A synchro control transformer functions as a position transducer and error detector. It detects the difference in angular positions between two shafts to produce an error voltage. A synchro generator has a circular rotor to distribute flux uniformly and high-impedance stator windings to produce sufficient voltage from a single rotor turn. A torque synchro system consists of a torque transmitter connected to a torque receiver. The transmitter rotor is geared to an input, while the receiver rotor synchronizes electrically to transmit the input position. A control transformer produces a sinusoidal output voltage based on the angle difference between its stator and rotor.

1. ICE 3015: CONTROL SYSTEM
COMPONENTS
Class 10: Applications of Synchros
Dr. S. Meenatchisundaram
Email: meenasundar@gmail.com
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

2. Control Transformers:
• A synchro control transformer (CT) functions as a position
transducer and error detector.
• The difference in angular positions of the two shafts is used to
detect error voltage and correction is applied.
• The synchro generator (transmitter) has the following difference:
1. The rotor is circular shape product to distribute uniformly the
magnetic flux in the air gap.
2. The stator windings have a number of turns of fine wire so as
to have a high input impedance drawing very little current.
• In this way sufficient high voltage is sought to be obtained even
for single turns of the rotor.
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

3. Control Transformers:
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

4. Control Transformers:
• The two inputs of the control transformer are the stator voltage
from the synchro transmitter and the position of the two shafts,
which are aligned.
• The stator voltage of the transmitter generated by the rotor of
transmitter is also applied to the stator of the control transformer.
• This set up a magnetic field within the device.
• The rotor of the CT is kept horizontal at right angles to the stator
windings S2 so that zero voltage is induced in the rotor.
• If the aligned shafts of the two Synchros are disturbed and rotor
moves counter clockwise, magnetic flux lines are cut and voltage
is induced in the rotor coil.
• The induced voltage will reach a maximum for rotor position of 90
degree from the horizontal.
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

5. Control Transformers:
• The output voltage of the rotor winding will be sinusoidal and can
be given as
ER = Emax sin (ɵ0 - ɵi)
Where,
Emax – Maximum rotor voltage
ɵ0 - ɵi – difference in angle between CT and CX.
• As the output is sinusoidal, it is non linear but can be considered
as linear for 20°or less.
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

6. Torque Synchro System:
• A torque transmitter (TX) and a torque receiver (TR) make up a
simple torque-synchro system.
• Basically, the electrical construction of synchro transmitters and
receivers is similar, but their intended functions are different.
• The rotor of a synchro transmitter is usually geared to a manual or
mechanical input.
• This gearing may drive a visual indicator showing the value or
quantity being transmitted.
• The rotor of the receiver synchronizes itself electrically with the
position of the rotor of the transmitter and thus responds to the
quantity being transmitted.
• A synchro transmission system consisting of a torque transmitter
connected to a torque receiver (TX-TR) is illustrated in figure.
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

7. Torque Synchro System:
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

8. Torque Synchro System:
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

9. Receiver Rotation:
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

10. Torque Differentials:
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

11. Torque Differentials:
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

12. TX-TDX-TR System Operation:
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

13. TX-TDX-TR System Operation:
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

14. TX-TDX-TR System Operation:
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

15. TX-TDX-TR System Operation:
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018

16. References:
• Navy Electricity and Electronics Training Series (NEETS)
Module 15—Principles of Synchros, Servos, and Gyros
http://www.rfcafe.com/references/electrical/NEETS-
Modules/NEETS-Module-15-1-1-1-10.htm
Control System Components (ICE 3015)
Dr. S.Meenatchisundaram, MIT, Manipal, Aug – Nov 2018