Determination of rotor eddy current losses in permanent magnet machines

A method has been presented for the calculation of losses in the sleeves of permanent magnet machines, and validated against a set of measurements. Subsequent simulation work has revealed the following conclusions regarding losses in non nonmagnetic and magnetic sleeves. At high speeds the eddy currents in a nonmagnetic sleeve are resistance limited. The eddy currents in a magnetic sleeve are skin limited. Losses in magnetic sleeves are considerably greater than in nonmagnetic sleeves. The loss in the sleeve of either material rises with the sleeve thickness. Buried magnet designs with nonmagnetic sleeves have significantly greater loss than their surface mounted design counterparts. Sleeve loss can be dramatically reduced if the slot opening is reduced. >