Synchronous motors. A synchronous engine is one where the rotor normally rotates at the same rate as the revolving field in the device. The stator is similar to that of an induction machine comprising a cylindrical iron body with windings, generally three-phase, positioned in slots around the internal periphery.
usually, synchronous motors are used for applications where precise and constant speed is required. Low power applications of these motors include positioning Stainless Steel Chain machines. These are also used in robot actuators. Ball mills, clocks, record participant turntables also utilize synchronous motors.
The principle of operation of a synchronous motor can be understood by taking into consideration the stator windings to be linked to a three-phase alternating-current supply. The effect of the stator current 
is definitely to establish a magnetic field rotating at 120 f/p revolutions per minute for a frequency of f hertz and for p poles. A primary current in a p-pole field winding on the rotor may also create a magnetic field rotating at rotor speed. If the rotor speed is made equal to that of the stator field and there is no load torque, these two magnetic fields will have a tendency to align with one another. As mechanical load is certainly applied, the rotor slips back again numerous degrees with regards to the rotating field of the stator, developing torque and continuing to be drawn around by this rotating field. The position between the fields raises as load torque is certainly increased. The utmost available torque is achieved when the angle by which the rotor field lags the stator field is certainly 90°. Software of more load torque will stall the motor.
One benefit of the synchronous motor is definitely that the magnetic field of the machine can be produced by the immediate current in the field winding, to ensure that the stator windings need to provide just a power element of current in phase with the applied stator voltage-i.e., the electric motor can operate at unity power factor. This problem minimizes the losses and heating system in the stator windings.