Multi-channel DMA Based Design of Voltage Monitoring Using Synchronous Frequency Trace-Sampling Technique

In order to eliminate the influence of frequency change on real-time voltage acquisition,a low-cost solution of voltage monitoring was proposed using the multi-channel DMA synchronous frequency trace-sampling technique.In-chip resources of the designed voltage monitor were fully utilized in hardware design to reduce external devices.The MQX RTOS was used to perform the functional tasks flexibly and efficiently;especially the Ethernet communication applications and USB device connection were realized using its TCP/IP protocol stack and USB driver.In addition,to ensure the safety of electrical records,data statistics and alarm information management were also implemented through the management of the storage in FLASH.The test results show that the voltage monitor designed in this paper has the advantages of accurate measurement,strong resistance to frequency interference and low cost,and can be widely applied in the field of voltage monitoring in distribution networks.

Exponential synchronization of chaotic Lur'e systems with time-varying delay via sampled-data control

In this paper, we study the exponential synchronization of chaotic Lur＇e systems with time-varying delays via sampled-data control by using sector nonlinearties. In order to make full use of information about sampling intervals and interval time-varying delays, new Lyapunov-Krasovskii functionals with triple integral terms are introduced. Based on the convex combination technique, two kinds of synchronization criteria are derived in terms of linear matrix inequal- ities, which can be efficiently solved via standard numerical software. Finally, three numerical examples are provided to demonstrate the less conservatism and effectiveness of the proposed results.

Exponential synchronization of complex dynamical networks with Markovian jumping parameters using sampled-data and mode-dependent probabilistic time-varying delays

In this paper, the problem of exponential synchronization of complex dynamical networks with Markovian jumping parameters using sampled-data and Mode-dependent probabilistic time-varying coupling delays is investigated. The sam- pling period is assumed to be time-varying and bounded. The information of probability distribution of the time-varying delay is considered and transformed into parameter matrices of the transferred complex dynamical network model. Based on the condition, the design method of the desired sampled data controller is proposed. By constructing a new Lyapunov functional with triple integral terms, delay-distribution-dependent exponential synchronization criteria are derived in the form of linear matrix inequalities. Finally, two numerical examples are given to illustrate the effectiveness of the proposed methods.

Sampled-data synchronization of coupled harmonic oscillators with controller failure and communication delays

In this letter, a distributed protocol for sampled-data synchronization of coupled harmonic oscillators with controller failure and communication delays is proposed, and a brief procedure of convergence analysis for such algorithm over undirected connected graphs is provided. Furthermore, a simple yet generic criterion is also presented to guarantee synchronized oscillatory motions in coupled harmonic oscillators. Subsequently, the simulation results are worked out to demonstrate the efficiency and feasibility of the theoretical results.

Stochastic asymptotical synchronization of chaotic Markovian jumping fuzzy cellular neural networks with mixed delays and the Wiener process based on sampled-data control

We investigate the stochastic asymptotical synchronization of chaotic Markovian jumping fuzzy cellular neural networks （MJFCNNs） with discrete, unbounded distributed delays, and the Wiener process based on sampled-data control using the linear matrix inequality （LMI） approach. The Lyapunov–Krasovskii functional combined with the input delay approach as well as the free-weighting matrix approach is employed to derive several sufficient criteria in terms of LMIs to ensure that the delayed MJFCNNs with the Wiener process is stochastic asymptotical synchronous. Restrictions （e.g., time derivative is smaller than one） are removed to obtain a proposed sampled-data controller. Finally, a numerical example is provided to demonstrate the reliability of the derived results.

Free-matrix-based time-dependent discontinuous Lyapunov functional for synchronization of delayed neural networks with sampled-data control

This paper is concerned with the synchronization of delayed neural networks via sampled-data control. A new technique, namely, the free-matrix-based time-dependent discontinuous Lyapunov functional approach, is adopted in constructing the Lyapunov functional, which takes advantage of the sampling characteristic of sawtooth input delay. Based on this discontinuous Lyapunov functional, some less conservative synchronization criteria are established to ensure that the slave system is synchronous with the master system. The desired sampled-data controller can be obtained through the use of the linear matrix inequality（LMI） technique. Finally, two numerical examples are provided to demonstrate the effectiveness and the improvements of the proposed methods.

Fault tolerant synchronization of chaotic systems based on T-S fuzzy model with fuzzy sampled-data controller

In this paper the fault tolerant synchronization of two chaotic systems based on fuzzy model and sample data is investigated. The problem of fault tolerant synchronization is formulated to study the global asymptotical stability of the error system with the fuzzy sampled-data controller which contains a state feedback controller and a fault compensator. The synchronization can be achieved no matter whether the fault occurs or not. To investigate the stability of the error system and facilitate the design of the fuzzy sampled-data controller, a Takagi Sugeno （T-S） fuzzy model is employed to represent the chaotic system dynamics. To acquire good performance and produce a less conservative analysis result, a new parameter-dependent Lyapunov-Krasovksii functional and a relaxed stabilization technique are considered. The stability conditions based on linear matrix inequality are obtained to achieve the fault tolerant synchronization of the chaotic systems. Finally, a numerical simulation is shown to verify the results.

Impulsive effect on exponential synchronization of neural networks with leakage delay under sampled-data feedback control

We consider the impulsive effect on the exponential synchronization of neural networks with leakage delay under the sampled-data feedback control. We use an appropriate Lyapunov-Krasovskii functional combined with the input delay approach and some inequality techniques to derive sufficient conditions that ensure the exponential synchronization of the delayed neural network. The conditions are formulated in terms of the leakage delay, the sampling period, and the exponential convergence rate. Numerical examples are given to demonstrate the usefulness and the effectiveness of the results.

Network-Wide Time Synchronization in Multi-Channel Wireless Sensor Networks

Recent advances in wireless sensor technology have enabled simultaneous exploitation of multiple channels in wireless sensor systems. In this paper, a novel time synchronization algorithm is proposed for multi- channel Wireless Sensor Networks (WSNs) called Multi-Channel Time Synchronization (MCTS) protocol. Time synchronization is critical for many WSN applications and enables efficient communications between sensor nodes along with intelligent spectrum access. Contrary to many existing protocols that do not exploit multi-channel communications, the protocol takes advantage of potential multiple channels and distributes the synchronization of different nodes to distinct channels and thus, reduces the convergence time of synchronization processes significantly.

Pinning sampled-data synchronization for complex networks with probabilistic coupling delay

We deal with the problem of pinning sampled-data synchronization for a complex network with probabilistic time-varying coupling delay. The sampling period considered here is assumed to be less than a given bound. Without using the Kronecker product, a new synchronization error system is constructed by using the property of the random variable and input delay approach. Based on the Lyapunov theory, a delay-dependent pinning sampled-data synchronization criterion is derived in terms of linear matrix inequalities （LMIs） that can be solved effectively by using MATLAB LMI toolbox. Numerical examples are provided to demonstrate the effectiveness of the proposed scheme.

直扩水声通信机的码同步技术研究

为了降低扩频码同步技术对硬件的依赖,提高水声通信机的性能,对传统直接序列扩频码同步技术进行了一些改进。扩频码同步技术包括码捕获和码跟踪两个阶段,在码捕获阶段,采用双倍补零法扩展接收信号与接收机本地扩频码序列,使两者满足基二快速傅里叶变换运算的要求;在控制逻辑部分采用蓄水池抽样算法来确定范围内载波频偏值的计算顺序,无需按照固定顺序遍历范围内的载波频偏值,从而减少了计算量。在码跟踪阶段,采用了全时间超前-滞后非相干相关同步跟踪回路,采用双Δ值延迟锁相环的设计,扩大了跟踪范围,降低了失锁概率。最后基于DSP平台实现了直接序列扩频水声通信系统,该系统通过了水箱实验环境的测试。

改进细菌觅食算法的永磁同步电机参数辨识

应用群智能算法对永磁同步电机(PMSM)进行参数辨识后期容易进入局部最优,从而导致辨识误差大,为此提出一种融合小生境技术的改进细菌觅食算法(MBFA)。通过构建目标追踪函数,利用电机电流、电压和转速等直接测量的信号实现对电机d轴电感、q轴电感、定子电阻和永磁体磁链的快速、准确辨识;辨识过程中通过引入格型准则对目标解空间进行拟蒙特卡罗采样提高算法的全局搜索能力;基于小生境技术进行在线多种群协同搜索策略提高算法的搜索效率和寻优精度;最后通过引入一种种群实时监测和动态更新机制保证了算法在整个寻优过程的鲁棒性。仿真和实验结果表明,所提算法在参数辨识的快速性、准确性、稳定性方面均表现优越,辨识结果能够满足对永磁同步电机进行建模和仿真的精度要求。

基于同步采样SDFT的高性能单相锁相环方法研究

在电力机车及动车组的牵引传动控制系统中,网侧变流器通过锁相环获取相位信息并进行精确控制。牵引供电网电压的幅值及频率存在波动,而且网压经常出现严重畸变及含有大量谐波,复杂的电网环境对锁相环性能提出了很高的要求。文章结合同步采样,提出一种基于SDFT的高性能锁相环方法,并通过数字仿真及半实物仿真对所述方法的性能进行了验证。仿真结果表明,与其他几种主流的锁相环对比,该方法稳态锁相精度高,动态响应速度快,并有较强的谐波抑制能力与抗偏置能力,适宜在轨道交通领域应用。

基于改进零脉冲插入法的永磁同步电机相电流重构策略

直流母线单电流采样永磁同步电机系统存在相电流重构盲区,导致电流采样失真,提出一种改进零脉冲插入法,实现相电流重构。首先,分析传统固定零脉冲插入法的缺点,由于各相插入零脉冲作用时间相同,未能发挥“双开关PWM”模式抑制电流纹波的优势;其次,通过各相PWM占空比调整零脉冲时间,延长电流采样窗口,提出改进零脉冲插入法重构策略,消除重构盲区,并针对该方法重构盲区出现其他扇区有效电压矢量的情况,分析其空间电压矢量合成关系,证明参考电压矢量合成的准确性;最后,基于戴维南电路法,提出不同电压矢量作用时的电路简化模型,对比两种方法的电流纹波幅值,并搭建永磁同步电机实验平台进行实验。结果表明,改进零脉冲插入法的电流重构误差低于3%,相比传统方法,电流纹波抑制效果达到50%,相电流畸变率从12.72%下降到6.87%。

同步采样下的智能分布式馈线自动化配电网网格化规划方法

分布式馈线自动化配电网网格化规划合理性直接影响供电效果,目前提出的规划方法合理性较差。为了解决上述问题,文章在同步采样分析基础上研究了一种新的智能分布式馈线自动化配电网网格化规划方法,采用网格化定位技术建立分布式馈线自动化配电网,将配电网电力需求的预测值作为定位依据,在配电网供电区域内划分出多个用电范围,分析用电要求,通过告警和闭锁研究实现信息配置,采用层级分析法完成网格分类,计算待规划范围的电力负荷技术参数,采用差异性导入方法实现网格化规划。实验结果表明:同步采样下的智能分布式馈线自动化配电网网格化规划方法规划合理性在90%以上,能够很好地满足配电网的规划要求,很少出现断电事故,更适合于实际应用。

变电站网络采样自适应传输方式设计

阐述一种基于自适应传输方式的变电站网络采样方法。利用卫星同步技术实现采样值报文的同步,消除传统同步方式中的延迟问题。采用数字采样技术提高采样精度和减少采样误差。通过自适应传输方式提高网络的传输效率和稳定性。测试结果表明,该方法能够实现可靠的变电站数据采样和传输,提高监测和保护系统的响应速度和准确性。

基于FPGA的OFDM采样时钟同步设计

相比于传统的逻辑电路和门阵列,FPGA具有可重复编程、低功耗、低延时等优点。OFDM技术具有抗衰落能力强、频率利用率和频谱效率高以及对多径效应的鲁棒性强等优点,适合高速数据传输且易于实现,在现代无线通信系统中得到了广泛的应用。在OFDM技术中,接收机同步技术对于系统的通信质量有很重要的影响,该同步技术主要包括定时同步、载波频率同步和采样时钟同步三个部分,其中采样时钟同步的目的在于消除接收端A/D采样的频率、相位与发送端的D/A时钟频率以及相位的偏差对系统性能的影响,为了补偿采样频率偏移,在经过FFT后,利用导频信号在频域进行校正,最后基于FPGA设计采样时钟同步模块,主要包括导频提取和数据缓存、导频相关、频偏估计、频偏补偿和顺序调整5个部分。

基于FPGA的永磁同步电机三相电流同步采样方案

在永磁牵引控制平台中,为了实现永磁同步电机控制更优,需根据控制周期对电机的三相电流进行同步采样;同时,为了满足过流故障的实时保护,需要对电流以较小的时间间隔进行持续采样。为此,文章基于FPGA设计了一种利用一套ADC芯片同时满足永磁同步电机控制所需电流同步采样和过流实时保护需求的快速定时采样方案。该方案通过实时获取用户配置的同步采样周期,并结合定时采样周期,智能地生成ADC转换启动信号的方式,从而实现对永磁同步电机电流的同步采样和定时采样控制。最后,基于实际永磁牵引控制平台进行实验,结果验证了所提方案的可行性和有效性。

基于采样控制的时滞Lur’e系统的渐近同步分析

本研究探讨了基于采样数据控制的时滞Lur’e系统的全局渐近同步问题。首先构建了时滞主从系统的模型,并设计了相应的采样控制器。接着,通过构造新的李雅普诺夫函数并结合稳定性理论,再利用不等式性质及时滞分解技术,推导出了时滞Lur’e系统渐近同步的新判据,并以矩阵不等式形式加以表述。最后,利用数值模拟来验证了所得结果的有效性与实用性。

FAST ALGORITHM FOR NON-UNIFORMLY SAMPLED SIGNAL SPECTRUM RECONSTRUCTION

In this paper, a fast algorithm to reconstruct the spectrum of non-uniformly sampled signals is proposed. Compared with the original algorithm, the fast algorithm has a higher computational efficiency, especially when sampling sequence is long. Particularly, a transformation matrix is built, and the reconstructed spectrum is perfectly synthesized from the spectrum of every sampling channel. The fast algorithm has solved efficiency issues of spectrum reconstruction algorithm, and making it possible for the actual application of spectrum reconstruction algorithm in multi-channel Synthetic Aperture Radar (SAR).