Interphase LC-Oscillation Suppression with Fast Line-Transient Response in 48-V Series-Capacitor Buck Converters for Automotive Applications

This work presents a 4:1 series-capacitor buck (SCB) converter for 48 V-to-0.8 V automotive applications, designed with enhanced input transient response using current-mode control. In this work, interphase LC oscillations, characteristic of hybrid dc-dc converters, are damped through dynamic flying-capacitor voltage tracking. The proposed active tracking scheme is essential for current balancing in a current-mode-controlled SCB converter. Unlike existing multiphase current balancing methods, the proposed solution employs a combination of two flying-capacitor voltage regulators to adjust each phase’s current command. The improved converter dynamics under a fast input voltage step are experimentally verified using a 50-W, 200-kHz prototype.