What Is Power Electronics Engineering Essay

What Is force play Electronics Engineering EssayPower electronics involves the study of electronic travels intended to lead the commingle of galvanic ability. These rophys handle advocate flow at levels such(prenominal) postgraduateer than the individual gimmick ratings.It has been said that peck do not use electric carity, but rather they use communication, light, robotic work, entertainment, and all the tangible benefits of both zipper and electronics. In this sense, galvanizing engineering is a discip line of work very much involved in brawn modulation and information. In the general world of electronics engineering, the circuits engineers design and use atomic number 18 intended to convert information, with energy merely a secondary servant in most cases. This is true of both analog and digital circuit design. In radio frequency applications, energy and information be fewtimes on a more equal footing, but the main social occasion of every circuit is that of information transfer.What about the conversion and control of galvanising energy itself? Electrical energy authors are varied and of umpteen types. It is natural, whence, to watch how electronic circuits and systems can be applied to the challenges of energy conversion and monitorment. This is the exemplar of authority electronics, a discipline that is defined in terms of electrical energy conversion, applications, and electronic devices. More specifically, Rectifiers are probably the most tumesce-known(prenominal) example of circuits that meet this definition. Inverters (a general term for dc-ac converters) and dc-dc converters for index number supplies are excessively common applications. As shown in Fig. 1.1, actor electronics represents a median insinuate at which the topics of energy systems, electronics, and control converge and combine 1.Any useful circuit design for the control of mogul must address issues of both devices and control, as well as of the energ y itself. Among the uncommon aspects of role electronics are its tension on large semiconductor devices, the application of magnetic devices for energy storage, and finical control methods that must be applied to nonlinear systems. In any study of electrical engineering, motive electronics must be placed on a level with digital, analog, and radio-frequency electronics if we are to reflect its distinctive design methods and unique challenges.FIGURE 1.1 Control, energy, and advocator electronics are interrelated.All power electronic circuits manage the flow of electrical energy between some sort of kickoff and a load. The parts in a circuit must occupy electrical flows, not impede them. A general power conversion system is shown in Fig. 1.2. The function of the power converter positi integrityd at the core is that of controlling energy flow between a given electrical source and a given load. For our purposes, the power converter depart be implemented with a power electronic circuit. As a power converter appears between a source and a load, any energy used within the converter is lost to the overall system. A all important(p) point emergesto build a power converter, we should consider single lossless components. A realistic converter design must approach degree Celsius% efficiency. A power converter connected between a source and a load also affects system reliability.FIGURE 1.2 General systems for electric power conversionA circuit build from ideal switches depart be lossless. As a result, switches are the main components of power converters, and many people equate power electronics with the study of switching power converters. magnetic transformers and lossless storage elements such as capacitors and inductors are also effectual candidates for use in power converters. The complete concept, shown in Fig. 1.3, illustrates a power electronic system. Such a system consists of an energy source, an electrical load, a power electronic circuit, and con trol functions. The power electronic circuit contains switches, lossless energy storage elements, and magnetic transformers. The controls take information from the source, load, and designer and then determine how the switches operate to achieve the desired conversion. The controls are usually built up with conventional low-power analog and digital electronics.FIGURE 1.3 a base power electronic systemTrends in Power Supplies As represent of electronics decline, the power supply becomes a larger fraction of system speak to and design effort. One major manufacturer estimates that power supply cost will soon reach 50% of the total cost of a usual electronic product such as a cordless telephone or personal computer. Thus, new technology festerings in power supplies are critically important.In the past, bulky linear power supplies were intentional with transformers and rectifiers from the ac line frequency to provide low-level dc voltages for electronic circuits.Late in the 1960s, use of dc sources in aero aloofness applications led to the development of power electronic dc-dc conversion circuits for power supplies. In a typical power electronics ar be givenment today, an ac source from a wall venthole is rectified without any transformation the resulting luxuriously dc voltage is born-again finished a dc-dc circuit to the 5V, 12 V, or different level required. These switched- path power supplies are rapidly supplanting linear supplies across the all-embracing spectrum of circuit applications. A personal computer commonly requires three divers(prenominal) 5V supplies, two .12 V supplies, a 12 V supply, a 24 V supply, and perhaps a few more.This does not include supplies for 1 Introduction 3 video display or peripheral devices. unless a switched-mode supply can support such complex requirements without high costs. The bulk and weight of linear supplies make them infeasible for hand-held communication devices, calculators, notebook computers, and simila r equipment. Switched-mode supplies often take advantage of MOSfield-effect transistor semiconductor technology. Trends toward high reliability, low cost, and miniaturization have reached the point at which a 5 V power supply sold today might exit 1,000,000 hr (more than 100 yr), provide 100Wof output in a software product with volume This type of supply brings an interesting dilemma the ac line cord to plug it in actually takes up more space than the power supply itself. Innovative concepts such as integrating a power supply within a connection cable will be used in the future.Device technology for power supplies is organism driven by expanding needs in the automotive and telecommunications industries as well as in markets for portable equipment. The automotive industry is making a transition to 42 V systems to handle increasing electric power needs. Power conversion for this industry must be cost effective, nevertheless rugged enough to survive the high vibration and wide tempe rature range to which a passenger car is exposed. Global communication is possible only when sophisticated equipment can be used almost anywhere.This brings a specific challenge, because electrical supplies are neither reliable nor consistent throughout much of the world. While in North America voltage swings in the interior(prenominal) ac supply are often Given the enormous sizing of worldwide markets for telephones and consumer electronics, there is a clear need for flexible-source equipment. Designers are challenged to get maximum perpetrateance from small batteries, and to create equipment with minimal energy requirements. eddy TYPE CHARACTERISTICS OF POWER DEVICESDiode Current ratings from 5000 A. Voltage ratings from 10V to 10 kV or more. The fastest power devices switch in BJT (Bipolar Junction Transistor) Conducts accumulator register certain (in one direction) when sufficient base current is applied. Power device current ratings from 0.5 to 500 A or more voltages fro m 30 to 1200V. break times from 0.5 to 100 ms. The function applies to dc-dc circuits combinations with diodes are used in inverters. Power BJTs are being supplanted by FETs and IGBTs.FET (Field Effect Transistor) Conducts drain current when sufficient render voltage is applied. Power FETs (nearly always enhancement mode MOSFETs) have a parallel connected get up diode by virtue of their construction. Ratings from _1 to _100 A and 30 up to 1000V. change by reversal times are fast, from 50 or less up to 200 ns. The function applies to dc-dc conversion, where the FET is in wide use, and to inverters.IGBT (Insulated Gate Bipolar Transistor) A special type of power FET that has the function of a BJT with its base driven by a FET. Faster than a BJT of similar ratings, and easy to use. Ratings from 10 to 600 A, with voltages of 600 to 1700V. The IGBT is general in inverters from _1 to 100kW or more. It is found almost unaccompanied in power electronics applications.SCR (Silicon Contr olled Rectifier) A thyristor that conducts like a diode after a gate measure is applied. Turns off only when current becomes zero. Prevents current flow until a pulse appears. Ratings from 10 up to more than 5000 A, and from 200V up to 6 kV. Switching requires 1 to 200 ms. widely used for controlled rectifiers. The SCR is found almost exclusively in power electronics applications, and is the most common member of the thyristor family.GTO (Gate Turn-Off Thyristor) an SCR that can be turned off by sending a negative pulse to its gate terminal. Can substitute for BJTs in applications where power ratings must be very high. The ratings approach those of SCRs, and the speeds are similar as well. Used in inverters rated 100 kW.TRIAC A semiconductor constructed to resemble two SCRs connected in reverse parallel. Ratings from 2 to 50 A and 200 to 800V. Used in lamp dimmers, shoes appliances, and hand tools. Not as rugged as many opposite device types, but very convenient for many ac appli cations.MCT (MOSFET Controlled Thyristor) A special type of SCR that has the function of a GTO with its gate driven from a FET. Much faster than conventional GTOs, and easier to use. These devices are supplanting GTOs in some application areas.POWER CONVERTERSThe power processors usually consist of more than one power conversion stage where the operation of these stages is decoupled on an fast behind by means of energy storage elements such as capacitors and inductors. Therefore, the instantaneous power input does not have to equal the instantaneous power output.We will call to each power conversion stage as a converter. Thus, a converter is a basic module (building block) of power electronic systems. It utilizes power semiconductor devices controlled by signal electronics (integrated circuits) and possibly energy storage elements such as inductors and capacitors. Based on the form (frequency) on the two sides, converters can be divided into the following broad categories1. AC to DC2. DC to AC3. DC to DC4. AC to ACWe will use converter as a generic tenn to refer to a single power conversion stage that may perform any of the functions listed above. To be more specific, in ac-to-dc and dc-to-ac conversion, rectifier refers to a converter when the comely power flow is from the ac to the dc side. Inverter refers to the converter when the average power flow is from the dc to the ac side. In fact, the power flow through the converter may be reversible.Power Electronic Applications(a) Residential infrigidation and freezersSpace heatingAir conditioningCooking liberationElectronics (personal computers,other entertainment equipment)(b) CommercialHeating. ventilating, and airconditioningCentral refrigeration inflamingComputers and office equipmentUninterruptible power supplies(UPSs)Elevators(c) IndustrialPumpsCompressorsBlowers and fansMachine tools (robots)Arc furnaces, induction furnacesLightingIndustrial lasersInduction heatingWelding(d) TransportationTraction con trol of electric vehiclesBattery chargers for electric vehiclesElectric locomotivesStreet cars, trolley busesSubways self-propelled electronics including enginecontrols(e) Utility systemsHigh-voltage dc transmission (HVOC)Static var compensation (SVC)Supplemental energy sources (wind,photovoltaic), fuel cellsEnergy storage systemsInduced-draft fans and kettle holefeed water pumps(f) AerospaceSpace shuttle power supply systemsplanet power systemsAircraft power systems(g) TelecommunicationsBattery chargersPower supplies (dc and UPS)