未建模动态对Buck变换器滑模控制系统的影响分析

Influence of Unmodeled Dynamics on Sliding Mode Controlled Buck Converter

研究传感器未建模动态对Buck变换器滑模控制系统的性能影响,提出一种基于奇异摄动理论的稳定性和输出电压谐波分析的新方法.给出滑模控制器的参数整定方法,选取传感器的上升时间作为摄动时间,建立其未建模动态的奇异摄动模型,在多时间尺度框架下,揭示传感器稳定输出与摄动时间的影响关系.在此基础上,构造一个类Lyapunov函数分析未建模动态对整个闭环控制系统的稳定性影响,证明未建模动态诱发谐波的必然性.针对输出电压的谐波,在频域内利用描述函数法推导出未建模动态摄动时间与其谐波幅值和频率的数学影响关系.仿真结果验证所提方法的正确性和有效性.

This paper investigates the influence of unmodeled dynamics from the sensor in a sliding mode controlled(SMC)Buck converter,and presents a quantitative analysis approach for the stability and output voltage harmonics on the basis of singular perturbation theory.The design parameter of SMC is first given.Taking the rise time of sensor as a perturbed param-eter,the buck converter is modeled as a singularly perturbed system.Then in the frame of multiple-time scale,the influence relationship of stable sensor and the time constant is deduced,and further the stability of the whole closed-loop buck converter system is given by constructing a Lyapunov-like function,prov-ing the existence of harmonics induced by unmodeled dynam-ics.The describing function method is introduced to analyze the frequency and amplitude of the output voltage harmonics.Simulations validate the proposed method.