Interphase $LC$ Resonance and Stability Analysis of Series-Capacitor Buck Converters
Ping Wang, Daniel H. Zhou, Haoran Li, David M. Giuliano, Gregory Szczeszynski, Stephen Allen, Minjie Chen
Abstract
Hybrid switched capacitor power converters, such as the series-capacitor buck (SCB) converter, have intrinsic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$LC$</tex-math></inline-formula> resonant dynamics that might influence its control stability and transient response. This letter presents a systematic approach to analyzing this intrinsic resonant behavior, which can be classified into output <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$LC_{o}$</tex-math></inline-formula> resonance and interphase <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$LC_{B}$</tex-math></inline-formula> resonance based on common-mode and differential-mode decomposition. The impacts of coupled inductors on the resonant amplitude, frequency, and settling time during a step line transient are analyzed. The influence of intrinsic resonance on control stability is clarified, providing guidance for controller design. A two-phase SCB prototype was built and tested with discrete and coupled inductors under different operating conditions. All the analyses are verified by simulation or experimental results.