Analysis of the DC bias phenomenon by the harmonic balance method based on the electromagnetic coupling model

The harmonic balance method is applied to study the DC bias phenomenon of the power transformer in frequency domain. The harmonic balance equation has been set up, establishing the electromagnetic coupling model. Every frequency solution of the exciting current and the magnetic flux can be calculated by updating the reluctance in iterative computation. A single-phase two-limb core model is employed to carry out the DC bias experiment. The measured results obtained from experiments are in accordance with the calculated ones, confirming the effectiveness of the proposed method.