Difference Between Synchronous motor and Induction Motor

Difference between Synchronous motor and Induction Motor:

In this we are going to see the main difference between the synchronous motor and induction motors. Synchronous motors are rotating the speed of the rotating magnetic field, the speed is constant, it has only one speed which means the speed of the motor always synchronized with supply frequency.

Induction Motor is working under the principle of the rotating transformer; the rotor magnetic flux always tries to catch the stator magnetic field. Since the speed of the induction motor is less than the synchronous speed of the motor. The synchronous speed of the motor is Ns=120f/P

1. 1. For given frequency synchronous motor runs at a constant speed (synchronous speed), the speed of the motor does not depend on the motor Load. Wherever in induction motor speed decreases as increasing the motor load. The principle of induction motor is to catch the motor’s synchronous speed; the rotating magnetic field tries to catch its original synchronous speed.
   2. Motor Power factor: The synchronous motor can be operated both leading and lagging power factor according to its excitation, but induction motor cannot be operated at leading power factor, induction operates at lagging power factor.
   3. Synchronous motors are doubly excited motors which means it needs two windings and two separate excitations it needs, whereas squirrel cage induction motors are having only single winding. But slip ring induction motors are having a double winding, which has wound rotor to increase the resistance of the rotor winding, however, these motors are not required separate excitation system like an asynchronous motor. Stator applied voltage is enough to run the motor.
   4. Synchronous motor can be operated as generator to supply electricity, but induction motor never produces electricity, it consumes electricity.
   5. Synchronous motors are not self-starting motors, where’s induction motors are self-starting motors, it does not require a piece of separate staring equipment.
   6. Synchronous motors are having better efficiency, than induction motors
   7. Synchronous motors are costlier, almost 25% of the motors cost goes to rotor windings, but induction motors are cheaper
   8. It is used in constant speed application; the speed of the induction motor can be variable.