Asynchronous motors are widely used in various fields. The working principle of asynchronous motors is mainly based on the phenomenon of electromagnetic induction. The specific process is as follows:
1. The stator generates a rotating magnetic field，When three-phase alternating current is passed through the stator winding, a rotating magnetic field is produced. The rotational speed of this magnetic field is called the synchronous rotational speed, denoted by the symbol n.
2. Rotor induced electromotive force and current，As the rotor conductors are initially stationary, there is a relative motion between the rotor conductors and the rotating magnetic field of the stator, causing the rotor conductors to cut the magnetic field lines and thereby generating an induced electromotive force in the rotor windings. The direction of the induced electromotive force can be determined by the right-hand rule. Since the rotor winding is closed, an induced current will be generated in the rotor conductors under the action of the induced electromotive force.
3. Generation of electromagnetic torque，The induced current in the rotor interacts with the rotating magnetic field of the stator. According to the left-hand rule, the rotor conductors are subjected to electromagnetic force, which generates an electromagnetic torque on the rotor shaft, driving the rotor to rotate along the direction of the rotating magnetic field.
4. Asynchronous operation， The rotational speed n of the rotor is always slightly lower than the synchronous speed n1 of the stator magnetic field. This is because if the two speeds were the same, the rotor conductors would no longer cut the magnetic field lines, and no induced electromotive force or current could be generated, and thus no electromagnetic torque could be produced. This rotational speed difference is called the slip rate and is one of the important characteristics of asynchronous motors.
Asynchronous motors, with their advantages such as simple structure, reliable operation and low cost, are widely used in various fields including industry, agriculture and transportation, and are indispensable power equipment in modern society.
