A Two-Phase Zero-Inductor Voltage Converter for Datacenter and Server Applications

Sever power supplies and board level voltage regulators are currently the bottleneck limiting efficiency of overall server power architecture efficiency. In order to address this Google has proposed and implemented a 48 volt server architecture that brings a higher voltage level throughout the server rack to reduce distribution losses, and conversion losses upstream of the server power supply. However this change places additional burden on the board-level regulators that must now regulate from 48 volts down to below 1 volt for some components. The most common approach is a two stage approach called the "Intermediate Bus Architecture". A novel topology for an Intermediate Bus Architecture was proposed at APEC 2018. This topology featured extremely high efficiency, very simple control and low component count. However two other critical metrics for a bus converter are scability and power density. The work proposed in this paper demonstrates that the Zero-Inductor Voltage (ZIV) Converter can be easily scaled to multiple phases, and shows a very high density design while maintaining efficiency above other cutting edge solutions. The two-phase prototype achieves up to 800W/in(3) power density, 99.2% peak efficiency, and 97.9% full load efficiency for 840W output while maintaining good current sharing across all load conditions. The two-phase prototype requires no additional control, and is highly scalable to different power levels through paralleling.