开关电容滤波器在放大电路中的应用

本文利用开关电容滤波器和运放组成共模抑制比为120dB的仪用放大器及能由频率控制的可变增益放大器。     

双运放电压模式二阶通用滤波器的实现

视无限增益多路反馈低通滤波器为变形状态变量滤波器,用2个运算放大器、2个电容和4个电阻实现了电压模式二阶通用滤波器.该电路不仅可同时实现低通、带通和高通输出,具有低的无源灵敏度,而且其品质因数、极点角频率与电容比值和电阻比值有关,从而可实现二者的独立、精确调节,实现高精度滤波.此外,该电路中两运算放大器承受的共模电压为零,降低了对运放的要求,电路简单,适合VLSI单片集成技术.通过计算机仿真表明,所提出的电路方案是可行的.     

旋转电容滤波器主要性能指标研究

旋转电容滤波器RCF(RotaryCapacitorFilter)可以用通用运放、模拟开关及一般RC元件等器件组成。有中心频率稳定、电路简单、成本低廉等优点。介绍了RCF基本原理并对其幅频特性、相频特性及自身噪声等3个主要性能指标进行了实验研究,结果表明RCF具有良好的滤波特性,且输出噪声很小,能满足一般电路的要求。     

基于MATLAB/Simulink的数字滤波器设计与仿真

介绍了一种利用MATLAB中滤波器设计分析工具(FDATool)快速有效地设计数字滤波器的方法.给出了如何进行滤波器参数设定,得到最优结果的步骤.最后介绍了利用MATLAB环境下的仿真软件Simulink对所设计的滤波器进行模拟仿真的方法.     

H_∞滤波技术在伺服系统中的应用

研究了伺服系统的H_∞滤波器设计问题.首先对无刷直流电动机控制系统进行了保性能控制器设计,在外界干扰不可避免的情况下,设计了H_∞滤波器.使得滤波误差系统渐近稳定且满足一定的H_∞性能指标,给出了滤波器存在的充分条件,并通过矩阵变换得到了设计滤波器的LMI方法.通过求解LMI,可以得到滤波器参数.范数小于指定上界的充分条件,并解出了滤波器的参数.最后仿真实例证明了该方法的有效性.     

无变压器电流源型高压变频器滤波器设计

针对新型无变压器空间矢量调制的电流源型高压变频器的特点,提出了一种方便有效的输入和输出滤波器设计方法.此方法根据空间矢量调制电流的谐波特性,并基于LC滤波器的高低频等效电路,分析滤波器电感电流和电容电压的总谐波畸变率,由此得到滤波器设计的限定值.又从位移功率因数角度对滤波器设计值加以限定.据此方法即可确定滤波器参数取值范围.通过建立仿真模型进行仿真研究,仿真结果进一步说明了此方法的正确性和可行性.     

基于光学电流互感器的低频高精度锁相环

针对低频区信号锁相所面临的精度低、稳定性差等缺点,提出了一种提高锁相精度的方法.以光学电流互感器测试系统为研究对象,设计了以CD4046为核心的锁相环电路,并对影响锁相精度的原因进行了研究.于被测信号进入锁相环之前,采用运放形成2次过零比较,克服了专用快速比较器产生自激振荡的同时,缩短了入锁信号的上升沿时间;设计了用于滤除工频噪声的二阶有源带通滤波器;将锁相环路中压控振荡器的固有中心频率进行了参数优化,使得2个输入的固有频差在理论上最小.结果表明,引入该锁相方法后的锁相精度由0.3%周期提高到0.03%周期(1°变为6'),并且锁相的稳定性和抗干扰性等其他性能指标都有了显著提高.     

基于遗传算法的EBFB小波滤波器优化设计

EBFB是基于伯恩斯坦多项式的偶数长滤波器组.针对伯恩斯坦多项式中参数的不确定性,提出了一种基于遗传算法的具有EBFB特征的小波滤波器优化设计方法.该方法在保证滤波器组具有完全重构性和消失矩特性的前提下,设定伯恩斯坦多项式中不确定性参数的个数,采用遗传算法对参数进行分阶段优化,得到任意长度的反对称双正交小波滤波器组.实验结果表明,利用此方法设计的小波滤波器具有较大的阻带衰减和良好的数据压缩性能.     

基于二次规划的2D FIR滤波器设计

本文提出了一种新型的基于McClenllan变换和二次规划的2D FIR滤波器设计方法.该方法使用McClenllan变换来实现从1D原型滤波器向2D滤波器的频率映射.在设计过程中,使用二次规划方法来求解McClenllan变换的最优系数,通过对二次规划使用一些限制条件,避免了传统的尺度变换问题.与传统的2D FIR滤波器设计方法相比,该方法使映射中1D FIR通带截止频率和阻带截止频率两点误差平方和达到最小,通过实际的扇形滤波器和菱形滤波器设计证明,本文的基于二次规划的方法是一种有效的2D FIR滤波器设计方法.     

通用型运算放大器的特点及应用

何为通用?一般这样认为,在对参数没有特殊要求情况下使用的价廉且应用广泛、互换性好的运放。我们叫它为通用运放。现在,进口、国产的通用运放品种繁多,其型号也不断更新,各厂商给出的产品参数也不尽相同,其实,它们的内部结构有许多相同之处,特别是基本单元更是这样。现把常用的几种具有代表性的通用运放列于表     

An improved prediction method of subsequent commutation failure of an LCC-HVDC considering sequential control response

Subsequent commutation failure (SCF) can be easily generated during the frst commutation failure (CF) recovery process in a line-commutated converter-based high voltage direct-current system. SCF poses a signifcant threat to the safe and stable operation of power systems, and accurate prediction of CF is thus important. However, SCF is afected by the operating characteristics of the main circuit and the coupling efects of sequential control response in the inverter station. These are difcult to predict accurately. In this paper, a new SCF prediction method considering the control response is proposed based on the physical principle of SCF. The time sequence and switching conditions of the controllers at diferent stages of the frst CF recovery process are described, and the corresponding equations of commutation voltage afected by diferent controllers are derived. The calculation method of the SCF threshold voltage is proposed, and the prediction method is established. Simulations show that the proposed method can predict SCF accurately and provide useful tools to suppress SCF     

一种基于开关电容滤波器的快速基波检测方法

为了实时快速地检测电力系统中的基波,提出了一种基于开关电容滤波器(SCF)检测电网中基波信号的方法。分析了SCF的原理及其优缺点,并与传统的滤波方法进行了对照,给出了选择开关电容的原则。由于信号经过一个滤波电路后一般会有一定的相差,为了保证检测前后基波信号相位的一致性,在SCF后面设计了一个等幅移相电路。以一款SCF的IC(MAX291)为例,设计了整个巴特沃斯型低通滤波器电路和等幅移相电路。用MATLAB进行了仿真,分析了这种滤波器和移相电路整体的精度和动态响应,并将该滤波方式应用到实验装置中,实验结果表明这种检测方法有很好的检测效果和快速的动态响应。     

集成光学陀螺信号噪声抑制电路设计

集成光学陀螺采用光学Sagnac效应,通过检测谐振腔中相向传输两束光的谐振频率差得到转动角速度.针对陀螺输出信号及其噪声特征,提出了基于开关电容的滤波器的信号调理方法,理论分析表明了比传统带通滤波器更好的噪声抑制效果.建立了开关电容滤波器的频域模型,并利用该模型对滤波器参数进行了优化设计.同时,理论分析了其梳状滤波器特...     

A Novel Recovery Strategy to Suppress Subsequent Commutation Failure in an LCC-Based HVDC

A subsequent commutation failure (SCF) can easily occur during the recovery process after a first commutation failure (1st CF). This paper analyzes the interaction mechanism of extinction angle, AC voltage, DC current and firing angle, and reveals that the complex coupling relationship during the dynamic process after the 1st CF has a significant effect on the SCF. The mathematical equations when considering different fault durations, fault severities and AC system strengths are then established. An AC fault voltage detection method based on reactive power and fault duration is also proposed to measure the fault severity, and an SCF inhibition control strategy (SCFICS) based on AC fault detection and reactive power control is subsequently proposed. This can not only inhibit the SCF, but also enhance the DC recovery speed effectively. Finally, based on the SCFICS, a simulation model is built, and the simulation results with different cases indicate that the SCFICS can effectively inhibit the SCF with good recovery performance, for three-phase-to-ground (TPG) and single-phase-to-ground faults, and with a fault inductance range of 0.01 H to 1 H.     

基于无功反馈控制的后续换相失败抑制方法

基于电网换相换流器的高压直流输电故障后的动态恢复过程与交直流系统间的无功交换强相关,持续的无功交换过程往往伴随着换相电压持续波动,进而可能引发后续换相失败.基于此,提出采用闭环反馈控制的无功控制方法以降低后续换相失败的风险.首先,利用实时仿真分析了采用典型低压限流(VDCOL)控制的直流系统故障恢复过程与无功交换的关系.其次,利用交直流系统的无功功率特性方程以及隐函数存在定理,分析了直流电流分别与无功交换和关断角之间的微增量关系,并据此提出无功反馈控制结构.然后,提出了用来替代VDCOL的直流电流实时计算方法,该方法同时考虑了无功交换平衡和定关断角二维约束,并通过闭环控制抑制了干扰偏差,控制精度更高.最后,仿真结果表明,所提方法可以减小直流系统发生后续换相失败的概率,改善系统的恢复性能.     

配电线路故障定位中的复阻抗在线测量系统

在配电网接地故障定位中,常常要对复阻抗进行在线测量。本文提出一种复阻抗在线测量系统的实现方案,采用DDS和可编程开关电容滤波器,保证了对50Hz电网谐波的滤除以及多频率下增益的稳定性,实现了多频率下对复阻抗的精确测量。     

基于S变换相关度和深度学习的配电网单相接地故障选线新方法

针对配电网发生单相接地故障时特征信息不明显,且现有选线方法易受故障条件和环境噪声影响的问题,基于S变换相关度和深度学习,提出一种具有强抗噪声能力和高泛化水平的配电网单相接地故障选线新方法.首先,利用S变换获取零序电流时频信息,基于各线路零序电流的全频段信息计算线路故障信息相关度;其次,为提高故障特征的可辨识度和抗干扰性,提出一种S变换相关度图形(SCF)构建方法;在此基础上,建立含SCF层的卷积神经网络深度学习模型(S-CNN),并利用Simulink仿真模型生成的故障数据对其结构参数和超参数进行分步训练;最后,通过S-CNN提取配电网故障零序电流深层特征,实现故障选线,并测试了S-CNN在配电网不同运行状况和故障条件下的选线效果.仿真结果和实际配电网故障数据测试表明:在强噪声干扰场景中,基于S-CNN的故障选线模型在不同故障位置、故障相角、过渡电阻条件下可实现高正确率选线,且在各线路零序电流采样不同步条件下仍具有较强的鲁棒性.     

管道电磁超声传感器阵列检测技术研究

采用电磁超声传感器阵列对管道进行缺陷检测,不仅能够提高电磁超声检测信号的信噪比、灵敏度与分辨能力,同时也能增强电磁超声检测的直观性与灵活性。本文详细阐述了基于洛伦兹力的周期永磁铁阵列式电磁超声传感器(PPM-EMAT)激励超声导波的工作原理,及利用全聚焦算法结合极性一致性算法对缺陷进行定位与成像的工作机理。建立了有限元仿真模型,验证了准T(0,1)模态导波在管道结构中的传播过程。利用研制的多通道电磁超声检测系统,对含缺陷的不锈钢管道进行了检测实验,实验结果表明,研制的系统能够检测出管道试样中的多个通孔缺陷,纵向定位误差可控制在1.5%以下,实现了基于阵列电磁超声传感器的管道缺陷成像与定位。     

Multiple-critical-pole coupled active filters

In this paper realizations of low sensitivity narrow BP active filters implementing multiple-critical-pole (MCP) approximation methods and coupled filter structures are studied. In the first part of the paper, a synthesis procedure particularly developed for the realization of MCP transfer functions is described. According to that procedure the portion of the MCP transfer function containing multiple poles is realized as a follow-the-leader feedback (FLF) network, and the remaining part as a cascade. It is shown that the lower sensitivities of MCP functions in comparison with standard approximating functions (Butterworth, Chebyshev, etc.) can be further decreased by applying the FLF configuration instead of the cascade. the synthesis procedure is straightforward and in some cases it can be performed using identical second-order BP blocks. the final circuit sensitivities can be optimized according to given filter specifications and a user selected optimization criterion. In the second part of the paper, the MCP transfer functions are combined with the cascaded biquarts (CBQ), the shifted companion form (SCF), and the leap-frog (LF) structures, and sensitivity analysis is performed. It is shown that applications of the above mentioned structures can improve the filter sensitivites in a way similar to that of the given FLF configuration.     

EE-BESD: molecular FET modeling for efficient and effective nanocomputing design

Molecular transistor is a good candidate as substitute of CMOS device due to small size, expected good performance and suitability to be included in high density-circuits. To date a lot of effort has been carried out to understand the conduction properties in molecular devices. However, minor effort has been devoted to reduce their computational complexity to obtain a compact molecular model. First-principle based methods frequently used are highly computational demanding for a single device, thus they are not suitable for complex circuit design. In this paper we present an accurate and at the same time computationally efficient method (named Efficient and Effective model based on Broadening level, Evaluation of peaks, SCF and discrete levels, ee-besd) to calculate the electron transport characteristics of molecular transistors in presence of applied bias and gate voltages. The results obtained show a remarkable improvement in terms of computational time with respect to existing approaches, while maintaining a very good accuracy. Finally, the ee-besd model has been embedded in a circuit level simulator in order to show its functionalities and, particularly, its computational cost. This is shown to be affordable even for circuits based on a high number of devices.