基于过零检测的Buck变换器自适应连续滑模控制

Adaptive continuous sliding mode control of Buck converters based on zero-crossing detection

为提高Buck变换器的输出电压品质,本文提出一种基于在线过零检测自适应机制的连续滑模控制方法,可有效抑制抖振问题,且可保证系统稳态误差收敛到给定范围.本文建立变换器的数学模型,从滑模面和控制律两方面改进传统滑模控制算法,即有目的地将系统状态的积分项引入到滑模面的设计中,并将其收敛轨迹分成两阶段,实时测量其过零点的个数;将期望的稳态误差纳入到滑模控制律的设计中,引入由系统状态过零点个数决定的自适应变增益,在收敛轨迹的约束下,分阶段推导出其变增益的连续控制律,并给出相应的稳定性分析.最后,通过与传统一阶和二阶滑模的理论和仿真性能对比,证明所提方法在抖振抑制、响应速度和控制精度方面的优越性.

In order to improve the quality of the output voltage for Buck converters,this paper proposes a novel continuous sliding mode control(SMC)approach based on an adaptive mechanism of the online zero-crossing detection to realize the chattering elimination and better convergence within a given range.The mathematical model of the converter is established and the traditional SMC approach is modified both from the sliding surface and control law.In the design of the sliding surface,the integral term of the system state is introduced artificially and its convergence trajectory is divided into two stages,where the number of the zero-crossing points can be measured in real time.While in the design of the control law,the expected steady-state error and the adaptive variable gain determined by the number of zero-crossing points are introduced simultaneously.Restricted by the convergence trajectory,the corresponding control laws with variable gains are deduced in the two stages,following their stability analysis is given.Finally,comparative simulations with the traditional first-order SMC and second-order SMC proves the superiorities of the proposed approach in chattering elimination,fast response and control accuracy.