How does an electromagnetic variable-speed motor work?

An electromagnetic variable-speed motor consists of a single-speed or multi-speed squirrel-cage asynchronous motor and an electromagnetic slip clutch. Stepless speed control over a wide range is possible through the controller. The clutch is composed of two concentric components that rotate independently: one is called the pole (the inner rotor), and the other is called the armature (the outer rotor). When an alternating current passes through the excitation coil of the pole, a number of pairs of spatial magnetic fields that alternate rapidly are formed along the circumferential surface of the air gap. When the clutch armature drives the motor to rotate, eddy currents are generated within the armature due to the relative movement between the armature and the magnetic field ； This eddy current interacts with the magnetic flux. Torque is generated, causing the magnetic poles to rotate in the same direction; their rotation speed is always lower than that of the armature. By changing the excitation current, the output torque and speed of the clutch can be adjusted.