SPRINGER BRIEFS IN ELECTRICAL AND COMPUTER ENGINEERING Ahmed Masmoudi Design and Electromagnetic Feature Analysis of AC Rotating Machines 123 SpringerBriefs in Electrical and Computer Engineering Series editors Woon-Seng Gan, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore C.-C. Jay Kuo, University of Southern California, Los Angeles, CA, USA Thomas Fang Zheng, Research Institute of Information Technology, Tsinghua University, Beijing, China MauroBarni,DepartmentofInformationEngineeringandMathematics,University of Siena, Siena, Italy SpringerBriefs present concise summaries of cutting-edge research and practical applications across a wide spectrum offields. Featuring compact volumes of 50 to 125 pages, the series covers a range of content from professional to academic. 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More information about this series at http://www.springer.com/series/10059 Ahmed Masmoudi Design and Electromagnetic Feature Analysis of AC Rotating Machines 123 Ahmed Masmoudi National School ofEngineers of Sfax University of Sfax Sfax Tunisia ISSN 2191-8112 ISSN 2191-8120 (electronic) SpringerBriefs inElectrical andComputer Engineering ISBN978-981-13-0919-9 ISBN978-981-13-0920-5 (eBook) https://doi.org/10.1007/978-981-13-0920-5 LibraryofCongressControlNumber:2018943720 ©TheAuthor(s)2019 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped. 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Theregisteredcompanyaddressis:152BeachRoad,#21-01/04GatewayEast,Singapore189721, Singapore Preface Following the 70th oil crisis, the world realized for the first time what it would be likeiffuelswouldnolongerbecheaporunavailable.Inordertodampthefallouts ofsuchasituation,renewableenergieshavebeenthesubjectofanintensiveregain of interest. So many R&D programs were launched so far, with emphasis on the investigation of the power potential of conventional and emergent earth’s natural energy reserves. Moreover, until the 1960s, automotive manufacturers did not worry about the costoffuel.Theyhadneverheardofairpollutionandtheyneverthoughtaboutthe lifecycle.Easeofoperationwithreducedmaintenancecostsmeanteverythingback then. In recent years, clean air policies are driving the market to embrace new propulsion systems in an attempt to substitute or assist efficiently the internal combustion engine (ICE) by an electric drive unit, yielding respectively the so-called electric and hybrid propulsion systems. The above sustainable energy and mobility applications consider in most if not all cases a key component that achieves the electromechanical conversion of energy: the electric machine. It operates as a generator which directly converts the wind and wave energies and through a turbine the solar, biomass and geothermal ones, into electricity. It operates as a propeller fed by a battery or a fuel cell pack embedded on board of electric and hybrid vehicles. This said, it should be underlined that the great penetration of electrical machinesintheabove-citedandtheoverwhelmingmajorityofcurrentapplications hasbeenmade possiblethanks tothegreatprogress inthearea ofmachinedesign. Indeed, during several decades, electrical ac machines have been designed accounting for the fact that they will be connected to the network. This has led to the well-known conventional ac machines (induction and dc-excited synchronous machines) in which the stator windings are sinusoidally distributed in slots around the air gap to couple optimally with the sinusoidal supply. Starting from the 1980s, the emergence of power electronic converters has removed the need for such a concept as the basis for ac machine design. A new approachbasedontheprinciplethatthebestmachinedesignistheonethatsimply v vi Preface produces the optimum match between the ac electrical machine and the power electronic converter has led to the so-called “converter-fed machines”. Within this trendy topic, the manuscript is devoted to the design and analysis oftheelectromagneticfeaturesofacmachines,focusingtheinvolvedwinding,and covering both grid- and converter-fed machines. The manuscript is structured in three chapters: (cid:129) The first one deals with the basis of the design of rotating ac machines with an emphasis on their air gap magnetomotive force (MMF). The survey is initiated by the formulation of the air gap MMF using the Ampere's theorem and the conservation law, followed by the investigation of its harmonic content con- sidering the case of concentrated windings. Then, the case of distributed windings is treated applying the superposition approach that highlights their potentialities in reducing the MMF harmonic content. (cid:129) The second chapter is aimed at the formulation of the rotating fields that could be generated considering different techniques involving single and polyphase windings. It also emphasizes the effects of the rotating fields on the winding located on the other side of the air gap. These effects are initiated by the inductionofback-EMFswhich,aton-loadoperation,leadtothegenerationofa second rotating field whose synchronization with the initial one results in the production of an electromagnetic torque. (cid:129) The third chapter is dedicated to the design of fractional slot concentrated winding equipping permanent magnet synchronous machines. The study is initiated by the arrangement of the armature winding using the star of slots approach.Thislatteristhenappliedforthedeterminationofthewindingfactors of the back-EMF fundamental and harmonics. A case study is finally treated with emphasis on the armature MMF spatial repartition and harmonic content. Sfax, Tunisia Prof. Ahmed Masmoudi Head of the Renewable Energies and Electric Vehicles Lab. Contents 1 Air Gap Magnetomotive Force: Formulation and Analysis. . . . . . . . 1 1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Formulation and Repartition of the Air Gap MMF Created by Concentrated Windings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2.1 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2.2 Single Coil MMF Formulation . . . . . . . . . . . . . . . . . . . . . 2 1.2.3 MMF Spatial Repartition . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.2.4 Case of a Dual Diametral Coil Winding . . . . . . . . . . . . . . 10 1.2.5 Case of a Multi Diametral Coil Winding. . . . . . . . . . . . . . 13 1.2.6 Three Phase Windings . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1.3 Formulation and Repartition of the Air Gap MMF Created by Distributed Windings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 1.3.1 Motivations in Using Distributed Windings. . . . . . . . . . . . 20 1.3.2 Case Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 1.4 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 2 Rotating Fields: Creation and Effects on the Machine Features . . . . 31 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 2.2 Rotating Field Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.2.1 Case of a Single Phase Winding in the Rotor . . . . . . . . . . 32 2.2.2 Case of a Three Phase Winding . . . . . . . . . . . . . . . . . . . . 35 2.2.3 Case of a Two Phase Winding . . . . . . . . . . . . . . . . . . . . . 37 2.2.4 Case of a Five Phase Winding . . . . . . . . . . . . . . . . . . . . . 39 2.2.5 Generalisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2.3 Back-EMF Induction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2.3.1 Case of a Concentrated Coil. . . . . . . . . . . . . . . . . . . . . . . 42 2.3.2 Case of a Distributed Coil . . . . . . . . . . . . . . . . . . . . . . . . 43 2.3.3 Root-Mean-Square of the Induced Back-EMF . . . . . . . . . . 49 2.3.4 Case of a Distributed Winding . . . . . . . . . . . . . . . . . . . . . 50 2.4 Developed Electromagnetic Torque . . . . . . . . . . . . . . . . . . . . . . . 50 vii viii Contents 2.4.1 Torque Production in Smooth Pole AC Machines . . . . . . . 51 2.4.2 Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 2.4.3 Formulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 2.5 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 3 Fractional-Slot Concentrated Windings: Design and Analysis . . . . . 55 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3.2 Concentrated Winding Arrangement Based on the Star of Slots Approach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 3.2.1 Study Background. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 3.2.2 Basis of the Star of Slots . . . . . . . . . . . . . . . . . . . . . . . . . 58 3.2.3 Arrangement of Double-Layer Concentrated Windings. . . . 59 3.2.4 Arrangement of Single-Layer Concentrated Windings . . . . 67 3.3 Winding Factor Star of Slots Based-Prediction. . . . . . . . . . . . . . . 69 3.3.1 Winding Factor of the Fundamental Back-EMF. . . . . . . . . 70 3.3.2 Winding Factor of the Harmonic Back-EMFs . . . . . . . . . . 72 3.4 MMF Formulation and Analysis: A Case Study . . . . . . . . . . . . . . 77 3.4.1 Double-Layer Topology. . . . . . . . . . . . . . . . . . . . . . . . . . 77 3.4.2 Single-Layer Topology. . . . . . . . . . . . . . . . . . . . . . . . . . . 81 3.4.3 Double- Versus Single-Layer Topologies . . . . . . . . . . . . . 83 3.5 Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 About the Author AhmedMasmoudi receivedB.S.fromSfaxEngineeringNationalSchool(SENS), University of Sfax, Sfax, Tunisia, in 1984, Ph.D. from Pierre and Marie Curie University, Paris,France, in1994, and Research Management Ability from SENS, in 2001, all in electrical engineering. In August 1984, he joined Shlumberger as a field engineer. After this industrial experience, he joined the Tunisian University wherehehelddifferentpositionsinvolvedinbotheducationandresearchactivities. HeiscurrentlyaProfessorofElectricPowerEngineeringatSENS,theHeadofthe Research Laboratory on Renewable Energies and Electric Vehicles (RELEV) and the Coordinator of the Master on Sustainable Mobility Actuators: Research and Technology.Hepublishedupto85journalpapers,amongwhich19werepublished in IEEE transactions. He presented up 367 papers in international conferences, amongwhich9havebeenpresentedinplenarysessions,and3havebeenrewarded bythebestpresentedpaperprize.Heistheco-inventorofaUSApatent.Heisthe Chairman of the Program and Publication Committees of the International Conference on Ecological Vehicles and Renewable Energies (EVER), organized every year in Monte Carlo, Monaco, since 2006. He was also the Chairman of the Technical Program and Publication Committees of the first International Conference on Sustainable Mobility Applications, Renewables, and Technology (SMART) which has been held in Kuwait in November 2015. Its involvement in the above conferences has been marked by an intensive guest-editorship activity with the publication of many special issues of several journals including the IEEE TransactionsonMagnetics,COMPEL,ELECTROMOTION,andETEP.Professor MasmoudiisaSeniorMember,IEEE.Hismaininterestsincludethedesignofnew topologies of ac machines allied to the implementation of advanced and efficient controlstrategiesindrivesandgenerators,appliedtorenewableenergyaswellasto electrical automotive systems. ix