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,
Muthayammal Engineering 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, Namakkal Dist., Tamil Nadu, India.

2. Servo motor
 Servo Motor are also called Control motors.
 They are used in feedback control systems as output actuators and
does not use for continuous energy conversion.
 A servomotor is a rotary actuator or linear actuator that allows for
precise control of angular or linear position, velocity and
acceleration.
 The principle of the Servomotor is similar to that of the other
electromagnetic motor, but the construction and the operation are
different.

3.  The rotor inertia of the motors is low and have a high speed of
response.
 The rotor of the Motor has the long length and smaller diameter.
They operate at very low speed and sometimes even at the zero
speed.
 The power rating of the servo motor may vary from the fraction of
watts to few hundreds of watts.
 The rotor of servo motor have low inertia strength, and therefore
they have a high speed of inertia.

4. Applications of the Servo Motor
 They are used in Radar system and process
controller.
 Servomotors are used in computers and robotics.
 They are also used in machine tools.
 Tracking and guidance systems.

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
 DC Servo Motors are separately excited DC motor or
permanent magnet DC motors.
 The figure (a) shows the connection of Separately Excited
DC Servo motor and the figure (b) shows the armature MMF
and the excitation field MMF in quadrature in a DC machine.

7.  This provides a fast torque response because torque and flux are
decoupled. Therefore, a small change in the armature voltage or current
brings a significant shift in the position or speed of the rotor. Most of the
high power servo motors are mainly DC.
 The Torque-Speed Characteristics of the Motor is shown below.

8.  As from the above characteristics, it is seen that the slope is
negative. Thus, a negative slope provides viscous damping for the
servo drive system.
AC Servo Motor
 The AC Servo Motors are divided into two types 2 and 3 Phase AC
servomotor. Most of the AC servomotor are of the two-phase
squirrel cage induction motor type.
 They are used for low power applications. The three phase squirrel
cage induction motor is now utilized for the applications where
high power system is required

9. Difference between AC & DC servo motor

11. It is used as an error detector and as a rotary position sensor.
Synchros System Types:
 The synchro system is of two types. They are
1. Control Type Synchro.
2. Torque Transmission Type Synchro.
1. Torque Transmission Type Synchros:
 This type of synchros has small output torque, and hence
they are used for running the very light load like a pointer.

12. 2. Control Type Synchros System:
 The control type Synchro is used for driving the large loads.
The controls synchros is used for error detection in positional
control systems.
The synchro always works with these two parts.
The two main parts of the synchro are
1. Transmitter and
2. Control transformer

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

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