七维心脏-血液混沌动力系统的FPGA实现

本文基于七维心脏-血液混沌动力系统、数字化处理技术,通过对系统的连续时间状态方程进行离散化处理和变量比例变换,用FPGA技术硬件实现动力系统方程中的混沌吸引子;提出用FPGA技术产生混沌吸引子的一般设计原理并给出其硬件实现结果。为复杂高阶电路系统的设计与实现提供了一条切实可行的途径。     

Sinusoidal disturbance rejection in chaotic planar oscillators

The main goal of this paper is to design a compensator able to restore the nominal behavior of a planar system, which is rendered chaotic by an unmeasurable sinusoidal disturbance input. To reach such a goal, some instruments, taken from algebraic geometry, are used to estimate the unmeasurable disturbance from the time derivatives of the output of the system and of the control input. Copyright © 2015 John Wiley & Sons, Ltd.     

一类不确定参数混沌系统的鲁棒跟踪控制

提出了一种新型的鲁棒跟踪控制方法实现对一类不确定混沌系统的跟踪控制.基于李亚普诺夫稳定性理论,设计了一种能根据不同的应用环境方便地进行调整的鲁棒跟踪控制器.只要参数的不确定性是有界的,这种控制器就可以使混沌系统的状态向量跟踪期望轨迹.对R(o)ssler和Lorenz混沌系统的仿真结果验证了这种控制器是有效的.     

采用滑模方法实现多涡卷混沌系统的同步

针对基于滞环的多涡卷混沌系统的同步,提出了一种终端滑模变结构控制方案,使主动混沌系统和被动混沌系统之间实现了同步,使得误差系统在有限时间内到达设定的滑模面,保证误差系统在有限时间内到达系统的平衡点。仿真结果验证了所提出方法的有效性和分析的正确性。     

Current mode CCII oscillators using grounded capacitors and resistors

New realizations of grounded C, grounded R current mode oscillators using the current conveyor (CCII) are given. The proposed oscillators are classified into two classes depending on the number of feedback loops. In class I, there is a single current feedback loop, whereas in class II, there are two current feedback loops. Class I includes two types and it employs two CCIIs, three capacitors and three or four resistors. Class II employs two CCIIs having two-outputs each, two capacitors and three resistors and has independent control on the condition of oscillation and on the frequency of oscillation by varying two alternative resistors. PSpice simulations are included. Exact analysis based on the parasitic elements of the CCII is carried out indicating that class I has a third order characteristic equation. Class II has the advantage that the effects of the parasitic elements of the CCIIs can be absorbed in the circuit components. © 1998 John Wiley & Sons, Ltd.     

具有传输通道时间延迟的一类混沌系统脉冲控制同步

针对一类混沌系统同步控制问题,利用脉冲微分方程的稳定理论,研究了传榆信号具有时间延迟的混沌系统脉冲同步问题,给出了两个混沌系统实现全局渐进同步的判据方法。该方法仅采用具有时间延迟的驱动系统与响应系统输出偏差的线性反馈作为脉冲控制信号,驱动两个混沌系统达到全局渐进同步,且适用于绝大多数混沌系统的同步控制。所设计的控制器结构简单,收敛速度快,易于实现。Roessler混沌系统的仿真实验进一步验证了该方法的有效性和可行性。     

采用终端滑模实现多涡卷混沌系统的追踪控制

针对基于滞环非线性多涡卷混沌系统的追踪控制问题,提出了一种终端滑模控制方法,实现了受控混沌系统对给定参考信号的追踪控制。应用李亚谱诺夫稳定性定理证明了所提出控制方法的正确性。仿真结果验证了追踪误差系统的状态首先在有限时间内到达滑模面,然后在有限时间内收敛到原点,实现了追踪控制。     

Chaotic oscillator configuration using a frequency dependent negative resistor

A chaotic oscillator configuration employing a frequency‐dependent negative resistor (FDNR) as the only active element is proposed. The configuration relies on a simple two‐terminal passive device; namely a general purpose signal diode, to provide the necessary non‐linearity. The structure requires no floating elements and is independent of any circuit specific realization of the FDNR. Experimental results, PSpice simulations and numerical simulations of the derived mathematical models are included. Copyright © 2000 John Wiley & Sons, Ltd.     

Basic bifurcation analysis of a hysteresis oscillator

This paper carries out a basic bifurcation analysis of a ‘smooth’ version of a recently proposed piecewise‐linear oscillator based on hysteresis. The analysis is made referring mainly to two circuit parameters particularly easy to vary in a laboratory implementation of the circuit. By resorting to both analytical and numerical analyses, some local and global bifurcations of the dynamics of the oscillator are pointed out. The reported results completely agree with PSPICE simulations and experimental measures. Copyright © 2001 John Wiley & Sons, Ltd.     

用于磁滞类电机平行四边形模型的修正

平行四边形磁滞模型与其他常用模型相比更适合用于径向磁通的磁滞电机磁路分析。Copeland和Slemon教授发展的平行四边形模型认为剩磁密度在变换过程中是不动的,本文运用叠加原理、等效磁路和傅立叶变换的方法证明了该模型在变换过程中剩磁密度点是漂移的,漂移程度取决于模型中4个边的斜率。模型修正后,BH环矩形面积与变换前的平行四边形面积相等,符合模型变换的基本导则。最后用修正模型对30HP磁滞电机进行了分析验证,相对于原模型该电机剩磁漂移达到4%。     

数字滞环控制器设计

分析了滞环控制开关频率不固定的原因,并在原有基础之上进行改进,设计了一种新的数字滞环控制器,实验结果表明,可以方便限制最高开关频率及保持较高的控制精度。     

Design equations for fractional‐order sinusoidal oscillators: Four practical circuit examples

Four practical sinusoidal oscillators are studied in the general form where fractional‐order energy storage elements are considered. A fractional‐order element is one whose complex impedance is given by Z = a(jω)^±α, where a is a constant and α is not necessarily an integer. As a result, these oscillators are described by sets of fractional‐order differential equations. The integer‐order oscillation condition and oscillation frequency formulae are verified as special cases. Numerical and PSpice simulation results are given. Experimental results are also reported for a selected Wien‐bridge oscillator. Copyright © 2007 John Wiley & Sons, Ltd.     

CMOS digitally programmable quadrature oscillators

CMOS digitally programmable quadrature oscillators based on digitally controlled current followers and voltage followers are proposed. The proposed designs provide the advantage of programmability similar to the operational transconductance amplifier‐based oscillators while offering improved linearity. In mixed analog/digital systems, the digital tuning feature allows direct interfacing with the digital signal processing part. Novel realizations that provide both voltage‐mode and current‐mode quadrature sinusoidal signals are presented. Employing only grounded capacitors the designs achieve independent control of the frequency and condition of oscillation that can be tuned digitally. Experimental results obtained from a 0.35 µm CMOS chip fabricated using standard CMOS process are given. Copyright © 2008 John Wiley & Sons, Ltd.     

Analysis and synthesis of perturbed Duffing oscillators

Analysis and synthesis of perturbed Duffing oscillators have been presented. The oscillations in such systems are regarded as limit cycles in perturbed Hamiltonian systems under polynomial perturbations of sixth degree and are analysed by using the Melnikov function. It has been proved that there exists a polynomial perturbation depending on the zeros of the Melnikov function so that the system considered can have either two simple limit cycles, or one limit cycle of multiplicity 2, or one simple limit cycle. A synthesis of such oscillators based on the Melnikov's theory has been proposed. Copyright © 2006 John Wiley & Sons, Ltd.     

定环宽逆变器电压滞环控制环宽-谐波畸变分析

针对单相半桥逆变电源,提出一种恒定滞环宽度的电压滞环控制方法,并通过对输出电流的检测实现开关管的零电流开通(Zero Current Switching, ZCS)。控制器通过检测负载输出电压并与电压滞环比较,当输出电压超出控制滞环、且输出电流为零时控制相应开关管开通,直至输出电压重回控制滞环带或输出电流过流时关断,进一步的,本文研究了定环宽控制下,滞环宽度与输出电压总谐波畸变率之间的关系。仿真结果表明,基于定滞环宽度的电压滞环控制方式在零电流开通状态下可良好地跟踪上参考电压滞环,且在恒定滞环宽度控制下,滞环宽度与输出电压总谐波畸变率之间呈线性关系。     

The stability of a chaotic PWM boost converter

A novel chaotic pulse‐width‐modulation (PWM) boost converter has been previously proposed to reduce electromagnetic interference (EMI) in DC–DC converters, where the circuit design and simulations have been conducted, but the problems such as the mean value estimation of state variables for circuit parameter design, the ripple estimation of the input current and the stability analysis have been remained to be addressed in this paper. Here, a mean value estimation method is first proposed, which is used to estimate the mean values of state variables of chaotic PWM boost converters for facilitating the circuit parameter design and selection of circuit components. Although ripples are slightly increased, caused by adopting chaotic carriers, the DC–DC converter with reduced EMI is still stable under the chaotic PWM control. This work provides a theoretic verification of the effectiveness and practicability of the proposed chaotic PWM DC–DC converters. Copyright © 2010 John Wiley & Sons, Ltd.     

基于人工神经网络的Preisach磁滞模型与实现

在Preisach静态磁滞模型的基础上,利用极限磁滞回线的对称性,采用人工神经网络技术,建立了Preisach神经网络磁滞回线仿真模型,实现了对试验样片交流磁滞回线的理论计算;同时给出了一种采用爱泼斯坦方圈,对实验样片的动态磁滞回线进行数字测量的新方法,该方法实验设备简单,测量精度高,具有较好的工程实用价值。利用该方法得到的实验数据很好地验证了理论计算结果。     

Circuit implementation and model of a new multi‐scroll chaotic system

In this paper, a multi‐scroll chaotic system from the improved Chua's system is proposed. Moreover, non‐linear dynamics are analyzed including phase‐space trajectories, bifurcation diagrams, Poincaré maps and so on. The most important thing is that we discovered phase‐space trajectories, bifurcation diagrams and Poincaré maps are unified and closely related, which can describe different aspects of the multi‐scroll chaotic system. Furthermore, the corresponding improved module‐based circuits are designed for realizing two to four‐scroll chaotic attractors, and the experimental results are also obtained, which are consistent with the numerical simulations. Copyright © 2012 John Wiley & Sons, Ltd.     

Experimental comparison of phase‐noise in cross‐coupled RC‐ and LC‐oscillators

Relaxation RC‐oscillators are notorious for their poor phase‐noise performance. However, there are reasons to expect a phase‐noise reduction in quadrature oscillators obtained by cross‐coupling two relaxation oscillators. We present measurements on 5 GHz oscillators, which show that in RC‐oscillators the coupling reduces both the phase‐noise and quadrature error, whereas in LC‐oscillators the coupling reduces the quadrature error, but increases the phase‐noise. A comparison using standard figures of merit indicates that quadrature RC‐oscillators may be a viable alternative to LC‐oscillators when area and cost are to be minimized. Copyright © 2009 John Wiley & Sons, Ltd.     

基于Preisach磁滞模型的分布函数辨识与实验验证

基于Preisach磁滞模型,根据磁滞回线的对称性,提出辨识Preisach分布函数的方法,该方法把Preisach分布函数视为两个一维函数的乘积,将分布函数中复杂的双重积分求解问题转化为求解双线性方程组的问题。并基于爱泼斯坦方圈测量装置对变压器、电机中常用材料(B30P105)进行了相应的实验,仿真及实验结果的比对验证了该方法的可行性和实用性。