Non-isolated dual half-bridge ZVS/ZCS high step-down converter with zero DC bias current coupled inductor and active clamp

Abstract

A non-isolated dual half-bridge zero-voltage-switching (ZVS)/ zero-current-switching (ZCS) high step-down converter with zero dc bias current and active clamp is presented in this paper. Owing to the use of the dc-blocking capacitors, the dc magnetizing inductance current of the coupled inductor is zero. Thus, the magnetizing current can be both positive and negative, which means that the entire core B-H loop (four quadrants of the B-H loop) can be used. Therefore, the utilization of the coupled inductor can be upgraded, and hence the core loss can be reduced. The dc-blocking capacitors can be not only used to step down the voltage, but also used to eliminate the dc magnetizing inductance current. Furthermore, an active clamp is used to suppress voltage spike across the MOSFET switch which is connected between the two windings of the coupled inductor. Moreover, owing to a discrete output inductor, this converter also features a non-pulsating output current. Although there are four switches in the proposed converter, only two half-bridge drivers are needed. In this study, detailed theoretical analyses and experimental results are offered to verify the feasibility and effectiveness of the proposed converter.