Power Electronics and Power Systems For furthervolumes: http://www.springer.com/series/6403 Slobodan N. Vukosavic Electrical Machines SlobodanN.Vukosavic Dept.ofElectricalEngineering UniversityofBelgrade Belgrade,Serbia ISBN978-1-4614-0399-9 ISBN978-1-4614-0400-2(eBook) DOI10.1007/978-1-4614-0400-2 SpringerNewYorkHeidelbergDordrechtLondon LibraryofCongressControlNumber:2012944981 #SpringerScience+BusinessMediaNewYork2013 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionor informationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped.Exemptedfromthislegalreservationarebriefexcerpts inconnectionwithreviewsorscholarlyanalysisormaterialsuppliedspecificallyforthepurposeofbeing enteredandexecutedonacomputersystem,forexclusiveusebythepurchaserofthework.Duplication ofthispublicationorpartsthereofispermittedonlyundertheprovisionsoftheCopyrightLawofthe Publisher’s location, in its current version, and permission for use must always be obtained from Springer.PermissionsforusemaybeobtainedthroughRightsLinkattheCopyrightClearanceCenter. 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Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Preface This textbook is intended for undergraduate students of Electrical Engineering as theirfirstcourseinelectricalmachines.Itisalsorecommendedforstudentsprepar- ingacapstoneproject,wheretheyneedtounderstand,model,supply,controland specifyelectricmachines.Atthesametime,itcanbeusedasavaluablereferencefor other engineering disciplines involved with electrical motors and generators. It is alsosuggestedtopostgraduatesandengineersaspiringtoelectromechanicalenergy conversionandhavingtodealwithelectricaldrivesandelectricalpowergeneration. Unlikethemajorityoftextbooksonelectricalmachines,thisbookdoesnotrequire an advanced background. An effort was made to provide text approachable to studentsandengineers,inengineeringdisciplinesotherthanelectrical. The scope of this textbook provides basic knowledge and skills in Electrical Machines that should be acquired by prospective engineers. Basic engineering considerations are used to introduce principles of electromechanical energy con- version in an intuitive manner, easy to recall and repeat. The book prepares the reader to comprehend key electrical and mechanical properties of electrical machines, to analyze their steady state and transient characteristics, to obtain basic notions on conversion losses, efficiency and cooling of electrical machines, to evaluate a safe operating area in a steady state and during transient states, to understand power supply requirements and associated static power converters, to comprehendsomebasicdifferencesbetweenDCmachines,inductionmachinesand synchronous machines, and to foresee some typical applications of electrical motorsandgenerators. Developing knowledge on electrical machines and acquiring requisite skills is bestsuitedforsecondyearengineeringstudents.Thebookisself-containedandit includes questions, answers, and solutions to problems wherever the learning process requires an overview. Each Chapter is comprised of an appropriate set of exercises, problems and design tasks, arranged for recall and use of relevant knowledge. Wherever it is needed, the book includes extended reminders and explanations of the required skill and prerequisites. The approach and method used in this textbook comes from the sixteen years of author’s experience in teachingElectricalMachinesattheUniversityofBelgrade. v vi Preface Readership This book is best suited for second or third year Electrical Engineering undergraduates as their first course in electrical machines. It is also suggested to postgraduatesofallEngineeringdisciplinesthatplantomajorinelectricaldrives, renewables,andotherareasthatinvolveelectromechanicalconversions.Thebook is recommended to students that prepare capstone project that involves electrical machinesandelectromechanicalactuators.Thebookmayalsoserveasavaluable reference for engineers in other engineering disciplines that are involved with electricalmotorsandgenerators. Prerequisites Requiredbackgroundincludesmathematics,physics,andengineeringfundamentals taughtinintroductorysemestersofmostcontemporaryengineeringcurricula.The processofdevelopingskillsandknowledgeonelectricalmachinesisbestsuitedfor second year engineering students. Prerequisites do not include spatial derivatives andfieldtheory.Thistextbookismadeaccessibletoreaderswithoutanadvanced background in electromagnetics, circuit theory, mathematics and engineering materials.Necessarybackgroundincludeselementaryelectrostaticsandmagnetics, DCandACcurrentcircuitsandelementaryskillwithcomplexnumbersandphasors. Aneffortismadetobringthetextclosertostudentsandengineersinengineering disciplinesotherthanelectrical.Whereveritisneeded,thebookincludesextended reinstatements and explanations of the required skill and prerequisites. Required fundamentals are recalled and included in the book to the extent necessary for understandingtheanalysisanddevelopments. Objectives • Using basic engineering considerations to introduce principles of electrome- chanical energy conversion and basic types and applications of electrical machines. • Providing basic knowledge and skills in electrical machines that should be acquiredbyprospectiveengineers.Comprehendingkeyelectricalandmechani- calpropertiesofelectricalmachines. • Providingandeasytousereferenceforengineersingeneral. • Acquiringskillsinanalyzingsteadystateandtransientcharacteristicsofelectri- calmachines,aswellasacquiringbasicnotionsonconversionlosses,efficiency andheatremovalinelectricalmachines. Preface vii • Mastering mechanical characteristics and steady state equivalent circuits for principaltypesofelectricalmachines. • Comprehending basic differences between DC machines, induction machines andsynchronousmachines,studyingandcomparingtheirsteadystateoperating areaandtransientoperatingarea. • Studying and apprehending characteristics of mains supplied and variable fre- quencysuppliedACmachines,comparingtheircharacteristicsandconsidering theirtypicalapplications. • Understanding power supply requirements and studying basic topologies and characteristicsofassociatedstaticpowerconverters. • StudyingfieldweakeningoperationandanalyzingcharacteristicsofDCandAC machinesinconstantfluxregionandintheconstantpowerregion. • Acquiring skills in calculating conversion losses, temperature increase and coolingmethods.Basicinformationonthermalmodelsandintermittentloading. • Introducing and explaining the rated and nominal currents, voltages, flux linkages,torque,powerandspeed. Teaching approach • Theemphasisisonthesystemoverview-explainingexternalcharacteristicsof electrical machines - their electrical and mechanical access. Design and con- structionaspectsareofsecondaryimportanceoroutofthescopeofthisbook. • Where needed, introductory parts of teaching units comprise repetition of the requiredbackgroundwhichisappliedthroughsolvedproblems. • Mathematicsisreducedtoanecessaryminimum.Spatialderivativesanddiffer- entialformofMaxwellequationsarenotrequired. • Thegoalofdevelopingandusingmathematicalmodelsofelectricalmachines, their equivalent circuits and mechanical characteristics persists through the book.Atthesametime,thefocusiskeptonphysicalinsightofelectromechani- calconversionprocess.Thelaterisrequiredforproperunderstandingofconver- sion losses and perceiving the basic notions on specific power, specific torque, andtorque-per-Ampereratiooftypicalmachines. • Although machine design is out of the overall scope, some most relevant concepts and skills in estimating the machine size, torque, power, inertia and losses are introduced and explained. The book also explains some secondary losses and secondary effects, indicating the cases and conditions where the secondaryphenomenacannotbeneglected. viii Preface Field of application Equivalent circuits, dynamic models and mechanical characteristics are given for DC machines, induction machines and synchronous machines. The book outlines thebasicinformationonthemachineconstruction,includingthemagneticcircuits andwindings.Thoroughapproachtodesigningelectricmachinesisleftoutofthe book.Withinthebook,machineapplicationsaredividedintwogroups;(i)Constant voltage,constantfrequencysuppliedmachines,and(ii)Variablevoltage,variable frequencymachinesfedfromstaticpowerconverters.Anumberofmostimportant details on designing electric machines for constant frequency and variable fre- quency operation are included. The book outlines basic static power converter topologies used in electrical drives with DC and AC machines. The book also provides basic information on loses, heating and cooling methods, on rated and nominalquantities,andoncontinuousandintermittentloading.Formostcommon machines, the book provides and explains the steady state operating area and the transientoperatingarea,theareainconstantfluxandfieldweakeningrange. Acknowledgment The author is indebted to Professors Milosˇ Petrovic´, Dragutin Salamon, Jozˇef Varga, and Aleksandar Stankovic´ who read through the first edition of the book andmadesuggestionforimprovements. Theauthorisgratefultohisyoungcolleagues,teachingassistants,postgraduate students, Ph.D. students and young professors who provided technical assistance, helped prepare solutions to some problems and questions, read through the chapters,commented,andsuggestedindexterms. Valuabletechnicalassistanceinpreparingthemanuscript,drawings,andtables wereprovidedbyresearchassistantsNikolaPopovandDraganMihic. The author would also like to thank Ivan Pejcic, Ljiljana Peric, Nikota Vukosavic, Darko Marcetic, Petar Matic, Branko Blanusa, Dragomir Zivanovic, Mladen Terzic, Milos Stojadinovic, Nikola Lepojevic, Aleksandar Latinovic, and MilanLukic. ix