A Butterfly Interleaving Multiphase Coupled-inductor Buck Converter for Datacenters with 99.3% Peak Efficiency

Multiphase interleaved converters have be analyzed for decades. The multiphase coupled inductors have been recognized to reduce the current ripple and improve the transient performance. This paper proposes a magnetic core geometry along with a winding layout for a multiphase interleaved buck converter operating as the front stage for datacenters. The second stage is an LLC resonant converter as a DC transformer. The proposed method allows naturally interleaved inductor windings. No redundant conductor is required. The 3D simulation in Ansys results indicate that compared with the non-interleaved winding arrangement, this method has reduced the AC resistance by almost 60% at 700 kHz and the footprint of the magnetic core by nearly 30%. Experiments shows that the prototype employing this magnetic core and winding structure only requires a 6-layer PCB to transfer the kilowatt power, and achieves a peak efficiency of 99.3% and a power density of 912 W/inch³.