A Sensorless Feedforward Balancing Compensator for Improved Interphase Dynamics in Auxiliary-Assisted Dual-Inductor-Hybrid Converters

Hybrid Switched-Capacitor (SC) converters are well-suited for space-critical 48V automotive applications due to their high power density, however, the fast transient response necessary for the stringent regulation requirements of CPU core voltages remains a challenge. A Dual-Inductor Hybrid (DIH) dc-dc converter with a flying-capacitor-tapped auxiliary stage was proposed to improve the load transient response, however, the converter output and DIH interphase dynamics become coupled. This paper presents a sensorless feedforward compensation scheme for improving the interphase dynamics in the 48V-to-1V auxiliary-assisted DIH converter. The proposed scheme extracts the auxiliary duty cycle and adjusts the duration of the DIH switching states to reduce the balancing time of the interphase dynamics. A small-signal model of the auxiliary-assisted DIH converter is proposed and validated with simulation results to analyze the closed-loop stability of the proposed technique. Experimental results demonstrate that the feedforward compensation scheme reduces the settling time of the interphase dynamics by 65% while eliminating the use of an external sensor for active balancing in the auxiliary-assisted DIH converter.