High-Efficiency and High-Power Density DC-DC Converter for Data Center Application

Date of Award

12-1-2023

Degree Name

M.S. in Electrical Engineering

Department

Department of Electrical and Computer Engineering

Advisor/Chair

Advisor: Dong Cao

Abstract

Datacenter usage tends to increase as artificial intelligence (AI) grows and becomes more prevalent. High-power density and high efficiency power converters function as intermediate bus converters are required to increase the whole system efficiency for datacenter applications. This thesis presents solutions for intermediate bus converters and the second stage including a 9-times and a 22-times conversion ratio matrix autotransformer switched-capacitor DC-DC converter (MASC) and a detailed design of the 6V-1.5V interleaved buck converter as second stage for 48V dc bus data center applications. MASC has both advantages of switched tank converter and LLC converter. The high voltage side of MASC takes advantage of switched tank converter. The low voltage side of the MASC leveraged a new magnetic integrated autotransformer design that is like a current doubler rectifier in an LLC converter. Compared with the switched tank converter, MASC needs less switches on the low voltage rectifier side to achieve the same conversion ratio. All switches can achieve zero current switching and zero voltage switching. Thus, total power loss is reduced compared with switch tank converter. Compared with LLC converter, the use of matrix autotransformer further reduces the power loss of MASC by removing primary side winding. The optimum die area (phases) of traditional interleaved buck converter and series-capacitor interleaved is analyzed and their efficiency is compared. A 48V-5.33V MASC hardware prototype with a peak efficiency of 98.54%, a full load efficiency of 95.6%, and 654W/in3 power density is designed, built, and tested. A 22x MASC is simulated and the PCB layout is in process.

Keywords

Switched capacitor converter, Datacenter application, IBC, DC-DC converter, ZCS

Rights Statement

Copyright © 2023, author.

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