电气专业英语论文
关于电气工程专业英语的作文
关于电气工程专业英语的作文Diving into the realm of electrical engineering is like exploring a vast, intricate web of innovation and technology that powers our modern world. This field, with its heart set on the pulse of progress, is not just about circuits and currents; it's a language of its own, with English at its core, bridging the gap between theory and application.Electrical engineering is a discipline that has evolved dramatically over the decades, and its language has kept pace, incorporating a rich lexicon of terms that describeeverything from the most fundamental components to the most cutting-edge technologies. For students and professionals alike, mastering the English terminology is crucial for understanding the principles that underpin electrical systems, from the microchip to the power grid.In this dynamic field, the ability to communicate effectively in English is paramount. Whether it's discussing the intricacies of a power electronics converter or thedesign of a high-voltage transmission line, precision in language is as important as precision in engineering. English serves as the universal medium for scholarly articles, technical specifications, and international conferences,where the latest research and developments are shared.Moreover, the language of electrical engineering is not static; it evolves with the field. New terms emerge astechnologies advance, such as "smart grid," "renewable energy," and "Internet of Things (IoT)," each reflecting the ongoing expansion of the discipline. Keeping up with these developments requires a commitment to continuous learning and an openness to embracing new concepts and terminologies.The study of electrical engineering English also extends beyond the technical. It encompasses the ability to interpret and create diagrams, to understand and apply mathematical models, and to engage in critical thinking about the implications of new technologies on society and the environment.In essence, the mastery of electrical engineering English is not just about the words; it's about the ideas they represent and the solutions they enable. It's about theability to connect with a global community of engineers, to contribute to a field that is constantly pushing the boundaries of what is possible, and to be part of a conversation that shapes the future of our world.。
有关电气专业的英语作文
有关电气专业的英语作文I have always been fascinated by electricity and how it powers the world around us. The ability to manipulate and control the flow of electrons is truly amazing.When I first started studying electrical engineering, I was overwhelmed by the amount of knowledge and information I needed to absorb. However, as I delved deeper into the subject, I found myself becoming more and more passionate about it.One of the most exciting things about electrical engineering is the endless possibilities it offers. From designing circuits to working on power systems, there is always something new and challenging to explore.I love the hands-on aspect of electrical engineering. There is something incredibly satisfying about building and testing circuits, and seeing the results of your work come to life.The field of electrical engineering is constantly evolving, and it is crucial to stay updated with the latest technologies and advancements. This constant learning and adaptation keep the profession exciting and dynamic.The problem-solving aspect of electrical engineering is what drew me to the field in the first place. I enjoy the challenge of identifying and solving complex electrical issues, and the sense of accomplishment that comes with finding a solution.The impact of electrical engineering on the world is undeniable. From powering homes and businesses to driving technological innovations, electrical engineers play a crucial role in shaping the modern world.In conclusion, electrical engineering is a diverse and dynamic field that offers endless opportunities for learning and growth. I am excited to continue my journey in this field and see where it takes me.。
电气专业的英语作文
电气专业的英语作文In the heart of technological advancement lies the field of electrical engineering, a discipline that has been pivotal in shaping our modern society. This essay will explore the importance of electrical engineering, its applications, andits impact on various sectors.First and foremost, electrical engineering is the backbone of modern communication systems. The development of wireless technologies, such as Wi-Fi and cellular networks, has been made possible through the expertise of electrical engineers. These technologies have revolutionized the way we communicate, allowing for instant messaging, video calls, and the seamless sharing of information across the globe.Moreover, the field has played a crucial role in the advancement of renewable energy sources. Solar panels, wind turbines, and other forms of green energy rely heavily on electrical engineering to convert, distribute, and manage the energy they produce. This has led to a significant reductionin our reliance on fossil fuels, contributing to a cleanerand more sustainable future.In the medical sector, electrical engineering has also made a profound impact. Medical imaging technologies, such as MRIand CT scans, rely on complex electrical systems to function. These systems are essential for diagnosing and treating awide range of medical conditions, thereby improving patientoutcomes and saving lives.Furthermore, the automotive industry has been transformed by the integration of electrical engineering. Electric vehicles (EVs) are becoming increasingly popular due to their environmental benefits and efficiency. The design and production of EVs require a deep understanding of electrical systems, batteries, and power management, all of which are at the core of electrical engineering.Lastly, the field of electrical engineering is integral to the development of smart cities. Smart grids, intelligent transportation systems, and automated infrastructure are all dependent on sophisticated electrical systems. These systems are designed to optimize energy use, reduce waste, and improve the overall quality of life for city dwellers.In conclusion, electrical engineering is a multifaceted discipline that has a profound impact on various aspects of modern society. From communication to renewable energy, medical technology to transportation, and smart city development, the role of electrical engineering is indispensable. As we continue to innovate and push the boundaries of technology, the importance of this field will only continue to grow.。
电气工程及其自动化专业英语作文范文
电气工程及其自动化专业英语作文范文Electrical Engineering and Automation: An Integral Part of Modern SocietyIntroductionElectrical Engineering and Automation, a discipline that has evolved significantly over the past few decades, has become an integral part of modern society. Its widespread applications in industry, agriculture, national defense, and various other fields have propelled it to a pivotal position in the global economy.Historical PerspectiveThe field of Electrical Engineering and Automation was first established approximately forty years ago. As a relatively new discipline, it has quickly grown to encompass a wide range of subfields and applications. From the design of switches for aerospace aircraft to the development of complex automated systems, its influence is pervasive.Core ComponentsThe core of Electrical Engineering and Automation lies in its ability to integrate electricity, machines, and intelligent systems to automate various tasks. This integration enables efficiency, precision, and safety in a wide range of applications.•Electricity and Machines: Electricity provides the power that drives machines and systems. Understanding the behavior ofelectrical circuits, voltage sources, current sources, andvarious network elements is crucial for the effective designand operation of automated systems.•Automation: Automation refers to the use of technology to control and monitor processes and machines with minimal humanintervention. It relies on sensors, actuators, and intelligentcontrollers to achieve desired outcomes.Challenges and OpportunitiesWhile Electrical Engineering and Automation offers immense opportunities for growth and development, it also poses significantchallenges. The complexity of modern systems requires a high level of technical knowledge and expertise. Additionally, the rapid pace of technological advancement requires constant updating of skills and knowledge.However, these challenges also present opportunities for innovation and growth. As new technologies emerge, there is a need for engineers and technicians who can understand and apply them effectively. This creates opportunities for those with a passion for learning and a willingness to adapt to new challenges.ConclusionIn conclusion, Electrical Engineering and Automation is a dynamic and exciting field that offers immense opportunities for growth and development. Its applications are pervasive, and its influence on society is profound. As we continue to push the boundaries of technology, Electrical Engineering and Automation will play an increasingly important role in shaping our future.。
电气工程及其自动化专业英语课程论文完整版
电气工程及其自动化专业英语课程论文Document serial number【NL89WT-NY98YT-NC8CB-NNUUT-NUT108】重庆邮电大学移通学院《电气工程及其自动化专业英语》课程论文年级 2012专业电气工程与自动化姓名孙猜胜学号Three-phase asynchronous motorAbstract:The three-phase asynchronous motor is motor's one with single phase asynchronous motor, three-phase asynchronous motor operating performance is good, and can save various the structure to be simple, the manufacture is easy, firm durable, the service is convenient,cost inexpensive ,drag the ability is good,and so on a series of merits. thus becomes in each kind of electrical machinery the outputto be biggest utilizes the broadest one kind of electric motor.Key words:Moror Motor starting Star delta StartingThree-phase asynchronous motor principle:When the stator winding through into the three-phase ac three-phase symmetric arises when a synchronous speed n1 along the stator and rotor round for space in a clockwise rotation magnetic field. Because of a rotating magnetic field rotating speed to n1, rotor conductor of the static beginning, so the rotor conductor will cutthe stator and produce a rotating magnetic field induction emf (induction emf direction DingZe judge with the right hand). Because the child is short circuit loop ends conductor short meet, in therole of the induced emf, will produce the rotor conductor with induction emf direction basic consistent induced current. The rotor current-carrying conductor at stator magnetic field is the role ofthe electromagnetic force (the direction of the force with the left hand DingZe judge). The electromagnetic force of the rotor axis electromagnetic torque, drive along the rotor rotating magnetic field rotation direction.[1]Through the above analysis can be summed up the motor principle: when the three-phase motor stator winding (eachdiffer 120 KWH Angle), ventilation with three-phase ac, will producea rotating magnetic field, the rotating magnetic field cutting rotor winding, and thus to the rotor winding induced current (rotor windingis closed access), load flow of rotor stator conductor under the action of a rotating magnetic field will produce the electromagnetic force, thus in the motor shaft formed on the electromagnetic torque, driving motor rotation, and motor rotation direction and the rotating magnetic field in the same direction.Thestructureofthree-phaseasynchronousmotor:Types of three-phase asynchronous motor, but all kinds of three-phase asynchronous motor is the same basic structure, they are the stator and rotor of these two basic components, the stator and rotor has a certain air gap between. In addition, end caps, bearings, cable boxes, rings and other accessories,1).StatorpartStator is used to generate the rotating magnetic Three-phase motors generally shell, stator core, stator windings and other parts.a.Shell?Three-phase motor casing including base,end caps,bearingcaps,rings,such as junction boxes and comp onentsb. Stator CoreInduction motor stator core is part of the motor circuit from ~ thick coated with a thin insulating paint from silicon,c.ThestatorwindingsThree-phase motor stator windings are part of the circuit,there are three-phase three-phase motor windings,summetrical three-phase current access,it will have a rotating magnetic winding consists of three separate components of the winding, and each has a number of coil windings a phase of each winding, each winding in the space angle difference between the 120 ° electrical[2].2). Rotor parta. Rotor CoreWith mm thick steel from, set in the shaft, the role and the same stator core, on the one hand, as part of the motor magnetic circuit, on the one hand to place the rotor windings.b. Rotor windingsThe rotor winding induction motor winding is divided into two kinds of cage-shaped and which is divided into winding rotor asynchronous motor with cage induction motor.3). Other parts ofOther parts including the cover, fans, etc.Induction motor starting methods:There are several general methods of starting induction motors: full voltage, reduced voltage,wyes-delta,and part winding reduced voltage type can include solid state starters, adjustable frequency drives, and following is the most common method.1).Full voltageThe full voltage starting method, also known as across the line starting, is the easiest method to employ, has the lowest equipment costs, and is the most reliable. This method utilizes a control to close a contactor and apply full line voltage to the motor terminals. This method will allow the motor to generate its highest starting torque and provide the shortest acceleration method also puts the highest strain on the power system due to the high starting currents that can be typically six to seven times the normal full load current of the motor.2).AutotransformerThe motor leads are connected to the lower voltage side of the transformer. The most common taps that are used are 80%, 65%, and 50%. At 50% voltage the current on the primary is 25% of the full voltage locked rotor amps. The motor is started with this reduced voltage,and then after a pre-set condition is reached the connection is switched to line voltage. This condition could be a preset time, current level, bus volts, or motor speed. The change over can be done in either a closed circuit transition, or an open circuit transition method. In the open circuit method the connection to the voltage is severed as it is changed from the reduced voltage to the line level. Care should be used to make sure that there will not be problems from transients due to the switching. This potential problem can be eliminated by using the closed circuit transition. With the closed circuit method there is a continuous Voltage applied to the motor. Another benefit with the autotransformer starting is in possiblelower vibration and noise levels during starting.3).Star delta StartingThis approach started with the induction motor,the structure of each phase of the terminal are placed in the motor teminal box ,This allows the motor star connection in the initial start up,and then re-connected into a triangle run..The initial start time when the voltage is reduced to the original star connection,the startingcurrent and starting torque by 2/3. Depending on the applicationon,the motor switch to the triangle in the rotational speed of between 50% and the maximum be noted that the sameproblems,including the previously mentioned switch method ,if theopen circuit method,the transition may be a transient method isoften used in lesst than 600V motor,the rated voltage and higher are not suitable for star delta motor start method.[3]4).Series Resistor or Reactor StartingThis method is to use a series resistance or place in the motor loop the motor is started, a resistor to limit current and make the motor at the input voltage drop. Therefore plays a role of limitingcurrent at the small motor series resistor startup mode used more frequentlyConclusion:There are many ways asynchronous motor starting, each method hasits own benefits, according to the constraints of powersystems,equipment costs, load the boot device to select the best method.References:[1] Tang Tianhao Fundamentals of Electrical Machines and Drives [M] BeijingChina Machine Press 118-137[2] Wang Liming English for Electrical Engineering and Automation [M] BeijingTsinghua University Press 61-64[3] Stephen Electromechanics [M] America Electronic IndustryPress 340-370。
(完整word版)电气工程及其自动化专业外语作文
(完整word版)电气工程及其自动化专业外语作文A s a student, you will learn to apply related subjects such as computer technology，industrial electronics, instrumentation，electrical machines, robotics，power electronics，and automated control systems.作为一名学生，你将学会运用相关学科,如计算机技术，工业电子，仪器仪表，电器机械，机器人技术，电力电子和自动化控制系统。
Y ou will be able to understand written and oral instructions，as well as design, install, test，modify, troubleshoot，and repair electrical systems.您将能够理解书面和口头说明，以及设计,安装，测试，修改，故障排除和修复电力系统.U pon graduation，students of the Electrical Engineering Technology –Process Automation program can approach industrial electrical and electronic systems from the viewpoint of analysis，technical evaluation, design, and development。
The six—semester program concentrates on the in-depth study of electrical and electronic principles as they apply to automated systems using programmable logic controllers。
电气专业英语论文
院（系、部、中心）专业班级学生姓名学号任课教师Page1 Generators and Motors(发电机和电动机)1 English textFrom reference 11. Direct-current generators impress on the line a direct or continuous emf, one that is always in the same direction. Commercial dc generators have commutators, which distinguish them from ac generators. The function of a commutator and the elementary ideas of generation of emf and commutation are discussed in Div. 1. Additional information about commutation as applied to dc motors, which in general is true for dc generators, is given below.2. Excitation of generator fields. To generate an emf, conductors must cut a magnetic field which in commercial machines must be relatively strong. A permanent magnet can be used for producing such a field in a generator of small output, such as a telephone magneto or the magneto of an insulation tester, but in generators for light and power the field is produced by electromagnets, which may be excited by the machine itself or be separately excited from another source.Self-excited machines may be of the series, shunt, or compound type, depending upon the manner of connecting the field winding to the armature. In the series type of machine,the field winding (the winding which produces the magnetic field) is connected in series with the armature winding. In the shunt type, the field winding is connected inparallel,shunt, with the armature winding. Compound machines have two field windings on each pole. One of these windings is connected in series with the armature winding, and the other is connected in parallel or shunt with the armature winding.3. Armature winding of dc machines may be of the lap or the wave type. The difference in the two types is in the manner of connecting the armature coils to the commutator.A coil is the portion of the armature winding between successive connections to the commutator.In the lap type of winding (see Fig. 7.1) the two ends of a coil are connected to adjacent commutator segments. In the wave type of winding(see Fig. 7.2) the two ends of a coil are connected to commutator segments that are displaced from each other by approximately 360 electrical degrees.The type of armature winding employed affects the voltage and current capacity of the machine but has no effect upon the power capacity. This is due to the fact that the number of parallel paths between armature terminals is affected by the type of winding. For a wavewound machine there are always two paths in parallel in the armature winding between armature terminals. For a lap-wound machine there are as many parallel paths in the armature winding as there are pairs of poles on the machine. For the same number and size of armature conductors, a machine when wave-connected would generate a voltage that would equal the voltage generated when lap-connected times the number of pairs of poles.But the current capacity would be decreased in the same proportion that the voltage was increased. The current capacity of a machine when wave-connected is therefore equal to the capacity when lap-connected divided by the number of pairs of poles.4. The value of the voltage generated by a dc machine depends upon the armature winding, the speed, and the field current. For a given machine, therefore, the voltage generated can be controlled by adjusting either the speed or the field current. Since generators are usually operated at a constant speed, the voltage must be controlled by adjusting the field current.5. Separately excited dc generators are used for electroplating and for other electrolytic work for which the polarity of a machine must not be reversed.Self-excited machines may change their polarities. The essential diagrams are shown in Fig. 7.3. The fields can be excited from any dc constant-potential source, such as a storage battery, or from a rectifier connected to an ac supply.The field magnets can be wound for any voltage because they have no electric connection with the armature. With a constant field excitation, the voltage will drop slightly fromno load to full load because of armature drop and armature reaction.Separate excitation is advantageous when the voltage generated by the machine is not suitable for field excitation. This is true for especially low- or high-voltage machines.6. Series-wound generators have their armature winding, field coils, andexternal circuit connected in series with each other so that the same current flows through all parts of the circuit (see Fig. 7.4). If a series generator is operated at no load (external circuit open), there will be no current through the field coils, and the only magnetic flux presentin the machine will be that due to the residual magnetism which has been retained by the poles from previous operation. Therefore, the no-load voltage of a series generator will be only a few volts produced by cutting the residual flux. If the external circuit is closed and the current increased, the voltage will increase with the increase in current until the magnetic circuit becomes saturated. With any further increases of load the voltage will decrease. Series generators have been used sometimes in street-railway service. They have been connected in series with long trolley feeders supplying sections of the system distant from the supply point in order to boost the voltage. However, power rectifiers have replaced dc generators for most installations of this type.Keywords: generatorFrom reference 2Since triphased asynchronous generators are mainly used in conversion systems of a eolian energy into electric energy, their functional stability represent isof great importance. As a first step, the factors that radically affect the functional stability of these generators have been established. Thus, it was decelat the powerful influence of the capacitor bank – that provides the necessary reactive power for the magnetization of the ferromagnetic core – over the functional stability of the triphased asynchronous generator with short circuit rotor. The functional stability is greatly influenced by the charge character (type) as well. The experimental work emphasized – through the functional features – the way these parameters influence the stability area of the asynchronous generators. As far as triphased asynchronous generators with coiled rotor are concerned, the controllable blind power was analyzed the analogy being made with the situation of the necessary controllable generating capacity for of the triphased asynchronous generator with short circuit rotor.Keywords : triphased asynchronous generator.2 中文翻译及分析出资文献 1：1。
(完整版)电气专业中英文对照翻译毕业设计论文
优秀论文审核通过未经允许切勿外传Chapter 3 Digital Electronics3.1 IntroductionA circuit that employs a numerical signal in its operation is classified as a digital circuitputers,pocket calculators, digital instruments, and numerical control (NC) equipment are common applications of digital circuits. Practically unlimited quantities of digital information can be processed in short periods of time electronically. With operational speed of prime importance in electronics today,digital circuits are used more frequently.In this chapter, digital circuit applications are discussed.There are many types of digital circuits that electronics, including logic circuits, flip-flop circuits, counting circuits, and many others. The first sections of this unit discuss the number systems that are basic to digital circuit understanding. The remainder of the chapter introduces some of the types of digital circuits and explains Boolean algebra as it is applied to logic circuits.3.2 Digital Number SystemsThe most common number system used today is the decimal system,in which 10 digits are used for counting. The number of digits in the systemis called its base (or radix).The decimal system，therefore，the counting process. The largest digit that can be used in a specific place or location is determined by the base of the system. In the decimal system the first position to the left of the decimal point is called the units place. Any digit from 0 to 9 can be used in this place.When number values greater than 9 are used,they must be expressed with two or more places.The next position to the left of the units place in a decimal system is the tens place.The number 99 is the largest digital value that can be expressed by two places in the decimal system.Each place added to the left extends the number system by a power of 10.Any number can be expressed as a sum of weighted place values.The decimal number 2583,for example, is expressed as (2×1000)+(5×100)+(8×10)+(3×1).The decimal number system is commonly used in our daily lives. Electronically, the binary system.Electronically,the value of 0 can be associated with a low-voltage value or no voltage. The number 1 can then be associated with a voltage value larger than 0. Binary systems that use these voltage values are said to , this chapter.The two operational states of a binary system,1 and 0,are natural circuit conditions. When a circuit is turned off or the off, or 0,state. An electrical circuit that the on，or 1,state. By using transistor or ICs，it is electronically possible to change states in less than a microsecond. Electronic devices make it possible to manipulate millions of 0s and is in a second and thus to process information quickly.The basic principles of numbering used in decimal numbers apply ingeneral to binary numbers.The base of the binary system is 2,meaning that only the digits 0 and 1 are used to express place value. The first place to the left of the binary point,or starting point，represents the units，or is,location. Places to the left of the binary point are the powers of 2.Some of the place values in base 2 are 2º=1,2¹=2,2²=4,2³=8,2⁴=16,25=32,and 26=64.When bases other than 10 are used,the numbers should example.The number 100₂(read“one,zero,zero, base 2”)is equivalent to 4 in base 10,or 410.Starting with the first digit to the left of the binary point,this number this method of conversion a binary number to an equivalent decimal number，write down the binary number first. Starting at the binary point，indicate the decimal equivalent for each binary place location where a 1 is indicated. For each 0 in the binary number leave a blank space or indicate a 0 ' Add the place values and then record the decimal equivalent.The conversion of a decimal number to a binary equivalent is achieved by repetitive steps of division by the number 2.When the quotient is even with no remainder,a 0 is recorded.When the quotient process continues until the quotient is 0.The binary equivalent consists of the remainder values in the order last to first.3.2.2 Binary-coded Decimal (BCD) Number SystemWhen large numbers are indicated by binary numbers，they are difficult to use. For this reason，the Binary-Coded Decimal(BCD) method of counting was devised. In this system four binary digits are used to represent each decimal digit.To illustrate this procedure，the number 105，is converted to a BCD number.In binary numbers，To apply the BCD conversion process，the base 10 number is first divided into digits according to place values.The number 10510 gives the digits 1-0-5.Converting each displayed by this process with only 12 binary numbers. The between each group of digits is important when displaying BCD numbers.The largest digit to be displayed by any group of BCD numbers is 9.Six digits of a number-coding group are not used at all in this system.Because of this, the octal (base 8) and the binary form but usually display them in BCD,octal,or a base 8 system is 7. The place values starting at the left of the octal point are the powers of eight: 80=1,81=8,82=64,83=512,84=4096,and so on.The process of converting an octal number to a decimal number is the same as that used in the binary-to-decimal conversion process. In this method, equivalent decimal is 25810.Converting an octal number to an equivalent binary number is similar to the BCD conversion process. The octal number is first divided into digits according to place value. Each octal digit is then converted into an equivalent binary number using only three digits.Converting a decimal number to an octal number is a process of repetitive division by the number 8.After the quotient determined，the remainder is brought down as the place value.When the quotient is even with no remainder，a 0 is transferred to the place position.The number for converting 409810 to base 8 is 100028.Converting a binary number to an octal number is an importantconversion process of digital circuits. Binary numbers are first processed at a very output circuit then accepts this signal and converts it to an octal signal displayed on a readout device.must first be divided into groups of three，starting at the octal point.Each binary group is then converted into an equivalent octal number.These numbers are then combined，while remaining in their same respective places，to represent the equivalent octal number.3.2.4 Hexadecimal Number SystemThe digital systems to process large number values.The base of this system is 16，which means that the largest number used in a place is 15.Digits used by this system are the numbers 0-9 and the letters A-F. The letters A-P are used to denote the digits 10-15，respectively. The place values to the left of the .The process of changing a proper digital order.The place values，or powers of the base，are then positioned under the respective digits in step 2.In step 3，the value of each digit is recorded. The values in steps 2 and 3 are then multiplied together and added. The sum gives the decimal equivalent value of a . Initially，the converted to a binary number using four digits per group. The binary group is combined to form the equivalent binary number.The conversion of a decimal number to a ，as with other number systems. In this procedure the division is by 16 and remainders can be as large as 15.Converting a binary number to a groups of four digits，starting at the converted to a digital circuit-design applications binary signals arefar superior to those of the octal，decimal，or be processed very easily through electronic circuitry，since they can be represented by two stable states of operation. These states can be easily defined as on or off, 1 or 0，up or down，voltage or no voltage，right or left，or any other two-condition states. There must be no in-between state.The symbols used to define the operational state of a binary system are very important.In positive binary logic，the state of voltage，on，true，or a letter designation (such as A ) is used to denote the operational state 1 .No voltage，off，false，and the letter A are commonly used to denote the 0 condition. A circuit can be set to either state and will remain in that state until it is caused to change conditions.Any electronic device that can be set in one of two operational states or conditions by an outside signal is said to be bistable. Relays，lamps，switches，transistors, diodes and ICs may be used for this purpose. A bistable device .By using many of these devices，it is possible to build an electronic circuit that will make decisions based upon the applied input signals. The output of this circuit is a decision based upon the operational conditions of the input. Since the application of bistable devices in digital circuits makes logical decisions，they are commonly called binary logic circuits.If we were to draw a circuit diagram for such a system，including all the resistors，diodes，transistors and interconnections，we would face an overwhelming task, and an unnecessary one.Anyone who read the circuit diagram would in their mind group the components into standard circuits and think in terms of the" system" functions of the individual gates. Forthis reason，we design and draw digital circuit with standard logic symbols. Three basic circuits of this type are used to make simple logic decisions.These are the AND circuit, OR circuit, and the NOT circuit.Electronic circuits designed to perform logic functions are called gates.This term refers to the capability of a circuit to pass or block specific digital signals.The logic-gate symbols are shown in Fig.3-1.The small circle at the output of NOT gate indicates the inversion of the signal. Mathematically，this action is described as A=.Thus without the small circle，the rectangle would represent an amplifier (or buffer) with a gain of unity.An AND gate the 1 state simultaneously，then there will be a 1 at the output.The AND gate in Fig. 3-1 produces only a 1 out-put when A and B are both 1. Mathematically，this action is described as A·B=C. This expression shows the multiplication operation. An OR gate Fig.3-1 produces a when either or both inputs are l.Mathematically，this action is described as A+B=C. This expression shows OR addition. This gate is used to make logic decisions of whether or not a 1 appears at either input.An IF-THEN type of sentence is often used to describe the basic operation of a logic state.For example，if the inputs applied to an AND gate are all 1，then the output will be 1 .If a 1 is applied to any input of an OR gate，then the output will be 1 .If an input is applied to a NOT gate，then the output will be the opposite or inverse.The logic gate symbols in Fig. 3-1 show only the input and output connections. The actual gates，when wired into a digital circuit, would pin 14 and 7.3.4 Combination Logic GatesWhen a NOT gate is combined with an AND gate or an OR gate，it iscalled a combination logic gate. A NOT-AND gate is called a NAND gate，which is an inverted AND gate. Mathematically the operation of a NAND gate is A·B=. A combination NOT-OR ，or NOR，gate produces a negation of the OR function.Mathematically the operation of a NOR gate is A+B=.A 1 appears at the output only when A is 0 and B is 0.The logic symbols are shown in Fig. 3-3.The bar over C denotes the inversion，or negative function，of the gate.The logic gates discussed .In actual digital electronic applications，solid-state components are ordinarily used to accomplish gate functions.Boolean algebra is a special form of algebra that was designed to show the relationships of logic operations.Thin form of algebra is ideally suited for analysis and design of binary logic systems.Through the use of Boolean algebra，it is possible to write mathematical expressions that describe specific logic functions.Boolean expressions are more meaningful than complex word statements or or elaborate truth tables.The laws that apply to Boolean algebra are used to simplify complex expressions. Through this type of operation it may be possible to reduce the number of logic gates needed to achieve a specific function before the circuits are designed.In Boolean algebra the variables of an equation are assigned by letters of the alphabet.Each variable then exists in states of 1 or 0 according to its condition.The 1，or true state，is normally represented by a single letter such as A，B or C.The opposite state or condition is then described as 0，or false，and is represented by or A’.This is described as NOT A，A negated，or A complemented.Boolean algebra is somewhat different from conventional algebra withrespect to mathematical operations.The Boolean operations are expressed as follows:Multiplication:A AND B，AB，,A·BOR addition:A OR B .A+BNegation，or complementing:NOT A，，A’Assume that a digital logic circuit only C is on by itself or when A，B and C are all on expression describes the desired output. Eight (23) different combinations of A，B，and C exist in this expression because there are three，inputs. Only two of those combinations should cause a signal that will actuate the output. When a variable is not on (0)，it is expressed as a negated letter. The original statement is expressed as follows: With A，B，and C on or with A off, B off, and C on ，an output (X）will occur:ABC+C=XA truth table illustrates if this expression is achieved or not.Table 3-1 shows a truth table for this equation. First，ABC is determined by multiplying the three inputs together.A 1 appears only when the A，B，and C inputs are all 1.Next the negated inputs A andB are determined.Then the products of inputs C，A，and B are listed.The next column shows the addition of ABC and C.The output of this equation shows that output 1 is produced only when C is 1 or when ABC is 1.A logic circuit to accomplish this Boolean expression is shown in Fig. 3-4.Initially the equation is analyzed to determine its primary operational function.Step1 shows the original equation.The primary function is addition，since it influences all parts of the equation in some way.Step 2 shows the primary function changed to a logic gate diagram.Step 3 showsthe branch parts of the equation expressed by logic diagram，with AND gates used to combine terms.Step 4 completes the process by connecting all inputs together.The circles at inputs，of the lower AND gate are used to achieve the negative function of these branch parts.The general rules for changing a Boolean equation into a logic circuit diagram are very similar to those outlined.Initially the original equation must be analyzed for its primary mathematical function.This is then changed into a gate diagram that is inputted by branch parts of the equation.Each branch operation is then analyzed and expressed in gate form.The process continues until all branches are completely expressed in diagram formmon inputs are then connected together.3.5 Timing and Storage ElementsDigital electronics involves a number of items that are not classified as gates.Circuits or devices of this type the operation of a system.Included in this system are such things as timing devices，storage elements，counters，decoders，memory，and registers.Truth tables symbols，operational characteristics，and applications of these items will be presented an IC chip. The internal construction of the chip cannot be effectively altered. Operation is controlled by the application of an external signal to the input. As a rule，very little work can be done to control operation other than altering the input signal.The logic circuits in Fig. 3-4 are combinational circuit because the output responds immediately to the inputs and there is no memory. When memory is a part of a logic circuit，the system is called sequential circuit because its output depends on the input plus its an input signal isapplied.A bistable multivibrator，in the strict sense，is a flip-flop. When it is turned on，it assumes a particular operational state. It does not change states until the input is altered.A flip-flop opposite polarity.Two inputs are usually needed to alter the state of a flip-flop. A variety of names are used for the inputs.These vary a great deal between different flip-flops.1. R-S flip-flopsFig.3-5 shows logic circuit construction of an R-S flip-flop. It is constructed from two NAND gates. The output of each NAND provides one of the inputs for the other NAND. R stands for the reset input and S represents the set input.The truth table and logic symbol are shown in Fig. 3-6.Notice that the truth table is somewhat more complex than that of a gate. It shows, for example，the applied input, previous output，and resulting output.To understand the operation of an R-S flip-flop，we must first look at the previous outputs.This is the status of the output before a change is applied to the input. The first four items of the previous outputs are Q=1 and =0. The second four states this case of the input to NANDS is 0 and that is 0，which implies that both inputs to NANDR are 1.By symmetry，the logic circuit will also stable with Q0 and 1.If now R momentarily becomes 0，the output of NANDR，，will rise to resulting in NANDS be realized by a 0 at S.The outputs Q and are unpredictable when the inputs R and S are 0 states.This case is not allowed.Seldom would individual gates be used to construct a flip-flop，rather than one of the special types for the flip-flop packages on a single chipwould be used by a designer.A variety of different flip-flops are used in digital electronic systems today. In general，each flip-flop type R-S-T flip-flop for example .is a triggered R-S flip-flop. It will not change states when the R and S inputs assume a value until a trigger pulse is applied. This would permit a large number of flip-flops to change states all at the same time. Fig. 3-7 shows the logic circuit construction. The truth table and logic symbol are shown in Fig. 3-8. The R and S input are thus active when the signal at the gate input (T) is 1 .Normally，such timing，or synchronizing，signals are distributed throughout a digital system by clock pulses，as shown in Fig. 3-9.The symmetrical clock signal provides two times each period.The circuit can be designed to trigger at the leading or trailing edge of the clock. The logic symbols for edge trigger flip-flops are shown in Fig.3-10.2. J-K flip-flopsAnother very important flip-flop unpredictable output state. The J and K inputs addition to this，J-K flip-flops may employ preset and preclear functions. This is used to establish sequential timing operations. Fig.3-11 shows the logic symbol and truth table of a J-K flip-flop.3. 5. 2 CountersA flip-flop be used in switching operations，and it can count pulses.A series of interconnected flip-flops is generally called a register.Each register can store one binary digit or bit of data. Several flip-flops connected form a counter. Counting is a fundamental digital electronic function.For an electronic circuit to count，a number of things must beachieved. Basically，the circuit must be supplied with some form of data or information that is suitable for processing. Typically，electrical pulses that turn on and off are applied to the input of a counter. These pulses must initiate a state change in the circuit when they are received. The circuit must also be able to recognize where it is in counting sequence at any particular time. This requires some form of memory. The counter must also be able to respond to the next number in the sequence. In digital electronic systems flip-flops are primarily used to achieve counting. This type of device is capable of changing states when a pulse is applied，output pulse.There are several types of counters used in digital circuitry today.Probably the most common of these is the binary counter.This particular counter is designed to process two-state or binary information. J-K flip-flops are commonly used in binary counters.Refer now to the single J-K flip-flop of Fig. 3-11 .In its toggle state，this flip-flop is capable of achieving counting. First，assume that the flip-flop is in its reset state. This would cause Q to be 0 and Q to be 1 .Normally，we are concerned only with Q output in counting operations. The flip-flop is now connected for operation in the toggle mode. J and K must both be made the 1 state. When a pulse is applied to the T，or clock，input，Q changes to 1.This means that with one pulse applied，a 1 is generated in the output. The flip-flop the next pulse arrives，Q resets，or changes to 0. Essentially，this means that two input pulses produce only one output pulse. This is a divide-by-two function.For binary numbers，counting is achieved by a number of divide-by-two flip-flops.To count more than one pulse，additional flip-flops must be employed. For each flip-flop added to the counter，its capacity is increased by the power of 2. With one flip-flop the maximum count was 20，or 1 .For two flip-flops it would count two places，such as 20 and 21.This would reach a count of 3 or a binary number of 11.The count would be 00，01，10，and 11. The counter would then clear and return to 00. In effect, this counts four state changes. Three flip-flops would count three places，or 20，21，and 22.This would permit a total count of eight state changes.The binary values are 000，001，010，011，100，101，110 and 111.The maximum count is seven，or 111 .Four flip-flops would count four places，or 20，21，22，and 23.The total count would make 16 state changes. The maximum count would be 15，or the binary number 1111.Each additional flip-flop would cause this to increase one binary place.河南理工大学电气工程及其自动化专业中英双语对照翻译。
电气自动化专业介绍英语作文
电气自动化专业介绍英语作文Electrical Automation Engineering.Electrical automation engineering is a branch of engineering that deals with the design, installation, and maintenance of electrical systems that are used to automate industrial processes. These systems can range from simple relay-based circuits to complex computer-controlled networks.Electrical automation engineers work in a variety of industries, including manufacturing, transportation, and utilities. They are responsible for designing and implementing electrical systems that meet the specific needs of their clients. These systems can include:Programmable logic controllers (PLCs)。
Variable frequency drives (VFDs)。
Human-machine interfaces (HMIs)。
Distributed control systems (DCSs)。
Supervisory control and data acquisition (SCADA) systems.Motion control systems.Robotics.Electrical automation engineers must have a strong understanding of electrical engineering principles, as well as a working knowledge of computer science and mechanical engineering. They must also be able to work independently and as part of a team.中文回答：电气自动化专业介绍。
电气工程及其自动化专业英语》课程论文
重庆邮电大学移通学院《电气工程及其自动化专业英语》课程论文年级专业姓名学号Insulated-gate Bipolar Transistor Basics 【Abstract】Modern Power Electronics makes generous use of MOSFETs and IGBTs in most applications, and, if the present trend is any indication, the future will see more and more applications making use of MOSFETs and IGBTs. For high-voltage or high-power applications, it may be necessary to realize a logical switch by connecting smaller units in parallel and series to achieve high availability, high-frequency operation, and low cost due to build-in redundancy, reduced dynamic losses, and modular use of standardized units, respectively. IGBTs are very convenient to realize such units, because of quasi-linear controllability via a gate terminal. This thesis investigates control methodologies for power MOS semiconductor switches with focus on combined parallel and series connection of IGBT/diode modules. It is proposed to provide each IGBT with primary local control to monitor and adjust the IGBT's static and dynamic behavior. Secondary (global) control synchronizes the operation of multiple IGBTs. A globally synchronous clock can also be derived locally. This makes it possible to use low-cost low-bandwidth data links between series-connected units. Thereby, a flexible master- slave approach can avoid the need of dedicated global control. That is, the entire system is manageable by the local gate drive circuitry.Keywords:IGBT applications MOSFET characteristicIntroduction:The IGBT is a semiconductor device with four alternating layers (P-N-P-N) that are controlled by a metal-oxide-semiconductor (MOS) gate structure without regenerative action. This mode of operation was first proposed by Yamagami in his Japanese patent S47-21739, which was filed in 1968. This mode of operation was first experimentally reported in the lateral four layer device (SCR) by B.W. Scharf and J.D. Plummer in 1978.[1] This mode of operation was also experimentally discovered in vertical device in 1979 by B. J. Baliga.[2]The device structure was referred to as a ‘V-groove MOSFET device with the drain region replaced by a p-type Anode Region’ in this paper and subsequently as 'the insulated-gate rectifier' (IGR), the insulated-gate transistor (IGT), the conductivity-modulated field-effect transistor (COMFET) and "bipolar-mode MOSFET".[3]IGBT Fundamentals:The Insulated Gate Bipolar Transistor (IGBT) is a minority-carrier device with high input impedance and large bipolar current-carrying capability. Many designers view IGBT as a device with MOS input characteristics and bipolar output characteristic that is a voltage-controlled bipolar device. To make use of the advantages of both Power MOSFET and BJT, the IGBT has been introduced. It’s a fun ctional integration of Power MOSFET and BJT devices in monolithic form. It combines the best attributes of both to achieve optimal device characteristics.1.The main advantages of IGBT over a Power MOSFET and a BJT are:1. It has a very low on-state voltage drop due to conductivity modulation and has superior on-state current density. So smaller chip size is possible and the cost can be reduced.2. Low driving power and a simple drive circuit due to the input MOS gate structure. It can be easily controlled as compared to current controlled devices (thyristor, BJT) in high voltage and high current applications.3. Wide SOA. It has superior current conduction capability compared with the bipolar transistor. It also has excellent forward and reverse blocking capabilities.2.The main drawbacks are:1. Switching speed is inferior to that of a Power MOSFET and superior to that of a BJT. The collector current tailing due to the minority carrier causes the turn-off speed to be slow.2. There is a possibility of latchup due to the internal PNPN thyristor structure. The IGBT is suitable for scaling up the blocking voltage capability. In case of Power MOSFET, the on-resistance increases sharply with the breakdown voltage due to an increase in the resistively and thickness of the drift region required to support the high operating voltage.Basic Structure:An IGBT cell is constructed similarly to a n-channel vertical construction power MOSFET except the N+ drain is replaced with a P+ collector layer, thus forming a vertical PNP bipolar junction transistor. This additional P+ region creates a cascade connection of a PNP bipolar junction transistor with the surface n-channel MOSFET. Some IGBTs, manufactured without the N+buffer layer, are called non-punch through IGBTs whereas those with this layer are called punch-through IGBTs. The presence of this buffer layer can significantly improve the performance of the device if the doping level and thickness of this layer are chosen appropriately. Despite physical similarities, the operation of an IGBT is closer to that of a power BJT than a power MOSFET. It is due to the P + drain layer (injecting layer) which is responsible for the minority carrier injection into the N-drift region and the resulting conductivity modulation.IGBT Characteristics：Because the IGBT is a voltage-controlled device, it only requires a small voltage on the Gate to maintain conduction through the device unlike BJT’s which require that the Base current is continuously supplied in a sufficient enough quantity to maintain saturation.Also the IGBT is a unidirectional device, meaning it can only switch current in the “forward direction”, that is from Collector to Emitter unlike MOSFET’s which have bi-directional current switching capabilities (controlled in the forward direction and uncontrolled in the reverse direction).The principal of operation and Gate drive circuits for the insulated gate bipolar transistor are very similar to that of the N-channel power MOSFET. The basic difference is that the resistance offered by the main conducting channel when current flows through the device in its “ON” state is very much smaller in the IGBT. Because of this, the current ratings are much higher when compared with an equivalent power MOSFET.[4]The main advantages of using the Insulated Gate Bipolar Transistor over other types of transistor devices are its high voltage capability, low ON-resistance, ease of drive, relatively fast switching speeds and combined with zero gate drive current makes it a good choice for moderate speed, high voltage applications such as inpulse-width modulated (PWM), variable speed control, switch-mode power supplies or solar powered DC-AC inverter and frequency converter applications operating in the hundreds of kilohertz range. A general comparison betwe en BJT’s, MOSFET’s and IGBT’s is given in the following table.IGBT Operating area:The safe operating area is defined as the current-voltage boundary within which a power switching device can be operated without destructive failure. For IGBT, the area is defined by the maximum collector-emitter voltage V CE and collector current I C within which the IGBT operation must be confined to protect it from damage. The IGBT has the following types of SOA operations: forward-biased safe operating area , reverse-biased safe operating area and short-circuit safe operating area .1.Pulsed Collector Current (I CM ): Within its thermal limits, the IGBT can be used to a peak current well above the rated continuous DC current. The temperature rise during a high current transient can be calculated with the help of the transient thermal impedance curve or simulated in SPICE with the parameters provided in the curve. The test circuit is shown in the data sheet.2.Collector-to-Emitter Voltage (V CES ): V oltage across the IGBT should never exceed this rating, to prevent breakdown of the collector-emitter junction. The minimum value of the breakdown is stated in the Table of Electrical Characteristics.3.Maximum Gate-to-Emitter Voltage (V GE): The gate voltage is limited by the thickness and characteristics of the gate oxide layer. Though the gate dielectric rupture is typically around 80 volts, the user is normally limited to 20 or 30V to limit current under fault conditions and to ensure long term reliability.4.Clamped Inductive Load Current (I LM ):This rating is described in Section 6 and is important in most hard-switching applications. The test circuit can be found in the data sheet (it has changed over the years) and is the same as the switching loss test circuit. This circuit exposes the IGBT to the peak recovery current of the free-wheeling diode, which adds a significant component to the turn-on losses. This rating guarantees that the device can sustain high voltage and high current simultaneously, i.e. a square switching SOA. The test conditions for I LM are specified in the data sheet. This complements the information supplied by the RBSOA.References:[1] B.W. Scharf and J.D. Plummer, 1978 IEEE International Solid-State Circuits Conference, SESSION XVI FAM 16.6 "A MOS-Controlled Triac Devices"[2] B.J. Baliga, "ENHANCEMENT- AND DEPLETION-MODE VERTICAL-CHANNEL M.O.S. GA TED THYRISTORS" Electronics Letters p.645(1979)[3] A.Nakagawa et al., "High voltage bipolar-mode MOSFETs with high current capability", Ext. Abst. of SSDM, pp. 309–312(1984)[4] Ralph Locher, “Introduction to Power MOSFETs and their Applications” Fairchild Semiconductor, Application Note 558, October 1998.。
电气工程方面的英汉论文
Electric Devices and SystemsAlthough transformers have no moving parts , they are essential to electromechanical energy conversion . They make it possible to increase or decrease the voltage lever that results in low costs ,and can be distributed and used safely . In addition , they can provide matching of impedances , and regulate the flow of power in a network.When we see a transformer on a utility pole all we is a cylinder with a few wires sticking out. These wires enter the transformer through bushings that provide isolation between the wires and the tank. Inside the tank these is an iron core linking coils, most probably made with copper, and insulated. The system of insulation is also associated with that of cooling the core/coil assembly. Often the insulation is paper, and the whole assembly may be immersed in insulating oil, used to both increase the dielectric strength of the paper and to transfer beat from the core-coil assembly to the outer walls of the tank to air. Figure shows the cutout of a typical distribution transformer. Few ideal versions of human constructions exist, and the transformer offers no exception. An ideal transformer is based on very simple concepts, and a large number of assumptions. This is the transformer one learns about in high school.Let us take an iron core with infinite permeability and two coils wound around it, one with N1 and the other with N2 turns, as shown in figure. Allthe magnetic flux is to remain in the iron. We assign sots at one terminal of each coil in the following fashion: if the flux in the core changes, inducing a voltage in the coils, and the dotted terminal of one coil is positive with respect its other terminal, so is the dotted terminal of the other coil. Or, the corollary to this, current into dotted terminals produces flux in the same direction,Assume that somehow a time varying flux is established in the iron. Then the flux linkages in each coil will be. Voltages will be induced in these two coil.On the other hand, currents flowing in the coils are related to the field intensity H. if currents flowing in the direction shown, i1 into the dotted terminal of coil 1, and i2 out of the dotted terminal of coil 2. we recognize that this is practically impossible, but so is the existence of an ideal transformer.Equations describe this ideal transformer, a two port network. The symbol of a network that is defined by these two equations is in the figure. An ideal transformer has an interesting characteristic. A two-port network that contains it and impedances can be replaced by an equivalent other, as discussed below. Consider the circuit in figure. Seen as a two port network. Generally a circuit on a side 1 can be transferred to side 2 by multiplying its component impedances , the voltage sources and the current sources,while keeping the topology the same. To develop the equivalent for a transformer we’ll gradually relax the assumptions that we had first imposed. First we’ll relax the assumption that the permeability of the iron is infinite. In that case equation does not revert to, but rather it becomes where is the reluctance of the path around the core of the transformer and the flux on this path. To preserve the ideal transformer equations as part of our new transformer, we can split i1 to two components: one i1, will satisfy the ideal transformer equation, and the other, i1 will just balance the right hand side. The figure shows this. We can replace the current source, i1 , with something simpler if we remember that the rate of change of flux is related to the induced voltage.Since the current i1 flows through something , where the voltage across it Is proportional to its derivative, we can consider that this something could be an inductance. This idea gives rise tothe equivalent circuit in figure,. Let us now relax the assumption that all the flux has to remain in the iron as shown in figure. Let us call the flux in the iron, magnetizing flux, the flux that leaks out of the core and links only coil 1. since links only coil 1, then it should be related only to the current there, and the same should be true for the second leakage flux.Again for a given frequency, the power losses in the core increase with the voltage. These losses cannot be allowed to exceed limit, beyond which thetemperature of the hottest spot in the transformer will rise above the point that will decrease dramatically the life of the insulation. Limits therefore are put to E1 and E2, and these limits are the voltage limits of the transformer. Similarly, winding Joule losses have to be limited, resulting in limits to the currents I1 and I2. Typically a transformer is described by its rated voltages, that give both the limits and turns radio. The ratio of the rated currents is the inverse of the ratio of the voltages if we neglect the magnetizing current. Instead of the transformer rated currents, a transformer is described by its rated apparent power.Under rated conditions, maximum current and voltage, in typical transformers the magnetizing current, does not exceed 1% of the current in the transformer. Its effect therefore in the voltage drop on the leakage inductance and winding resistance is negligible.Under maximum current, total voltage drops on the winding resistances and leakage inductances do not exceed in typical transformer 6% of the rated voltage. The effect therefore of the winding current on the voltages E1 and E2 is small, and their effect on the magnetizing current can be neglected.These considerations allow us to modify the equivalent circuit in figure, to obtain the slightly inaccurate but much more useful equivalent circuits in figures.Adjustable Speed DrivesBy definition, adjustable speed drives of any type provide a means of variably changing speed to better match operating requirements. Such drives are available in mechanical, fluid and electrical typed.The most common mechanical versions use combinations of belts and sheaves, or chains and sprockets, to adjust speed in set, selectable ratios-2:1,4:1,8:1 and so forth. Traction drives, a more sophisticated mechanical control scheme, allow incremental speed adjustments. Here, output speed is varied by changing the contact points between metallic disks, or between balls and cones. Adjustable speed fluid drives provide smooth, stepless adjustable speed control. There are three major types. Hydrostatic drives use electric motors or internal combustion engines as prime movers in combination with hydraulic pumps, which in turn drive hydraulic motors. Hydrokinetic and hydroviscous drives directly couple input and output shafts. Hydrokinetic versions adjust speed by varying the amount of fluid in a vortex that serves as the input-to-output coupler. Hydroviscous drives, also called oil shear drives, adjust speed by controlling oil-film thickness, and therefore slippage, between rotating metallic disk. An eddy current drive, while technically an electrical drive, nevertheless functions much like a hydrokinetic or hydrovidcous fluid drive in that it serves as a coupler between a prime mover and driven load. In an eddycurrent drive, the coupling consists of a primary magnetic field and secondary fields created by induced eddy currents. They amount of magnetic slippage allowed among the fields controls the driving speed.In most industrial applications, mechanical, fluid or eddy current drives are paired with constant-speed electric motors. On the other hand, solid state electrical drives, create adjustable speed motors, allowing speeds from zero RPM to beyond the motor’s base speed. Controlling the speed of the motor has several benefits, including increased energy efficiency by eliminating energy losses in mechanical speed changing devices. In addition, by reducing, or often eliminating, the need for wear-prone mechanical components, electrical drives foster increased overall system reliability, as well as lower maintenance costs. For these and other reasons, electrical drives are the fastest growing type of adjustable speed drive..There are two basic drive types related to the type of motor controlled-dc and AC. A DC direct current drive controls the speed of a DC motor by varying the armature voltage (and sometimes also the field voltage ). An alternating current drive controls the speed of an AC motor by varying the frequency and voltage supplied to the motor.Direct current drives are easy to apply and technologically straightforward, They work by rectifying AC voltage from the power line to DC voltage, then feeding adjustable voltage to a DC motor. With permanent magnet DCmotors, only the armature voltage is controlled. The more voltage supplied, the faster the armature turns. With wound-field motors, voltage must be supplied to both the armature and the field. In industry, the following three types of DC drives are most common, as shown in the figure.Drives: these are named for the silicon controlled rectifiers (also called thyristors ) used to convert AC to controlled voltage DC. Inexpensive and easy to use, these drives come in a variety of enclosures, and in unidirectional or reversing styles.Regenerative SCR Drives: Also called four quadrant drives, these allow the DC motor to provide both motoring and braking torque, Power coming back from the motor during braking is regenerated back to the power line and not lost.Pulse Width Modulated DC Drives: Abbreviated PWM and also called, generically, transistorized DC drives, these provide smoother speed control with higher efficiency and less motor heating, Unlike SCR drives, PWM types have three elements. The first converts AC to DC, the second filters and regulates the fixed DC voltage, and the third controls average voltage by creating a stream of variable width DC pulses. The filtering section and higher level of control modulation account for the PWM drive’s improved performance compared with a common SCR drive.AC drive operation begins in much the same fashion as a DC drive. Alternating line voltage is first rectified to produce DC. But because an AC motor is used, this DC voltage must be changed back, of inverted, to an adjustable-frequency alternating voltage. The drive’s inv erter section accomplishes this, In years past, this was accomplished using SCR. However, modern AC drives use a series of transistors to invert DC to adjustable-Frequency AC. An example is shown in figure.This synthesized alternating current is then fed to the AC motor at the frequency and voltage required to produce the desired motor speed. For example, a 60 Hz synthesized frequency, the same as standard line frequency in the United states, produces 100% of rated motor speed. A lower frequency produces a lower speed, and a higher frequency a higher speed. In this way, an AC drive can produce motor speeds from, approximately,15 to200% of a motor’s normally rated RPM-- by delivering frequencies of 9 HZ to 120 Hz, respectively.Today, AC drives are becoming the systems of choice in many industries,. Their use ofsimple and rugged three-phase induction motor means that AC drive systems are the most reliable and least maintenance prone of all. Plus, microprocessor advancements have enabled the creation of so-called vector drives, which provide greatly enhance response, operation down to zero speed and positioning accuracy. Vector drives, especially whencombined with feedback devices such as tachometers, encoders and resolvers in a closed-loop system, are continuing to replace DC drives in demanding applications. An Example is shown in the figure.By far the most popular AC drive today is the pulse width modulated type. Though originally developed for smaller-horsepower applications, PWM is now used in drives of hundreds or even thousands of horsepower—as well as remaining the staple technology in the vast majority of small integral and fractional horsepower ―micro‖ and ―sub-micro‖ AC drives, as shown in the figure. Pulse width modulated refers to the inverter’s ab ility to vary the output voltage to the motor by altering the width and polarity of voltage pulses, The voltage and frequency are synthesized using this stream of voltage pulses. This is accomplished through microprocessor commands to a series of power semiconductors that serve as on-off switches. Today, these switches are usually IGBTs, of isolated gate bipolar transistor. A big advantage to these devices is their fast switching speed resulting in higher pulse of carrier frequency, which minimizes motor noise.Power semiconductor devicesThe modern age of power electronics began with the introduction of thyristors in the late 1950s. Now there are several types of power devices available for high-power and high-frequency applications. The most notable power devices are gate turn-off thyristor, power darlington transistors,power mosfets, and insulated-gate bipolar transistors. Power semiconductor devices are the most important functional elements in all power conversion applications. The power devices are mainly used as switches to convert power from one form to another. They are used in motor control systems, uninterrupted power supplies, high-voltage dc transmission, power supplies, induction heating, and in many other power conversion applications. A review of the basic characteristics of these power devices is presented in this section.The thyristor, also called a silicon-controlled rectifier, is basically a four-layer three-junction pn device. It has three terminals: anode, cathode, and gate. The device is turned on by applying a short pulse across the gate and cathode. Once the device turns on, the gate loses its control to turn off the device. The turn-off is achieved by applying a reverse voltage across the anode and cathode. The thyristors symbol and its volt-ampere characteristics are shown in the figure. There are basically two classifications of thyristors: converter grade and inverter grade. The difference between a converter-grade and an inverter-grade thyristor is the low turn –off time (on the order of a few microseconds) for the latter. The converter-grade thyristors are slow type and are used in natural commutation (or phase-controlled) applications. Inverter-grade thyristors are used in forced commutation applications such as dc-dc choppers and dc-ac inverters. The inverter-grade thyristors are turned off by forcing thecurrent to zero using an external commutation circuit. This requires additional commutating components, thus resulting in additional losses in the inverter. Thyristors are highly rugged devices in terms of transient currents, di / dt, and dv/dt capability. The forward voltage drop in thyristors is about 1.5 to 2 V, and even at higher currents of the order of 100 A, it seldom exceeds 3 V. While the forward voltage determines the on-state power loss of the device at any given current, the switching power loss becomes a dominating factor affecting the device junction temperature at high operating frequencies. Because of this, themaximum switching frequencies possible using thyristors are limited in comparison with other power devices considered in this section.Thyristors have withstand capability and can be protected by fuses. The nonrepetitive surge current capability for thyristors is about 10 times their rated root mean square current. They must be protected by snubber networks for dv/dt and di/dt effects. If the specified dv/dt is exceeded, thyristors may start conducting without applying a gate pulse. In dc-to-ac conversion applications it is necessary to use an antiparalled diode of similar rating across each main thyristor. Thyristors are available up to 6000 V, 3500 A.Power mosfets are marketed by different manufacturers with differences in internal geometry and with different names such as megamos, hexfet,sipmos, and tmos. They have unique features that make them potentially attractive for switching applications. They are essentially voltage-driven rather than current-driven devices, unlike bipolar transistors.The gate of a mosfet is isolated electrically from the source by a layer of silicon oxide. The gate draws only a minute leakage current of the order of nanoamperes. Hence the gate drive circuit is simple and power loss in the gate control circuit is practically negligible. Although in steady state the gate draws virtually no current, this is not so under transient conditions. The gate-to-source and gate-to-drain capacitances have to be charged and discharged appropriately to obtain the desired switching speed, and the drive circuit must have a sufficiently to output impedance to supply the required charging and discharging currents. The circuit symbol of a power mosfet is shown in the figure.Power mosfets are majority carrier devices, and there is no minority carrier storage time. Hence they have exceptionally fast rise and fall times. They are essentially resistive devices when turned on, while bipolar transistors present a more or less constant over the normal operating range. Power dissipation in mosfets is I, and in bipolar it is Ic, and in bipolar it is Id. At low currents, therefore, a power mosfet may have a lower conduction loss than a comparable bipolar device, but at higher currents, the conduction loss will exceed that of bipolar. Also, the R increases with temperature.An important feature of a power mosfet is the absence of a secondary breakdown effect, which is present in a bipolar transistor, and as a result, it has an extremely rugged switching performance. In mosfets, R increases with temperature, and thus the current is automatically diverted away from the hot spot. The drain body junction appears as an antiparalled diode between source and drain. Thus power mosfet will not support voltage in the reverse direction. Although this in verse diode is relatively fast, it is slow by comparison with the mosfet. Recent devices have the didde recovery time as low as 100 ns. Since mosfet cannot be protected by fuses, an electronic protection technique has to be used.With the advancement in MOS technology, ruggedized MOSF are replacing the conventional MOSEFs. The need to ruggedize power MOSFETs is related to device reliability. If a MOSFET is operating within its specification range at all times, its chances for failing catastrophically are minimal. However, if its absolute maximum rating is exceeded, failure probability increases dramatically. Under actual operating conditions, a MOSFET may be subjected to transients—either externally from the power bus supplying the circuit or from the circuit itself due, for example, to inductive kicks going beyond the absolute maximum ratings. Such conditions are likely in almost every application, and in most cases are beyond a designer’s control. Rugged devices are made to be more tolerant for over-voltage transients. Ruggedness is the ability of aMOSFET to operate in an environment ofdynamic electrical stresses, without activating any of the parasitic bipolar junction transistors. The rugged device can withstand higher levels of diode recovery dv/dt and static dv/dt.译文：变压器尽管变压器没有旋转的不见，但是它在本质上还是属于几点能量交换设备。
电气专业英文作文
电气专业英文作文As an electrical engineering major, I am fascinated by the way electricity powers our world. From the circuits in our phones to the power grid that keeps our cities running, electricity is everywhere and I want to understand it all.I love the hands-on aspect of electrical engineering. There's something so satisfying about designing a circuit on paper and then actually building it in the lab. It'slike bringing your ideas to life and seeing them work in the real world.One of the most challenging parts of studyingelectrical engineering is the math. It can be really tough to wrap your head around all the complex equations and calculations, but when you finally solve a difficult problem, it's incredibly rewarding.I'm also really interested in the future of electrical engineering, especially when it comes to renewable energy.I think it's so important for us to find sustainable ways to power our world, and I want to be a part of that innovation.In the end, I chose to study electrical engineering because I want to make a real impact on the world. Whether it's through designing more efficient power systems or creating new technology, I believe that electrical engineering has the potential to change the way we live for the better.。
电气英语作文模板及范文
电气英语作文模板及范文Title: Electrical Engineering English Writing Template and Sample。
Introduction。
Electrical engineering is a diverse and challenging field that encompasses the study and application of electricity, electronics, and electromagnetism. As a result, writing about electrical engineering in English can be a daunting task for many students and professionals. In this article, we will provide a template and sample for writing a comprehensive and well-structured essay on electrical engineering in English.Template for Writing an Electrical Engineering Essay。
1. Introduction。
Provide a brief overview of the topic。
Introduce the main points that will be discussed in the essay。
State the purpose of the essay。
2. Background Information。
Provide relevant background information on electrical engineering。
Discuss the history and development of electrical engineering。
电气自动化专业英语作文500字左右
电气自动化专业英语作文500字左右全文共6篇示例，供读者参考篇1Electrical Stuff is Really Cool!Hi there! My name is Timmy and I'm 8 years old. Today I want to tell you all about this super awesome thing called electrical automation. It's like magic, but with science and technology instead of wizards and wands!You see, electrical automation is all about using electricity to make machines and devices work automatically without needing people to control them directly. It's kind of like having little robot helpers that do things for you, except they're not actually robots – they're just regular machines and equipment that are really smart and can pretty much run themselves.Let me give you some examples so you can understand better. Have you ever pressed a button on a vending machine and then a drink just comes out? Or have you ever walked towards an automatic door and it just opened by itself? That's electrical automation at work! The vending machine and the automatic doors have special electrical systems and controls thatallow them to operate on their own based on things like sensing when someone puts money in or walks nearby.But that's just the start – electrical automation is used for sooo many important things! Like in factories, there are often huge machines and assembly lines that can manufacture products like cars or electronics or toys automatically with very little human involvement required. The machines are programmed to do all the work like cutting metal, putting pieces together, painting, etc. Electrical controls and computers make it all happen in a perfectly synchronized way.Electrical automation is also super important for things that help make our lives easier and more convenient. Like elevators –instead of having to pull yourself up with ropes, the elevator uses electrical motors and controls to move between floors automatically when you push a button. Or traffic lights that know when to turn green, yellow and red to control the flow of vehicles and pedestrians. Or heating and air conditioning systems that automatically adjust temperatures in buildings to keep things comfortable.And you know what's really cool? Electrical automation isn't just for big industrial things – it can be used for all kinds of neat gadgets and gizmos too! Like robot vacuums that can clean yourfloors automatically while you're at school. Or smart home systems where you can control the lights, temperature, music and more just by talking to a virtual assistant. It's like living in the future!My dad is actually an electrical engineer, which means he designs and builds a lot of the systems and equipment used for electrical automation. From what I understand, it involves using things like electrical circuits, programming, sensors, motors and other components in really clever ways to create automated control systems. It sounds pretty complicated to me, but my dad seems to really enjoy his job.I still have a lot to learn about how electrical automation really works behind the scenes, but I think it's just so amazing how it allows us to do so many tasks automatically and efficiently using the power of electricity. We can manufacture products, control environments, move things around and so much more –all with the help of smart automated systems running on electricity. Isn't that wild?Well, those are my thoughts on electrical automation for now. Maybe when I'm older and a little bit smarter, I can learn even more about this incredible technology. But for now, I'm justglad it exists to make so many awesome things possible! Electrical automation is the best!篇2The Magical World of Electrical AutomationHave you ever wondered how machines work? Things like robots, traffic lights, and even video games are powered by something called electrical automation. It's like magic, but it's real science!Electrical automation is all about using electricity to control and operate different machines and systems. It's like having a team of tiny, invisible helpers that make everything run smoothly.Imagine you're playing a video game, and your character needs to jump over a pit. When you press the jump button, an electrical signal is sent through wires to the game console. This signal tells the console to make your character jump on the screen. It happens so fast that it feels like magic!But electrical automation isn't just for games. It's used in all sorts of important places, like factories and power plants. In a factory, robots are controlled by electrical automation to buildthings like cars and toys. These robots can move quickly and precisely, following instructions from computers.Even something as simple as a traffic light uses electrical automation. When the light turns green, an electrical signal tells the cars that it's safe to go. When it turns red, another signal tells the cars to stop. This helps keep everyone safe on the roads.Electrical automation also plays a big role in keeping our homes comfortable. Your air conditioner, heater, and even your refrigerator all use electrical automation to work properly. Imagine if you had to manually turn on your fridge every time you wanted a cold drink!But how does electrical automation work? It's all thanks to a special kind of machine called a controller. Controllers are like the brains of electrical automation systems. They receive information from sensors, like buttons or switches, and then send out signals to control other parts of the system.For example, when you press the button on a remote control, a sensor sends a signal to the controller in your TV. The controller then sends a signal to the TV to change the channel or adjust the volume.Electrical automation is like having a team of helpers that can do things faster and more accurately than humans. It makes our lives easier and helps keep us safe. And who knows, maybe one day you'll become an expert in electrical automation and create your own magical machines!篇3Electrical Automation is Super Cool!Hi there! My name is Tommy and I'm 8 years old. I go to Oakwood Elementary School and I'm in third grade. Today I want to tell you all about this really cool thing called electrical automation. It's a major you can study in university and it's all about using electricity to control machines and systems. How awesome is that?So what exactly is electrical automation? Well, it's kind of like telling robots what to do using electrical signals and computer programs. These robots could be big industrial machines in a factory or even the electronics in our houses and cars. Basically, anything that uses electricity can likely be automated.The people who study electrical automation, called electrical automation engineers, spend a lot of time programming and writing code篇4My Big Dream JobHi, my name is Tommy and I'm 8 years old. I love building things with Legos and K'nex and putting together models and machines. My favorite subject in school is science because I get to learn about how things work. My dream is to become an electrical automation engineer when I grow up!What is an Electrical Automation Engineer?An electrical automation engineer is someone who designs and builds the control systems that operate big machines and factories. They use computers to program and automate things like robots, assembly lines, power plants, and more. It's a really high-tech and important job!Electrical automation engineers need to know a lot about electricity and electronics. They have to understand how circuits work and how to control electrical components like motors, sensors, and switches. But they also need strong computer programming skills to write the code that tells the machines what to do.On a typical day, an automation engineer might design the electrical wiring plans for a new factory robot. They would plan out where all the motors, sensors, and other components need to go and how they connect together electrically. Then they would write software code to control the timing and movements of the robot based on sensor inputs.Another day, they may analyze the performance of machines on an assembly line. They could use data and computer models to optimize the processes and improve efficiency. Or they may troubleshoot problems and update programming if a machine stops working right.The Skills You NeedTo become an electrical automation engineer, you first need a university degree, whic篇5My Daddy's Cool Job with Robots and ComputersMy daddy has a really neat job! He's an electrical engineer and works with robots and computers and all sorts of cool things.I don't really understand everything he does, but I think it's super awesome.Daddy says he works in something called "electrical automation." I'm not totally sure what that means, but I know it has to do with using electricity to make machines run by themselves without people having to control them. How wild is that?Daddy showed me his workplace once and it was like a scene from a sci-fi movie! There were these huge robot arms moving stuff around and assembling things. And there were tons of computers controlling everything. Daddy said the robots and computers can make things faster and better than humans can.Apparently, the robots get instructions from the computers on what to do and how to do it. The computers have special programs called "software" that tell the robots the right movements to make. If something gets messed up, the computers can detect it and fix it or stop the robots. It's like the computers are the brains and the robots are the muscle!I remember Daddy pointing out these things called "sensors" on the robots. These little gizmos can detect stuff like motion, heat, and even colors. The sensors send signals to the computer to let it know what's happening. Based on that information, the computer can adjust what the robots are doing.For example, if a sensor sees a red light, it might tell the robot to stop moving.Daddy also works a lot with things called PLCs - that's short for "programmable logic controllers." He programs them with code, sort of like the code in a computer or video game. The PLC then controls machines by turning motors and lights on and off. It decides what the machines should do based on the program Daddy writes and input from sensors.One of the hardest parts of Daddy's job is setting everything up just right. All the robots, computers, PLCs, sensors, and other equipment have to be installed and connected properly. There are miles of wires and cables everywhere! Even a little mistake can cause huge problems. That's why Daddy has to test and troubleshoot everything over and over.Daddy has a bunch of other duties too. He has to read diagrams and blueprints to understand how systems are designed. He programs human-machine interfaces (HMIs) so people can monitor and control the automated processes. And he's always analyzing data and looking for ways to improve efficiency, quality, and safety.I don't know about you, but this electrical automation stuff sounds unbelievably complex to me! Daddy has to be a master atcomputers, programming, electronics, robotics, and all kinds of other technical topics. I'm amazed he can keep it all straight!What I think is really cool, though, is how Daddy's work helps manufacture so many products more easily. The automation systems he designs are used to make all sorts of things like cars, electronics, food, medicine, and toys. Pretty much everything you buy was probably made with the help of robots and other automated equipment. Wild, right?I'm really proud of my daddy and the important work he does. Watching him is what first got me interested in science and technology. Who knows, maybe I'll end up doing something similar when I grow up! For now, I'll just keep asking Daddy a million questions about his fascinating job. Electrical automation is the coolest!篇6My Exciting Visit to the Electrical Automation FactoryHi friends! Last weekend, my dad took me on a super cool trip to visit an electrical automation factory. At first, I wasn't sure what that even meant, but boy was I in for an amazing surprise!When we arrived, a really nice lady named Emily greeted us. She had a bright yellow hard hat and a safety vest. Emily said she would be our tour guide for the day. She told us the factory makes all sorts of machines and robots that help run other factories and power plants. I thought that was already pretty neat!First, Emily took us into a huge room filled with big metal pieces and tools. She said this was the assembly area where all the automation equipment gets built. There were sparks flying everywhere as workers welded pieces of steel together. The loud clanging noises kind of made my ears hurt, but I still thought it looked awesome to see all the tough people working with fire and metal.Next, we went to another area where the robots were actually being put together. This room had way less noise, but it looked like a science lab with computers everywhere! Emily explained that highly skilled engineers and programmers work in this area to build the "brains" for the robots. They have to write tons of codes and instructions to make the robots smart and able to do tasks. It was mind-boggling to see how complicated it all looked.After that, we visited the testing zone, which was easily my favorite part. This is where they ran the finished robots and automation systems through trials to make sure they worked right before shipping them out. We saw robots picking up boxes, moving things around, and even building other little robot parts! The robots moved so smoothly and precisely, it was like watching a dance. Emily let me control one of the small robot arms, which was a little tricky but really fun.Towards the end of the tour, Emily brought us to a showroom area that had examples of all the amazing automation equipment the factory builds. There were little robot arms used for delicate work like electronics assembly, big heavy-duty robot cranes that can lift tons of weight, and automated conveyor systems that can move tons of parts and products around a factory. It seemed like there were machines there that could automate just about any task!On the way home, I asked my dad how the factory workers were able to build such incredible robots and automation systems. He said it took many years of education, training, and experience in fields like electrical engineering, programming, robotics, and manufacturing. He told me that if I worked reallyhard in school, especially in math, science and technology classes, maybe I could have an awesome job like that someday too!I had no idea what electrical automation really meant before the factory tour. But after seeing it in person, I think it's one of the coolest things ever! All those robots and automated machines running factories and plants is straight out of a science fiction movie. I definitely want to learn more about how it all works. Who knows, maybe I'll grow up to build amazing robots myself someday! For now, I just want to say a huge thanks to Emily and everyone at the factory for showing me their awesome automation world.。
电气工程专业英文作文
电气工程专业英文作文英文，As an electrical engineering major, I havelearned a lot of knowledge and skills in this field. Electrical engineering is a branch of engineering thatdeals with the study of electricity, electronics, and electromagnetism. It is a broad field that covers a wide range of topics, including power generation, transmission, and distribution, as well as the design and development of electrical systems and devices.One of the most important skills I have learned as an electrical engineering major is problem-solving. Electrical engineering involves a lot of problem-solving, whether itis designing a new electrical system or troubleshooting an existing one. I have learned how to approach problems systematically, break them down into smaller, more manageable parts, and use my knowledge and skills to find solutions.Another important skill I have learned is communication.Electrical engineering is a team-oriented field, and effective communication is essential to the success of any project. I have learned how to communicate technical information clearly and concisely, both verbally and in writing, to colleagues, clients, and other stakeholders.In addition to these technical skills, I have also developed a range of soft skills, such as time management, teamwork, and leadership. These skills have helped me to work effectively in a variety of settings, from group projects in the classroom to internships and co-op experiences in the industry.Overall, my experience as an electrical engineering major has been challenging, but also rewarding. I have gained a deep understanding of the principles and practices of electrical engineering, as well as the skills and qualities needed to be successful in this field.中文，作为一名电气工程专业的学生，我在这个领域学习了很多知识和技能。
电气工程学术论文电气工程论文英文版
电气工程学术论文电气工程论文英文版摘要：研究电气工程施工首先必须了解其所涉及的知识领域，主要包括工程技术、法律法规和经济学等。
笔者将对电气工程施工进行系统的分析与研究，从安全监理的角度出发进行详细的论述。
Abtract：Toundertandtherelevantknowledgeinthefieldfirtlyinecearytoreearch onelectricalengineeringcontruction，involvingengineeringtechniquelawandeconomic.Theauthorwill，makeaytemicanalyiandreearchontheelectricalengineeringcontruction fromtheperpectiveofafetyuperviion.关键词：电气工程;施工;研究Keyword：electricalengineering;contruction;reearch1电气工程施工安全监理的必要性分析作为一项危险系数较高的工程，电气施工中的安全控制是十分关键的环节。
为了保障施工现场的安全，减少不必要的意外损失，必须对每一个环节进行科学的安全监理，通过规范的施工制度，突进工程的开展进度，使投资者能够收到最理想的经济效益。
1.1工程施工安全监理影响到施工的效率、安全性及成本投入安全控制是电气工程建设的根本，如果想提高施工的效率以及安全性，首先就要解决存在于工程中较为普遍的安全隐患。
从利益的角度出发，存在于电气工程中的利益是巨大的，基于此种原因，一些施工单位为了追求经济上的盈利经常不按照规章制度施工，为安全生产埋下了极大的隐患。
这时候工程监理就必须发挥其作用，按照施工单位的委托，严格执行相关的法律法规和施工现场的各种规章，维护工程建设的正常秩序。
安全监理对于电气工程施工的意义还在于其直接影响了整个工程的成本投入。
正规的安全监理能够严把工程的质量关，规避施工中的各种质量隐患，这在无形中降低了返工的几率，也就减少了投入成本的支出，不但可以保证工程的质量，而且可以提高施工过程的安全度。
(完整版)电气专业英文文献
An Expert System for Transformer Fault Diagnosis Using Dissolved Gas Analysis1. INTRODUCTIONThe power transformer is a major apparatus in a power system, and its correct functioning its vital to minimize system outages, many devices have evolved to monitor the serviceability of power transformers. These devices, such as, Buchholz relays or differential relays, respond only to a severe power failure requiring immediate removal of the transformer from service, in which case, outages are inevitable. Thus, preventive techniques for early detection faults to avoid outages would be valuable. In this way, analysis of the mixture of the faulty gases dissolved in insulation oil of power transformer has received worldwide recognition as an effective method for the detection of oncipient faults. Many researchers and electrical utilities have reported on their experience and developed interpretative criteria on the basis of DGA. However, criteria tend to vary from utility to utility. Therefore, transformer diagnosis is still in the heuristic stage. For this reason, knowledge-based programming is a suitable approach to implement in such a diagnostic problem.Based on the interpretation of DGA, a prototype of an expert system for diagnosis of suspected transformer faults and their maintenance procedures is proposed. The significant source in this knowledge base is the gas ratio method. Some limitations of this approach are overcome by incorporating the diagnostic procedure and the synthetic expertise method. Furthermore, data bases adopted from TPC'S gas records of transformers are incorporated into the expert system to increase the practical performance. Uncertainty of diagnosis is managed by using fuzzy set concepts. This expert system is constructed with rule based knowledge representation, since it can be expressed by experts. The expert system building tool,knowledge Engineering System(KES), is used in the development of the knowledge system because, it has excellent man-machine interface that provides suggestions. Moreover,its inference strategy is similar to the MYCIN. A famous rule-based expert system used for medical diagnosis. The uncertainty of human qualitative diagnostic expertise, e.g., key gasanalysis, and another quantitative imprecision, such as, norms threshold and gas ratio boundaries etc., are smoothed by appropriate fuzzy models. With the results of such implementation, different certainty factors will be assigned to the corresponding expertise variables. Both event-driven(forward chaining) and goal-driven (backward chaining) inferences are used in the inference engine to improve the inference efficiency. To demonstrate the feasibility of the proposed expert system, around hundreds of TPC historical gas records have been tested. It is found that more appropriate faulty types and maintenance suggestions can support the maintenance personals to increase the performance of transformer diagnosis.2. DEVELOPMENT OF DIAGNOSIS AND INTERPRETATIONLike many diagnostic problems, diagnosis of oil-immersed power transformer is a skilled task. A transformer may function well externally with monitors, while some incipient deterioration may occur internally to cause a fatal problem in the latter development. According to a Japanese experience, nearly 80% of all faults result from incipient deteriorations. Therefore, faults should be identified and avoided at the earliest possible stage by some predictive maintenance technique. DGA is one of the most popular techniques for this problem. Fault gases in transformers are generally produced by oil degradation and other insulating material, e.g., cellulose and paper. Theoretically, if an incipient or active fault is present, the individual dissolved gas concentration, gassing rate, total combustible gas(TCG) and cellulose degradation are all significantly increased. By using gas chromatography to analyse the gas dissolved in a transformer's insulating oil, it becomes feasible to judge the incipient fault types. This study is concerned with the following representative combustible gases; hydrogen(H2), methane(C2H2), ethane(C2H6), ethylene(C2H2) and carbon monoxide(C0).Many interpretative methods based on DGA to the nature of incipient deterioration have been reported. Even under normal transformer operational conditions, some of these gases may be formed inside. Thus, it is necessary to build concentration norms from a sufficiently large sampling to assess the statistics. TPC investigated gas data from power transformers to construct its criteria. The developedknowledge base in this paper is partially based on these data. On the hand, Dornerburg developed a method to judge different faults by rating pairs of concentrations of gases, e.g., CH/H, GH/C3H4, with approximately equal solubility and fusion coefficients. Rogers established mare comprehensive ratio codes to interpret the thermal fault types with theoretical thermodynamic assessments. This gas ratio method was promising because it eliminated the effect of oil volume and simplified the choice of units. Moreover, it systematically classified the diagnosis expertise in a table form. Table 1 displays the ratio method as proposed by Rogers. The dissolved gas may vary with the nature and severity of different faults. By analyzing the energy density of faults, it's possible to distinguish three basic fault processes:overheating(pyrolysis), corona(partial dischatge) and arcing discharge. Corona and arcing arise from electrical faults, while overheating is a thermal fault. Both types of faults my lead to deterioration, while damage from overheating is typically less than that from electrical stress. Infect, different gas trends lead to different faulty types, the key gas method is identified. For example, large amounts of CH and H are produced with minor arcing fault 4 quantities of CH 2aid C2H2 may bea symptom of an arcing fault.3.THE PROPOSED DIAGNOSTIC EXPERT SYSTEMThis study is aimed at developing a rule-based expert system to perform transformer diagnosis similar to a human expert. The details of system processing are described below.3.1 The Proposed Diagnostic MethodDiagnosis is a task that requires experience. It is unwise to determine an approach from only a few investigations. Therefore, this study uses the synthetic expertise method with the experienced procedure to assist the popular gas ratio method and complete practical performance.3.1.1 Experienced Diagnostic ProcedureThe overall procedure of routine maintenance for transformers is listed. The core of this procedure is based on the implementation of the DGA technique. The gas ratio method is the significant knowledge source. Some operational limitations of the gasratio method exist. The ratio table is unable to cover all possible cases. Minimum levels of gases must be present. The solid insulation involving CO and CO are handled separately and the gas ratio codes have been developed mainly from a free-breathing transformer. Other diagnostic expertise should be used to assist this method. Norms, synthetic expertise method and data base records have been incorporated to complete these limitations. The first step of this diagnostic procedure begins by asking DGA for an oil sample to be tested. More important relevant information about the transformer's condition, such as the voltage level, the preservative type, the on-line-tap-changer(OLTC) state, the operating period and degassed time must be known for further inference. Norms(criteria) Set up by TPC power transformers' gas characteristic data are then used to judge the transformers' condition. For the abnormal cases, the gas ratio method is used to diagnose transformer fault type. If different or unknown diagnosis results are found from these ratio methods, a further synthetic expertise method is adopted. After these procedures, different severity degrees are assigned to allow appropriate corresponding maintenance suggestions.3.1.2 Synthetic Expertise MethodThe ratio trend, norms threshold, key gas analysis and some expertise are considered as different evidences to confirm some special fault types. In other words, more significant evidences have been collected for some special fault type, better assessment of the transformer status is obtained.The ratio trend can be seen as a modification of the conventional gas ratio and key gas method.Obviously, the above gas trends should be incorporated with other evidences under the experienced procedure for practical use. Norms threshold, the gassing rate, the quantity of total combustible gas(TCG), the TPC maintenance expertise and the fuzzy set assignment are all important evidences considered in the synthetic diagnosis.Other expertise based on a transformer historical data base is also used to analyse the characteristics of a case transformer. Section 3.4 gives some details of these rules.3.2 Expert System StructureThe proposed diagnostic expert system is composed of components, working memory, a knowledge base, an inference engine and a man-machine interface. Working memory (global data base) contains the current data relevant to solve the present problem. In this study, most of the diagnostic variables stored in the data base are current gas concentration, some are from the user, others are retrieved from the transformer's historical data base. Note that the fuzzy set concept is incorporated to create fuzzy variables on the request of system reasoning. A knowledge relationship, which uses these facts, as the basis for decision making. The production rule used in this system is expressed in IF-THEN forms. A successful expert system depends on a high quality knowledge base. For this transformer diagnostic system, the knowledge base incorporates some popular interpretative methods of DGA, synthetic expertise method and heuristic maintenance rules. Section 3.4 will describe this knowledge base. Another special consideration in the expert system is its inference engine. The inference engine controls the strategies of reasoning and searching for appropriate knowledge. The reasoning strategy employs both forward chaining(data-driven) and backward chaining(goal-driven). Fuzzy rules, norms rules, gas ratio rules, synthetic expertise rules and some of the maintenance rules and some maintenance rules, use forward chaining.As for the searching strategy in KES, the depth first searching and short-circuit evaluation are adopted. The former can improve the search efficiency by properly arranging the location of significant rules in the inference procedures. The latter strategy only searches the key conditional statements in the antecedent that are responsible for establishing whether the entire rule is true or false. Taking the advantages of these two approaches in the building and structuring of a knowledge base improves inference efficiency significantly.As for man-machine interface. KES has an effective interface which is better than typical knowledge programming languages, such as, PROLOG or LISP. With the help of this interface, the capability of tracing, explaining and training in an expert system is greatly simplified.4.IMPLEMENTATION OF THE PROPOSED EXPERT SYSTEMAn expert system is developed based on the proposed interpretative rules and diagnostic procedures of the overall system. To demonstrate the feasibility of this expert system in diagnosis, the gas data supported by MTL of TPC have been tested. In Taiwan, the MTL of TPC performs the DGA and sends the results to all acting divisions relating to power transformers. In return, these acting divisions are requested to collect and supply their transformer oil samples periodically.After analysing oil samples, more than ten years' worthy gas records are collected and classified into three voltage level, 69KV, 16KV and 345KV. Thus, gas records for one transformer are composed of several groups of data. In the process of DGA interpretation, all of these data may be considered, but only the recent data which have significant effects on diagnosis are listed in the later demonstration. In MTL, all gas concentrations are expressed by pm in volume concentration. 100 pm is equal to 0.01 ml(gas)/100ml(oil).From the expertise of diagnosis, the normal state can be confirmed only by inspection of the transformer's norms level. In practice, most of the transformer oil samples are normal, and this can be inferred successfully on the early execution of this expert system. However, the Success of an expert system is mainly dependent on the capability of diagnosis for the transformers in question. In the implementation, many gas records which are in abnormal condition are chosen to test the Justification of this diagnostic system. A total of 101 transformer records have been executed and the results are summarized in Table 5. Among those implemented, three are listed and demonstrated.Shown in Table 5 are the results of 101 units of transformers in three types of remedy: normal, thermal fault and arc fault. After comparing them with the actual state and expert judgement, a summary of results was obtained. As previously stated, one unit of transformer may include many groups of gas data. In evaluation, we depicted some key groups in one unit to justify because some transformers may have different incipient faults during different operational stages. Some mistakes implemented from testing are caused by the remaining oil in the oil sampling container, unstable gas characteristics of the new degassing sample and some obscuregas types. If more information or new techniques support other uncertain membership functions, they can be added into the knowledge has to enlarge the the performance of this prototype expert system. Furthermore, the parameters described in table 2,3 and 4 are suitable for TPC power transformer. Different regions may be modified the maintenance personnel find more suitable system parameters.5.CONCLUSIONSA prototype expert system is developed on a personal computer using KES. It can diagnose the incipient faults of the suspected transformers and suggest proper maintenance actions. Fuzzy set concept is used to handle uncertain norms thresholds, gas ratio boundaries and key gas analysis. The synthetic method and diagnostic procedure are proposed to assist the situation which can not be handled properly by the gas ratio methods. Results from the implementation of the expert system shows that the expert system is a useful tool to assist human expert and maintenance engineers.The knowledge base of this expert system is incorporated within the popular interpretative method of DGA, synthetic expertise and heuristic maintenance rules. The data base supported by TPC MTL for about 10 year collection of transformer inspection data is also used to improve the interpretation of diagnosis. Through the development of the proposed expert system, the expertise of TPC MTL can be reserved. In addition, this work can be continued to expand the knowledge base by adding any new experience, measurement and analysis techniques.。
电气专业话题英语作文
电气专业话题英语作文Electrical engineering is a fascinating field that deals with the study and application of electricity, electronics, and electromagnetism. It encompasses a wide range of topics, from power generation and distribution to the design of electronic devices. In this essay, I will discuss some interesting aspects of electrical engineering.One of the most exciting areas of electrical engineering is renewable energy. With the increasing concern about climate change and the depletion of fossil fuels, there is a growing demand for clean and sustainable sources of energy. Electrical engineers play a crucial role in developing and implementing renewable energy technologies such as solar panels, wind turbines, and hydroelectric power plants. These technologies not only help reduce greenhouse gas emissions but also provide a reliable and efficient source of electricity.Another fascinating aspect of electrical engineering isthe design and development of electronic devices. From smartphones and laptops to medical devices and automotive systems, electrical engineers are responsible for creating innovative and efficient electronic products. They work on improving the performance, reliability, and power efficiency of these devices, as well as ensuring their safety and compliance with industry standards. The rapid advancements in technology have made it possible for electrical engineers to create smaller, faster, and more powerful electronic devices that have revolutionized various industries.Power systems engineering is another important field within electrical engineering. Power systems engineers are involved in the design, operation, and maintenance of electrical power grids. They ensure that electricity is generated, transmitted, and distributed efficiently and reliably to meet the demands of consumers. Power systems engineers also work on improving the stability and resilience of power grids, especially in the face of increasing renewable energy integration and the growing complexity of the electrical network.In addition to these technical aspects, electrical engineering also requires strong problem-solving and analytical skills. Electrical engineers are trained to analyze complex systems, troubleshoot issues, and come up with innovative solutions. They use mathematical models, computer simulations, and experimental techniques to understand and predict the behavior of electrical systems. These skills are not only valuable in the field ofelectrical engineering but also transferable to other industries, making electrical engineers highly sought after in the job market.In conclusion, electrical engineering is a diverse and dynamic field that encompasses various areas such as renewable energy, electronic device design, power systems engineering, and problem-solving skills. It offers exciting opportunities for innovation and plays a crucial role in shaping the future of technology and sustainability. Whether it's designing the next generation of electronic devices or developing sustainable energy solutions,electrical engineers are at the forefront of technological advancements.。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
沧州师范学院专业外语阅读文献综述学院机械与电气工程学院姓名赵汝志学号**********专业电气工程及其自动化班级2014级1班2017 年 1 月电动机的简单介绍摘要：电动机是指依据电磁感应定律实现电能转换或传递的一种电磁装置。
它将电能转变为机械能，它主要包括一个用以产生磁场的电磁铁绕组或分布的定子绕组和一个旋转电枢或转子。
在定子绕组旋转磁场的作用下，其在电枢鼠笼式铝框中有电流通过并受磁场的作用而使其转动。
这些机器中有些类型可作电动机用，也可作发电机用。
它是将电能转变为机械能的一种机器。
通常电动机的作功部分作旋转运动，这种电动机称为转子电动机；也有作直线运动的，称为直线电动机。
关键词：电动机；电磁装置一、基本介绍1、发明过程：电动机使用了通电导体在磁场中受力的作用的原理，发现这一原理的是丹麦物理学家—奥斯特，由于受康德哲学与谢林的自然哲学的影响，坚信自然力是可以相互转化的，长期探索电与磁之间的联系。
1820年4月终于发现了电流对磁针的作用，即电流的磁效应。
同年7月21日以《关于磁针上电冲突作用的实验》为题发表了他的发现。
这篇短短的论文使欧洲物理学界产生了极大震动，导致了大批实验成果的出现，由此开辟了物理学的新领域──电磁学。
2、国内现状：我国的电动机生产开始于1917年，该行业在国内已经形成比较完整的产业体系。
我国电动机制造行业随着电力发展呈现出勃勃生机，产销规模和经济效益都有了大幅度提高。
我国电机产品虽然种类繁多，但效率普遍不高。
二、基本分类电动机按工作电源种类划分：可分为直流电机和交流电机。
直流电动机按结构及工作原理可划分：无刷直流电动机和有刷直流电动机。
有刷直流电动机可划分：永磁直流电动机和电磁直流电动机。
电磁直流电动机划分：串励直流电动机、并励直流电动机、他励直流电动机和复励直流电动机。
永磁直流电动机划分：稀土永磁直流电动机、铁氧体永磁直流电动机和铝镍钴永磁直流电动机。
其中交流电机还可分：同步电机和异步电机。
同步电机可划分：永磁同步电动机、磁阻同步电动机和磁滞同步电动机。
异步电机可划分：感应电动机和交流换向器电动机。
感应电动机可划分：三相异步电动机、单相异步电动机和罩极异步电动机等。
交流换向器电动机可划分：单相串励电动机、交直流两用电动机和推斥电动机。
三、工作原理电动机种类有很多种，下面简单介绍三相异步电动机的工作原理：当电动机的三相定子绕组通入三相对称交流电后，将产生一个旋转磁场，该旋转磁场切割转子绕组，从而在转子绕组中产生感应电流，载流的转子导体在定子旋转磁场作用下将产生电磁力，从而在电机转轴上形成电磁转矩，驱动电动机旋转，并且电机旋转方向与旋转磁场方向相同。
当三相异步电机接入三相交流电源时，三相定子绕组流过三相对称电流产生的三相磁动势并产生旋转磁场，该磁场以同步转速n0沿定子和转子内圆空间作顺时针方向旋转。
四、基本结构三相异步电动机的两个基本组成部分为定子和转子。
此外还有端盖、风扇等附属部分。
1、定子铁心：定子铁心是异步电动机主磁通磁路的一部分。
为了使异步电动机能产生较大的电磁转矩，希望有一个较强的旋转磁场，同时由于旋转磁场对定子铁心以同步转速旋转，定子铁心中的磁通的大小与方向都是变化的，必须设法减少由旋转磁场在定子铁心中所引起的涡流损耗和磁滞损耗，因此，定子铁心由导磁性能较好的0.5mm厚且冲有一定槽形的硅钢片叠压而成。
2、定子绕组：定子绕组是异步电机定子部分的电路，它也是由许多线圈按一定规律联接面成。
能分散嵌入半闭口槽的线圈由高强度漆包圆铜线或圆铝线绕成，放入半开口槽的成型线圈用高强度漆包扁沿线或扁铜线，或用玻璃丝包扁铜线绕成。
开口槽也放入成型线圈，其绝缘通常采用云母带，线圈放入槽内必须与槽壁之间隔有“槽绝缘”，以免电机在运行时绕组对铁心出现击穿或短路故障。
3、转子铁心：转子铁心也是电动机主磁通磁路的一部分，一般也由0.5毫米厚冲槽的硅钢片叠成，铁心固定在转轴或转子支架上。
整个转子铁心的外表面成圆柱形。
4、转子绕组：转子绕组分为笼型和绕线型两种结构，下面介绍绕线型绕组。
它是一个对称三相绕组，这个对称三相绕组接成星形，并接到转轴上三个集电环，再通过电刷使转子绕组与外电路接通。
五、结论电动机的运用在国内越来越多，种类繁多但是效率不高。
在了解了电动机的基本原理后，随着对电动机认识的加深，未来会有更多高效率的电机产生。
本文简单的提供了电动机的基础知识，是为了方便读者更好的了解电动机。
参考文献[1]孙建忠，刘凤春。
电机与拖动[M]。
机械工业出版社。
[2]邱关源。
电路[M]。
高等教育出版社。
A brief introduction to the motorAbstract:Electromagnetism is a kind of electromagnetism which can realize the conversion or transmission of electric energy according to the law of electromagnetic induction. It converts electrical energy into mechanical energy and consists essentially of an electromagnet winding or distributed stator windings for generating a magnetic field and a rotating armature or rotor. In the stator windings under the action of rotating magnetic field, the armature squirrel-cage aluminum in the current through the magnetic field and the role of its rotation. Some of these machines can be used for electric motors as well as generators. It is a machine that converts electrical energy into mechanical energy. Usually the work part of the motor for rotary motion, this motor is called the rotor motor; also for linear motion, known as the linear motor.Keywords: motor; electromagnetic deviceFirst, the basic introduction1, the invention process:The principle of the motor using the force of the conducting conductor in the magnetic field was discovered by the Danish physicist Oersted, because of the influence of Kant's philosophy and Schelling's natural philosophy, that the forces of nature can be transformed into each other , Long-term exploration of the relationship between electricity and magnetic. In 1820 April finally found the role of current on the magnetic needle, that is, the magnetic effect of the current. In July 21st the same year on the "needle on the power of the role of the experiment" as the title of his discovery. This short paper to the European physics community had a great shock, resulting in a large number of experimental results, which opened up a new field of physics ──electromagnetics.2, the domestic situation:China's motor production began in 1917, the industry in China has formed a relatively complete industrial system. China's electric motor manufacturing industry with the development of electric power has shown vitality, production and marketing scale and economic benefits have been greatly improved. Although a wide range of motor products in China, but the efficiency is generally not high.Second, the basic classificationThe motor according to the type of power supply division: can be divided into DC motor and AC motor. DC motor by structure and working principle can be divided into: brushless DC motor and brush DC motor. Brush DC motor can be divided into: permanent magnet DC motor and electromagnetic DC motor. Electromagnetic DC motor division: series excitation DC motor, shunt DC motor, he excited DC motor and DC motor excitation. Permanent magnet DC motor division:rare earth permanent magnet DC motor, ferrite permanent magnet DC motor and aluminum nickel cobalt permanent magnet DC motor. Which AC motor can be divided into: synchronous motor and asynchronous motor. Synchronous motor can be divided: permanent magnet synchronous motor, reluctance synchronous motor and hysteresis synchronous motor. Induction motor can be divided into: induction motor and AC commutator motor. Induction motor can be divided into: three-phase asynchronous motor, single-phase asynchronous motor and shaded pole asynchronous motor. AC commutator motor can be divided into: single-phase series motor, AC-DC dual-motor and repulsion motor.Third, the working principleThere are many types of motor, the following simple three-phase induction motor works: When the three-phase stator winding of the motor into the three-phase AC, will produce a rotating magnetic field, the rotating magnetic field rotor winding, which in the rotor winding The rotor current of the rotor will produce electromagnetic force under the action of the rotating magnetic field of the stator, so that the electromagnetic torque will be formed on the motor shaft, the motor will rotate and the direction of rotation will be the same as the rotating magnetic field. When the three-phase asynchronous motor access to three-phase AC power, three-phase stator windings flow through the three-phase symmetrical current generated by three-phase MMF and produce a rotating magnetic field, the synchronous speed of the magnetic field along the stator and rotor inner space for n0 Clockwise rotation.Fourth, the basic structureThe two basic components of a three-phase asynchronous motor are the stator and the rotor. In addition, end caps, fans and other ancillary parts.1, the stator core:The stator core is a part of the main magnetic flux path of the induction motor. In order to make the induction motor can produce a larger electromagnetic torque, it is desirable to have a strong rotating magnetic field, and the magnetic flux in the stator core is changed in size and direction due to the rotating magnetic field rotating at a synchronous speed to the stator core. So that the stator core is made of a 0.5 mm-thick silicon steel sheet having a good magnetic permeability and laminated with a certain groove-shaped silicon steel sheet, so as to reduce the eddy current loss and hysteresis loss caused by the rotating magnetic field in the stator core.2, the stator windings:Stator winding is the stator part of the asynchronous motor circuit, it is also by a number of coils connected by a certain law into the surface. Can be dispersed semi-closed slot embedded in the coil by the high-strength enamelled round copper wire or round aluminum wire into thehalf-slot slot into the forming coil with high-strength enamel along the flat or flat copper wire, or glass wire wrapped copper wire to make. Open slot is also placed in the forming coil, the insulation is usually used mica tape, the coil into the slot wall must be separated with the slot insulation to prevent the motor running in the winding of the core breakdown or short circuit failure.3, the rotor core:The rotor core is also part of the main magnetic flux path of the motor, and is usually also made of silicon steel sheet of 0.5 mm thick punching groove, and the iron core is fixed on the shaft or the rotor bracket. The outer surface of the entire rotor core is cylindrical.4, the rotor winding:Rotor winding is divided into two types of cage and winding structure, the following describes the winding winding. It is a symmetrical three-phase winding, the symmetrical three-phase windings connected to the star-shaped, and connected to the shaft on the three collector ring, and then through the brush to the rotor winding connected with the external circuit. V. ConclusionThe use of motors in the country more and more, but the efficiency is not high. In the understanding of the basic principles of the motor, with the deepening of the understanding of the motor, the future will have more efficient motor production. This article simply provides the basic knowledge of the motor is to facilitate the reader a better understanding of the motor.references[1] Sun Jianzhong, Liu Fengchun. Motor and drag [M]. Machinery Industry Press.[2] Qiu Guan source. Circuit [M]. Higher Education Press.。