考虑补偿环路谷值电流控制Boost变换器的稳定性分析

Stability analysis for valley-current-mode controlled boost converter considering compensation loop

在闭环情况下,除了占空比影响谷值电流(VCM)控制开关变换器的稳定性,补偿环路反馈增益和输出电容等效串联电阻(ESR)也对其稳定性产生影响。以比例积分(PI)补偿VCM控制Boost变换器为例,建立了其二阶分段线性模型。基于该模型,通过分岔图研究了PI补偿VCM控制Boost变换器随反馈增益和输出电容ESR变化的稳定性机理。结果表明,增大反馈增益将降低变换器的稳定性,而增大输出电容ESR将提高变换器的稳定性。电路仿真结果和硬件实验结果验证了理论分析的正确性。

When outer voltage loop is closed,the stability of valley-current-mode (VCM) controlled switching converters is not only affected by variation of duty-cycle,but also affected by variation of feedback gain of compensation loop and equivalent series resistance (ESR) of output capacitor.For VCM controlled boost converter,when proportional-integral (PI) compensator is used in its outer voltage loop,and its piecewise linear model is established.Based on the model,the stability mechanism of feedback gain of PI compensator and ESR of output capacitor in VCM controlled boost converter with PI compensator is studied by bifurcation diagrams.The results indicated that the stability of the converter can be reduced with increase of feedback gain,and can be improved with increase of output capacitor ESR.The validity of theoretical analyses is verified by circuit simulation results and hardware experimental results.