When a symmetrical three-phase alternating current is transmitted into the three-phase stator winding, a rotating magnetic field is generated which rotates clockwise along the internal circular space of the stator and the rotor at a synchronous speed n1. Since the rotating magnetic field rotates at a speed n1, the rotor conductor is stationary at the beginning, so the rotor conductor will cut the rotating magnetic field of the stator and generate an induced emf (the direction of the induced emf is determined by the right ruler).
Since both ends of the rotor conductor are short-circuited by the short-circuit ring, under the action of the induced electromotive force, an induced current will be generated in the rotor conductor which is basically consistent with the direction of the induced emf. The current-carrying conductors of the rotor are subject to electromagnetic forcesetics in the magnetic field of the stator (the direction of the force is determined by the left-hand rule). The electromagnetic force generates an electromagnetic torque on the rotor shaft, causing the rotor to rotate in the direction of the rotating magnetic field.
Through the above analysis, it can be concluded that the working principle of the motor is as follows: when the three-phase stator winding of the motor (each phase differs by 120 degrees in electrical angle) is powered by three-phase symmetrical alternating current, a rotating magnetic field will be generated. The magnetic field cuts the rotor windings, causing an induced current in the rotor windings (the rotor windings are closed paths).
The current-carrying rotor conductor will generate an electromagnetic force under the action of the rotating magnetic field of the stator, thereby forming an electromagnetic torque on the motor shaft, driving the rotation of the motor, andThe direction of rotation of the motor is the same as the direction of the rotating magnetic field.
Detailed information:
When a single-phase sinusoidal current passes through the stator winding , the motor An alternating magnetic field will be generated. The strength and direction of this magnetic field changes sinusoidally with time, but it is fixed in spatial orientation, so this magnetic field is also called an alternating pulsed magnetic field.
This alternating pulsed magnetic field can be decomposed into two rotating magnetic fields of the same speed and opposite directions. When the rotor is stationary, these two rotating magnetic fields produce two equal and opposite directions in the rotor. the opposing torque makes the resulting torque zero, so the motor cannot rotate.
When we use an external force to turn the motor in a certain direction (tit than clockwise rotation), the movement of the cutting magnetic field lines between the rotor and the clockwise rotating magnetic field becomes smaller. the movement between the rotor and counterclockwise becomes smaller. The movement of the cutting magnetic field lines between the rotating magnetic fields in the direction of rotation becomes larger. In this way, the balance is broken, the total electromagnetic torque generated by the rotor will no longer be zero, and the rotor will rotate in the direction of thrust.
Baidu Encyclopedia - Three-phase motor