Bifurcation analysis of buck converter with parasitic-parameter-induced sneak circuits

Purpose This study aims to investigate the effects of parasitic-parameter-induced sneak circuits on the stability and bifurcation behavior of the Buck converter, and to overcome the limitations of conventional ideal or weak-parasitic models in describing practical dynamic behavior and stability boundaries. Design/methodology/approach A three-mode piecewise state-space model is established, where the sneak-circuit mode is represented by an equivalent LCR network. A discrete-time mapping and Filippov monodromy matrix are derived for stability analysis. The bifurcation and stability characteristics of the proposed model are compared with those of the conventional discontinuous conduction mode (DCM) model, and experimental validation is conducted. Findings Sneak circuits are not simple parasitic disturbances but introduce additional dynamics that reconstruct the cycle-to-cycle mapping. This leads to changes in eigenvalue evolution, bifurcation boundaries and stability regions. The proposed model provides more realistic predictions and shows a delaying effect on complex bifurcations compared with the conventional DCM model. Research limitations/implications The study focuses on a Buck converter under proportional voltage-mode control and does not consider more complex control strategies or active suppression methods. Future work can extend the analysis to broader operating conditions and advanced control schemes. Practical implications Designs based solely on conventional DCM models may overestimate the stable operating range. The proposed model provides a more accurate basis for parameter tuning and helps ensure sufficient stability margins in practical applications. Social implications Improved stability analysis of the Buck converter enhances the reliability of power conversion systems used in processors, data centers and vehicular electronics, reducing the risk of instability and improving system safety. Originality/value This work integrates sneak-circuit mechanisms into nonlinear stability analysis of the Buck converter. The proposed model reveals how parasitic-induced dynamics reconstruct operating modes and stability boundaries, providing a new perspective and tool for practical converter design.