基于无差拍电压空间矢量控制的SVG仿真研究

提出一种静止无功发生器无功补偿的新方法——基于无差拍电压空间矢量控制.该方法通过瞬时无功功率理论的无功电流检测法实时检测无功电流,提高了系统响应速度.针对直接电流控制开关频率过高的不足,引入了电压空间矢量技术,分析了电压空间矢量在静止无功发生器中的应用原理.为了消除采样及计算等带来的延时,引入了无差拍控制技术.最后通过Matlab对控制方案做了系统仿真,将无差拍与电压空间矢量SVPWM相结合,分析实时的仿真波形,仿真结果验证了所选控制方案的有效性和可行性.     

模糊控制与PID结合控制在电石炉上的应用

提出一种模糊控制与PID控制结合的控制方法来实现对电石炉三相电极电流的控制,确保电石炉三相电极电流保持稳定平衡。     

基于神经网络的谐波检测研究

介绍了一种增加神经网络输入的谐波检测方法,即把负载电流矛口它在每一周期对应的角度作为BP神经网络的输入,基波电流作为输出。网络的训练精度也相应提高。然后把训练好的网络在Mat—lab／Simulink中仿真,使输出的基波电流与负载电流相减得到谐波电流。该方法与传统的基于瞬时无功功率理论的ip-i。谐波检测方法相比,其在实时性和精确度上有了很大的改善。     

张力控制方法

介绍各类卷绕设备采用的张力控制方法。目前常用的张力控制方法主要有闭环控制-速度给定补偿、闭环控制-控制电流限幅、直接卷取-控制电流限幅、切线卷取-控制电流限幅、直接卷取加闭环控制-控制电流限幅和切线卷取加闭环控制-控制电流限幅6种。设备设计时应根据实际要求,选取适合的张力控制方法。     

国外专利信息

正阴极表面电流分布控制方法及装置本发明公开了一种阴极表面电流分布控制方法及装置。该装置由电镀腔体、阳极、阳极夹具、基板、基板夹具等组成。电镀过程中,阳极和基板水平正对放置,两者之间装有起屏蔽阻挡作用的辅助阴极。通过优化辅助阴极的几何形状,实现控制阴极表面的电流分布。镍-铁合金镀液     

超低频高精度数控电流源研制

采用PC机和数据采集卡为核心处理器,使用Labview9.0编制控制软面板,设计并实现了超低频高精度数控电流源.系统采用双闭环控制方式,外环借助Labview9.0编写数字PID算法和数据采集卡的D/A,通过比较预置电流与采样电流实现数字PID控制;内环通过由大功率运放OPA548构成的V/I转换电路对负载电流进行自动...     

基于FPGA与AD7985的脉冲电源数据采集设计

为了满足精密电镀的控制需求,设计了一种基于FPGA和AD7985的高速高精度的数据采集系统,该数据采集系统可应用于高精度的脉冲电镀电源中,用于采集输出脉冲的电流和电压参数并用于电流调控.首先设计分析了采集系统的主要硬件电路,包括隔离放大电路、电压跟随电路和AD转换电路;然后对AD7985的控制时序进行了研究,给出了控制...     

抑制微溶盐在供水过程中沉淀

本发明提供了一种通过抑制垢在供水过程中沉淀防止含水系统中垢沉淀的方法和装置,该装置包括：（1）一种电解电池流动连接到该系统,包括①接收供水的槽,该槽中的铜表面形成一种电池阴极;②在槽内具有被处理后的锌表面的元件,并且形成电池的阳极;（2）一种控制设备用于控制来自电源的电流（I）;（3）一个流量计,用于测量供水流速与进入系统的水流速有关的流速,其中控制设备被设计用于根据流速控制电流,     

拉丝炉成本平衡点日产量的计算与控制

介绍了从成本控制角度提出的一种通过建立拉丝炉台的成本一产量控制模型,通过盈利法和保本控制法确定成本模型(函数)的成本控制点,并对玻纤产品成本平衡点的拉丝炉台·日产量进行计算的方法.以应用实例解说拉丝炉成本平衡点日产量的计算与控制.     

放大电路中电压反馈与电流反馈的判定方法

本文对放大电路电压反馈和电流反馈传统的判定方法进行了分析,指出了存在的缺陷,提出了一种利用反馈原理来进行电压反馈和电流反馈判定的方法.     

Effect of polarization type on properties of Ni–W nanocrystalline electrodeposits

Nickel–tungsten nanocrystalline coatings were electrodeposited from a Watts type bath onto a copper substrate, at different current densities selected from activation, mixed and diffusion controlled regions in the cathodic scan plot at room temperature. The results confirm that tungsten codeposition proceeds via the adsorption and reduction of complexes produced in the bulk of solution. The coatings obtained were single phase solid solutions and their grain sizes increased with current density. A cauliflower-type surface morphology with highest hardness was obtained when the current density was in the activation controlled region. The surface morphology obtained in the mixed controlled region was distorted, and then converted to a nodular morphology in the diffusion controlled region. In the mixed control region, coatings with the highest corrosion resistance were obtained due to the lowest exchange current density for water reduction.     

基于预测电流控制的有源功率滤波器的研究

通过分析APF的数学模型和预测电流理论,推导出了预测电流控制在有源滤波器中的应用.利用预测电流控制的数学推导过程,对反馈调节和最优化处理做了分析,并对控制参数与系统性能之间的关系进行了讨论.     

Improvement of the stoichiometric network analysis for determination of instability conditions of complex nonlinear reaction systems

Stoichiometric network analysis (SNA), a known method for analyzing complex reaction systems including biochemical ones, is improved and applied to a nonlinear process studied far from equilibrium in a continuously fed, well stirred tank reactor (CSTR). A particular attention is focused on the determination of the narrow range of the control parameter values where the main steady state is unstable and where different dynamic states can be simulated numerically. The instability region, the most important feature of nonlinear reaction systems, is calculated as a function of the SNA parameters (current rates and reciprocal concentrations of intermediate species in the steady state) and simplified by retaining only the dominant terms. Since the number of the current rates is usually larger than the number of linearly independent equations to be used for their calculation, it is shown here that the current rates can be replaced with a smaller number of reaction rates at the steady state. These rates are related to the experimental data in a simple manner. The instability condition is also written as a function of dimensionless parameters derived from the SNA. This general approach is applied to a model of the Bray–Liebhafsky (BL) reaction having seven reactions without direct autocatalysis or autoinhibition, studied under CSTR conditions. Since the model has six intermediate species, it would be very difficult to analyze its instability condition by the conventional procedure, where a sixth order characteristic equation would have to be solved. On the other hand, the instability condition, obtained easily by the improved SNA, locates correctly the oscillatory region using numerical integration. Other dynamic states found earlier with a larger model of the BL reaction, such as mixed-mode oscillations, period doubling and chaos, are also obtained within the theoretically predicted oscillatory region. Thus, besides the general advantages of the improved stoichiometric network analysis as a method appropriate for the examination of complex nonlinear reactions, we show that the various mentioned dynamic states can be obtained by a very simple variant of the model of the BL reaction realized under CSTR conditions.     

Charge–discharge characteristics of polythiopheneas a cathode active material in a rechargeable battery

Polythiophene films were electrochemically deposited on glassy carbon substrates under potentiostatic control and used as cathode active material together with a Zn anode in a rechargeable battery with propylene carbonate, Zn(ClO4)2, LiClO4 electrolyte. Charge–discharge characteristics were studied. The average discharge voltage of the polythiophene/Zn cell was 1.25V. In the low current density region (i.e. 10–50μAcm?2) the cycling coulombic efficiency was above 95%, but in the fast charge–discharge region, where current densities were 0.1–0.5mAcm?2, the coulombic efficiency decreased to 55% with increasing discharge rate. Additionally, it was found that the cyclic coulombic efficiency was a function of the charging depth.     

Electropolishing of chromium in phosphoric acid-sulphuric acid electrolytes

The anodic dissolution of chromium in phosphoric acid-sulphuric acid electropolishing electrolytes has been investigated using a rotating disc electrode. The influence of electrolyte composition on mass transport and the resulting surface finish has been investigated. It was found that electropolishing of chromium occurs in the transpassive potential region under mass transport control. The transport limiting species is the anodically generated hexavalent chromium ion. The rate of nucleation of the anodic film present is potential dependent, and film instabilities occur in a certain potential region of the limiting current plateau.     

一种基于软伺服放大器的自动控制系统

介绍软伺服放大器控制系统的组成及其控制方法。实际应用结果表明:软伺服放大器控制系统的灵敏区、迟钝区和死区可以任意设定,且死区可以设定很小,控制精度高达0.1%,解决了长期困扰自动控制系统的硬伺服放大器死区大、控制精度低的问题。     

宽域废气氧传感器的控制方法研究

宽域废气氧传感器在汽车发动机空燃比控制系统中应用广泛,它对工作温度有严格要求,可通过控制泵电流实现空燃比测量。笔者研究温度和泵电流控制方法。将冷启动和PI控制方法相结合,缩短了传感器冷启动时间并提高了温度控制精度;针对泵电流模型参数的不确定性,研究了基于H∞回路成形的鲁棒PID参数整定方法。仿真实验结果表明:宽域废气氧传感器冷启动速度快,温度控制精度较高;泵电流控制调节时间短,稳态精度高。     

Measurement of dissolved hydrogen supersaturation during water electrolysis in a magnetic field

The cathode potential on the gas-evolving electrode in 0.5 M H₂SO₄ solution was measured under a uniform magnetic field. The current interrupter method allowed us to study the IR-drop and the supersolubility of dissolved hydrogen gas. MHD convection by Lorenz force slightly reduced the ohmic resistance between the working and reference electrode, considerably restricted the increase of supersolubility and simultaneously promoted the mass transfer coefficient of the dissolved gas above 50 mA cm⁻². Moreover, the supersolubility peak position displayed a strong dependence on the current density in the intermediate current density region from 5 to 30 mA cm⁻². The peak location shifted toward lower current density with increasing in magnetic flux density. Our data show that applying a magnetic field has a much greater effect on the supersolubility at intermediate current density region than the mass transfer coefficient.     

水冷PEMFC热管理系统控制策略及仿真研究

针对目前燃料电池热管理系统在变载时存在温度波动较大、调节时间较长和响应速度较慢等问题,本文提出了流量同时跟随电流及功率方式和神经网络自抗扰方法两种热管理控制策略。结果表明：流量同时跟随电流及功率控制策略能够有效地削弱水泵和散热器风扇的耦合作用,明显减少电堆进出口冷却水温度及其温差的超调量和调节时间。此外,虽然神经网络自抗扰控制策略在最大功率工况下的控制效果较差,但总体控制效果比流量跟随电流控制策略好。     

Analytical and triangular solutions to operational flexibility analysis using quantifier elimination

The main purpose of operational flexibility analysis is to determine and describe the flexibility region. The existing methods are mainly developed by numerical calculation methods to estimate the contour of the flexibility region. In this article, a novel method is proposed for solving operational flexibility models described by polynomials. The proposed method can accurately describe the flexibility region and explicitly express the functional relationships between uncertain parameters and control variables. First, the original flexibility analysis model is represented as an existential quantifier formula. Then, a technique of quantifier elimination is introduced to deduce the formula to a series of explicitly triangular quantifier‐free formulas. Last, a logical combination of the quantifier‐free formulas can be used to depict the complete flexibility region. The case studies show that the deduced explicit expressions can accurately and effectively describe the flexibility region and guide the steady‐state control operations, regardless of convex or nonconvex systems. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3894–3911, 2018