Asynchronous electric motors

An asynchronous motor or induction motor is a type of alternating current (AC) electric motor where the rotor is not in phase with the rotating magnetic field of the stator. This means that the speed of the rotor is always slightly lower than the speed of the rotating magnetic field, hence the term ‘asynchronous’. Asynchronous motors can be single-phase or three-phase.

Stator

The stator of an asynchronous motor is the fixed part of the electric motor, made up of wire coils wound around iron poles. When an alternating current passes through these coils, it generates a rotating magnetic field.

Rotor

The rotor is the moving part of the asynchronous motor. There are two types of rotor used in asynchronous motors: the squirrel-cage rotor, the most common, made up of conductor bars embedded in slots and connected by rings at each end, and the wound rotor, made up of wire coils wound around an iron core, connected to commutator rings.

Enclosure

The asynchronous motor casing houses and protects the stator and rotor, providing a stable structure for the motor.

Creation of the magnetic field

When an alternating current passes through the stator coils, a rotating magnetic field is created.

Electromagnetic induction

The rotating magnetic field of the stator induces a current in the rotor bars in the case of a squirrel cage rotor, or in the rotor coils in the case of a wound rotor.

Torque generation

The current induced in the rotor creates its own magnetic field. This field interacts with the magnetic field of the stator, producing a force that turns the rotor.

Phase shift or slip

The speed of rotation of the rotor is always slightly lower than the speed of the rotating magnetic field of the stator. This difference in speed, known as slip, is essential for current induction in the rotor.

Asynchronous motors are widely used in many industrial applications. Asynchronous motors are reliable, economical motors that are widely used in many applications because of their simplicity and robustness.