An induction electric motor or 3 phase induction motor 
is an AC electric engine in which the electric current in the rotor had a need to create torque is obtained by electromagnetic induction from the magnetic field of the stator winding
An induction engine which connects with a 3-stage supply called 3-stage induction motor. Three Phase Motor Example fans,blowers, cranes,traction .It really is a ac engine. The primary drawback of DC motors may be the existence of commutator and brushes, which require frequent maintenance and we can not use DC motor in explosive and dirty environment. But induction motors are cheaper,tough,lighter,smaller,require much less maintenance and may use in dirty and explosive environment. Slip s is the imp factor in this type of motor.
There are 2 types of IM.
Squirrel cage IM
Slip ring IM
There are various starting and braking condition.
Important starting methods are
Star-delta starter
Auto transformer starter
Ac voltage controller starter
Rotor resistance starter
Important braking methods are
Regenerative braking
Plugging or invert voltage braking
Dynamic braking
But one thing speed control technique of induction engine is important
Pole changing
Stator voltage control
V/f control
Slip power recovery
Rotor resistance control