Coupled Inductor-Based ZVS Interleaved Buck Converter with Optimal Coupling Coefficient and Fully Digital BCM Control

In this paper, a coupled-inductor-based interleaved Buck converter is presented. By employing a negatively coupled inductor, the proposed topology reduces magnetic component number and improves dynamic response. Operating in boundary conduction mode (BCM), the proposed converter can achieve zero-voltage switching (ZVS) under a wide voltage and load range. The control strategy is fully digital, allowing the switching frequency to be adaptively adjusted without the need for a zero-crossing detection (ZCD) circuit. Furthermore, an optimal coupling coefficient design is proposed, which minimizes the frequency adjustment range. In addition, the design process for a coupled inductor with an interleaved winding structure is introduced in detail. Finally, a 300 W experimental prototype is built, the experimental results of which demonstrate its effectiveness and feasibility.