Effective frequency range of ladder network realization for complex permeability of magnetic sheets

By using Cauer realization, the complex permeability of magnetic sheets is realized by a finite‐order ladder network. The effective frequency range of this ladder network is derived by using the corner frequency of the network. It is shown that Cauer realization can cover a wide frequency range with a very small number of circuit components. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

组合式二用一备变频系统PL C控制器

介绍了组合式二用一备变频系统PLC控制器。系统主回路用2个变频器控制3个受控电动机;控制回路采用PLC控制器,通过PLC梯形图程序,实现由2个变频器对3个受控电动机进行二用一备任意组合状态的切换控制。采用的控制系统适用于集中控制场合,具有控制精度高、最大限度减少设备硬件成本等特点。     

Generalized analytical formulae to compute electrical characteristics of a homogenous ladder network of the transformer winding

Many electrical systems are expressed as a complex ladder network consisting of combinations of resistances, inductances, and capacitances. Computation of electrical characteristics, such as voltages, currents, and equivalent impedances of these ladder networks require the solution of complicated differential‐algebraic equations that are quite tedious and cumbersome. The earlier works have given particular attention to purely resistive ladder networks ignoring the inductance and capacitance parameters. Moreover, there are no direct expressions available to quickly compute these characteristics. This paper derives generalized analytical expressions that can be directly used to obtain the electrical characteristics of a finite as well as semi‐infinite homogenous ladder network by simply plugging the values of its constituent parameters. Expressions are deduced for excitation source applied to the input terminal and across 2 arbitrary nodes, respectively. Kirchhoff mesh and node laws along with ordinary algebra and trigonometric theorems are applied to derive these expressions. Boundary‐value technique is used to circuit equations to determine unknown coefficients of the expressions. The derivation given in these paper would surely help the readers to quickly compute the electrical characteristics without solving recursive circuit equations and avoiding complex state‐space matrices.     

On the representation of static hysteresis curves by a PWL ladder circuit

Some important features of static hysteretic phenomena can be suitably represented by a recently proposed ladder circuit model. The elementary cell of this ladder is constituted by a linear capacitor and a non-linear resistor with a proper piecewise linear (PWL) characteristic. With respect to the original formulation, the representation capabilities of the model can be improved by introducing proper generalizations. These generalizations concern the definition of the hysteretic (output) variable and the initial states of the circuit capacitors. After introducing these concepts, this paper addresses the determination of the model parameters that give the best fit of the experimental data of a scalar rate-independent hysteresis. The solution of this identification problem is obtained both for a limit cycle and for a cycle together with its first polarization curve. © 1998 John Wiley & Sons, Ltd.     

新型晶体管特性图示仪扫描信号发生器电路设计

本文介绍了一种基于555定时器的晶体管特性图示仪扫描信号发生器的电路设计方法,通过555定时器产生同步的锯齿波和阶梯波触发信号,从而获得线性度良好的扫描信号.实验证明,该电路结构简单实用,其波形显示效果优于通用的晶体管特性图示仪.     

Wave propagation and reflection on the ladder‐type circuit

In this paper, we study wave propagation and reflection in the linear ladder‐type circuit. Several examples of the exact linear response of this circuit were found. It was established that the bandpass ladder‐type circuit has a peculiar property with respect to the wave propagation, namely, that directions of the phase and group velocities of the wave in this circuit can oppose one another. In addition, the wave reflection in the ladder‐type circuits was considered. Reflection and transmission coefficients of the wave were calculated, and the nonreflection condition was found. From this condition, the nonreflection terminal circuit was constructed. © 1999 Scripta Technica, Electr Eng Jpn, 130(3): 9–18, 2000     

A frequency-locked adaptive filter

A frequency-locked RC active ladder filter is described, which is frequency-locked to a sinusoidal control tone. The tunable ladder filter is used as a frequency discriminator by using two of the filter branch voltages to generate a control voltage. The control voltage is then used to tune or frequency-scale the ladder filter transfer function to lock the filter to the frequency of the control tone. A simple linear frequency-signal control system is developed to describe the frequency-locked performance of the adaptive filter. The frequency-locked filter can be designed so that the sinusoidal control tone is rejected at the filter output, making it possible to adapt the filter transfer function during transmission of a message. A practical frequency-locked filter is given in which a frequency-locked third order elliptic lowpass filter is designed. The performance of the practical filter is analysed using a simple linear control system model.     

移植法设计PLC梯形图的几条规则

把继电器控制电路图直接移植成PLC梯形图是一种简捷可靠的设计方法。文章给出了采用移植法时应遵守的几条规则：输入触点常态规则：时间触点等效规则：输出电路安全规则：梯级可执行规则及逻辑等价性规则。     

Optimal fitting of high-frequency cable model parameters by applying evolutionary algorithms

Due to the widespread use of electronic power converters, low-voltage high-frequency cable models are being increasingly applied in industry, automobile or aeronautics applications among others. It is known that depending on switching frequency, cable configuration and length, transient overvoltage effects comprising a wide frequency range from dc up to several tens of MHz can appear. However, to accurately reproduce the wide-band frequency response, such models often require the use of ladder networks, thus being necessary to adjust the values of a relatively large number of R, L and C components, which is a complex task. This paper is focused to solve this problem, which is done by applying an iterative genetic algorithm (IGA) optimization approach. From a set of experimental short circuit and open circuit tests the high-frequency cable model of a given cable configuration is obtained, whose parameters are fitted by means of the proposed IGA-based method. Finally, the accuracy of the model obtained is validated experimentally by comparing the frequency-domain and time-domain responses through overvoltage predictions of different samples of the analyzed cable.     

三逆变桥的组合逆变/充电器主电路设计

在单个逆变桥的基础上,为了获得输出波形接近正弦波的阶梯波,设计了一个新颖的逆变/充电器,其最大特点是3个逆变电路的输出各通过一个变压器进行升压,且3个变压器串联输出.通过控制MOSFET的通断,输出是一个接近正弦的阶梯波.再通过简单的滤波,最后得到非常好的正弦波.     

工业继电器控制系统的PLC改造方法

详细描述了由继电器控制电路图设计梯形图的方法、步骤和注意事项.     

基于三菱FX2N系列PLC的智能供水控制系统设计

文章以三菱FX2N-32MR型PLC为智能核心元件,设计了可能在工作/备用状态下任意切换的两台供水泵电机的自动控制系统,包括控制方案、主电路、控制电路(I/O接线图)、控制程序(梯形图),并阐明了水位信号的PLC识别问题等技术细节,经过生产实际运行检验,设计合理、运行可靠。     

Development and design of wave SC filters

A direct z-domain simulation of LC ladder and unit-element filters by means of wave SC circuits is presented. the development of a wave SC circuit is achieved by interconnecting a limited number of basic SC building blocks. the derived circuits are fully parasitic-free, symmetric and can be optimally designed for dynamic range maximization and capacitance area minimization. the number of operational amplifiers in the simulated unit-element filters is essentially low in comparison to earlier presented parasitic-insensitive wave SC filters and to leap-frog-type SC filters. Four- and two-phase multiplexed simulated LCR filters can be developed. Bilinear s-z transformation applies for all the circuits; thus the design is exact and there is no requirement for a high clock frequency. Filters with transmission zeros can be developed. the simulated responses of various types of filters are in good agreement with the theory. Detailed examples of different designs are given.     

可编程序控制器控制交流双速电梯

本文介绍了可编程序控制器（ＰＬＣ）在电梯控制中的应用，给出相应的硬件配置，设计了梯形图控制软件。实际应用表明：电梯的ＰＬＣ控制系统具有相当的可靠性，现场运行取得满意效果。     

锁相环自锁定技术的研究及应用

利用LC电路的振荡频率在回路参数出现变化时会明显变化这一特征,可以根据频率的改变量实现多项测量功能.测量中是依赖LC电路振荡频率的改变量得到测量结果.要想精确测量出瞬时频率差,就要求实现初始频率和当前频率的运算,初始频率的保持是测量过程关键.本文通过对锁相环自锁定技术的研究,从压控振荡器(VCO)的控制电压入手,实现频率的自锁定.实践证明,利用自锁定技术较好地解决了这一问题.     

用PLC技术改造继电器电路的探讨

指出继电器电路进行PLC技术改造的必要性,并详细描述了由继电器控制电路图设计梯形图的基本方法、步骤和注意事项。     

PLC梯形图程序的顺序控制设计法

介绍了可编程控制器（ＰＬＣ）梯形图程序的顺序控制设计法,顺序功能图的基本结构及其转换实现的基本规则。在实际工程中,采用起动－保持－停止电路的顺序控制梯形图的设计方法设计的控制程序具有实现方便、容易掌握、可读性强等优点,可用来设计复杂系统的梯形图及用于各种型号的ＰＬＣ。     

Skin effect and dielectric loss models of power cables

In power electronics applications, power cables spread paths of conducted disturbances throughout the system. This paper proposes a high frequency modeling method for power cables that takes into account phenomena which appear when the switching frequency of the static converter increases, such as skin effects, proximity effects and dielectric losses. The proposed power cable models are obtained by the seriesassociation of n identical RLCG basic cells. The skin and proximity effects are represented as the impedance of an R-L ladder and the dielectric losses as the admittance of an R-C ladder. The proposed method was successfully applied to a threewire unshielded cable and extended to a four-wire shielded cable.     

含分布式电源的配电网故障分析的解耦相分量法

分布式发电系统的接入改变了配电系统的故障电流分布,传统的配电网故障分析方法已经不能满足未来分布式发电系统的需求.针对含分布式电源的配电网故障分析开展研究,提出了合分布式电源的配电网故障分析计算的解耦相分量法.将含有分布式电源的配电网分解成"梯形"网络和"辐射状"网络,选择短路点为边界节点,借助于相序参数变换技术,通过三相解耦等值电路计算故障点短路电流,并利用支路电流分流系数计算任意节点电压.所提算法无需形成配电网节点复数导纳或阻抗参数矩阵;可以精确地模拟故障;可方便地计及短路点接触电阻的影响;避免了复杂的序网连接.采用20节点算例对所提方法进行了测试,算例结果证明了该算法的可行性和有效性.     

基于FX2N的三相交流异步电动机综合保护设计

利用负序电流法和零序电流法监测三相异步电动机的运行状态,并设计电动机保护电路和PLC的控制梯形图,用FX系列PLC进行故障类型判别和报警处理,设计方案原理简单、工作可靠.