Studying rotor eddy current loss of PM machines using nonlinear FEM including rotor motion

This paper studies distribution of eddy currents and eddy current losses in the rotor of concentrated winding exterior rotor permanent magnet machines in flywheels. The two-dimension nonlinear transient finite element method (FEM) model including rotor motion was used. Influence of slot opening on the eddy current loss in magnets and rotor back iron is investigated. Segmented magnets for reducing the eddy current loss are also surveyed. The proposed approach and results can be used to select the slot opening that minimizes rotor eddy current losses while maximizing the internal voltage. The used method allows monitoring of the eddy current losses in rotor as function of time, rotor speed, operating mode and stator slot opening. It therefore constitutes an indispensable tool in the design of PM machines taking the eddy current losses in the rotor into account.