Computationally efficient 3D FEM rotor eddy-current loss calculation for permanent magnet synchronous machines

Rotor eddy-current loss calculation by means of 3D finite element analysis is often necessary during later design stages of a new machine, but can still be very time-consuming. This paper proposes two FEM-based methods that potentially require less time to solve than a transient model of the complete machine geometry and are relatively straightforward to implement. Both methods apply an airgap boundary condition obtained from a limited number of solutions of a full 3D model, to a model containing only the rotor geometry. An important property of both methods is that they can account for shielding effects in the rotor. The performance of the methods in terms of accuracy and speed is demonstrated and guidelines for implementation are presented, showing that the rotor losses can be calculated 2-3 faster without loss of accuracy. Finally, using the methods a number of rotor loss trends are confirmed.