Working principle of three-phase external rotor motor.

The working principle of a three-phase external rotor motor is based on the principle of electromagnetic induction, and the rotor is driven to rotate through the rotating magnetic field generated by the three-phase alternating current. Specifically, when a three-phase AC power supply is applied to the stator coil of the three-phase external rotor motor, a rotating magnetic field will be formed. This rotating magnetic field is formed by superposition of the magnetic fields generated by the three-phase current in the stator coil, and its rotation speed is related to the power supply frequency and the number of poles of the stator winding. Since the rotor of the outer rotor motor is located outside the stator, the conductor circuit in the rotor is passed through by a rotating magnetic field. When the rotating magnetic field cuts the rotor conductor, an electromotive force is induced in the conductor, thereby generating an induced current on the conductor. This induced current forms another magnetic field in the rotor, interacting with the rotating magnetic field to generate electromagnetic force. This electromagnetic force acts on the rotor shaft, forming an electromagnetic torque, which drives the rotor to rotate in the direction of the rotating magnetic field. Therefore, the working principle of a three-phase external rotor motor can be summarized as: cutting the rotor conductor through the rotating magnetic field generated by the three-phase alternating current, inducing the electromotive force and current, and then generating electromagnetic force to drive the rotor to rotate.