Asymmetric ZVS Buck Converters With High-Step-Down Conversion Ratio

This article proposes a family of asymmetric high-step-down converters in which zero voltage switching (ZVS) is achieved and common ground between the input and the output is retained. The proposed converters are derived from the multiphase coupled-buck converter and both coupled inductors and series capacitors are employed in order to achieve a high-step-down conversion ratio. Therefore, the voltage stress across the freewheeling diodes and the current stress of the main switches are reduced. Furthermore, switching losses including turn-on, turn-off, capacitive turn-on, and reverse recovery losses are considerably reduced due to the soft switching of semiconductor devices. As a result, the converter can efficiently operate at higher switching frequencies. Also, in comparison to the conventional interleaved buck converter (IBC) the cost, volume, weight, and complexity of the proposed topologies have not increased significantly as the proposed converters use the minimum number of auxiliary components and, similar to the conventional IBC, share the common ground. The validity of this research is confirmed by the experimental results of a 150 V to 12 V/15 A prototype.