Buck变换器非线性控制器设计

针对Buck变换器的非线性特性,提出了采用反步法和反步滑模法控制非线性系统的控制策略。基于对Buck变换器数学模型的分析,论述了反步法控制器的设计,实现了当Buck变换器参数发生变化时,电容电压和电感电流对给定参考信号较好的跟踪;将反步法与滑模控制相结合,设计了反步滑模控制器,进一步改善了系统的跟踪性能。使用System Generator在Matlab环境下进行系统建模及仿真研究,结果表明,反步法和反步滑模法的非线性系统控制器效果良好。     

一种新型Buck单周控制变换器

基于单周控制器控制的Buck变换器具有很强的抗输入电压干扰能力,但抑制负载扰动能力较差、输出有稳态误差.根据单周控制Buck变换器存在的主要问题,通过将单周控制器和一种类似滞环控制的非线性控制器组合起来形成一种新型误差自适应单周控制器.该控制器根据输出误差的不同为单周控制器选择不同的参考信号,从而提高了变换器的动态响应性能,比传统的单周控制器具有更好的动态性能以及指令跟踪能力.仿真结果证明了这种控制方法的有效性.     

一种新型Buck单周控制变换器

基于单周控制器控制的Buck变换器具有很强的抗输入电压干扰能力,但抑制负载扰动能力较差、输出有稳态误差。根据单周控制Buck变换器存在的主要问题,通过将单周控制器和一种类似滞环控制的非线性控制器组合起来形成一种新型误差自适应单周控制器。该控制器根据输出误差的不同为单周控制器选择不同的参考信号,从而提高了变换器的动态响应性能,比传统的单周控制器具有更好的动态性能以及指令跟踪能力。仿真结果证明了这种控制方法的有效性。     

基于电荷控制的Buck变换器

介绍了一种新的单周期控制方法——电荷控制法。通过对开关电流的控制,使其在一个周期内达到期望值。在详细分析电路工作原理的基础上,推导出电荷控制Buck电路的控制电路和主电路数学模型。Pspice仿真和实验结果表明,系统的稳定性不仅与占空比D有关,而且与电路的电感、负载及工作频率有关。若参数选择合理,则系统可在D>0.5条件下稳定工作。该控制在每个周期对开关管上的电流进行积分,有较强的抗干扰性,所以能有效抑制负载扰动。实验测得电荷控制Buck电路功率因数PF=0.99,电流畸变率THD=8.4%。     

Lyapunov模式控制Buck变换器

探索了开关功率变换器的Lyapunov模式非线性控制策略。以Buck变换器为例,构造了含有电容电压误差项、电感电流误差项及其积分项的三项式Lyapunov能量函数,导出了满足系统稳定收敛的控制方程。通过引入积分复位控制电路和简化的电压外环控制电路,构建出Lyapunov模式控制的等效模拟控制电路,基于系统线性化模型给出了控制参数的选取以及系统性能分析。最后给出仿真和实验结果验证了所提控制策略的有效性。     

谷值电流控制三电平Buck变换器

三电平Buck变换器能使开关管的电压应力减小为输入电压的一半,使电感电流脉动频率为开关频率的两倍,减小滤波器的尺寸.为了实现以上的优点,使变换器具有较高的功率密度,必须保持飞跨电容的电压为输入电压的一半.为此,采用谷值电流控制的方法,通过平衡电感电流来调节飞跨电容上的电压,实现飞跨电容电压稳定.建立三电平Buck变换器谷值电流控制的小信号模型,以获得小信号传递函数模型,进而对其补偿网络进行了设计.仿真验证了理论的正确性和控制策略的可行性.     

控制受限滑模控制Buck变换器设计

针对脉冲功率负载的周期性功率突变造成接口变换器输出电压瞬时跌落和持续扰动的问题,提出一种Buck变换器的自适应阻尼比控制方法,使得输出电压的响应性能能够直接通过阻尼比实现精确调节,不依赖于控制参数,且对输入电压扰动具有抑制作用。该方法通过引入类电压环消除了时变的输入和占空比的非线性饱和,建立输出电压与其参考值的单输入单输出二阶系统,将不确定负载扰动的控制问题转化为二阶系统的阻尼比控制问题。此外,在不影响电压调节性能的前提下,通过附加占空比调节实现并联变换器供电结构的均流控制。仿真和硬件在环实验结果表明,在脉冲功率负载的不同暂态过程,并联变换器均能够实现快速平滑的电压调节和输出电流均衡。

     

电压控制型Buck DC/DC变换器输出阻抗优化设计

提出了电压控制型Buck DC/DC变换器最优截止频率fc选择,在此基础上给出了电压控制型Buck变换器输出阻抗的优化设计准则:采用PI调节器或单极点双零点补偿器,当截止频率满足最优截止频率选择时,能够有效抑制输出阻抗尖峰,从而确保系统良好的稳定与动态性能.实验结果验证了理论分析的正确性.     

基于自适应超螺旋滑模观测器的Buck变换器无模型预测控制

针对三相交错并联Buck变换器在外部干扰下影响系统鲁棒性和动态性能的问题,本文提出一种基于自适应超螺旋滑模观测器的无模型预测控制策略。首先,建立超局部模型代替原有的数学模型,设计自适应超螺旋滑模观测器估计超局部模型中的动态部分。然后,引入最小二乘法预测电流误差趋势,动态调整观测器增益矩阵。最后,构建离散方程,设计代价函数,实现无模型预测控制。实验结果验证了所提算法可以有效抑制因外部扰动产生的稳态误差,且相较于传统无模型预测控制具有更好的鲁棒性和动态性能。     

基于切换线性系统理论的DC-DC变换器控制系统的能控性和能达性

该文将电力电子电路视为一类混杂动态系统，尝试在DC-DC变换器控制系统研究中引入切换线性系统的概念和理论。将基本DC-DC变换器建立为切换线性模型，由此提出DC-DC变换器能控性和能达性等基本控制特性，为DC-DC变换器控制系统的优化控制和其它控制策略的实现提供理论依据。以Buck变换器控制系统设计为例进行仿真验证，分析了能控性和能达性研究的理论意义。该文的研究还表明，研究方法也适应于其它电力电子电路能控性和能达性的研究。     

Adaptive prescribed performance tracking control for uncertain strict-feedback Multiple Inputs and Multiple Outputs nonlinear systems based on generalized fuzzy hyperbolic model

This article proposes an adaptive prescribed performance tracking control methodology for a class of strict-feedback Multiple Inputs and Multiple Outputs nonlinear systems. A combination of backstepping technique and the generalized fuzzy hyperbolic model was used in recursive design of adaptive controller. A novel performance constraint function guarantees the tracking control performance. Lyapunov stability analysis proves that the designed controller can ensure the predefined transient and all signals within the closed-loop systems are semiglobally uniformly ultimately bounded. In the end, simulation results illustrate the validity of the proposed approach.     

Reinforcing robustness of adaptive dynamic surface control

Adaptive dynamic surface control (ADSC) design was proposed as an alternative to adaptive backstepping, capable of curing the ‘explosion of complexity’ problem, caused by the repeated differentiations of the so called intermediate control signals. However, as it is clearly demonstrated in this work, ADSC schemes are sensitive to modeling uncertainties and/or additive external disturbances. In fact, it is shown that a uniformly bounded exogenous perturbation of unknown upper bound may easily destabilize the closed‐loop system. Subsequently, a constructive methodology based on the recently developed by the authors prescribed performance control technique, is proposed, which combined with an ADSC design, results in a modified scheme possessing significantly increased robustness properties. Simulation studies illustrate the approach. Copyright © 2012 John Wiley & Sons, Ltd.     

Prescribed performance adaptive fuzzy control for nonstrict-feedback nonlinear systems with dead zone outputs

This paper presents an adaptive fuzzy control scheme for a class of nonstrict-feedback nonlinear systems with dead zone outputs and prescribed performance. By utilizing the monotonically increasing property of system bounding functions and the Nussbaum function, the design difficulties caused by the nonstrict-feedback structure and dead zone output are overcome. Combining backstepping technique with prescribed performance algorithm, a feasible adaptive fuzzy controller is designed to guarantee the boundedness of all signals of the closed-loop system and the prescribed tracking performance of the system. Finally, simulation results are depicted to illustrate the effectiveness of the proposed control approach.     

Finite-time adaptive control for nonlinear systems with uncertain parameters based on the command filters

The trajectory tracking control problem for a class of nonlinear systems with uncertain parameters is considered in this article. A new adaptive finite-time tracking control is designed based on the adaptive backstepping method via the command filters. The command filter mechanism can avoid the calculation of partial derivatives and solve the “explosion of complexity” in the backstepping design. The compensation signals are introduced to eliminate errors produced by the command filters. The proposed adaptive backstepping control can guarantee the tracking error remains in a small neighborhood of the origin in finite time, while the practical finite-time stability of the control systems with uncertain parameters is proven by the stability criterion. The effectiveness of the proposed scheme is verified by some simulation results.     

Small-gain technique-based adaptive fuzzy command filtered control for uncertain nonlinear systems with unmodeled dynamics and disturbances

This article studies the adaptive tracking control problem for a class of uncertain nonlinear systems with unmodeled dynamics and disturbances. First, a fuzzy state observer is established to estimate unmeasurable states. To overcome the problem of calculating explosion caused by the repeated differentiation of the virtual control signals, the command filter with a compensation mechanism is applied to the controller design procedure. Meanwhile, with the help of the fuzzy logic systems and the backstepping technique, an adaptive fuzzy control scheme is proposed, which guarantees that all signals in the closed-loop systems are bounded, and the tracking error can converge to a small region around the origin. Furthermore, the stability of the systems is proven to be input-to-state practically stable based on the small-gain theorem. Finally, a simulation example verifies the effectiveness of the proposed control approach.     

Adaptive finite-time output feedback control for Markov jumping nonlinear systems

In this article, the problem of output feedback tracking control for uncertain Markov jumping nonlinear systems is studied. A finite-time control scheme based on command filtered backstepping and adaptive neural network (NN) technique is given. The finite-time command filter solves the problem of differential explosions for virtual control signals, the NN is utilized to approximate the uncertain nonlinear dynamics and the adaptive NN observer is applied to restructure the state of system. The finite-time error compensation mechanism is established to compensate the errors brought by filtering process. The proposed finite-time tracking control algorithm can ensure that the solution of the closed-loop system is practically finite-time stable in mean square. Two simulation examples are employed to demonstrate the effectiveness of the proposed control algorithm.