Stability of buck converter cascaded systems via Filippov–Floquet analysis with front-stage current-feedback damping
Wei Hu, Yuefeng Zeng, Xiaokai Su, Qun Yu, Fangying ZhangPurpose
This paper addresses the stability issue of Neimark–Sacker bifurcation in voltage-feedback Buck converter cascaded systems within direct current (DC) grids. This paper aims to assess system stability and synthesize effective damping control to suppress these nonlinear phenomena, which are triggered by system interactions and wide input-voltage excursions.
Design/methodology/approach
The authors develop a monodromy-matrix framework augmented by the Filippov convex methodology. The approach involves classifying the operating modes of the dual-stage topology, deriving the monodromy matrix from full switching-cycle sampled-data models and mapping input-voltage-dependent loci of Neimark–Sacker bifurcations via Floquet multipliers.
Findings
Two working types governed by duty-cycle ratios are revealed. One sustains persistent quasi-periodic behavior, while the other transitions from bifurcation to period-1 stability with increasing Uin. A decentralized front-stage current-feedback modulation is proposed as active damping, with gains tuned by contracting dominant Floquet multipliers, which effectively suppresses bifurcation and recovers stability.
Originality/value
The paper’s originality lies in connecting periodic-orbit stability to damping-oriented control via a monodromy-matrix framework. It provides a practical pathway for stabilizing cascaded converters by introducing a decentralized control that preserves modularity while expanding stability margins across varying input voltages and bus impedances.