An Auxiliary-Assisted Dual-Inductor Hybrid DC-DC Converter with Adaptive Inductor Slew Rate for Fast Transient Response in 48-V Automotive PoL Applications

Abstract

This paper presents an auxiliary-assisted control scheme for fast transient response in 48V-to-1V automotive Point-of-Load (PoL) applications. The proposed scheme performs dc power delivery and output voltage regulation using a main and auxiliary stage, respectively. A 4:1 Dual-Inductor Hybrid (DIH) dc-dc converter delivers dc load power by regulating the auxiliary capacitor voltage, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V_{AUX}$</tex> , which enables adaptive control of the auxiliary inductor current slew rate for fast transient response. An auxiliary AC-coupled Buck (ACB) converter regulates the output voltage based on an output-capacitor current-based Hys-teretic Current-Mode-Control (HCMC) scheme. An Adaptive-Voltage-Positioning (AVP) control scheme is proposed for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V_{AUX}$</tex> , which prepositions the auxiliary-inductor slew rate for improved transient response. A simulation model was built to validate the proposed control scheme. Simulation results demonstrate that the proposed control scheme including AVP decreases the auxiliary capacitance by 40%, the auxiliary output rms current by 28%, and the main-stage peak current by 30 A. The system achieves a peak simulated efficiency of 92.6% with an output capacitance of only 640 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu \mathrm{F}$</tex> and an auxiliary capacitance of 30 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mu \mathrm{F}$</tex> .