An induction electric motor which connects with a 3-stage supply called 3-stage induction motor. Example three phase ac induction motor china supporters,blowers, cranes,traction .It really is a ac engine. The primary drawback of DC motors is the presence of commutator and brushes, which require frequent maintenance and we 
can not use DC electric motor in explosive and filthy environment. But induction motors are cheaper,tough,lighter,smaller,require less maintenance and may use in dirty and explosive environment. Slip s may be the imp aspect in this type of motor.
There are 2 types of IM.
Squirrel cage IM
Slip ring IM
There are many 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 motor is important
Pole changing
Stator voltage control
V/f control
Slip power recovery
Rotor resistance control