The forecasting method of core loss under DC bias based on the jiles atherton hysteresis theory

The exciting current distortion and significant loss increment of transformer due to DC bias can result in overheating and insulation aging. To analyze the effect of DC bias on the core loss of transformer, the forecasting method of core loss under DC bias was proposed based on the Jiles Atherton (JA) hysteresis theory. Firstly, depending on the JA hysteresis theory and the Bertotti's field separation approach, the dynamic hysteresis model was established without DC bias considering the eddy current and the anomalous loss, and the model parameters were identified. Secondly, the hysteresis loop measuring system under DC bias was built by adopting Epstein frame and power inverter, where the hysteresis loops were measured under different DC bias, and the identification results of model parameters were obtained. Finally, the influence of DC bias on the parameters of the dynamic hysteresis model was analyzed, and the dynamic loss coefficient was fitted, according to which the dynamic hysteresis model was modified. Then the forecasting method of core loss was proposed under DC bias. The method in this paper is verified by the comparison between the calculated and experimental results. © 2017 Chin. Soc. for Elec. Eng.