Modified loss separation in FeSi laminations under arbitrary distorted flux

Accurate iron loss prediction of the laminated transformer cores becomes vital for efficiency improvement and thermal optimization. In this paper, an investigation of the frequency dependence of the excess loss is carried out. The excess loss, which is mostly influenced by the domain motion and relaxation of dynamic magnetizing, is proposed to obey a new nonlinear function of the magnetizing frequency. Two excess loss factors are defined to describe the effect of frequency on dynamic excess magnetizing. A modified piecewise hysteresis loss model is proposed to represent the influence of domain rotation under a strong applied field. Then, a modified loss separation model is proposed under the sinusoidal flux. Furthermore, a correction factor of hysteresis loss is introduced to improve the modified model to predict the harmonic loss, considering the influence of the distorted flux on the hysteresis loss. In this case, the total energy loss can be modeled with a sufficient accuracy even under conditions that the statistical theory of loss is not applicable.