Magnetic Characteristics and Core Losses in Machine Laminations: High-Frequency Loss Prediction From Low-Frequency Measurements

To study the fundamental essence of core losses and to achieve an accurate core loss separation formula, a dynamic finite-element model for the nonlinear hysteresis loop of laminations has been established. In the model, Maxwell´s equations are solved for the hysteresis character in the magnetic lamination, using the Galerkin finite-element method, where the hysteresis is represented by an energetic hysteresis model. Based on the simulation results, the magnetic characteristics, skin effect, time delay, and magnetic field distribution are discussed. Then, core losses, particularly excess losses, affected by the magnetic characteristics are carefully examined. It is concluded that excess current loss formula is only applicable for the cases where skin effect is negligible and the sum of hysteresis losses and eddy current losses can more generally represent total losses.