Servomotor

Mr. C.S.Satheesh, M.E.,
Servomotor
Control motors
Two Phase AC Servo Motor
Three Phase AC Servo Motor
DC Servo Motor
AC Servo Motor
Control Type Synchro.
Torque Transmission Type Synchro
Synchros

1. Servomotor
Presented by
Mr.C.S.Satheesh, M.E.,
Assistant Professor, Department of EEE,
MuthayammalEngineering College (Autonomous),
Namakkal(Dt), Rasipuram–637408.
MUTHAYAMMAL ENGINEERING COLLEGE
(An Autonomous Institution)
(Approved by AICTE, New Delhi, Accredited by NAAC, NBA & Affiliated to Anna University),
Rasipuram -637 408, NamakkalDist., Tamil Nadu, India.

2. Servo motor
Servo Motorare also called Control motors.
They are used in feedback control systems as output actuators and
does not use for continuous energy conversion.
Aservomotorisarotaryactuatororlinearactuatorthatallowsfor
precisecontrolofangularorlinearposition,velocityand
acceleration.
TheprincipleoftheServomotorissimilartothatoftheother
electromagneticmotor,buttheconstructionandtheoperationare
different.

3. Therotorinertiaofthemotorsislowandhaveahighspeedof
response.
TherotoroftheMotorhasthelonglengthandsmallerdiameter.
Theyoperateatverylowspeedandsometimesevenatthezero
speed.
Thepowerratingoftheservomotormayvaryfromthefractionof
wattstofewhundredsofwatts.
Therotorofservomotorhavelowinertiastrength,andtherefore
theyhaveahighspeedofinertia.

4. Applications of the Servo Motor
TheyareusedinRadarsystemandprocess
controller.
Servomotorsareusedincomputersandrobotics.
Theyarealsousedinmachinetools.
Trackingandguidancesystems.

5. Classification of Servo Motor
They are classified as AC and DC Servo Motor.
The AC servomotor is further divided into two types.
Two Phase AC Servo Motor
Three Phase AC Servo Motor

6. DC Servo Motor
DCServoMotorsareseparatelyexcitedDCmotoror
permanentmagnetDCmotors.
Thefigure(a)showstheconnectionofSeparatelyExcited
DCServomotorandthefigure(b)showsthearmatureMMF
andtheexcitationfieldMMFinquadratureinaDCmachine.

7. Thisprovidesafasttorqueresponsebecausetorqueandfluxare
decoupled.Therefore,asmallchangeinthearmaturevoltageorcurrent
bringsasignificantshiftinthepositionorspeedoftherotor.Mostofthe
highpowerservomotorsaremainlyDC.
TheTorque-SpeedCharacteristicsoftheMotorisshownbelow.

8. Asfromtheabovecharacteristics,itisseenthattheslopeis
negative.Thus,anegativeslopeprovidesviscousdampingforthe
servodrivesystem.
AC Servo Motor
TheACServoMotorsaredividedintotwotypes2and3PhaseAC
servomotor.MostoftheACservomotorareofthetwo-phase
squirrelcageinductionmotortype.
Theyareusedforlowpowerapplications.Thethreephasesquirrel
cageinductionmotorisnowutilizedfortheapplicationswhere
highpowersystemisrequired

9. Difference between AC & DC servo motor

11. Itisusedasanerrordetectorandasarotarypositionsensor.
SynchrosSystem Types:
The synchrosystem is of two types. They are
1. Control Type Synchro.
2. Torque Transmission Type Synchro.
1. Torque Transmission Type Synchros:
This type of synchroshas small output torque, and hence
they are used for running the very light load like a pointer.

12. 2. Control Type SynchrosSystem:
The control type Synchrois used for driving the large loads.
The controls synchrosis used for error detection in positional
control systems.
The synchroalways works with these two parts.
The two main parts of the synchroare
1. Transmitterand
2. Controltransformer

16. Advantages of using a Synchro
Synchro'shave a low failure rate.
Synchrosand resolvers have a very long life expectancy
as they are inductive devices.
As soon as transmission is engaged, the Synchrowill align
to the correct positioning and therefore isself-
synchronising.
No mechanical stops.

17. References :
A.Nagoorkani, Control Systems,
RBA Publications.
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18. Thank You
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