(1) In the three-phase symmetric wi

(1) In the three-phase symmetric winding, the three-phase symmetric current generates the circular rotating magnetic field with asynchronous speedN = 60 f/pWhere, F is the power frequency and the unit is Hertz; P is the number of magnetic poles of the motor(2) Induction electromotive force and current generated by rotor conductor cutting rotating magnetic field(3) The rotor current-carrying conductor is affected by the electromagnetic force in the magnetic field to form electromagnetic torque and drive the rotor of the motor to rotate. Its velocity n is less than the synchronization velocity n1. The rotational speed of an asynchronous motor cannot reach the rotational speed of the stator rotating magnetic field, that is, the synchronous speed, because if the rotational speed reaches the same step, there is no long-distance movement. The rotating magnetic field is relative to the rotor conductor, and then electromotive force and current are induced in the rotor. Electromagnetic force will not be generated directly.(4) The rotation direction of the asynchronous motor is always consistent with the rotation direction of the rotating magnetic field, which depends on the three-phase current phase sequence of the asynchronous motor. Therefore, the rotation direction of three-phase asynchronous motor is caused by the phase sequence of current. By changing the rotation direction of the motor, the phase sequence of the current can be changed. In other words, the two power lines of the motor can be adjusted arbitrarily to make the motor reverse.(iii) Motor classificationMotors are widely used with many kinds, different performance and many classification methods.(1) According to the structure and working principle, dc motor can be divided into brushless DC motor and brushless DC motor.(2) Brushless DC motor can be divided into permanent magnet DC motor and electromagnetic DC motor.(3) Electromagnetic DC motor can be divided into series DC motor, parallel DC motor, other DC motor and composite DC motor.(4) Permanent magnet DC motor Business Department: Rare earth permanent magnet DC motor, ferrite DC motor.