Simulating Analysis of Exciting Current of Single Phase Transformer on DC Bias

Based on Jiles-Atherton theory on ferromagnetic hysteresis, model of nonlinear magnetization characteristics for saturate transformer is set up. Programmed using MATLAB, exciting current of transformer under DC bias is computed and simulated in time domain under short circuit and no-load condition. Synchronously harmonics content of excited current is analyzed in frequency domain. The result shows that the degree of DC bias for core and the flux density increase when DC increases, the waveform of exciting current became much more distort. When the DC increases enough, the exciting current inclines to half-circle saturation. The harmonics content become more and more abundant. The first and third order harmonic increase steadily with increases of DC. Especially the second order harmonic increases rapidly with increases of DC. A few of fourth order harmonic arises.