Shielding Cylinder Effect in High-Speed Electric Machines

B. Hannon[1], P. Sergeant[1]
[1]Ghent University, Ghent, Belgium
Published in 2013

In the field of electric machines, a trend towards both higher efficiency and higher power density is observed. This has led to a growing importance of Permanent Magnet Synchronous Machines. However, the magnets used in these machines risk demagnetization at high temperatures. Especially in machines operated at high speeds.

A commonly proposed solution is the shielding cylinder (SC), a conductive sleeve wrapped around the magnets. At the one hand eddy currents are induced in this shielding cylinder, resulting in additional loss. But at the other hand unwanted harmonics in the rotor field are suppressed by the shielding cylinder’s magnetic field, reducing the rotor’s eddy-current losses.

This work studies the effect of the SC on the rotor losses.