Two-Stage 48V-to-16V-to-1V Hybrid-Switched-Capacitor Converter for High Performance Computing

This paper proposes a two-stage hybrid-switched-capacitor converter for high-current 48V-to-1V applications. The first stage is a 3-to-1 unregulated Dickson converter and the intermediate bus voltage is 16 V. The second stage is a multiphase two-level series-capacitor buck converter with an 8-V equivalent input voltage. This design achieves balanced voltage conversion ratio of both stages. This design utilizes a 3:1 Dickson circuit to convert 48V to a 16V intermediate bus voltage. By re-optimizing the number of stages in the series-capacitor buck converter and removing a significant portion of the intermediate bus capacitance, it achieves high efficiency and power density under high-current operating conditions. Furthermore, the current flowing through the inductor in the series-capacitor buck stage is employed to charge and discharge the flying capacitors in the Dickson stage. As a result, the charge redistribution loss is significantly reduced. To validate the effectiveness of the design, a prototype with a 48V-to-1V/240A conversion capability was constructed and subjected to testing.