The electromagnetic speed regulating motor consists of cage motor, electromagnetic slip clutch and DC excitation power supply (controller). The power of DC excitation power supply is small, which is usually composed of single-phase half-wave or full-wave thyristor rectifier. Changing the conduction angle of thyristor can change the magnitude of excitation current. The electromagnetic slip clutch is composed of armature, magnetic pole and excitation winding. The armature has no mechanical connection with the latter and can rotate freely. The armature is coaxial with the motor rotor to weigh the active part, which is driven by the motor, and the magnetic pole is connected with the load shaft to connect and weigh the follower part.

When both the armature and the pole are static, if the excitation winding is DC, a number of pairs of N, S polar poles will be formed along the circular surface of the air gap, and the magnetic flux will pass through the armature. When the armature rotates with the driving motor, the armature induction vortex is produced because of the relative motion between the armature and the magnetic pole, and the interaction between the vortex and the flux produces torque, which drives the rotor with the magnetic pole to rotate in the same direction, but its rotating speed is always lower than the armature speed N1. This is a kind of slip speed regulation mode, which can change the output torque and speed of the clutch by changing the DC excitation current of the slip clutch. The method is suitable for medium and low power, and requires smooth movement. Short-term and low-speed operation of production machinery.

The speed regulation characteristics of electromagnetic speed regulation motor are as follows. 

1, The structure and control circuit of the device is simple, the operation is reliable and the maintenance is convenient. 

2, The speed regulation is smooth and stepless speed regulation. 

3, It has no harmonic effect on the power grid. 

4, The speed loss is large and the efficiency is low.