EVOLUTION OF MOTOR AND VARIABLE …

1 , ,ControlTechniquesDrives~EmersonElectric ABSTRACTT hepurposeofthispaperis nottodescribeindetailtheoperationandcons tructionofvariablefrequencydrives(VFD's) ,twospecificapplicationexamplesusingstan dardACdrivesintwodifferentindustrieswill beexploredgivingthereadera , a 's, ,earlyACvariablefrequencydrives(VFD)were bulky~ ,thereisanincreasingneedforenergyconserv ationandefficientuseofenergyenablingcomm ercialandindustrialfacilitiestominimizep roductioncosts, ~1997mustmeetthenewenergystandardsfoundi ntheNationalElectricalManufacturersAssoc iation(NEMA) , ,generalpurpose,T framesquirrel-eageinductionmotorunderNEM AD esignsA andB,through200hp.

2 ,singlespeed,footmountedandpolyphaseoper atingat230 ! (VFD's)togetherwithmotorshaveemergedthro ughoutindustryasthepopularapproachtoimpr oveprocesscontrol,productquality, , , ,MotorChallengeProgramManagerforTheDepar tmentOfEnergy,"Nationally, $30billionannuallyonmotorsystemsenergyco st."1 OverthepastfifteenyearstheuseofVFD' ,duringthemideightiesthepetroleumandchem icalindustrycriticallyviewedVFD'switha , ' motordrivecombination;thepumping, ,traditionallythemotivatingforcetoapplyV FD's inthepastwastoobtainspeedcontrolcomparab letoa ,weseethestandardACdrivesmarketasawholeg rowingata10% ,thisis , 'sassumetheengineunderthehoodis runningat , a veryinefficientapproach, fixedwhilethecubicfeetperminute(cfrn) , ,ifwelookatatypicalappliedHVAC system,850/0ofthetimethepercentofairflow neededtooperatea commercialsystemis between40%and85% ,98%ofthetimetheairflowcanbevariedthroug htheuseofa variablefrequencydrivewhilestillmaintain ingsystemefficiency.

3 (figure4)2 Withanenergyefficientmotortheuserreceive sa premiummotormanufacturedspecificallytolo werenergyconsumption. Energyefficientmotorscommonlyuselowlosss teellaminationsalongwithahighdegreeofcop per contentthereby ,additionaltapingand/orlacingonthestator endturnsaswellasanimprovedstatorinsulati ononendturns, clearlystatesthatasindustrialusersapplie dstandardmotorsinthepastwith1,200orabove HzPWMdriveswehavegrownaccustomedtoahalfl ifefroma standardmotorcomparedto"InverterGrade" )Westronglyfeelour"InverterGrade"motorde mandwillincreaseatapacegreater thanthedriveindustrygrowthrateoncethemar ketplacerealizesthebenefitsofincreasedmo torlifethrough""InverterGrade" ,ifthefrequencyorvoltageischangedwithout changingtheother, thetorquecharacteristicschangeasa 'sLate1960'sThe1970'sPre1985 DevelopmentSolidstatepowerdevicesdevelop knownasSCR' 's (LSI) 's/GTO' , , , 'susedsiliconcontrolledrectifiers(SCRs)o rgatetumoffthyristors(GTOs)andwereeither variablevoltageinverter(VVI)orcurrentsou rceinverter(CSI) (PWM) ,withtheintroductionoftheinsulatedgatedb i-polartransistor(IGBT)

4 Inthelate1980'svastimprovementsinthedesi gnofACVFD' ' ' ,rotor-flux-orientedcontrol, theDCmarketdeadnorwillitbeinthenearfutur e, 's havecomedowndramaticallyprimarilyfromthe improvedtechnologyofpowerdevices, ,a10horsepowerdrivemanufacturedintheearl y1980' :constanttorque, ,rotarylobepumps,positivedisplacementpum psandcompressors,punchpresses,wiredrawin gmachines, 'stothesetypeloadswillbestartingtorquere quirements,speedregulation, directlyproportionaltospeed,pressureis proportionaltothesquareofthespeedandpowe ris , {orpower)tospeediscubic, ,beitvalves, ,mixersandcenterdrivenwinders :NorthTonawanda, , 'sandenergyefficientmotors, ,thisresultedinunevenairflow,wastedenerg y, :InstallationCostUtilityRebateActualCost ProjectedYearlySavingsExpectedSimplePayb ack$46,286$(18,560)$27,726$29,08811month s545546 ActualResultswere.}

5 Firstyearenergysavingsexceeded$40,000 IncreasedoperatinghoursReduceddemandchar gesImprovedproductqualityduetotighterpro cesscontrolArealizednetwastereductionof4 0/0 AnetrealizedpaybackeachmonthByapplyingVF D' ,at90%speed(airflow)theenergyconsumedwas 250/0lessthanatfullmotorspeed(100%) (airflow)theVFD'sconsumed20%to25%oftheen ergycomparedto67% ,thetotalenergysavingsvariedfrom25%to50% fromtheoriginalcontrolschemewhichconsist edofrunningthemotorsata customerhasexperiencedthebenefitswediscu ssedearlierintheintroductionofthispaper, improvedprocesscontrol,increasedproductq ualityanda :SanDiego, , ,a VFDmanufactureranda 'stotwenty-twoairhandlers, ,theVFD' (airhandlersandchillers)was$478,000witha rebateof$140, 30%.

6 Estimatedannualunitsofenergysavingsis ,savingswereguaranteedata minimumof30%.Withthreeseparatecompaniesc ooperatingtogethertowarda commongoalofrealizedsavingsthecustomeris seeinga substantial ,presentandfuturedevelopmentsandtrendsin ACinduction motorsandVFD' distinctincreaseinvectorcontrolleddrives aswellasacontinuedbuta continuossearchfornewmaterialswhichwillc ombinethermalconductivity, , ,~'MotorChallengeOverview:KeepingProduct ionHighWhileBringingCostsOO\\ln"TurningP oint,DepartmentOfEnergy, 'Brien,~"Energy-EfficientMotorDriveSyste msinCommercialBuildings:AProfitableEnvir onmentalOpportunity"EnergyEfficientElect ricMotorSystemsNationalConferenceFebruar y9-10, ~"'AdjustableSpeedElectricalMotors~April " , ,FIEE~ , ,FlEE~IoFutureDevelopluentsandTrendsInEl ectricalMachinesandDrives.

7 "1994547yCALENEMPTIONTNe*V1~00 UMPS31 kMACHINETOOLgOk14% kBLOWERS&FANFIGURE1 YHPRATINGDRIVESTmBHP151-200H27%>750HP14% 1-5HP705-50H25%U1~lOFIGURE2V1V1oCHARACTE RISTICSAPPLICATIONPROFILEFANSIIPUMPSIIWE BHNDLJ lillDRYER_STRIPFRMG~IIMTLeHNDLIIEXTRUDIN G[illCONVERTINGIICOMPRESSORtilMETALFAB8 IIPACKGeIIMOLDINGtilELEV~IITESTSTANDlRMI XINGIIISTAMPINGBlOTHERSPS13%WEBHNDL100/0 ElEV:TESTMIXINGMJ%J%2%20/02%STAMP4%1%COM PRESSOTHERS30/0EX~~U0'..::);::~l~~::8:t: t::~:~~~~B~ ';~ ~~ ::~ ., :;::,, ..>~:.~.~'. ,'..',.'~:F~~~MTleHNDLSOkSTRIPFRMGe10/0 FIGURE3 Profileof'y,icalAirfliowReq:'uiire'lflen tsHottestday~"\ :.:.:.:.:.:.:.:.:.:.:-~.'.I ~IColdest86o4210 PercentofAnnualOperatinaHours12253035404 550556065707580859095100rcentMaximumAirF lowNeBdeU1~Source:YorkAppliedSystemsFIGU RE4U1U1 NSWITCHINGFREQUENCYIMPACTMAGNETWIRELIFEv sSWITCHINGFREQUENCYUSEM"InverterGrade" (IGBT)6-Step250/0-TypicalHeavyFihnLifeat SwitchingFrequencyLevelofBasicPWM50%-1-- -- -- - --- -- - ----- - - -----100%150%0 (Hertz)FIGURE5 Basedontestresultsofacceleratedmagnetwir etestingina30 CambientwithalOOOV peak/]