Electric Circuit and Magnetic Circuit Combined Model of DC Biased Power Transformer

An electric circuit and magnetic circuit coupled model of the DC biased power transformer was presented. In the model, the magnetic circuit of power transformer was set up in accordance with spatial geometries of the core and that of the coil, representing effectively the magnetic flux linking in power transformer. To take account of the effects of eddy currents in ferromagnetic materials, a frequency-dependent formula for nonlinear reluctance of the transformer core was developed. Based on the formula of the reluctance the equivalent magnetic circuit was built up by virtue of network synthesis techniques. The experiment and computation were performed on a model of three-phase power transformer. The results of the computation coincide well with those of the experiment. It means that the model presented in the paper can be used in the research of the DC biased power transformer.