Magnetic Characteristics and Excess Eddy Current Losses

To study the fundamental essence of excess losses and to achieve an accurate core loss separation formula, a dynamic finite element model for the non-linear 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, especially excess losses, affected by the magnetic characteristics are carefully examined. It is concluded that excess current losses are due to the non-uniform magnetic field distribution resulting from the skin effect and the non-linear diffusion of magnetic flux from the boundary to the inside of the lamination.