标准化组织GIS(gas insulated substation, geographic information system)气体绝缘变电站地理信息系统 IEC(international Electrotechnical Commission)国际电工(技术技术)委员会国际电工技术委员会 IEEE(Institute of Electrical and Electronic Engineers)电气与电子工程师学会(美)美IEE(Institution of Electrical Engineers)电气工程师学会(英电气工程师学会英)scale 刻度量程 calibrate 校准刻度,量程 rated 额定的 terminal 接线端子保险丝,熔丝 fuse 保险丝熔丝 humidity 湿度 resonance 谐振共振 moisture 潮湿湿气谐振,共振潮湿,湿气 analytical 解析的 operation amplifier 运算放大器numerical 数字的amplitude modulation(AM)调幅frequency-domain 频域frequency modulation(FM)调频time-domain 时域binary 二进制 operation amplifier 运算放大器 octal 八进制 active filter 有源滤波器decimal 十进制passive filter 无源滤波器hexadecimal 十第三篇:电气工程及其自动化专业英语电气工程及其自动化专业英语老师:学生:专业:电气工程及其自动化学院:学号:Automatic Control system自动控制系统When a specific systemis proposed for a given application,it mustsatisfy certain requirements.This may involve the system response or optimization of the system in a specified way.These requirements that a control system must meet are generally called performance specifications.当一个精细的系统被推引入一个给定的应用程序的时候,它必须满足这个特定的要求。
(电气工程与自动化专业英语)Chapter 3 Signals and Systems
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3.3 Discrete-Time Signals
1 The basic definition signals
The fundamental results of signal theory : Analog signal can be converted into a discrete-time one and retrieved without error. This result is important because discrete-time signals can be manipulated by systems instantiated as computer programs. Subsequent modules describe how virtually all analog signal processing can be performed with software.
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3.2 Signal Decomposition
As an example of signal complexity, we can express the pulse as a sum of delayed unit steps.
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Section 1 Semiconductor Switches
give rise to power losses in the switching devices. We will examine these switching losses in two cases separately: the inductive and capacitive loads. Switching with Inductive Load The inductor is assumed to be large so that the current through it in steady state is nearly constant Io. Assume that initially the switch is off. The inductor current is +Io and freewheels through diode V1. When the switch is turned on, the current through the switch begins to build up linearly (an assumption) to +Io while the diode V1 is still on.
Section 1 Semiconductor Switches
over, the diode Vl begins to conduct and the voltage on the switch is clamped at Uo, and the current through the switch ramps linearly (again an assumption) down to zero. When the switch is closed, the current begins to build up linearly to IS while the diode V1 is still on. The voltage on the switch remains clamped at UO. After the switch current reaches IS, the diode turns off and the voltage on the switch begins to ramp down to zero.
Section 1 Semiconductor Switches
the current through the switch begins to decrease below Io , as the remaining current is now steered through the diode V1, which has now turned on. The current through the switch ramps down to zero ultimately. Switching waveforms with inductive load are shown in Fig.3-1.
Section 1 Semiconductor Switches
The on diode has zero voltage across it (an ideal diode), hence, the voltage on the switch is held constant at +Us. When the current buildup is over, the diode Vl ceases to conduct and the voltage on the switch ramps linearly (again an assumption) down to zero. When the switch is turned off, the voltage begins to build up linearly to +Us while the diode V1 is off. While the diode is off the current through the switch equals the inductor current, which is constant Io. After the switch voltage reaches zero,
Section 1 Semiconductor Switches
On-State Losses The electrical switches conduct heavy current and have nonzero voltage across the switch in the onstate. The on-state power losses are given by
Chapter 3
Power Electronic Technology
Section 1 Semiconductor Switches
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New Words and Expressions Transition of part of speech
Exercises
End
Section 1 Semiconductor Switches
Fig.3-1 Switching waveforms with inductive load
Section 1 Semiconductor Switches
The switching losses are given by The switching power losses increase linearly with the switching frequency like in the resistive case but about six times more. The upper bound on the switching frequency is also about half.
Section 1 Semiconductor Switches
power losses are very significant. Off-State Losses The electrical switches withstand high voltages and have nonzero leakage current through the switch in the off-state. The off-state power losses are given by
Poff usoff ir
(3-2)
Section 1 Semiconductor Switches
The usoff and ir are respectively the reverse bias voltage in the off-state and the reverse current through the switch. For example, the typical power diodes and the power transistors have high reverse voltages in hundreds to thousands of volts and microamps to milliamps through them in the off state. Transition-State Losses The practical switching devices have limited capabilities of rate of voltage transition and the rate of current steering. These nonabrupt transition rates
f s max t on1 t on 2 1 t off 1 t off 2
(3-4)
1 Psw Us I o [ton1 ton 2 toff 1 toff 2 ] fs 2
(3-3)
Section 1 Semiconductor Switches
Switching with capacitive load The capacitor is assumed to be large so that the voltage through it in steady state is nearly constant Uo. Assume that initially the switch is on, hence, the current through the switch is IS. The capacitor voltage is Uo, the voltage across the switch is zero and the diode V1 is reverse biased. When the switch is turned off, the switch voltage begins to ramp up to + Uo while the diode V1 is still off. During this buildup, the current through the switch is held constant at IS . When the voltage buildup is
Semiconductor switches are very important and crucial components in power electronic systems. These switches are meant to be the substitutions of the mechanical switches, but they are severely limited by the properties of the semiconductor materials and the process of manufacturing.