Working Principle Of Three-phase Asynchronous Motor

When symmetrical three-phase alternating current is introduced into the stator winding, a rotating magnetic field is generated that rotates clockwise along the inner circular space of the stator and rotor at synchronous speed n1. Due to the rotating magnetic field rotating at n1 speed, the rotor conductor is initially stationary, so the rotor conductor will cut the stator rotating magnetic field and generate induced electromotive force (the direction of induced electromotive force is determined by the right-hand rule). Due to the short-circuit ring at both ends of the rotor conductor, an induced current in the direction of the induced electromotive force will be generated in the rotor conductor. The current carrying conductor of the rotor is subjected to electromagnetic force in the stator magnetic field (the direction of the force is determined by the left-hand rule). Electromagnetic force generates electromagnetic torque on the rotor shaft, driving the rotor to rotate in the direction of the rotating magnetic field.
Based on the above analysis, the working principle of an electric motor can be summarized as follows: when the three-phase stator windings of the motor (each with a difference of 120 degrees in electrical angle) are fed with three-phase symmetrical alternating current, a rotating magnetic field is generated, which cuts the rotor winding and induces current in the rotor winding (the rotor winding is a closed path). The current carrying rotor conductor will generate electromagnetic force under the action of the stator rotating magnetic field, thereby forming electromagnetic torque on the motor shaft, driving the motor to rotate, and the direction of motor rotation is the same as that of the rotating magnetic field.