DCS自动控制系统与变频器的电磁兼容

介绍了制药厂发酵罐用变频器干扰DCS自动控制系统的实例分析及干扰处理方法.通过在变频器输入、输出端加装匹配的电源滤波器,有效解决了变频器工作时产生的电磁干扰.经过多次整机调试及试验,实现了制药厂发酵车间DCS自动化控制系统与变频器的电磁兼容.     

锅炉给粉机变频调速系统改造

本文介绍了在连云港碱厂热电站DCS改造时，锅炉给粉机由滑差电机调速改为变频器调速，给出了变频器原理控制图，简述了DCS对给粉机的控制原理，并对变频器的编程进行了说明。投入运行后对锅炉负荷的调节和稳定运行起到了很好的作用。     

变频器在电力系统工程应用中的干扰问题及解决探究

随着科技的进步,变频器的应用越来越广泛,其在工业、电子等领域发挥着自身优势,促进了系统工作效率的提升。但变频器在电力系统的应用易受到多方面的电气干扰,继而对其他设备造成影响。文章在简要介绍变频器后,对电力系统工程中变频器的干扰问题进行详细分析,并着重探讨有效抗电磁干扰对策,完善变频器功能,促进变频器在电力系统工程中更高效地应用。     

ACS800变频器在棒材精整设备控制中的应用

介绍了ABBACS800变频器和DCS600传动单元在棒材精整设备控制中的应用，对如何实现DCS600传动单元的主从控制、ACS800变频器的位置计数器复位和标量控制等做了详细讨论。     

基于改进离散布谷鸟算法的干扰资源分配研究

该文对二次雷达机制的协同式敌我识别系统的干扰资源分配问题进行研究,将离散布谷鸟算法(Discrete Cuckoo Search, DCS)引入敌我识别系统的干扰资源分配问题。首先给出协同式敌我识别系统的干扰效果评估指标,建立干扰资源分配模型,将模型简化为一对一、多对少模型,使用DCS算法求解模型。针对Levy飞行后期出现搜索速度慢和精度低的问题,将遗传算法中的交叉与变异操作引入DCS算法得到改进的离散布谷鸟算法(Improved Discrete Cuckoo Search, DCS),用以求解分配模型。仿真分析表明:所提干扰效果评估指标可以合理地评估干扰效果;IDCS算法比IDCS算法收敛更快、耗时更短;IDCS算法与做出相应改进的遗传算法(Improved Genetic Algorithm, IGA)相比具有更好的寻优能力。     

高压变频器应用中的若干问题及对策

通过对高压变频器谐波干扰源和干扰途径的分析,本文提出了抑制干扰的方法、对策和高压变频器应用中需要注意的一些问题。     

工厂DCS控制系统抗干扰问题及对策

DCS控制系统结合计算机技术、通信网络技术和过程控制技术,实现分散控制、集中操作、分级管理、配置灵活和组态方便。随着工厂的现代化发展,对DCS控制系统的要求越来越高了,工厂设备的安装不当都会对系统产生一定的干扰。本文就工厂DCS控制系统中的干扰问题进行分析,探讨抗干扰的方法对策。     

在烟机除尘设备中如何解决变频干扰问题的探究

近年来,变频技术在烟草行业中逐渐得到推广与应用,但随着变频器应用的越来越多,变频干扰问题也越来越严重。本文就要就除尘器变频干扰问题,通过分析其干扰现象,研究干扰原因,减小变频器本身电磁干扰的方法解决使用中的除尘设备干扰问题。     

变频工况下电磁流量计信号失真的研究

用变频器来调节、控制供水流量的方法方便、节能,但在线监测系统的流量信号易受变频器影响而出现信号失真和信号大幅度波动。本文根据电磁流量计和变频器同时使用出现的干扰现象,分析了干扰的有关问题,并且对这种信号失真和信号波动现象进行了深入研究,提出了用信号隔离的方法可消除变频器对流量信号干扰的方案。实际应用表明,这些技术有较好的抗干扰效果。     

变频器应用中抗干扰问题的探讨

变频器在工业生产中的应用越来越广泛,其干扰问题日益引起人们的重视。本文主要讨论变频器应用系统中干扰产生的来源及其传播途径,提出了抗干扰的实际解决方法,阐述了在变频器应用系统设计和安装中抑制干扰的具体措施。     

A monolithic digital chirp synthesizer chip with I andQ channels

A monolithic digital chirp synthesizer (DCS) chip has been developed using GaAs/AlGaAs HI²L technology. The 6500-HBT-gate DCS chip is capable of producing linear frequency-modulated (chirp) waveforms or single-frequency waveforms. The major components of the DCS are two 28-b pipelined accumulators, a 1.8 kb sine ROM, a 1.8 kb cosine ROM, and two 8 b digital-to-analog converters (DACs). The total chip area is 4.877 mm×6.172 mm using a minimum feature size of 1.5 μm. All components of the DCS are fully functional and the device has been clocked to 450 MHz with a power dissipation of 18 W     

Zero-voltage-switching half-bridge DC-DC converter with modified PWM control method

Asymmetric control scheme is an approach to achieve zero-voltage switching (ZVS) for half-bridge isolated dc-dc converters. However, it is not suited for wide range of input voltage due to the uneven voltage and current components stresses. This paper presents a novel "duty-cycle-shifted pulse-width modulated" (DCS PWM) control scheme for half-bridge isolated dc-dc converters to achieve ZVS operation for one of the two switches without causing the asymmetric penalties in the asymmetric control and without adding additional components. Based on the DCS PWM control scheme, an active-clamp branch comprising an auxiliary switch and a diode is added across the isolation transformer primary winding in the half-bridge converter to achieve ZVS for the other main switch by utilizing energy stored in the transformer leakage inductance. Moreover, the auxiliary switch also operates at ZVS and zero-current switching (ZCS) conditions. Furthermore, during the off-time period, the ringing resulted from the oscillation between the transformer leakage inductance and the junction capacitance of two switches is eliminated owing to the active-clamp branch and DCS PWM control scheme. Hence, switching losses and leakage-inductance-related losses are significantly reduced, which provides the converter with the potential to operate at higher efficiencies and higher switching frequencies. The principle of operation and key features of the proposed DCS PWM control scheme and two ZVS half-bridge topologies are illustrated and experimentally verified.     

Distributed compressed sensing for multi-sourced fusion and secure signal processing in private cloud

In this paper, a novel scheme is proposed for multi-sourced signal fusion and secure processing. Within a distributed compressed sensing (DCS) framework, traditional sampling, compression and encryption for signal acquisition are unified under the secure multiparty computation protocol. In the proposed scheme, generation of the pseudo-random sensing matrix offers a natural method for data encryption in DCS, allowing for joint recovery of multiparty data at legal users’ side. Experimental analysis and results indicate that the secure signal processing and recovery in DCS domain is feasible, and requires fewer measurements than the achievable approach of separate CS and Nyquist processing. The proposed scheme can be also extended to other cloud-based collaborative secure signal processing and data-mining applications.     

叠层母排的技术优势及其应用综述

叠层母排是一种新兴、低电感、便捷的重要电气连接部件,由于其自身的优点,使其可在中、高功率变流场合普遍使用,不仅涉及光伏、风电产业,也可在各类变频器、整流装置中使用,是电力电子行业发展不可或缺的重要部件。本文具体探讨了与传统母排相比,其技术优势及实际的应用。     

双向Buck/Boost变换器的教学探析

本文针对现有“电力电子技术”相关教材中存在的对双向变换器的分析不完善和各知识点之间缺乏联系等问题,探析了双向Buck/Boost变换器的拓扑生成原理,并且详细分析了变换器运行于电感电流过零模式下实现零电压开关的具体过程,并推导出了软开关的实现条件。本文有助于学生理解并加深双向变换器与基本Buck和Boost变换器之间的联系和差别,并了解软开关技术在基本变换器中的应用,具有一定的教学指导意义。     

正态频率调制降低开关变换器电磁干扰的研究

利用正态频率调制技术从噪声产生源头上降低了开关变换器的电磁干扰。简单地分析了具有不变概率密度分布的离散随机信号频率调制降低开关变换器EMI噪声的原理,并试制了一台正态频率调制开关变换器电源样机。给出了开关管电流信号的频谱以及传导干扰测试的结果。实验结果表明该技术能有效降低开关谐波峰值,使开关变换器易于通过EMI测试,具有应用的前景。     

Integrable devices for wavelength multiplexing optical communication systems

Devices for wavelength division multiplexing (wdm) applications become very important in today’s communication systems. Here the operation principle and the main characteristics of some key components in wdm-systems are given. Various types of tunable lasers, wavelength converters and tunable filters are discussed.     

基于XGM的SOA波长变换器噪声特性分析及实验研究

本文将半导体光放大器的ASE噪声功率引入到SOA分段动态模型,得到随SOA长度变化的ASE噪声功率,并讨论了偏置电流、泵浦光功率、SOA长度对变换性能影响.理论计算结果表明,大的偏置电流有利于提高消光比(ER)和信噪比(SNR);对于长度一定的SOA和一定的偏置电流,泵浦光功率存在最佳值;SOA长度存在信噪比最佳值.我们对2.5Gbit/s SDH信号进行了XGM方式波长变换,实验结果与理论分析一致.     

The low power analogue and digital baseband processing parts of a novel multimode DECT/GSM/DCS1800 terminal

In order to support a multimode DECT/GSM/DCS1800 terminal architecture, with low power characteristics and integrated support for direct conversion terminal architecture, the critical parts of such a terminal were designed and implemented using three different chips. These parts include a baseband processor, a modem and suitable analogue parts. The baseband processor was designed to support multimode operation, all baseband processing required and different terminal architectures (heterodyne or direct conversion). The modem features a GMSK/GFSK modulator and a novel, low power detection algorithm supports a direct conversion terminal. The analogue circuitry includes analogue filters and Digital-to-Analog and Analog-to-Digital converters. The architecture of the direct conversion wireless terminal is presented along with details on the low power characteristics of the processor and the modem. Experimental results from the operation of the multimode terminal are presented.     

Scalable 3D video streaming over P2P networks with playback length changeable chunk segmentation

3D video distribution over P2P networks has been thought as a promising way for 3D video entering home. The convergence of scalable 3D video coding and P2P streaming can provide diverse 3D experiences for heterogeneous clients with high distribution efficiencies. However, the conventional chunk segmentation and scheduling algorithms originally aiming at the non-scalable 2D video streaming are not very efficient for scalable 3D video streaming over P2P networks due to the particular data characteristics of scalable 3D video. Based on this motivation, this paper first presents a playback length changeable 3D video chunk segmentation (PLC3DCS) algorithm to provide different error resilience strengths to video and depth as well as layers with different importance levels in the 3D video transmission. Then, a hybrid-priority based chunk scheduling (HPS) algorithm is proposed to be tied in with the proposed chunk segmentation algorithm to further promote the overall 3D video P2P streaming performance. The simulation results show that the proposed PLC3DCS algorithm with the corresponding HPS can increase the success delivery rates of chunks with more important levels, and further improve the user’s quality of 3D experience.