classification of ac motors

Here present the knowledge about the definition of ac motors and classification of ac motors. And working principle

Defination: Ac motor is an electric motor that is driven by alternating current. The basic principle of AC motor is convert electrical energy into machanical energy.

➡Ac motors can be classified on the basis of following:
⏩Based on their principle of operation
(A) synchronous motors:-

synchronous motor is an ac motor which converts electrical energy into mechanical energy while rotating at a constant speed equal to synchronous speed.
Synchronous motors are constant speed motors.
They operate in synchronism with the line frequency and are commonly used where precise constant is required.

(B) asynchronous motors:-

The asynchronous motor is an ac motor in which the rotor rotates at a speed slightly less than the synchronous speed.
An induction motor is also called asynchronous motor as it does not run at synchronous speed.
There are two type of asynchronous motor.

(A) induction motor

(1) squirrel cage type

(2) slip - ring or wound rotor

(B) commutator motors

⏩ based on the nature of current

(1) single phase

(2) three phase

⏩ based on their speed

(1) constant speed

(2) variable speed

(3) adjustable speed

⏹Working principle:

The basic principle of induction motor is to power takes place in the rotating part of the motor.
In induction motor there is no electrical connection to the rotor i.e. no supply is given to rotor from any external source of supply, but the current which includes in the rotor conductors is by the relative motion of the rotor conductors and the stator rotating magnetic field.
The rotor does not receive electric power by conduction but by induction.That is why this AC motor is called an induction motor
The three phase induction motor operates on the principle of mutual induction.When the 3-Phase stator winding of a three phase induction motor is supplied by a 3-Phase AC supply, a rotating magnetic field of constant magnitude is set up,which rotates at constant speed equal to synchronous speed.
This rotating flux cuts the stationary rotor conductors and induces e.m.f. in them by mutual induction.
Due to the relative speed between the rotating magnetic field of the stator and the stationary rotor conductors, an e.m.f. is induced in the rotor conductors.
This e.m.f.causes the heavy circulating current to flow due to very small resistance of the rotor and also the rotor circuit is closed.
The frequency of the induced e.m.f. or current at the time of starting is equal to the supply frequency.
The rotor induced current,according to Lenz's law flows in such a direction that it opposes the cause, which is inducing the current.In three phase induction motor,the cause producing the currents in the rotor is the relative speed between the rotating magnetic field of stator and the stationary rotor conductors.