Analysis, Design, and Investigation of a Soft-Switched Buck Converter With High Efficiency

In this article, a new simple buck converter with zero voltage switching (ZVS) performance and almost zero output current ripple is proposed. The proposed structure's auxiliary circuit contains a capacitor and an inductor without any switches, which makes it possible to minimize the switching losses and eliminate other additional losses. The main power diode also turns
off
under zero current switching condition and the reverse recovery losses of the power diode is minimized. Eliminating the switching losses and the reverse recovery losses allows the converter to operate with high power efficiency, which makes it a good option for high power efficiency-required applications. In this article, five operational modes are explained. The design section includes the designing criteria of the components. Also, the efficiency analysis, control system for stabilizing the output voltage, and applying a variable inductor to ensure the soft-switching operation are analyzed. The comparison results are also discussed. Moreover, an experimental prototype of the proposed structure at 200 W output power and 75 kHz frequency is built to prove the above-mentioned advantages. Finally, the soft-switching waveforms are obtained for different output powers with various duty cycles and equal switching frequency to verify the ZVS performance of the converter at different loads and changes in input voltage and duty cycle.