Calculation of No-Load Rotor Eddy-Current Power Loss in PM Synchronous Machines

Abstract

Three analytical methods, and finite-element analysis (FEA), are used to calculate no-load flux harmonics traveling with respect to the rotor of a surface permanent magnet machine. Rotor eddy-current losses caused by each harmonic are calculated analytically using a multilayer eddy-current model of the machine, in which each harmonic is represented by an equivalent current sheet on the bore of a slotless stator. Losses are also calculated using transient time-stepping FEA coupled with the equation of motion of the rotor. Significant discrepancies are observed between the results obtained from the different methods and FEA, especially when the level of saturation in the stator core is significant.