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1、SizingDynamicBrakeResistors andChopperModulesDynamicBrakeModuleCircuitUsingaDynamicBrakeorChopperIngeneral,themotorpowerrating,speed,torque,anddetailsoftheregenerativedutycycleneedtobeknown.Generally,adynamicbrakecanbeusedwheneverregenerativeenergyisdissipatedonanoccasionalorperiodicbasis.Ifthedriv
2、ewillconsistentlyberegenerating,seriousconsiderationshouldbegiventoreturningthepowertotheACutility.GathertheInformationFirstThenameplatepowerratingofthemotorinwatts,kilowatts,orhorsepower.Thenameplatespeedratingofthemotorinrpm,orrps.Themotorinertiaandloadinertiainkilogram-meters2,orlb-ft2.Thegearra
3、tio,ifagearispresentbetweenthemotorandload,GR.Themotorshaftspeed,torque,andpowerprofileofthedriveapplication.ExampleSpeed,Torque,andPowerProfiletttHowtoChooseaDynamicBrake/ChopperCalculatethetotalinertiaofthesystemCalculatethepeakregenerativepoweryouneedtodissipate.Thiswilldeterminethemaximumallowa
4、bleresistancevalueoftheDBresistor.CalculatetheaveragepowerdissipationThiswilldeterminetheaveragepowerdissipationcapacityneededintheDBresistor.Third,checktoseethatthepeaktemperatureofthedynamicbrakingresistordoesnotexceeditscapacity.PlottheAverageLoadandPeakLoadonthecurveinthesizingguide.Thisisneces
5、saryonlyonthedynamicbrakemodules!Dynamicbrakemodulesshouldonlybeusedondrives75HPandsmaller.HowtoSizeADynamicBrakeModuleStep1-TotalInertiaJT=totalinertiareflectedtothemotorshaft,kilogram-meters2(kg-m2)orpound-feet2(lb-ft2)Jm=motorinertia,kilogram-meters2(kg-m2)orpound-feet2(lb-ft2)GR=thegearratiofor
6、anygearbetweenthemotorandload,dimensionless.2:1=0.5JL=loadinertia,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,lessthanrat
7、edspeed(canbezero)Rad/sNb=maximumapplicationspeedinRPMt3-t2=totaltimeofdecelerationfromwbtowo,secondsPb=peakbrakingpower,wattsNote:1.0HP=746wattsDBModuleStep3-MaximumDBResistorValueVd=thevalueofDCBusvoltage
