Analysis and Simulation of Errors in Software Synchronous Sampling in Periodic-Signal Measurement

Software synchronous sampling is widely employed in periodic signal measurement, but measurement errors occur very commonly. This paper analyses the cause of the errors, deduces the mathematical model for the measurement errors in measuring RMS voltage, RMS current and active power using the software synchronous sampling method. Some measures to reduce the errors are put forward by simulating.

Non-PLL high-precision synchronous sampling method among lots of acoustics acquisition channels for underwater multilinear array seismic exploration system

Synchronous sampling is very essential in underwater multilinear array seismic exploration system in which every acquisition node(AN)samples analog signals by its own analog-digital converter(ADC).Aiming at the problems of complex synchronous sampling method and long locking time after varying sampling rate in traditional underwater seismic exploration system,an improved synchronous sampling model based on the master-slave synchronous model and local clock asynchronous drive with non phase locked loop(PLL)is built,and a high-precision synchronous sampling method is proposed,which combines the short-term stability of local asynchronous driving clock with the master-slave synchronous calibration of local sampling clock.Based on the improved synchronous sampling model,the influence of clock stability,transmission delay and phase jitter on synchronous sampling error is analyzed,and a high-precision calibration method of synchronous sampling error based on step-by-step compensation of transmission delay is proposed.The model and method effectively realize the immunity of phase jitter on synchronous sampling error in principle,and compensate the influence of signal transmission delay on synchronous sampling error.At the same time,it greatly reduces the complexity of software and hardware implementation of synchronous sampling,and solves the problem of long locking time after changing the sampling rate in traditional methods.The experimental system of synchronous sampling for dual linear array is built,and the synchronous sampling accuracy is better than 5 ns.

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.

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。

分布式间歇采样转发信号对机载干涉仪参数测量影响分析

针对反机载干涉仪侦察场景,该文提出一种基于间歇采样转发技术生成分布式信号对干涉仪参数测量施加干扰的方法。辐射源与转发干扰机分布部署构成干扰系统,转发干扰机对辐射源脉冲信号进行间歇采样并向干涉仪转发,转发信号与辐射源信号准同步到达干涉仪,实现对干涉仪空域参数和时域参数的同时干扰。对于机载干涉仪运动过程中与干扰系统发生的位置关系变化,给出信号准同步约束并构建分布式信号叠加模型。然后针对干涉仪体制对脉冲空域和时域参数的测量机理,分析分布式信号实施干扰的原理,并分析信号参数对干扰效果的影响,进而提出分布式信号设计原则。仿真实验和暗室实验结果表明,该文所提出分布式波形可有效扰乱干涉仪对信号到达方位角、脉宽和脉冲重复周期等空时域参数的正确测量。

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%。

基于西门子840Dsl系统的数控折边单元效率分析与优化

基于西门子840Dsl系统的数控折边单元效率分析与优化,可以从部件选型、参数匹配、逻辑优化、同步控制等方面入手,不需要改变修改硬件配置和设备的机械结构,实现性能较大提升,从而实现设备的高性价比。

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。

基于同步预测的无线传感网络自适应采样节能策略研究

针对无线传感网络(Wireless Sensor Network,WSN)固定周期数据传输导致的数据冗余和节点能耗高等问题,提出了一种基于同步预测的WSN自适应采样节能策略。通过在终端节点和协调器之间建立指数平滑同步预测模型,根据实际值和预测值的误差实现自适应通信;在同步预测模型基础上引入了传输控制协议(Transmission Control Protocol,TCP)拥塞控制思想,自适应地调整节点的采样间隔和睡眠时间,通过动态调整采样间隔,避免频繁的数据采集及传输,减少数据冗余。为验证节能性,基于ZigBee的室内甲醛监测系统平台进行仿真与实验。实验结果表明,在均方根误差(Root Mean Square Error,RMSE)为4.2×10^(-4)的情况下,相较于固定周期采样策略,所提出的策略能够节省能耗89.7%。对于提高WSN的能源效率具有参考价值。

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。