S-Hybrid Step-Down DC-DC Converter-Analysis of Operation and Design Considerations

Gabsu Seo, Hanh-Phuc Le

Research output: Contribution to journalArticlepeer-review

26 Scopus Citations


This paper presents a new highly integrable hybrid step-down converter that merges switched-inductor and switched-capacitor operations and significantly reduces onboard loss by using the input cable's parasitic inductance as its main inductor. This converter has the inductor placed at the input with a smaller voltage swing, leading to possible use of a smaller inductor and low-voltage rating switches that generally translate to reduced conduction losses. Analyses of converter operation and losses to reveal its original characteristics and design guidelines are presented to facilitate the components optimization. The converter architecture is verified by a proof-of-concept 15-W inductor-less lithium-ion battery charger prototype that uses a 1-m USB 3.0 cable as inductor. The converter, switched at 2 MHz from a 5-V input, experimentally achieves 89.7% peak efficiency and 6% higher efficiency at full load than a Buck converter counterpart. This high efficiency and zero onboard inductor yield a relative 45.7% onboard loss reduction at full load, promising excellent integration feasibility and superior system thermal management.

Original languageAmerican English
Article number8641480
Pages (from-to)265-275
Number of pages11
JournalIEEE Transactions on Industrial Electronics
Issue number1
StatePublished - 2020

Bibliographical note

Publisher Copyright:
© 1982-2012 IEEE.

NREL Publication Number

  • NREL/JA-5D00-73128


  • Buck converter
  • DC-DC
  • inductor-less power converter
  • S-Hybrid converter
  • smart power cable
  • step-down power conversion


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