An inductor-less hybrid step-down DC-DC converter architecture for future smart power cable

This paper presents a DC-DC step-down power conversion architecture that allows a power cable, such as USB cable, to deliver both power transmission and power conversion functions. In this architecture, an S-Hybrid converter topology is proposed to utilize parasitic inductance readily available in the cable for power conversion stage. As a result, the explicit inductor often required in a buck converter counterpart and its associated loss can be eliminated, promising better full integration and improved efficiency especially in mid to heavy load conditions. In addition, this S-Hybrid converter architecture requires less inductance and achieves smaller inductor current ripple that in turn contributes to better performance. The architecture is experimentally verified with a proof-of-concept 15 W inductor-less Li-ion battery charger prototype using 1 m USB 3.0 cable. The converter, switched at 2 MHz from a 5 V input, experimentally achieves 89.7% maximum efficiency and 6.0% higher efficiency at full load than a buck converter counterpart. In addition, a relative 45.7% on-board loss reduction at full load highly promises its excellent integration feasibility.