Exploring Permanent Magnet Magnetic Couplings

Magnetic Coupling Machine

Magnetic coupling systems allow torque transmission from a primary driver to a follower/load without any mechanical contact. As the torque could be transmitted across a separation wall, contactless magnetic couplings are well suited for use in isolated systems.

Compared to mechanical couplings, magnetic couplings present many advantages such as protection against overloads, reduced maintenance, and a high tolerance to misalignment between the prime mover and the load.

There are several types of magnetic coupling such as synchronous, eddy current, and reluctance couplers with axial or radial flux directions.

Radial and Axial Flux Synchronous Coupling Machine Types

In the synchronous coupler type, both the drive and the load side of the coupler rotate synchronously, and the poles are paired simultaneously. The torque production results from the magnetic field interaction in the air gap separating the two sides. Hence, the torque applied to one disk is transferred through this air gap to the other disk.

 

Permanent Magnet Arrangement in a Coupling Machine

 

Radial Flux Coaxial Permanent Magnet Coupling

The first synchronous coupling machine design was made of two coaxial inner and outer back iron rings mounted with radially magnetized permanent magnets. Coaxial couplers are generally characterized by the rotation of the inner driver inside the outer follower. This type of coupling is used to produce a larger transmitted torque independent of speed and dependent only on the relative displacement angle of the coupler halves.

The three different configurations were studied to investigate the effect of the number of poles on the coupling performance.