Advanced Motion Controls 12A8 - Control Modes

MNALAZIN-02 6
Products and System Requirements / Control Modes
Control Modes
TheAZfamilyofanalogdrivesoffersavarietyofdifferentcontrolmethods.Whilesomedrives
intheseriesaredesignedtooperatesolelyinonemode,onotherdrivesitispossibletoselect
thecontrolmethodbyDIPswitchsettings.Consultthedatasheetforthedriveinusetosee
whichmodesareavailableforuse.
Thenameofthemodereferstowhichservoloopisbeingclosedinthedrive,nottheend‐result
oftheapplication.Forinstance,adriveoperatinginCurrent(Torque)Modemaybeusedfora
positioningapplicationiftheexternalcontrollerisclosingthepositionloop.Oftentimes,mode
selectionwillbedependentontherequirementsandcapabilitiesofthecontrollerbeingused
withthedriveaswellastheend‐resultapplication.
Current (Torque)
InCurrent(Torque)Mode,theinputcommandvoltagecontrolstheoutputcurrent.Thedrive
willadjusttheoutputdutycycletomaintainthecommandedoutputcurrent.Thismodeisused
tocontroltorqueforrotarymotors(forceforlinearmotors),butthemotorspeedisnot
controlled.Theoutputcurrentcanbemonitoredthroughananalogcurrentmonitoroutput
pin.Thevoltagevaluereadatthe“CurrentMonitorOutput”canbemultipliedbyascaling
factorfoundonthedrivedatasheettodeterminetheactualoutput
current.AllAZdrivesare
abletooperateinCurrent(Torque)Mode.
While in Current (Torque) Mode, the drive will maintain a commanded
torque output to the
motor based on the input reference command.
Sudden changes in the motor load may cause the drive to be outputting
a high torque command with little load resistance, causing the motor to
spin rapidly. Therefore, Current (Torque) Mode is recommended for
applications using a digital position controller to maintain system stability.
Open Loop (PWM Duty Cycle)
InOpenLoop(PWMDutyCycle)Mode,theinputcommandvoltagecontrolstheoutputPWM
dutycycleofthedrive,indirectlycontrollingtheoutputvoltage.However,anyfluctuationsof
theDCpowersupplyvoltagewillaffectthevoltageoutputtothemotor.Thismodeisavailable
asaDIPswitchselectablemodeonAZBExxA8andAZBHxxA8drives.
This mode is recommended as a method of controlling the m
otor
velocity when precise velocity control is not critical to the application,
and when actual velocity feedback is unavailable.
Hall Velocity
InHallVelocityMode,theinputcommandvoltagecontrolsthemotorvelocity,withtheHall
Sensorfrequencyclosingthevelocityloop.Ananalogvelocitymonitoroutputallows
observationoftheactualmotorspeedthroughaHz/Vscalingfactorfoundonthedrive
datasheet.Thevoltagevaluereadatthevelocitymonitoroutputcanbeusedtodeterminethe
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