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1、SizingDynamicBrakeResistorsandChopperModulesDynamicBrakeModuleCircuitUsingaDynamicBrakeorChopperIngeneral,themotorpowerrating,speed,torque,anddetailsoftheregenerativedutycycleneedtobeknown.Generally,adynamicbrakecanbeusedwheneverregenerativeenergyisdiss
2、ipatedonanoccasionalorperiodicbasis.Ifthedrivewillconsistentlyberegenerating,seriousconsiderationshouldbegiventoreturningthepowertotheACutility.GathertheInformationFirstThenameplatepowerratingofthemotorinwatts,kilowatts,orhorsepower.Thenameplatespeedrati
3、ngofthemotorinrpm,orrps.Themotorinertiaandloadinertiainkilogram-meters2,orlb-ft2.Thegearratio,ifagearispresentbetweenthemotorandload,GR.Themotorshaftspeed,torque,andpowerprofileofthedriveapplication.ExampleSpeed,Torque,andPowerProfiletttHowtoChooseaDynam
4、icBrake/ChopperCalculatethetotalinertiaofthesystemCalculatethepeakregenerativepoweryouneedtodissipate.ThiswilldeterminethemaximumallowableresistancevalueoftheDBresistor.CalculatetheaveragepowerdissipationThiswilldeterminetheaveragepowerdissipationcapacit
5、yneededintheDBresistor.Third,checktoseethatthepeaktemperatureofthedynamicbrakingresistordoesnotexceeditscapacity.PlottheAverageLoadandPeakLoadonthecurveinthesizingguide.Thisisnecessaryonlyonthedynamicbrakemodules!Dynamicbrakemodulesshouldonlybeusedondriv
6、es75HPandsmaller.HowtoSizeADynamicBrakeModuleStep1-TotalInertiaJT=totalinertiareflectedtothemotorshaft,kilogram-meters2(kg-m2)orpound-feet2(lb-ft2)Jm=motorinertia,kilogram-meters2(kg-m2)orpound-feet2(lb-ft2)GR=thegearratioforanygearbetweenthemotorandload
7、,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=angularrotationals
8、peed,lessthanratedspeed(canbezero)Rad/sNb=maximumapplicationspeedinRPMt3-t2=totaltimeofdecelerationfromwbtowo,secondsPb=peakbrakingpower,wattsNote:1.0HP=746wattsDBModuleStep3-MaximumDBResistorValueVd=thevalueofDCBusvoltage