A Dual Active Bridge Derived Hybrid Switched Capacitor Converter Based Two-Stage 48 V VRM

Abstract

This article proposes a two-stage 48-V voltage regulator module using a hybrid switched-capacitor converter in the first stage. Apart from being compact in nature, this first-stage converter has several other advantages such as efficient regulation ability and hence scalability, inherent full/partial soft switching for most of the switches, reduced switch voltage and current stresses, and the possibility of wide range variable switching frequency operation. These combined features together help to obtain a flat high-efficiency curve for the first stage. The second-stage multiphase buck converter also exhibits flat high-efficiency characteristics through phase shedding. Steady-state circuit operation and analysis of the first-stage converter is presented in this article. An accurate discrete-time model of the first-stage converter is also developed. Thereafter, a design guideline for the two-stage converter is discussed. Finally, experimental results from an 80-W laboratory prototype show that the proposed converter possesses a relatively flat high-efficiency profile and exhibits a faster load transient response compared to that of the state-of-the-art solutions.