Numerical Modeling of Excess Loss in SiFe Sheet Considering Pinning Effect

Compared with grain-oriented SiFe sheets, the domain structure of nonoriented (NO) SiFe sheets is very different, and the magnetization processes of NO SiFe sheets are much less investigated. Thus, the excess loss of NO SiFe sheets is less well-known. In this paper, we propose a numerical method to estimate the excess loss in NO SiFe sheets, considering the pinning and skin effects. We apply an initial magnetic field distribution that reflects the pinning effect in our nonlinear eddy current finite element analysis model, which reflects the skin effect of the magnetic flux. Thus, the pinning effect can be coupled with the skin effect in the proposed numerical method. The hysteresis loss and eddy current loss calculated from the flux and eddy current distributions are directly obtained from the proposed analysis method. Thus, excess loss is included in both the hysteresis and the eddy current loss calculations. We first apply the proposed method to two different grades of NO SiFe sheets. The calculated iron losses in one sheet are compared at various frequencies with the measured losses from catalogue data, and less than 2% deviation can be achieved. Finally, we apply the proposed method to the loss calculation for the iron core of a reactor.