Publish Time: 2023-10-15 Origin: Site
This article will give a brief introduction to the basic principles of asynchronous electric motors, how they work, and what is slip rate.
Here is the list
how does this work
slip rate
The above picture is the working principle diagram of the asynchronous electric motor, which consists of two parts, the stator and the rotor, and there is a small air gap between them.
(1) The symmetrical three-phase windings of the stator are connected to the symmetrical three-phase alternating current, and the three-phase composite rotating electromotive force of the stator is established to generate a rotating magnetic field. The dotted line in the figure represents the magnetic flux of the rotating magnetic field of the stator at a certain moment. It rotates clockwise at synchronous speed n1. The rotor conductor cuts off the magnetic field to generate an induced electromotive force. The direction of the induced electromotive force can be determined by the right-hand rule. The electromotive force creates a current in the closed-circuit rotor winding. .
(2) The current-carrying rotor winding is subjected to electromagnetic force in the rotating magnetic field. Using the left-hand rule, it can be determined that the rotor winding is subjected to electromagnetic force and electromagnetic torque in a clockwise direction, so that the rotor follows the stator at a speed n. The direction of the rotating magnetic field rotates.
(3) The rotor speed n of the asynchronous electric motor cannot be equal to the stator rotating magnetic field speed n1, because if n=n1, there is no relative motion between the rotor and the stator rotating magnetic field, and there is no induced electromotive force and induced current in the rotor windings. Therefore, during the operation of the asynchronous electric motor, there is a difference between the rotor speed n and the stator rotating magnetic field speed n1, and n is always less than n1, and the name "asynchronous" comes from this.
(1) There is a speed difference between the rotor speed n of the asynchronous electric motor and the speed n1 of the stator rotating magnetic field. This speed difference is the speed at which the rotating magnetic field of the stator cuts the rotor conductors. Its size determines the size of the rotor electromotive force and its frequency, which directly affects the working state of the asynchronous electric motor. The speed difference can be represented by the important physical quantity of slip s: s=(n1-n)/n1
(2) When the rotating magnetic field starts to rotate at the synchronous speed n1, the rotor has not yet rotated due to mechanical inertia, the instantaneous speed of the rotor is n=0, and the slip ratio is s=1 time. After the rotor rotates, n>0, the difference (n1-n) decreases, and the electric motor slip is s<1. If the resistance torque on the rotating shaft increases, the rotor speed n decreases, that is, the asynchronous degree increases, so that a sufficiently large induced electromotive force and induced current can be generated, so that a sufficiently large electromagnetic torque can be generated. At this time, the slip ratio s increases. 0<s<1 when the asynchronous electric motor is running. Under rated load operating conditions, s=0.01~0.06.
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