Electrical machines are categorized into two..

Motor.
Generator.
There are two types of motor.

AC motor.
DC motor.
There are two kinds of three phase motor.

Synchronous motor.
12v Motor asynchronous motor.
The basic difference between asynchronous and synchronous electric motor , slip presents in asynchronous electric motor .At running condition slip of an asynchronous engine lies from 0 to at least one 1. . In asynchronous motor both starting and operating torque is necessary. Asynchronous motor has moderate beginning torque . Asynchronous motor is usually a single fed electric motor.In asynchronous motor field is stationary armature rotates .

Three phase synchronous machines have got a stationary three phase armature and a wound rotor. They are of two types:

synchronous generator or Alternator: Primary workhorse of the energy generation industry; they are rotated mechanically by a prime mover at synchronous swiftness and it generates three phase electricity. Picture of PMA used in cars:
2. Synchronous motor: These are constant speed three phase machines capable of working at synchronous speed. They are mostly used in constant velocity mechanical drives. They are more efficient in comparison to induction motors.
A synchronous machine has derived its name from the idea that the rotor will rotate in synchronicity with the rotating magnetic field.

Simply speaking, for a 2 Pole machine (electric motor) the rotating magnetic field rotates at 3000 rpm; the rotor of synchronous machine also rotates at the same velocity i.electronic. 3000 rpm. This is achieved through unique constructional features in production this types of machines. There is no slip in synchronous devices like regular induction motors.

Normally three phase supply is available commercially and the look is also designed for the same. This is why ‘three phase’ is certainly added with synchronous machine name.