Sampled-data modeling and dynamical effect of output-capacitor time-constant for valley voltage-mode controlled buck-boost converter

• 来源期刊: 中国物理B（英文版）
• 关键词: buck-boost converter valley voltage-mode control sampled-data modeling dynamics
• 年，卷（期）: 2017,（11）
• 页码范围: 515-525
• 页数: 11页
• 语种: 英文
• DOI: 10.1088/1674-1056/26/11/118401

摘要

By analyzing the output voltage ripple of a buck-boost converter with large equivalent series resistance (ESR) of output capacitor,one valley voltage-mode controller for buck-boost converter is proposed.Considering the fact that the increasing and decreasing slopes of the inductor current are assumed to be constant during each switching cycle,an especial sampled-data model of valley voltage-mode controlled buck-boost converter is established.Based on this model,the dynamical effect of an output-capacitor time-constant on the valley voltage-mode controlled buck-boost converter is revealed and analyzed via the bifurcation diagrams,the movements of eigenvalues,the Lyapunov exponent spectra,the boundary equations,and the operating-state regions.It is found that with gradual reduction of output-capacitor time-constant,the buck-boost converter in continuous conduction mode (CCM) shows the evolutive dynamic behavior from period-1 to period-2,period-4,period-8,chaos,and invalid state.The stability boundary and the invalidated boundary are derived theoretically by stability analysis,where the stable state of valley voltage-mode controlled buck-boost converter can enter into an unstable state,and the converter can shift from the operation region to a forbidden region.These results verified by time-domain waveforms and phase portraits of both simulation and experiment indicate that the sampled-data model is correct and the time constant of the output capacitor is a critical factor for valley voltage-mode controlled buck-boost converter,which has a significant effect on the dynamics as well as control stability.