Improvement of Input Current Waveform for Soft-Switching Boost DCM Converter with Unity Power Factor

In this paper, a soft-switching discontinu­ous mode (DCM) power factor corrected (PFC) converter is analyzed by applying the double Fourier series expan­sion. It is found that the fundamental component and higher-order harmonics included in the input current waveform are obtained by the Fourier series expansion of the mean value of the inductor current. From the theo­retical analysis, a new method removing the distortion of the input current waveform is proposed. In spite of an open loop system, the proposed method makes a great improvement of the total harmonic distortion even if the ratio of output voltage to input voltage is very low.