Three-Dimensional Interconnect <i>LLC</i>-DCX Converter for Datacenter Application

Driven by substantial amount of electricity consumption in datacenters, the demand for efficient power management has led to the adoption of the 48 V bus power distribution system. To deliver the required high current to xPUs, the unregulated intermediate bus converter (IBC) is typically needed to step down the 48 V bus voltage. For high power density and high efficiency, this article proposes a three-dimensional interconnect (3Di) LLC-DCX converter with 8:1 voltage ratio as the unregulated IBC. Two different winding configurations and their corresponding operation modes, diagonal operation mode (DOM) and same-side operation mode (SOM), are presented. DOM enables higher leakage inductance and winding resistance due to poor interleaving, but its overall AC resistance can be reduced by over 50% compared to SOM at the 550 kHz switching frequency due to much lower termination resistance. Finally, two prototypes using DOM and SOM configurations are implemented with similar circuit parameters. Experiment results indicate the prototype in DOM achieves higher power density and higher efficiency. The power density is 725 W/inch3 with 606 W maximum output power, and the peak efficiency is 96.3%. While, in SOM, the power density is 441 W/inch3 with 368 W maximum output power, and the peak efficiency is 94.1%.