The magnetic coupling is mainly composed of copper rotor, permanent magnet rotor and controller. The copper rotor is fixed on the motor shaft, and the permanent magnet rotor is fixed on the load shaft. There is a gap (called air gap) between the copper rotor and the permanent magnet rotor. In this way, the original hard (Mechanical) connection between the motor and the load is changed into soft (magnetic) connection. By adjusting the air gap between the permanent magnet and the copper conductor, the output torque on the load shaft can be changed, so as to realize the change of the load speed. The air gap can be controlled in different ways. The magnetic coupling can be divided into standard type, extended type, torque limiting type, speed regulation type and other different characteristics of magnetic coupling.