A Novel ZVS Interleaved Series-Capacitor Tapped Buck Converter with Low Start-Up Voltage Stress for High Step-Down DC-DC Application

SC-Buck Converters are widely utilized in high voltage conversion ratio DC-DC applications such as modern communications and industrial equipment. However, the efficiency and the power density of the traditional SC-Buck converter are not high enough to meet application requirements. In addition, the switching tube voltage stress is too high when starting so high voltage resistant switching tube needs to be used, which means that the cost of the circuit is increased. In order to figure out the problem, a novel soft-switched interleaved series-capacitor tapped buck converter is proposed in this article. On the high-voltage side, two switching tubes on the same bridge are connected in parallel with a capacitor. On the low-voltage side, based on the series-capacitance tapping inductor, ZVS for all switching tube is realized by using LC resonator. In this article, the operating strategies of the proposed converter is analyzed, the formula of voltage conversion ratio is derived, and the condition of realizing soft switching is instructed. Finally, a simulation model with input of 24V and output of 1.8V is used to verify the property of this topology.