Hybrid Approach for Determining Eddy-Current Losses in High-Speed PM Rotors

Abstract

This paper presents a novel method for calculating rotor eddy-current losses of PM machines using an analytically derived current sheet (2D) in combination with commercially available FE software (3D). First, an equation-based approach is used to determine the total magnetic field at the stator inner diameter. A 2D current sheet is formulated from the total field in the rotor reference frame. Next, the 2D current sheet is extended axially and used in a 3D FE analysis of the machines un-magnetized rotor. Using this procedure, rotor loss caused by armature current time harmonics, slot permeance variation and winding MMF harmonics has been calculated that properly considers axial variation with limited computing resources.