基于电压双闭环模糊PI控制的三相变频调压电源控制方案

在变频调压电源逆变器输出侧电压的瞬时值、有效值电压双闭环PI控制基础上,通过添加模糊控制规则,设计了一种参数自调节电压双闭环模糊PI控制方法.仿真结果表明:该控制方法超调量较小、响应较快,稳定性高,其效果明显优于单一的电压双闭环PI控制方法.     

非线性负载下逆变器并联系统控制策略研究

微电网并联逆变器接入非线性负载时出现的谐波电流,会引起逆变器输出电压畸变严重.以两逆变器并联运行模型为研究对象,提出一种综合控制策略.首先,在电压外环采用比例积分控制和重复控制串联控制方法的同时,考虑下垂控制所引起的基波频率偏移会进一步恶化输出电压质量,改进重复控制方法,实现在频率变化时对电压谐波的有效抑制.其次,由于SOGI可以抑制输入信号的谐波,将基于SOGI的虚拟复阻抗引入到电流反馈环,抑制谐波电流对虚拟复阻抗影响,有效改善功率均分效果和抑制逆变器间环流.最后,对所提出的综合控制策略进行仿真研究,验证所提控制策略的正确性和可行性.     

带LC滤波器的UPS三电平NPC逆变器改进模型预测控制

在UPS系统中,逆变器输出电压波形的质量决定了系统的性能,而总谐波失真(THD)是决定电压波形质量的重要因素.由于UPS逆变器输出端一般直接与负载相连,因此,在输出端加入LC滤波器可以有效改善电压波形,产生谐波失真较低的正弦电压.针对该逆变器结构,文章提出一种改进模型预测控制来解决传统有限集模型预测控制(FCS-MPC)延迟对系统的影响,利用Matlab/Simulink仿真工具,给出在线性和非线性负载下两种预测控制逆变器输出电压波形和THD仿真结果.结果表明,改进的MPC可有效提高系统性能.     

基于交流比例积分控制器的单相逆变器

提出一种电感电流、输出电压瞬时值反馈控制和负载电流前馈控制相结合的复合控制策略。在此基础上,研制了一台800W的单相逆变器。实验结果表明,提出的控制策略改善了逆变器输出电压的波形,提高了系统的暂态特性。     

改进电流型三相并网逆变器控制建模和仿真

研究改善传统三相并网逆变系统并网功率不易控制的问题,针对电网稳定控制供电,为了提高并网动特性,提出了一种基于正弦波脉宽调制与电流控制相结合的新型控制方案.对三相逆变器的输出参数应用PARK变换,并采取双电流环PI加前馈控制策略,实现了对电流的有功分量与无功分量对并网逆变器系统输出性能的控制.在Simulink环境下建立了系统的仿真模型,仿真结果表明,改进型的电流控制方法可以有效控制并网系统的有功与无功功率,谐波畸变小,是一种有较强应用价值的三相逆变器控制方案,为设计提供了科学依据.     

构网型变流器多环控制阻抗建模与稳定性分析

构网型变流器的控制方式按照是否存在电压电流控制双环可以分为只含有功率控制环的单环控制和含有功率控制环和电压电流控制双环的多环控制。两种控制方式并网运行特性在不同频段有较大区别。该文首先建立考虑电压电流解耦控制双环的构网型变流器多环控制序阻抗模型,对比分析两种控制方式对变流器输出阻抗的影响;其次针对加入电压电流控制双环造成的低频相位裕度不足问题,提出引入虚拟阻抗方法提高变流器并网稳定性;最后利用仿真与实验验证了稳定性分析的准确性。     

基于双环控制的航空静止变流器的建模与仿真

针对航空静止变流器在非线性负载条件下输出电压谐波含量大以及逆变器动态响应过程十分缓慢的问题,采用电容电流内环电压外环的双环控制技术,给出了控制器参数基于极点配置的方法,建立了单相航空静止变流器的数学模型。通过Matlab/Simulink软件平台对模型仿真。结果表明:设计方法能真实反映系统的动、静态性能,同时也验证了采用双环控制技术解决航空静止变流器带非线性负载时输出波形畸变以及动态响应缓慢的问题是行之有效的。     

一种基于下垂特性的逆变器并联控制改进方法

针对传统下垂特性控制存在的不足,提出基于下垂特性的改进并联控制方案。改进方案在传统下垂特性控制的基础上增加电压频率、幅值修正环,提高了逆变器并联工作性能,削弱了连线阻抗等电气参数对逆变器的影响。最后在Matlab/Simulink仿真平台对该方案进行仿真实验,结果验证了改进方案的良好性能。     

Z源逆变器高阶微分反馈控制研究

以航空静止变流器控制为研究对象,针对传统两级逆变结构效率低且系统复杂以及死区效应带来的死区波形畸变问题,引入Z源逆变器设计航空静止变流器。针对Z源逆变器系统高阶且非最小相位造成的控制器设计复杂的问题,引入了一种基于高阶微分器的反馈控制策略,该控制策略利用高阶微分器对系统各阶状态变量进行估计,具有不依赖于精确系统模型的特点。仿真实验表明,将此反馈控制器用于Z源逆变器输出电压控制时能够有效跟踪给定输出电压,系统受到外部扰动时依然能保持良好的静态和动态性能,满足静变流器控制需求。     

单相有源电力滤波器非线性统一控制策略

目前有源电力滤波器控制策略都采用电流内环和电压外环的双环控制.本文提出了一种基于精确反馈线性化的单相有源电力滤波器统一控制策略.在单相有源电力滤波器仿射非线性模型基础上,通过求解偏微分方程得到一个包含补偿电流变量和直流侧电压变量的输出函数,并推导出了其状态反馈精确线性化非线性控制律,将原非线性系统转换成微分同胚的二阶线...     

Multi-loop design of multi-scale controllers for multivariable processes

Based on the recently proposed (SISO) multi-scale control scheme, a new approach is introduced to design multi-loop controllers for multivariable processes. The basic feature of the multi-scale control scheme is to decompose a given plant into a sum of basic modes. To achieve good nominal control performance and performance robustness, a set of sub-controllers are designed based on the plant modes in such a way that they are mutually enhanced with each other so as to optimize the overall control objective. It is shown that the designed multi-scale controller is equivalent to a conventional PID controller augmented with a filter. The multi-scale control scheme offers a systematic approach to designing multi-loop PID controllers augmented with filters. Numerical studies show that the proposed multi-loop multi-scale controllers provide improved nominal performance and performance robustness over some well-established multi-loop PID controller schemes.     

双凸极启动/发电系统的控制策略研究

介绍了一种可以适用于航空低压直流、变速恒频、高压直流电气系统的新型双凸权启动／发电机系统(DSS／G)，首先对双凸极电机的电动及发电机理进行了理论分析，给出双凸极启动／发电机的相应控制策略，启动运行时采用恒转矩控制策略，发电运行时采用是两极发电模式。在此基础上研制了一台18kW样机，并进行了试验研究，试验结果表明双凸极电机启动／发电系统方案具有良好的性能。     

Improved fractional augmented control strategies for continuously stirred tank reactors

Controlling concentration and temperature of continuously stirred tank reactor (CSTR) is an extremely challenging task in chemical process industries. This is because conventional unity feedback schemes do not guarantee stable operating conditions for the CSTR process. Therefore, fractional calculus is augmented with multi-loop control to achieve enhanced stability and closed-loop performance than unity feedback structure in this work. Accordingly, three different fractional-order-based novel multi-loop control structures are proposed based on time domain analysis. In two of the proposed strategies, fractional-order PID controller (FOPID) and internal model control (IMC)-based FOPID controller with fractional filter are used in the inner-loop. Moreover, fractional-order-based Lyapunov stability rule of model reference adaptive control (MRAC) is used in outer-loops for both of the above mentioned methods. Finally, an advanced multi-loop predictor with FOPD controller in the inner-loop and FOIMC controller in the outer-loop is also proposed. In this work, fractional-order, filter parameters, and FOPID settings are obtained by minimizing multi-objective functions using modified particle swarm optimization (PSO) algorithm. Closed-loop responses and control efforts of the proposed control strategies are compared with that of FO-Lyapunov-based MRAC scheme. Quantitative performance analysis is also carried out on all proposed methods based on error metrics and total variation of the control signal.     

Control performance assessment based on sensor fusion techniques

Control performance assessment techniques are widely studied and many performance assessment indices have been proposed. In this paper, a control performance assessment technique for multi-loop control systems is presented based on the decision fusion strategy. Since decisions based on individual indices can lead to erroneous results, decision fusion of different indices can improve the assessment accuracy, especially in multi-loop control systems in the presence of loop interactions. Performance assessment indices are individually evaluated and decisions based on these indices are fused. The results of simulation and practical implementation on series cascade control structures illustrate the effectiveness of the proposed algorithm.     

四旋翼飞行器带速度补偿的多回路PID位置跟踪控制

针对四旋翼飞行器的位置跟踪问题,采用ADAMS(automatic dynamic analysis of mechanical system)软件搭建了四旋翼飞行器的非线性数学模型,并将模型导入到Matlab中,采用多回路PID位置控制策略对飞行器的位置跟踪进行控制,并在此基础上提出采用速度PID进行补偿多回路PID的位置跟踪控制策略.仿真结果表明:所设计的速度PID对多回路PID的位置跟踪控制策略进行补偿,对于四旋翼飞行器位置控制具有响应速度快、超调小、鲁棒性强等特点;所采用的联合仿真方法效果直观.     

压电加筋壁板结构的多模态自抗扰振动控制

针对压电加筋壁板结构多模态主动控制时存在振动模型和外界干扰难以确定等问题, 提出一种不依赖结构数学模型的多模态自抗扰振动控制方法. 首先,采用多回路的扩张状态观测器实时估计其他模态的输出叠加、输入耦合、高次谐波以及外界激励等组成的集总干扰, 并将估计值通过前馈补偿的方式消除干扰对整个控制系统的影响. 然后, 针对每个控制模态设计独立的PD反馈控制器. 为了提高整个控制系统的振动抑制性能, 结合多模态振动控制的特点, 引入一种具有实际意义的性能指标函数. 并基于此性能函数, 提出基于logistic映射的自抗扰振动控制器参数自动优化方法. 最后, 利用dSPACE半实物仿真平台, 搭建了四面固支壁板结构的压电振动控制实验系统.最后, 多模态干扰激励的实验结果表明了所提的多模态自抗扰振动主动控制方法的有效性.     

Digital hysteresis sliding mode control for interleaved DC–DC converters

This paper presents a digital constant frequency sliding mode control (SMC) law for interleaved DC–DC converters. Constant switching frequency and interleaving are achieved by dynamically adjusting the hysteresis of the control signals generating comparators. The interleaving method neither imposes constraints on the number of required phases to obtain a specific output voltage nor uses quasi-SMC. Hence, the control scheme achieves high flexibility, robustness, and performance. Furthermore, a sliding mode observer (SMO) for reconstructing the inductor currents is proposed. Experimental results for a two-phase buck converter are reported. The control concept accomplishes an improved dynamic performance in comparison with quasi-SMC.     

Independent design of multi-loop PI/PID controllers for interacting multivariable processes

The interactions between input/output variables are a common phenomenon and the main obstacle encountered in the design of multi-loop controllers for interacting multivariable processes. In this study, a novel method for the independent design of multi-loop PI/PID controllers is proposed. The idea of an effective open-loop transfer function (EOTF) is first introduced to decompose a multi-loop control system into a set of equivalent independent single loops. Using a model reduction technique, the EOTF is further approximated to the reduced-order form. Based on the corresponding EOTF model, the individual controller of each single loop is then independently designed by applying the internal model control (IMC)-based PID tuning approach for single-input/single-output (SISO) systems, while the main effects of the dynamic interactions are properly taken into account. Several illustrative examples are employed to demonstrate the effectiveness of the proposed method.     

Application of predictive control methods for Radio telescope disk rotation control

Radio telescope (RT) installations are highly valuable assets and during the period of their service life they need regular repair and maintenance to be carried out for delivering satisfactory performance and minimizing downtime. Same down time can be expected during machinery usage. Constant control of telescope rotation angle is done manually using visual inspection of hardware. The accuracy of this procedure is very low, therefore, automation and computer control systems are required. With the growing automation technologies, predictive control can prove to be a better approach than the traditionally applied visual inspection policy and linear control models. In this paper, Irbene Radio telescope RT-16 disk rotation control motors are analysed using control voltage from the converters. Retrieved data from the small DC motor is used for the predictive control approach using two different methods: a neural network trained with Basic Levenberg-Marquardt method and a linear model. A multilayer perceptron network approach is used for prediction of the indicator voltage output which affects the monitoring of the disk rotating angle. Finally, an experimental control system was proposed and installed using National Instruments equipment.     

CONWIP based control of a lamp assembly production line

Efficient and effective production control systems are very important for manufacturing plants. CONWIP, one of these production control systems, has a high potential of becoming the best one available because it suits a variety of production environments and is easy to implement. In the following paper, we compare the single-loop and multi-loop CONWIP production control systems for an actual lamp assembly production line producing different kinds of products with discrete distribution processing time and demand. A model is formulated with respect to total cost and service level. A novel rule-based genetic algorithm (GA) approach is proposed for the multi-loop CONWIP system to find the optimum parameter setting. The results have shown that the single-loop CONWIP production control system is more efficient than the multi-loop system. It can greatly decrease the total cost and the WIP (Work-In-Process) with zero shortage probability.