Three-phase asynchronous motors are widely used in industrial and domestic fields due to their simplicity, reliability, and high efficiency. Their operation relies on the interaction between a rotating magnetic field and induced currents.
The motor consists of two main parts: the stator and the rotor. The stator, a stationary component, has three sets of windings evenly distributed around the inner circumference. These windings are connected to a three-phase alternating current (AC) power supply. When energized, the three-phase AC creates a rotating magnetic field in the stator. This field rotates at a constant speed called the synchronous speed, determined by the frequency of the power supply and the number of pole pairs in the stator windings.
The rotor, a rotating part made of a cylindrical iron core with conductive bars, is placed inside the stator. As the rotating magnetic field cuts through the rotor bars, electromagnetic induction occurs, generating induced currents in the rotor. According to Fleming’s left-hand rule, these induced currents experience a magnetic force in the rotating magnetic field, creating a torque that drives the rotor to rotate.
A key characteristic is the slip—the rotor speed is always slightly lower than the synchronous speed. Without this slip, no relative motion would exist between the magnetic field and the rotor, and no induced currents or torque would be produced. This slip ensures the motor maintains continuous rotation, making three-phase asynchronous motors essential for powering countless machines and equipment.