Introduction:
In electrical engineering, various types of motors are used for different applications. One important classification of motors is based on the interaction between the stator field and the rotor field. In some motors, the stator field and rotor field rotate simultaneously, while in others they do not. In this context, we will discuss the motor in which the stator and rotor fields rotate simultaneously.

Synchronous Motor:
The motor in which the stator and rotor fields rotate simultaneously is called a synchronous motor. It is a type of AC motor that operates at a constant speed with respect to the frequency of the applied voltage. The speed of the motor is synchronized with the rotating magnetic field produced by the stator.

Working Principle:
The working principle of a synchronous motor is based on the interaction between the stator and rotor fields. The stator field is produced by the three-phase AC supply, which creates a rotating magnetic field. The rotor field is produced by the direct current flowing through the rotor windings.

Simultaneous Rotation:
In a synchronous motor, the stator field and rotor field rotate simultaneously due to the magnetic locking effect. When the rotor field is magnetically locked with the stator field, the rotor starts rotating at the same speed as the stator field. This synchronous rotation is achieved by adjusting the excitation of the rotor field.

Applications:
Synchronous motors are commonly used in various applications, including:
1. Power generation: Synchronous generators are used in power plants to convert mechanical energy into electrical energy.
2. Industrial machinery: Synchronous motors are used in industrial machinery such as compressors, pumps, and fans.
3. Electric vehicles: Synchronous motors are used in electric vehicles for propulsion.
4. Robotics: Synchronous motors are used in robotic systems for precise motion control.

Conclusion:
In summary, the synchronous motor is the type of motor in which the stator and rotor fields rotate simultaneously. This synchronous rotation is achieved by magnetically locking the rotor field with the rotating stator field. Synchronous motors are widely used in various applications that require precise speed control and synchronization with the power supply frequency.