基于未知系统动态估计器的Buck型变换器快速固定时间控制

Unknown system dynamic estimator-based fast fixed-time control of Buck converters

针对存在参数不确定、输入电压波动以及负载变化等未知动态的Buck型变换器系统,提出一种基于未知系统动态估计器的快速固定时间控制方法.首先,设计基于一阶低通滤波器的估计器,实现对系统未知动态的前馈补偿.在此基础上,基于输出电压误差和未知动态估计值设计固定时间滑模面和反馈控制器,保证输出电压快速收敛至参考电压附近邻域内,且控制器具有较好的抗干扰能力.同时,构造基于反余切型函数的增强型趋近律,能够提高滑模变量的收敛速度和有效减小控制器抖振.最后,给出仿真和实验结果验证所提出方法的有效性.

This paper proposes an unknown system dynamic estimator-based fast fixed-time control scheme for Buck converters with unknown system dynamics including parameter uncertainties,input voltage fluctuations and load variations,etc.A first-order low-pass filter-based estimator is first designed to realize feedforward compensation for the unknown system dynamics.Based on the output voltage error and unknown dynamic estimation,a fixed-time sliding surface and feedback controller are designed,such that the output voltage can quickly converge to the neighborhood near the reference,and the controller has good anti-disturbance ability.Meanwhile,by constructing an arc cotangent auxiliary function,a novel enhanced reaching law is presented to improve the convergence speed of the system states and reduce the controller chattering.Finally,simulation and experimental results validate the effectiveness of the proposed scheme.