Basic working principle of three-phase asynchronous motor

A three-phase asynchronous motor is a motor powered by a 380V three-phase AC power supply (with a phase difference of 120 degrees) at the same time. Because the rotor and stator rotating magnetic fields of a three-phase asynchronous motor rotate in the same direction and at different speeds, there is a difference in speed, so it is called a three-phase asynchronous motor. The three-phase asynchronous motor is an induction motor. After the current is applied to the stator, part of the magnetic flux will pass through the short circuit and generate current in it.

The current in the short-circuit ring of the motor hinders the change of the magnetic flux, so that the magnetic flux generated by the part with the short-circuit ring and the part without the short-circuit ring has a phase difference, thereby forming a rotating magnetic field. After energization, due to the relative movement between the rotor and the magnetic field, the rotor windings will induce electromotive force and current. In other words, the rotating magnetic field and the rotor have a relative speed, and interact with the magnetic field to generate electromagnetic torque, which causes the rotor to rotate and realize energy conversion. The working principle of the three-phase asynchronous motor: Assuming that the rotation of the magnetic field is counterclockwise, this is equivalent to the metal frame cutting the magnetic field lines in a clockwise direction relative to the permanent magnet, and marking the metal frame in a small circle in the graphic direction.

At this time, the metal frame has become a conductive conductor, so it will be subjected to the magnetic force of the magnetic field, and the direction of the force can be judged by the left-hand law. The two sides of the metal frame are subjected to two opposite forces f, which generate electromagnetic torque (magnetic moment) relative to the rotating shaft, so that the closed metal frame rotates. The motor rotates in the same direction as the magnetic field, but the permanent magnets rotate. The speed n1 is greater than the speed n at which the metal frame rotates.