基于Riemann-Liouville分数阶模型的Buck变换器改进分数阶互补滑模控制

主要研究分数阶Buck变换器的互补滑模控制(CSMC)方法.首先,基于电子元件实际非整数阶的特性与Riemann-Liouville(R-L)定义相比,Caputo定义更能准确描述Buck变换器模型的结论,建立基于R-L定义的分数阶Buck变换器数学模型.然后,将参数不确定性和外部扰动统一为匹配干扰和不匹配干扰,建立两个分数阶干扰观测器(FDOB)分别实现对干扰及其分数阶导数的跟踪.进而,设计新型分数阶互补滑模面,利用CSMC的高精度和分数阶微积分的记忆特性提升滑模运动的鲁棒性和稳态精度;设计新型趋近律,提升趋近速度的同时保证滑模面邻域内的鲁棒性.最后,基于Mittag-Leffler稳定性理论证明滑模控制器的稳定性.仿真结果验证了所提出FDOB的优越性,控制器相比传统滑模方法能够得到更好的动态性能和更低的稳态误差.     

Buck变换器的鲁棒终端滑模控制

针对Buck变换器中负载的不确定性,研究了Buck电路的鲁捧控制问题。针对Buck电路中的误差系统利用终端滑供控制的方法,可使Buck电路的输出电压快速达到期望值。最后用仿真结果验证了本文所提方法的可行性。     

基于Buck变换器的全局时变滑模控制器设计

为克服普通滑模变结构控制系统中系统到达滑模面之前鲁棒性差的特点,针对Buck变换器输入电压纹波干扰问题设计了一种全局时变滑模面。消除了滑模控制的趋近阶段,能够保证系统从初始时刻到终止时刻对参数摄动和干扰具有鲁棒不变性,并用仿真结果验证所用方法的有效性。     

基于RBF网络自适应的Buck变换器终端滑模控制

对于Buck变换器系统,考虑到实际应用中负载变动引起系统参数的不确定性,且不确定性上界无法测量的情况,本文拟采用RBF神经网络对不确定性上界进行自适应学习。针对Buck变换器输出电压的控制问题,为了避免普通滑模控制跟踪误差渐进收敛的问题,改善其动态响应速度和稳态性能,本文拟设计一种基于RBF神经网络的上界自适应的终端滑模控制器,并通过Simulink仿真验证这种方法的可行性。     

基于Buck变换器的新型滑模控制策略

为获得比较理想的直流输出电压,优化变换器的动态性能,基于Buck变换器采用新型滑模变结构控制策略,阐述其工作原理,并结合状态方程,推导出滑模面的存在条件和到达条件,然后对电路参数及控制系数进行设计.仿真结果表明采用这种新型滑模控制策略的Buck变换器对系统扰动和负载变化具有很强的鲁棒性,系统具有良好的动态响应.     

Buck直流变换器的滑模变结构控制研究

研究了Buck滑模变结构控制系统的滑模面函数和控制函数,分析了系统具有最大广义滑模区域及理想稳态输出特性的等效控制条件。使用PSIM仿真软件对Buck滑模变结构控制系统进行仿真研究,并与常规线性控制进行比较。仿真结果表明,滑模变结构控制在快速性和抗干扰性均优于常规线性控制。     

基于过零检测的Buck变换器自适应连续滑模控制

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.     

Buck型变换器非奇异固定时间滑模控制

针对存在参数不确定性的Buck变换器系统,提出一种非奇异固定时间滑模控制方法。首先,设计非奇异固定时间滑模面,并基于该滑模面设计固定时间控制器,保证系统输出电压误差在固定时间内收敛到平衡点的邻域内,且其收敛时间上界与系统初始状态无关。其次,设计自适应律估计系统不确定干扰上界,有效抑制不确定干扰对系统的影响,该方法无需干扰上界的先验知识。最后,仿真结果验证了所提方法的有效性。     

基于GPI观测器的Buck型变换器趋近律控制

针对Buck型变换器中存在的匹配和非匹配扰动,提出一种基于广义比例积分观测器(GPIO)和增强型变速趋近律的控制方法;首先,设计广义比例积分观测器来估计匹配和非匹配扰动,并将估计值引入控制器中进行前馈补偿;同时,构造了基于双曲正切型函数的变速趋近律,可以缩短系统状态的到达时间,并减小在滑动阶段的抖振现象,并与广义比例积分观测器结合,使系统具有良好的抗干扰性能和跟踪性能;最后,证明了观测器的收敛性和闭环控制系统的稳定性,并通过仿真验证该方法可以有效地抑制扰动带来的影响,提高整个系统的抗干扰性能。     

Buck变换器的离散时间全程滑模控制

针对含有匹配不确定项的线性离散时间系统,设计了一种全程滑模控制器,使系统状态在初始时刻就在切换区内．给出了一种双曲正切离散趋近律,由这种改进的趋近律所设计的控制器不但可以减小系统稳态误差,而且能够削弱系统的抖振强度．将该方法应用在Ｂｕｃｋ变换器的控制器设计中,对Ｂｕｃｋ变换器的电压进行跟踪控制,仿真结果验证了所给控制策略的有效性．     

Buck三电平变换器的PWM滑模控制

针对Buck三电平变换器飞跨电容电压闭环与输出电压闭环相互耦合的问题,利用解耦控制技术分别独立地设计控制器对两个闭环进行控制。其中,为了降低对参数变化和负载扰动的敏感性,设计基于PWM的滑模变结构控制器对输出电压进行控制。仿真试验结果表明,与传统PWM控制器相比,该方法在保持对飞跨电容电压进行有效控制的同时能减小输出电压的超调量,缩短调节时间。     

Adaptive sliding mode control for plants with mismatched perturbations to achieve asymptotical stability

In this paper an adaptive sliding mode control (ASMC) scheme based on the Lyapunov stability theorem is proposed for a class of multi‐input multi‐output (MIMO) systems with mismatched perturbations to solve robust tracking problems. Adaptive mechanisms are employed in the design of a specific sliding surface function, so that when the dynamics of controlled system enters the sliding surface, the adaptive gains are capable of adapting the upper bounds of mismatched perturbations and the trajectories of tracking errors can achieve the objective of asymptotical stability. Some adaptive mechanisms are also employed in the controller's design, so that the reaching phase can be accomplished in a finite time without the requirement of the information of upper bounds of partial mismatched perturbations. Finally the control scheme is applied to control an AC motor for showing the feasibility of the proposed methodology. Copyright © 2006 John Wiley & Sons, Ltd.     

Centralized sliding mode frequency regulation approach for an uncertain islanded micro grid integrated with disturbance observer

This paper proposes a novel secondary frequency regulation technique for an uncertain islanded micro grid (MG). The major motivation of the work is to integrate the intrinsic robustness of the sliding mode control scheme with the disturbance observer to estimate and alleviate the unknown mismatched uncertainties caused by renewable resources and load variations. To this end, a dynamical sliding manifold is first utilized and then a control law is derived with Lyapunov's method which stabilizes the MG dynamics. Moreover, in order to ensure faster time domain responses of the closed‐loop system, we employ a power rate reaching law in our proposed control design. Thereafter, the performances of the introduced control strategy are tested on an islanded MG using MATLAB/Simulink, and robustness analysis is also carried out by considering five different case studies. Further, in contrast to the existing approaches such as robust H _∞ and robust PID control, the proposed strategy renders appealing time domain characteristics such as settling time, peak overshoot, and integral absolute frequency error.     

基于变速趋近律的Buck型变换器抗扰动控制

针对带有输入电压波动、输出负载突变以及电感电容参数摄动等匹配和非匹配扰动的Buck型变换器系统,提出一种基于变速趋近律和扰动观测器的抗扰动控制方法.设计反余切型辅助函数构造变速趋近律,通过改变系统状态的收敛速度,保证系统具有较快的瞬态响应速度和较小的控制器抖振.通过对系统模型进行低通滤波,设计一种新型扰动观测器估计系统...     

Second-order terminal sliding mode control for hypersonic vehicle in cruising flight with sliding mode disturbance observer

This paper focuses on the design of nonlinear robust controller and disturbance observer for the longitudinal dynamics of a hypersonic vehicle (HSV) in the presence of parameter uncertainties and external disturbances. First, by combining terminal sliding mode control (TSMC) and second-order sliding mode control (SOSMC) approach, the secondorder terminal sliding control (2TSMC) is proposed for the velocity and altitude tracking control of the HSV. The 2TSMC possesses the merits of both TSMC and SOSMC, which can provide fast convergence, continuous control law and hightracking precision. Then, in order to increase the robustness of the control system and improve the control performance, the sliding mode disturbance observer (SMDO) is presented. The closed-loop stability is analyzed using the Lyapunov technique. Finally, simulation results illustrate the effectiveness of the proposed method, as well as the improved overall performance over the conventional sliding mode control (SMC).