Effect of DC bias on magnetization current waveforms of single phase power transformer

An investigation of magnetizing current waveforms of single phase power transformer due to DC bias injection through simulation and experimental study is present in this paper. A method base on MATLAB simulation that is capable of predicting of magnetizing current without and with DC bias is used. The experimental study is done by the DC bias current injected simultaneously with AC source to primary winding of transformer and the secondary side is open circuit. The results show that the waveforms distorted when the DC bias exist. The pulsated waveforms are pushed to half cycle in which the bias current is in the same direction as magnetizing current (unsymmetrical pulsated) and even harmonics are significant. The simulated waveforms have good agreement with the measured one.