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1、SizingDynamicBrakeResistors andChopperModulesDynamicBrakeModuleCircuitUsingaDynamicBrakeorChopperIngeneral,themotorpowerrating,speed,torque,anddetailsoftheregenerativedutycycleneedtobeknown.Generally,adynamicbrakecanbeusedwheneverregenerativeenergyisdissipated
2、onanoccasionalorperiodicbasis.Ifthedrivewillconsistentlyberegenerating,seriousconsiderationshouldbegiventoreturningthepowertotheACutility.GathertheInformationFirstThenameplatepowerratingofthemotorinwatts,kilowatts,orhorsepower.Thenameplatespeedratingofthemotor
3、inrpm,orrps.Themotorinertiaandloadinertiainkilogram-meters2,orlb-ft2.Thegearratio,ifagearispresentbetweenthemotorandload,GR.Themotorshaftspeed,torque,andpowerprofileofthedriveapplication.ExampleSpeed,Torque,andPowerProfiletttHowtoChooseaDynamicBrake/ChopperCal
4、culatethetotalinertiaofthesystemCalculatethepeakregenerativepoweryouneedtodissipate.ThiswilldeterminethemaximumallowableresistancevalueoftheDBresistor.CalculatetheaveragepowerdissipationThiswilldeterminetheaveragepowerdissipationcapacityneededintheDBresistor.T
5、hird,checktoseethatthepeaktemperatureofthedynamicbrakingresistordoesnotexceeditscapacity.PlottheAverageLoadandPeakLoadonthecurveinthesizingguide.Thisisnecessaryonlyonthedynamicbrakemodules!Dynamicbrakemodulesshouldonlybeusedondrives75HPandsmaller.HowtoSizeADyn
6、amicBrakeModuleStep1-TotalInertiaJT=totalinertiareflectedtothemotorshaft,kilogram-meters2(kg-m2)orpound-feet2(lb-ft2)Jm=motorinertia,kilogram-meters2(kg-m2)orpound-feet2(lb-ft2)GR=thegearratioforanygearbetweenthemotorandload,dimensionless.2:1=0.5JL=loadinertia
7、,kilogram-meters2(kg-m2)orpound-feet2(lb-ft2)Note:1.0lb-ft2=0.04214011kg-m2DBModuleStep2-PeakRegenerativePowerJT=totalinertiareflectedtothemotorshaft,kg-m2wb=maxangularrotationalspeed,Rad/s=2pNb/60wo=angularrotationalspeed,lessthanratedspeed(canbezero)Rad/sNb=
8、maximumapplicationspeedinRPMt3-t2=totaltimeofdecelerationfromwbtowo,secondsPb=peakbrakingpower,wattsNote:1.0HP=746wattsDBModuleStep3-MaximumDBResistorValueVd=thevalueofDCBusvoltage
