A Multi-Phase Cascaded Series-Parallel (CaSP) Hybrid Converter for Direct 48 V to Point-of-Load Applications

The rapid growth in data-center electricity consumption has created an imperative need for more energy-efficient solutions to data center power delivery. This work proposes a multi-phase hybrid switched-capacitor (SC) converter for direct 48 V to point-of-load (PoL) conversion with high performance. The proposed topology can be viewed as a 6to-1 cascaded series-parallel (CaSP) converter merged with a three-phase interleaved buck converter with automatic current balancing. Due to multi-phase operation, the CaSP stage is able to achieve a higher conversion ratio compared to twophase SC converters with the same number of components as well as lower turn-on voltage for switching devices. Moreover, the proposed CaSP-PoL topology benefits from the frequency multiplication effect similar to that in flying capacitor multilevel converters, which allows for lower frequency operation of higher voltage rated switches and doubled frequency operation of buck inductors, contributing to a further reduction in switching loss and inductor size. A 48 V-to-PoL hardware prototype was built in vertical assembly structure for compact packaging and tested up to 90 A output current, achieving 94.1% peak efficiency (93.2% including gate drive loss) and 702 W/in 3 power density (by box volume) at 2.0 V output voltage.