Ultra-thin Coupled Inductor for a GaN-Based CRM Buck Converter

A interleaved Buck converter with wide input voltage range and critical conduction mode based on coupled inductor is studied. Due to the limitation of high-frequency filter inductor on the size of power module, the flux distribution characteristics of coupled inductor and its influence on the volume and loss of magnetic components are deeply studied. With ultra-thin and low loss as objective, a four-pole planar coupled inductor structure based on PCB winding is proposed. Meanwhile, the design method of its structure parameters is given as well as a design example. Finally, an experimental prototype with height of only 7mm, power density of 790W/in³ and maximum efficiency of 99% is developed. The experimental results show the effectiveness of the proposed scheme.