Current-Cancellation-Based Heterogeneous Integration of <i>LLC</i>-DCX With Ultralow-Voltage High-Current Output for Data Centers
Hongfei Wu, Yufeng Song, Xu Zhang, Yuanchi Zhang
Abstract
The efficiency and power density of ultra-low voltage (<IV) high-current output DC-transformers (DCXs) are limited by the losses and footprint area of the high-current windings. High-frequency current cancellation and power switches and high-current windings heterogeneous integration methods are proposed to reduce the length, area, as well as losses of high current windings. With the proposed current cancellation-based heterogeneous integration method, most of the high-current PCB windings of the transformer are replaced by power switches and capacitors, and almost zero-PCB-winding is achieved for the high-current secondary windings of the DCX. As a result, both power density and efficiency are improved significantly. A 36V-to-0.75V/150A output DCX with a 48:1 turnratio transformer is designed and implemented with four-layer PCB. 94.1% peak efficiency is achieved, while the power density of the high frequency transformer in the DCX is 0.66A/mm2.