Advanced Motion Controls 12A8 - Power Supply Specifications

FIGURE 2.8 AZ20 Power Supply Selection
AZ Drive Over Voltage Shutdown (88V)
0
20
40
60
80
100
VDC
Acceptable Power Supply
Range (26 V-72V)
Shunt Regulator Turn-On Voltage (80V)
AZ Drive Under Voltage Shutdown (9V)
System Power Supply Requirement (24V)
MNALAZIN-02 16
Products and System Requirements / System Requirements
Power Supply Specifications
AZservodrivesoperateoffanisolatedunregulatedDCPowerSupply.TheAZ12andAZ6drives
haveaDCsupplyrangeof20‐80VDC,whiletheAZ20serieshasarangeof10‐80VDC.AllAZ
servodriveshaveanover‐voltageshutdownof88VDC.Toavoidnuisanceover‐orunder‐
voltageerrorscausedbyfluctuationsinthepowersupply,thesystempowersupplyvoltage
shouldbeatleast10%abovetheentiresystemvoltagerequirement,andatleast10%below
thelowestvalueofthefollowing:
• Driveovervoltage
• Externalshuntregulatorturn‐onvoltage
Useofashuntregulatorisnecessaryinsystemswheremotordecelerationoradownward
motionofthemotorloadwillcausethesystem’smechanicalenergytoberegeneratedviathe
drivebackontothepowersupply.Thisregeneratedenergycanchargethepowersupply
capacitorstolevelsabovethatoftheAZdriveover‐voltageshutdownlevel.Ifthepowersupply
capacitanceisunabletohandlethisexcessenergy,orifitisimpracticaltosupplyenough
capacitance,thenanexternalshuntregulatormustbeusedtodissipatetheregenerated
energy.Theshuntregulatorwill"turn‐on"atacertainvoltagelevel(setbelowthedriveover‐
voltageshutdownlevel)anddischargetheregeneratedelectricenergyintheformofheat.
Thediagrambelowprovidesapossibleexampleofanappropriatesystempowersupply
voltageforanAZ20driveusinganexternalshuntregulator.
Thepowersupplycurrentratingisbasedonthemaximumcurrentthatwillberequiredby
thesystem.Ifthepowersupplypowersmorethanonedrive,thenthecurrentrequirements
foreachdriveshouldbeaddedtogether.Duetothenatureofservodrives,thecurrentintothe
drivedoesnotalwaysequalthecurrentoutofthedrive.However,thepowerinisequaltothe
powerout.Usethefollowingequationtocalculatethepowersupplyoutp utcurrent,I
PS
,
basedonthemotorcurrentrequirements.
Where:
V
PS
‐nominalpowersupplyvoltage
I
M
‐motorcurrent
V
M
‐motorvoltage
I
PS
V
M
I
M
⋅
V
PS
0.98()⋅
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