What is the Difference Between Synchronous and Asynchronous Motor?

The main difference between synchronous and asynchronous motors lies in their rotation speed, stator and rotor synchronization, and starting methods. Here are the key differences between the two:

Synchronous Motor:
Rotor speed and stator magnetic field speed are equal, resulting in no slip.
Requires an additional input supply for the rotor to produce a magnetic field.
Has a constant speed that does not depend on the load.
Not self-starting and requires external means for starting.
Examples include brushless motors, variable reluctance motors, switched reluctance motors, and hysteresis motors.
Asynchronous Motor:
Rotor speed is less than the synchronous speed, resulting in slip (slip is always greater than 0).
Does not require an additional input supply for the rotor.
Speed depends on the load, rotor resistance, and slip.
Self-starting and does not require external means for starting.
Also known as an AC induction motor.

In summary, synchronous motors have a constant speed and require an additional input supply for the rotor, while asynchronous motors have a variable speed depending on the load and are self-starting. Synchronous motors are used in specialized applications like power factor correction and driving loads at constant speed, while asynchronous motors are used in various general-purpose applications.

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What is the Difference Between Synchronous and Asynchronous Motor?

Comparative Table: Synchronous vs Asynchronous Motor

Here is a table comparing the key differences between synchronous and asynchronous motors:

Feature	Synchronous Motor	Asynchronous Motor
Definition	A synchronous motor is an AC machine whose rotor speed is synchronized with the rotatory magnetic field of the stator.	An asynchronous motor is an AC machine whose rotor speed is not synchronized with the rotatory magnetic field of the stator.
Speed of Rotor	The rotor speed of the synchronous motor is the same as that of the rotational speed of the stator.	The rotor speed of the asynchronous motor is less than that of the rotational speed of the stator, i.e., N < NS.
Slip	Synchronous motors do not have slip, meaning their rotors move in sync with the stator's magnetic field.	Asynchronous motors have slip, meaning there is a difference between the rotor's speed and the stator's magnetic field speed.
Type	Synchronous motors include brushless motors, variable reluctance motors, switched reluctance motors, and hysteresis motors.	Asynchronous motors are also known as AC induction motors.
Starting	Synchronous motors are not self-starting and require an external means of starting, such as a damper winding to provide starting torque.	Asynchronous motors are self-starting and do not require any additional starting source.
Rotor Supply	The rotor of a synchronous motor requires an extra input supply to produce the rotor magnetic field.	In the case of asynchronous motors, if the rotor is squirrel cage type, only one input supply is required.
Speed and Load	The speed of the synchronous motor does not vary with the variation in the load.	The speed of an asynchronous motor varies with the change in the load.
Applications	Synchronous motors find applications in power factor correction and operation of mechanical loads.	Asynchronous motors are used only to operate mechanical loads.

In summary, the main difference between synchronous and asynchronous motors lies in the speed and synchronization of their rotors compared to the stator's magnetic field. Synchronous motors have a rotor speed that matches the stator's magnetic field, while asynchronous motors have a rotor speed that is less than the stator's magnetic field speed.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.