Hard- and Soft-Switched
Technical Lecture Session
Hybrid DC-DC Converters
dc-dc converter, multi-level, high step-down, flying capacitor, series capacitor, passive balancing
This paper introduces a novel two-phase dc-dc multi-level flying capacitor converter topology. This topology is well-suited for emerging high step-down applications. It features both natural balancing of the inductor phase currents as well as inherent flying capacitor voltage stabilisation. The switching node voltage swing reduction of 1/4Vg is achieved with the same number of switches required by the 5-level multi-level flying capacitor buck, which does not have inherent balancing features, and the 4-phase series capacitor buck which requires a larger number of components with higher voltage ratings. The functionality of the topology is demonstrated with a 40W, 200kHz switching frequency prototype with operating efficiencies of 92.9% at 24-to-1V, and 90.0% at 48V-to-1V.