Magnetic core loss excited by high-frequency rectangle waveform

The variation tendency of magnetic core loss under different duty cycles is studied for high-frequency transformer.With same frequency and flux swings,the excitation current waveform change caused by duty cycle variation has little effect on the area encircled by the hysteresis curve and the hysteresis loss is taken as a constant.The relationship between eddy current loss and excitation voltage is approximately linear,based on which,a method for computing the eddy current loss under different duty cycles is presented.The theoretical calculation shows that,when the duty cycle varies between 0.283 and 0.717,the core loss excited by rectangle waveform is smaller than that excited by sinusoidal waveform;the magnetic core loss is minimal when the duty cycle is 0.5.Experimental data prove the correctness of theoretical analysis.