Optimal Frequency Operating Points for Hybrid Switched Capacitor Converters and Lossless Current Sense Method

Abstract:
Data center electricity consumption has been increasing rapidly in the last few years as computation moved into cloud computing. With the introduction of the 48 V power delivery architecture, powering digital loads (CPUs, GPUs, ASICs, . . . ) is typically accomplished by means of a two-stages approach. Most commonly, the regulation is established at second-stage level, with an unregulated first stage. In general, the first stage is made with a fixed ratio dc-dc converter, such as LLC or Hybrid Switched Capacitor (HSC) converter. In this paper a novel optimal frequency feed-forward control and a lossless current sense methods are presented for HSC converters. The goal of the feed-forward method is to optimize the converter efficiency over the entire input voltage range, by tracking the optimal operating point. Experimental results for an HSC 5:1 750 W prototype in down-solution 18 x 47.5 x 7 mm are showing the effectiveness of the proposed approach.