Large-Signal Stability Guarantees for Cycle-by-Cycle Controlled DC-DC Converters

TL;DR

This paper introduces a new large-signal stability theory for cycle-by-cycle controlled dc-dc converters, addressing the limitations of traditional fixed inductor ramp assumptions and providing a practical stability criterion.

Contribution

It develops a novel large-signal stability framework modeling converters as feedback systems, revealing how L/R and RC time constants influence stability.

Findings

New stability criterion based on feedback interconnection theory

Identification of L/R and RC time constants as key design parameters

Enhanced understanding of large-signal transient behavior in converters

Abstract

Stability guarantees are critical for cycle-by-cycle controlled dc-dc converters in consumer electronics and energy storage systems. Traditional stability analysis on cycle-by-cycle dc-dc converters is incomplete because the inductor current ramps are considered fixed; but instead, inductor ramps are not fixed because they are dependent on the output voltage in large-signal transients. We demonstrate a new large-signal stability theory that treats cycle-by-cycle controlled dc-dc converters as a particular type of feedback interconnection system. An analytical and practical stability criterion is provided based on this system. The criterion indicates that the L/R and RC time constants are the design parameters that determine the amount of coupling between the current ramp and the output voltage.