Modular Isolated Vertically Symmetric Dual Inductor Hybrid Converter For Differential Power Processing

Abstract

In this paper, a new isolated DC-DC converter is proposed and demonstrated for Point-Of-Load (POL) applications in data centers. The converter includes a novel architecture where a stacked switched-capacitor (SC) stage provides an efficient course step-down and reduces the voltage swing for the transformer and inductive stage. Compared with a conventional Dickson SC converter, the new SC stage features an advantageous 2X reduction in maximum operating voltage for flying capacitors, enabling capacitor size reduction. Through the transformer, two inductors at the output stage provide soft-charge and soft-discharge operations for the primary side flying capacitors and ensure a lossless capacitive power transfer operation. To support higher input voltages and larger conversion ratios, multiple modules of the proposed converter can be stacked in a series-input/parallel-output configuration. This modular architecture provides advantages of differential power processing with reduced input voltage and processed power for each converter module. A prototype of the modular architecture has been demonstrated for a 100V-to-3V point-of-load conversion with a maximum load of 60A. The peak efficiency of 91% is achieved at 57W/20A output.