The principle of asynchronous and synchronous motors are both based on the law of electromagnetic induction. The difference is that the symmetrical three-phase windings of the asynchronous motor are connected to the AC power supply. Even if the stator does not roll, a rotating magnetic field will occur because of the AC power supply. At this moment, the current will occur in the closed winding circuit. Therefore, according to the left-hand screw rule, the effect of the force on the current carry