D

1. SERVO MOTORS

2. • Servo motors are also called Control motors. They are used in feedback control
systems as output actuators and does not use for continuous energy conversion.
• The principle of the Servomotor is similar to that of the other electromagnetic
motor, but the construction and the operation are different. Their power rating
varies from a fraction of a watt to a few hundred watts.
• They operate at very low speed and sometimes even at zero speed. The servo
motor is widely used in radar and computers, robots, machine tools, tracking and
guidance systems, processing controlling, etc.

3. • A servomotor is a linear actuator or rotary actuator that allows for precise control of linear or
angular position, acceleration, and velocity.
• It consists of a motor coupled to a sensor for position feedback. It also requires a relatively
sophisticated controller, often a dedicated module designed specifically for use with
servomotors.
• There are some special types of applications of an electric motor where the rotation of the
motor is required for just a certain angle. For these applications, we require some special types
of motor with some special arrangement which makes the motor rotate a certain angle for a
given electrical input (signal). For this purpose, servo motor comes into the picture.

4. Applications of the Servo Motor
The power rating of the servo motor may vary from the fraction of watts to a few hundred
watts. The rotor of the servo motor has low inertia strength, and therefore they have a high
speed of inertia. The Applications of the Servomotor are as follows:
• They are used in Radar systems and process controllers.
• Servomotors are used in computers and robotics.
• They are also used in machine tools.
• Tracking and guidance systems.
• Toy cars for controlling the direction of motion.
• It is also very widely used as the motor which moves the tray of a CD or DVD player.

5. • The main reason behind using a servo is that it provides angular precision, i.e. it
will only rotate as much we want and then stop and wait for the next signal to
take further action.
• The servo motor is unlike a standard electric motor which starts turning as
when we apply power to it, and the rotation continues until we switch off the
power.
• We cannot control the rotational progress of electrical motor, but we can only
control the speed of rotation and can turn it ON and OFF.

7. • A servo (servomechanism) is an electromagnetic device that converts electricity
into precise controlled motion by use of negative feedback mechanisms.
• Servos can be used to generate linear or circular motion, depending on their type.
In other words, servo motors get their name from the fact that they can be relied
upon to operate "exactly as commanded". Any electric motor capable of
controlling parameters like position and speed is called a servo motor, regardless
of how this control is achieved
• The main function of the servo motor is to convert the control signal of the
controller into the rotational angular displacement or angular velocity of the motor
output shaft.

8. CLASSIFICATION

33. SYNCHROS
SYNCHRO TRANSMITTER

36. • The coils in the stator link with this sinusoidal distributed magnetic flux and voltages
are induced in the three coils due to transformer action.
• The three voltages are in time phase with each other and the rotor voltage.
• The magnitudes of the voltages are proportional to the cosine of the angle between the
rotor position and the respective coil axis.

37. SYNCHRO CONTROL TRANSFORMER

38. SYNCHRO ERROR DETECTOR

39. • Let the transmitter rotate through an angle 𝜃 in the direction indicated and let
the control transformer rotor rotate in the same direction through an angle 𝛼
• Net angular separation of the 2 rotors = ( 90° - 𝜃 + 𝛼)
• The general voltage across the rotor terminals of the control transformer is
E(t) = 𝐾𝐼
𝑣𝑟 cos ∅ sin 𝜔0𝑡
• Substituting the value of ∅,
• E(t) = 𝐾𝐼 𝑣𝑟 sin(𝜃 - 𝛼) sin 𝜔0𝑡