The Research of Transient Magnetic Field and Eddy Current Loss of Single Phase Three-Legged Transformer under AC/DC Condition

In order to analyze the local overheating of single phase three-legged transformer under AC/DC condition, the transient magnetic field and eddy current loss in the iron core of transformer are studied. This paper builds a coupling model of electric circuit and magnetic circuit considering nonlinearity of ferromagnetic materials and iron core topology. The distribution and variation of magnetic field and eddy current loss of single phase three-legged transformer are researched. The results show that the amplitudes of magnetic field and eddy current loss in the central leg are greater than those in two side legs without DC, and they grow nonlinearly as DC enlarges. The magnetic field amplitudes in the central leg grow faster than those in two side legs, while the eddy current loss amplitudes in two side legs grow faster than those in the central leg.