共查询到19条相似文献,搜索用时 93 毫秒
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对于Buck/Boost变换器,传统的控制器如PID控制器、Ⅲ型误差放大器等存在超调量过大、响应时间过长、鲁棒性不强等问题,为克服这些缺点,提出基于离散指数趋近律的开关电源模糊滑模控制方案.首先,针对工作在电感电流连续模式(CCM)的Buck/Boost变换器采用状态空间平均法建立平均线性模型;然后设计离散指数趋近律的滑模控制器,并分析了切换参数对系统的影响;最后,为改善控制效果,设计了模糊控制器.仿真结果表明,相对于传统的控制器,指数趋近律的模糊滑模控制器有效地降低了超调量,提高了系统的响应时间,并且对外部干扰的鲁棒性较好.利用所设计的控制算法实现了对50 W高频开关电源样机的良好控制,进一步证明了所提方法的有效性. 相似文献
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直流变换器在能量转换系统中起到至关重要的作用.针对直流降压变换器系统中存在的多源干扰问题,本文提出了一种基于观测器的复合离散滑模控制方案.为获得高电压跟踪精度和强抗干扰能力,在控制器中引入了干扰估计信息的二阶差分.通过干扰估计和前馈补偿,有效地消除了干扰对变换器电压跟踪精度的影响.同时,为削弱抖振影响,文中设计了一种新型的自适应滑模趋近律,并针对闭环系统给出了严格的稳定性与收敛性能分析.此外,本文基于快速原型控制器进行不同工况下变换器系统实验测试.结果表明,相比于传统离散滑模控制,文中所研究的复合控制器具备较强的抗干扰能力和较高电压跟踪精度. 相似文献
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根据一类典型的三轴动中通系统的耦合特性及载体扰动特点,提出一种新型滑模趋近律方法,并在此基础上设计了滑模稳定跟踪控制器.理论证明和仿真实验均表明了所设计的基于新型趋近律的滑模稳定跟踪控制器的合理性和有效性. 相似文献
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针对离散时间系统变结构控制的设计问题进行了研究。为了改善离散指数趋近律的趋近过程,提出了一种新的趋近律,利用该趋近律设计的变结构控制器,不仅能够大幅度削弱抖振,使系统运动最终趋于原点不存在稳态振荡,而且能使系统的准滑动模态保持步步穿越切换面的基本属性,有效地改善了趋近过程,提高了控制品质。仿真分析验证了该方法的合理性与有效性。 相似文献
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针对一类离散时间系统,提出一种变结构控制设计方法。为了减小离散指数趋近律的抖振现象,本文构造一种趋近律, 利用它设计变结构控制器,能够大幅度削弱抖振,有效地改善控制品质,使系统最终趋于原点,并使系统稳定。给出数值计算和仿真算例。 相似文献
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Dina Shona Laila Author Vitae Author Vitae 《Automatica》2003,39(5):821-835
We present results on changing supply rates for input-output to state stable discrete-time nonlinear systems. Our results can be used to combine two Lyapunov functions, none of which can be used to verify that the system has a certain property, into a new composite Lyapunov function from which the property of interest can be concluded. The results are stated for parameterized families of discrete-time systems that naturally arise when an approximate discrete-time model is used to design a controller for a sampled-data system. We present several applications of our results: (i) a LaSalle criterion for input to state stability (ISS) of discrete-time systems; (ii) constructing ISS Lyapunov functions for time-varying discrete-time cascaded systems; (iii) testing ISS of discrete-time systems using positive semidefinite Lyapunov functions; (iv) observer-based input to state stabilization of discrete-time systems. Our results are exploited in a case study of a two-link manipulator and some simulation results that illustrate advantages of our approach are presented. 相似文献
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In this communique, the properties of a class of discrete-time dynamic systems with power rule are studied and comparisons with their continuous-time counterparts as well as the linear discrete-time systems are made. It is shown that using power rule can be beneficial for improving dynamic behaviors of discrete-time systems. For example, a power control law may stabilize a discrete-time system which is not stabilizable by the linear control law. 相似文献
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本文应用文献[2]中离散系统共轭化概念。去掉T_2~(-1)(z)必须是反稳定的限制条件,解决了更一般的离散系统H~∝模型匹配问题。 相似文献
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针对二阶离散式模糊追踪系统,提出用于构造一种最优模糊追踪器的设计方式,
并用于追踪一类时变目标或任意模型目标.为了能让所提出的设计方法完整并达到总体最小
化,提出了一种近似线性化的离散模糊动态系统的表示法.另外,为了简化计算量,一个多
层分解方式被用于本文所提出的最优设计程序中,模拟结果显示,本文提出的最优模糊追踪
设计方式确能达到预期效果. 相似文献
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离散系统最速控制综合函数 总被引:6,自引:0,他引:6
针对自抗扰控制技术中的fhan()函数,指出其只是离散系统最速控制综合函数的一种简化.详细推导了离散系统真正的最速控制综合函数——fsun(),完善了自抗扰控制技术的理论框架.理论分析和数值仿真表明,采用fsun()函数后的二阶离散系统,状态变量达到稳态时位置和速度曲线均不会出现超调,且达到稳态时所用的步数少于函数fhan(). 相似文献
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In this paper, the discrete-time control of decentralized continuous-time systems, which have approximate decentralized fixed modes, is studied. It is shown that under certain conditions, discrete-time controllers can improve the overall performance of the decentralized control system, when a linear time-invariant continuous-time controller is ineffective. In order to obtain these conditions, a quantitative measure for different types of approximate fixed modes in a decentralized system is given. In this case, it is shown that discrete-time zero-order hold (ZOH) controllers, and in particular, that generalized sampled-data hold functions (GSHF), can significantly improve the overall performance of the resultant closed-loop system. The proposed sampled-data controller is, in fact, a linear time-varying controller for the continuous-time system. 相似文献
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This paper presents a fundamental study of the connection between continuous- and discrete-time systems. Provided is a definition for discrete-time models, that is discrete-time systems with a continuous-time counterpart, whose order can be higher than that of the continuous-time system. This definition is based on a comparison in a certain sense on the time responses of continuous- and discrete-time systems. A theorem is presented for relating the higher-order discrete-time models to their continuous-time counterparts, which is an extension of a previous theorem for models with order equal to that of the continuous-time system. State-space forms are derived for models obtained through the use of a certain class of hold elements and through the use of mapping models, and these discrete-time systems are shown to be valid according to the definition. Special cases are models obtained using first-order and slewer hold devices, whose convergence to a continuous-time counterpart has not been shown mathematically before, and mapping models corresponding to two-step linear multi-step methods, which have not previously presented in the state-space form. The derived state-space forms provide a convenient way to implement these models for purposes of analysis, design, and implementation of discrete-time systems and finds applications in such areas as digital signal processing, digital simulation, and digital control. 相似文献
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The constrained controllability of the discrete-time system xk+1=A(k)xk+B(k)u,k is considered where the control uk is termed admissible if it satisfies specified magnitude constraints. Constrained controllability is concerned with the existence of an admissible control which steers the state x to a given target set from a specified initial state Conditions for checking constrained controllability to a given target set from a specified initial state are presented. These conditions involve solving finite-dimensional optimization problems and can be checked via numerical computation. In addition, conditions for checking global constrained controllability to a given target set are presented. A system is globally constrained controllable if for every initial state, there exists an admissible control that steers the system to the target. If a given discrete-time system is constrained controllable, it may be desirable to obtain an admissible control that steers the system to the target from a specified initial state. Such a control is called a steering control. Results for computing steering controls are also presented This paper is concluded with a numerical example. In this example, it is shown that the constrained controllability of a continuous-time system which has been discretized is dependent on the discretization time. The set of states which can be steered to the target changes as the discretization time changes. Furthermore, the example shows that a discrete-time steering control cannot always be obtained by discretizing a continuous-time steering control; the steering control for the discrete-time system must be obtained directly from the discrete-time model. 相似文献