Zero-Voltage-Switching Buck Converter with Low Voltage Stress using Coupled Inductor

This paper presents a new design of zero-voltage-switching (ZVS) buck converter. This new converter utilizes a coupled inductor to implement the output filter inductor as well as the auxiliary inductor which is commonly employed to realize ZVS for switches. Additional magnetic core for the auxiliary inductor in traditional designs is removed and hence manufacture cost is reduced. Moreover, thanks to the series connection between the input and output, the switch voltage stress in the steady-state is reduced and thus the ZVS operation can be easier achieved. Then the leakage inductor current circulating in the auxiliary switch is decreased, contributing to reduced conduction losses. Especially, low voltage rating devices with low on-state resistance can be adopted to further improve efficiency in the application with non-zero output voltage all the time, such as the battery charger. Furthermore, the reverse-recovery problem of the diode is significantly alleviated by the leakage inductor of coupled inductor. In the paper, operation principle and steady-state analysis of the proposed converter are presented in detail. Meanwhile, design considerations are given to obtain circuit parameters. Finally, the simulation and experimental results of a 200W prototype circuit are demonstrated to validate the advantages and effectiveness of the proposed converter. None of the material in this paper has been published or is under consideration for publication elsewhere.