Analysis, Optimization and Control of Grid-Interfaced Matrix-Based Isolated AC-DC Converters PDF
Preview Analysis, Optimization and Control of Grid-Interfaced Matrix-Based Isolated AC-DC Converters
Springer Theses Recognizing Outstanding Ph.D. Research Jaydeep Saha Analysis, Optimization and Control of Grid-Interfaced Matrix-Based Isolated AC-DC Converters Springer Theses Recognizing Outstanding Ph.D. Research AimsandScope The series “Springer Theses” brings together a selection of the very best Ph.D. theses from around the world and across the physical sciences. Nominated and endorsed by two recognized specialists, each published volume has been selected foritsscientificexcellenceandthehighimpactofitscontentsforthepertinentfield of research. For greater accessibility to non-specialists, the published versions includeanextendedintroduction,aswellasaforewordbythestudent’ssupervisor explainingthespecialrelevanceoftheworkforthefield.Asawhole,theserieswill provide a valuable resource both for newcomers to the research fields described, and for other scientists seeking detailed background information on special questions. 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Jaydeep Saha Analysis, Optimization and Control of Grid-Interfaced Matrix-Based Isolated AC-DC Converters Doctoral Thesis accepted by National University of Singapore, Singapore, Singapore Author Supervisor Dr.JaydeepSaha Assoc.Prof.SanjibKumarPanda ResearchFellow,DepartmentofElectrical DirectorofPowerandEnergyGroup, andComputerEngineering DepartmentofElectricalandComputer NationalUniversityofSingapore Engineering Singapore,Singapore NationalUniversityofSingapore Singapore,Singapore ISSN 2190-5053 ISSN 2190-5061 (electronic) SpringerTheses ISBN 978-981-19-4901-2 ISBN 978-981-19-4902-9 (eBook) https://doi.org/10.1007/978-981-19-4902-9 ©TheEditor(s)(ifapplicable)andTheAuthor(s),underexclusivelicensetoSpringerNature SingaporePteLtd.2022 Thisworkissubjecttocopyright.AllrightsaresolelyandexclusivelylicensedbythePublisher,whether thewholeorpartofthematerialisconcerned,specificallytherightsoftranslation,reprinting,reuse ofillustrations,recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,and transmissionorinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilar ordissimilarmethodologynowknownorhereafterdeveloped. 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The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore TomybelovedWife,Pratirupa Supervisor’s Foreword Itisagreatpleasuretowriteaforewordtothisbookoninterestingandinnovative modulation,controlanddesigntechniquesforgrid-connectedisolatedsingle-stage AC-DCconversion. Startingwiththeinstallationofthefirstdistributionsystemstowardstheendof the 19th century, the electrical power system has undergone a variety of changes. However, the 21st-century power grid has been undergoing a plethora of changes, mainlyfuelledbythecommitmentsmadebyanumberofgovernmentsaroundthe worldtocombatclimatechange.Theemergenceofsmartgridisreversingtheorga- nizationalapproachofthepowergridfromatop-downtoabottom-upapproach,with renewable-baseddistributedgenerationbecomingacommonplace.Thoughahuge AC-based generation-transmission-distribution power network is in place, there is increasing penetration of DC power (mainly in the power distribution grid) due to proliferationofDCsources(e.g.solarphotovoltaic,fuelcells),batteryenergystorage systemsandDCloads(e.g.electronics,electricvehicles,smartlightingsolutions). Thus, AC-DC and DC-AC conversions would be a necessity for the foreseeable future. Power electronics is becoming a more common technology in the power grid, ranging from integration of renewables, battery, electric vehicles and so on. Theapplicationofgrid-connectedpowerelectronicshasitsnuancesandchallenges whichneedstobecarefullyinvestigated,buttheopportunitiesandpossibilitiesare magnanimous. Powertransformerspresentinthepowersystemtodayoperateatthedesignated linefrequency(50HzforSingaporeand60HzforUSA)andareveryrobustsolutions, buthavelimitedfunctionalities,whichmaynotbesufficientforalltherequirements ofthefuturegrid.Forexample,whenitcomestointegrationofrenewablesorbattery energystorageorrenewable-richmicrogridswiththeutilitygrid,apartfromgalvanic isolation,anAC-DCconversionsolutionisnecessary.Thus,thereisnochoicebutto resorttopowerelectronicstechnology.Aboutadecadeago,powerelectronicrein- forcementoftransformerswouldbecriticizedasitwouldaffecttheefficiencyand powerqualityoftheequipment.Buttoday,thewide-bandgap(WBG)semiconductor deviceswithhighbandwidthofswitchingfrequencyandhighpowerhandlingcapa- bilities have helped to eliminate many bottlenecks with respect to grid-connected vii viii Supervisor’sForeword powerconversion.Thishasnotonlymadepower-electronics-reinforcedsmarttrans- formersareality,butalsohelpedtonurturethegrowthofconceptslikesolid-state transformer,whichnestsahigh-/medium-frequencytransformerandthusprovides acompactisolatedpowerconversionsolutionthatcanmeettheexpectationsofthe modernsmartgrid. Thebookisdedicatedtowardsinvestigationanddevelopmentofhigh-efficiency, high power-density AC-DC converters for medium-voltage AC (MVAC) and low- voltage AC (LVAC) grid-connected applications. Firstly, a qualitative analysis of the grid-connected MVAC-LVDC conversion reveals the merits of cascaded modular conversions, and a further quantitative analysis of the submodule possi- bilities for cascaded modular conversion shows superiority of the single-stage front-end half-bridge matrix-based dual-active-bridge (FE-HB MB-DAB) AC-DC submoduletopology.Secondly,anelaboratediscussionontheanalysisofmodula- tion, optimal design methodology and soft-switching strategy for the FE-HB MB- DAB is presented, with experimentally obtained efficiency (η) of 96.6%, power density(ρ)of2.49kW/L,unity-power-factoroperationandnearfull-cycleZVSof allSiC-MOSFETsoverawideloadrange(12–100%).Thisdemonstratesasignif- icantimprovementovertheperformanceoftheconventionaltwo-stageconversion strategy.Thirdly,amachine-learning(ML)-aidedη-ρoptimalsolid-statetransformer (SST) design framework is proposed and experimentally validated. Subsequently, the issue of power routing imbalance in single-stage MVAC-LVDC converters is studied,andamitigatingpowerbalancecontrolsolutionisproposedandexperimen- tally validated. Lastly, the single-stage three-phase isolated LVAC-LVDC conver- sion strategies for LV grid-connected applications are investigated, which exhibit that DAB-type conversion (experimental η = 96.35%, ρ = 2.4 kW/L and LVAC sidecurrentTHDof4.1%)demonstratessuperiorperformancethannon-DAB-type conversion(experimentalη=93.6%,ρ=2.1kW/LandLVACsidecurrentTHDof 5.6%).Hence,thisbookextensivelycoverstheory,analysis,designandcontrolofa newgenerationofisolatedAC-DCconversionforgrid-connectedapplications,with adequateexperimentalverification. Accordingtome,thisbookwillbebeneficialforprofessionalsbothattheindustry and academia. Industry professionals will get to familiarize with the need-of-the- hourresearchthrusttowardsdesignandcontrolofgrid-connectedpowerelectronic converter,whereastheresearchcommunitywouldgetatasteofthenewdirectionto explorethepossibilitiesofML-assistedoptimalpowerconverterdesign,modulation andcontroltechniquesthatcanpotentiallyimprovepowerconverterperformance.I amsurethatthebookwouldappearfascinatingtoallthepeoplewhoare,inanyway, associatedwiththepowerelectronicsdomain.Thisworkhasthepotentialtoopenup newavenuesfortechnologyadoptionintheemergingareasoffast-chargingofelectric vehicles,greendatacentres,energy-controlcentreofrenewable-richmicrogrids,etc. Singapore Assoc.Prof.SanjibKumarPanda May2022 Summary Thetraditionalfossil-fuel-basedpowersystem(withunidirectionalelectricalpower andinformationflowalongthethreesegmentsofgeneration,transmissionanddistri- bution)isexperiencingaparadigmshiftduetoincreasingpenetrationofrenewable energysources,asaresultofrisingenvironmentalconcernsanddwindlingexpense ofrenewableenergyharvestinginfrastructure.Asaresult,thepowersystemisgetting revampedtowardsthesmartgridconcept,wheremicrogrids/nanogrids(consistingof distributedenergyresources,storageandactive/passiveloads)areexpectedtoform thefunctionalblocks.Thecentralizedutility-gridconceptanditsenormousinfras- tructure would still be existing with the distribution system getting modernized in thecomingfewdecades.Powerelectronicsisalreadyavisibletechnologyintoday’s gridwithapplicationssuchasFACTS,HVDCtransmission,powerelectronics-based circuitbreakers,inverters,convertersforintegratingrenewableenergysources,etc. Thepowerelectronicstechnologyisexpectedtodominatethepowersystemofthe future due to the necessity of continuous controllability and enhanced smart func- tionalitiesatthepointofinterconnectionofthemicrogrids/nanogridswiththeutility gridandduetotheproliferationofotherpowerelectronicsdependentapplications likebatteryenergystorageintegration,vehicle-to-grid,electricvehiclefastcharging, etc.AdedicatedoverviewofthevariousMVgrid-connectedisolatedMVAC-LVDC conversionstrategiesisdiscussedtoestablishthemeritsofcascadedmodularmulti- level conversion strategy for MV grid-connected applications. Simultaneously, a focused discussion on the solid-state transformer (SST) technology (a MV grid- connected application with medium-frequency isolation) is provided to show its relevance and applicability for MVAC-LVDC conversion, which reveals the need forhigh-powerdensitySSTarchitectureswithcomparableefficiencyandcostwith respecttocontemporaryline-frequencytransformer(LFT)-basedsolutions.Abrief overviewoftheLVgrid-connectedLVAC-LVDCconversionstrategiesispresented whichshowstheneedformoreresearcheffortstowardsthedevelopmentofsingle- stagethree-phaseLVAC-LVDCconverterswithenhancedefficiency,powerdensity andreliability. There is a literature gap in terms of the quantitative evaluation of the AC- DCsubmoduletopologiesformodularMVgrid-connectedisolatedMVAC-LVDC ix x Summary conversion.Briefdescriptionsforeachoftheavailablesingle-phaseAC-DCconver- sion submodules in literature along with other possible submodule topologies are providedinthisthesis,andacomparativeevaluationisprovidedwhileconsidering thecriteriaofpowerdensity,efficiency,cost,failurerate,numberofcomponentsand controlcomplexity.Thiscomparativestudyshowsthemeritsofsingle-stageisolated AC-DC submodules over the conventional two-stage isolated AC-DC submodules andrevealsthatthedirectmatrix-baseddual-active-bridge(MB-DAB)submoduleis themostsuitablesubmoduletopologyforisolatedMVAC-LVDCconversionappli- cation (based on the considered criteria). Subsequently, the two direct MB-DAB configurations, i.e. front-end half-bridge (FE-HB) and front-end full-bridge (FE- FB),arestudiedtorevealtheirmodulationboundaries(whichhasnotbeenanalysed intheliteratureyet).ThisstudyrevealsthattheFE-HBMB-DABtopologyhasbetter meritscomparedtotheFE-FBMB-DAB,asitofferstwicethemodulationflexibility andtwicetheAC-DCstep-downwitha33%reductioninnumberofsemiconductor devicesandtherequiredcontrolflexibility. The single-stage single-phase FE-HB MB-DAB topology is relatively nascent, and its modulation has not been discussed in great detail in the recent literature. In this thesis, a holistic description and associated formulations of the exhaustive setofzerocurrentswitching(ZCS)andzerovoltageswitching(ZVS)constrained modulation modes of the FE-HB MB-DAB converter are presented. The subse- quent theoretical analysis of the modulation boundaries reveals that there are only four feasible modulation modes that can form six feasible modulation schemes as acombinationofvariousfeasiblemodulationmodes.Amultiobjectiveefficiency— powerdensity(η–ρ)designoptimizationalgorithmisalsopresentedthatresultsin the η–ρ optimal design limits for the six feasible modulation schemes for various combinations of component datasets and switching frequencies. A complete SiC- MOSFET-basedFE-HBMB-DABhardwareprototypeisfabricatedaccordingtothe componentandoperationalspecificationsofthemultiobjectiveη–ρdesignoptimiza- tionresultsandtheexperimentallyobtainedη=96.1%andρ=2.49kW/Lillustrate strongcoherencewiththetheoreticallyobtainedoptimalMB-DABdesign’sresults (thus validating the theoretical analysis and optimization results). As far as ZVS soft-switchingstrategiesforSiC-MOSFET-basedMB-DABAC-DCconvertersare concerned, the proposed methodologies in the literature either suffer from incom- pleteZVSofSiC-MOSFETsduetomodetransitionorcomputationallyexpensive optimalmodulationschemebyrestrictingtheswitchingschemetoasinglemodu- lationmode.AnanalyticalexpressionbasedZVSmodulationstrategyispresented in this thesis to achieve near full-cycle ZVS turn-on of all the SiC-MOSFETs in the FE-HB MB-DAB converter over a wide range of loading conditions with the capabilityofpowerfactorcorrection,whichensureslowcomputationalcomplexity and direct implementability on a common microprocessor. A PSIM simulation is developed for a 2.2 kW(pk) MB-DAB converter using component manufacturer’s PSPICE models to study the working principle of the proposed ZVS modulation schemebeforehardwareimplementation.Finally,theexperimentalresultsexhibita conversionefficiencyof96.6%,UPFoperation,ACcurrent’sTHDof2.9%atfull- load, along with near full-cycle ZVS turn-on of all MOSFETs over a wide range
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