An optimal filter based MPC for systems with arbitrary disturbances

In this study, a linear model predictive control (MPC) approach with optimal filters is proposed for handling unmeasured disturbances with arbitrary statistics. Two types of optimal filters are introduced into the framework of MPC to relax the assumption of integrated white noise model in existing approaches. The introduced filters are globally optimal for linear systems with unmeasured disturbances that have unknown statistics. This enables the proposed MPC to better handle disturbances without access to disturbance statistics. As a result, the effort required for disturbance modeling can be alleviated. The proposed MPC can achieve offset-free control in the presence of asymptotically constant unmeasured disturbances. Simulation results demonstrate that the proposed approach can provide an improved disturbance õrejection performance over conventional approaches when applied to the control of systems with unmeasured disturbances that have arbitrary statistics.     

正弦波形参量对ADC有效位数评价的影响

针对ADC动态有效位数评价过程中激励正弦信号参数变化对其影响进行了详细深入的实验研究,发现动态有效位数评价误差最小的条件为:正弦信号峰峰值为最小量化阶梯的奇数倍,直流偏移为最小量化阶梯的整数倍,激励信号相位变化对于动态有效位数误差没有明显影响。直流偏移为最小量化阶梯的整数倍加上半个最小量化阶梯时,给动态有效位数造成的误差最大。研究所得结论可用于动态有效位数评价时的正弦信号参量选取实践中。     

三电平空间矢量与载波调制策略统一理论的研究

两电平空间矢量脉宽调制(space vector pulse widthmodulation,SVPWM)与正弦脉宽调制(sinusoidal pulse widthmodulation,SPWM)存有一定的本质关系,对于三电平,在常见的8段式SVPWM序列中可以证明,SVPWM与SPWM本质上也存在某种统一。实际的SVPWM调制中,由于要考虑中点电压平衡、减少谐波等其它性能问题,一般会利用开关冗余状态得到8段以上的开关调制序列。目前的文献中还未曾有对这些情况进行统一性地验证,因此三电平SVPWM与SPWM的统一理论存在一定的不足。研究发现,可通过严格地理论推导将传统意义上的调制波分解为2个子调制波,再进行SPWM调制,可以得到与SVPWM完全吻合的序列。该文在此方法基础上深入研究了8段以上(10、12、14段)的SVPWM调制序列与SPWM的统一。经过严格地理论推导,成功实现了含任意段数的SVPWM序列与SPWM的统一。仿真结果证明了该理论的正确性。     

Adaptive disturbance rejection control for compartmental systems with application to intraoperative anesthesia influenced by hemorrhage and hemodilution effects

Compartmental system models involve dynamic states whose values are nonnegative. These models are widespread in biological and physiological sciences and play a key role in understanding these processes. In this paper, we develop a direct adaptive disturbance rejection control framework for compartmental dynamical systems with exogenous bounded disturbances. The proposed framework is Lyapunov based and guarantees partial asymptotic stability of the closed‐loop system, that is, asymptotic stability with respect to part of the closed‐loop system states associated with the plant dynamics. The remainder of the states associated with the adaptive controller gains are shown to be Lyapunov stable. In the case of bounded energy ??₂ disturbances, the proposed approach guarantees a nonexpansivity constraint on the closed‐loop input–output map between the plant disturbances and performance variables. Finally, a numerical example involving the infusion of the anesthetic drug propofol for maintaining a desired constant level of depth of anesthesia for surgery in the face of continuing hemorrhage and hemodilution is provided. Copyright © 2008 John Wiley & Sons, Ltd.     

无阻尼绕组双轴励磁同步发电机的静态稳定分析

文章对无阻尼绕组双轴励磁同步发电机的静态稳定性进行了详细地分析,建立了其基本方程以及微干扰分析的线性化数学模型。并通过实例,根据计算机结果,对单轴励磁和双轴励磁两种发电机的稳定性进行了比较,从而说明在一定条件下,双轴励磁可以提高同步发电机的静态稳定性.     

Operational transform technique for generating Lyapunov functions

An operational transform technique is established to generate Lyapunov functions for the transient stability study of a power system modelled to full complexity. This method requires the system equations in state-space form without any additional assumption. A modifiable skew symmetric transformation matrix is shown to exist, via which the Lyapunov functions for a power system are generated. The power and the simplicity of the presented method is demonstrated by applying it to a single-machine, infinite-bus system, taking into account the effects of transfer conductances and all control equipment. The applicability of the method to a typical multimachine power system is examined and presented.     

Adaptive robust control of nonholonomic systems with stochastic disturbances

Based on the Brockett’s necessary condition for feedback asymptotic stabilization[1], nonholonomic systems fail to be stabilized at the origin by any static continuous state feedback though they are open loop controllable. There are two novel approaches …     

卷绕传输系统偏心张力干扰的自适应消除法

提出一种自适应算法可用于补偿工业卷绕传输系统中因卷绕轴轮的偏心所造成的影响.轴轮的偏心导致卷绕物张力干扰,干扰信号的频率随轴轮转速而缓慢变化.提出的自适应算法基于锁相回路结构,可在线估测出干扰信号的相位及幅值大小并消除其影响.还给出了这种算法的频域分析及参数设计方法,并通过仿真结果验证该算法消除轴轮偏心所造成的张力干扰的能力.     

新型单相正弦车载电源

介绍了一种新型的单相正弦车载电源，该电源由单芯片产生正弦脉宽调制信号，以实现由直流12v到交流220V／50Hz的转换。给出了电源的系统结构图，详细分析了其主要部分的功能，并给出了实验结果。     

微弱正弦信号幅值混沌检测的一种改进方案

本文根据混沌系统在特定状态下对参数的敏感性,提出了一种检测微弱正弦信号幅值的改进方案.该方案采用线性最小二乘方法找到了待测微弱信号幅值与混沌动力系统特征指数之间的关系,给出了弱信号幅值的估计式.理论与数值仿真实验表明该方案的估计精度较高,计算量小,易于工程实现.