机床用永磁同步电机预测电流控制方法研究

近年来,随着数字信号处理器和先进控制理论的发展,模型预测控制得到越来越多的关注和应用。针对数控机床用永磁同步电机常规单矢量模型预测直接电流控制方法存在电流谐波较大的问题,基于两电平电压源逆变器的基本电压矢量构造了6个虚拟电压矢量,并基于所构造的虚拟矢量建立了扩展电压矢量集。然后,设计了一种基于扩展电压矢量集的永磁同步电机预测电流控制方法。与常规的单矢量法相比,所提方法可明显降低电流的谐波,改善永磁同步电机的稳态控制性能。仿真和实验结果均验证了该方法的有效性,能够为同步电机在数控机床或相近的应用场合提供较好的理论支撑。     

Generalized predictive control for a coupled four tank MIMO system using a continuous-discrete time observer

This paper deals with the problem of the observer based control design for a coupled four-tank liquid level system. For this MIMO system's dynamics, motivated by a desire to provide precise and sensorless liquid level control, a nonlinear predictive controller based on a continuous-discrete observer is presented. First, an analytical solution from the model predictive control (MPC) technique is developed for a particular class of nonlinear MIMO systems and its corresponding exponential stability is proven. Then, a high gain observer that runs in continuous-time with an output error correction time that is updated in a mixed continuous-discrete fashion is designed in order to estimate the liquid levels in the two upper tanks. The effectiveness of the designed control schemes are validated by two tests; The first one is maintaining a constant level in the first bottom tank while making the level in the second bottom tank to follow a sinusoidal reference signal. The second test is more difficult and it is made using two trapezoidal reference signals in order to see the decoupling performance of the system’s outputs. Simulation and experimental results validate the objective of the paper.     

电压源逆变器混合多矢量预测共模电压抑制方法

近年来,为了减小共模电压对电压源逆变器的影响,模型预测共模电压抑制方法得到广泛研究。然而,常规的电压源逆变器模型预测共模电压抑制方法每个控制周期仅采用一个非零电压矢量作用,导致其电流谐波较大。为此,提出了一种混合多矢量模型预测共模电压抑制方法。首先给出了所提多矢量模型预测共模电压抑制方法的实现原理。其次详细分析了死区和电流纹波对共模电压的影响,并进一步对所提多矢量法进行改进。改进的方法在电流扇区7内使用单个非零电压矢量作用,而在其他扇区内使用多个非零电压矢量作用,从而不仅可以完全将共模电压限制在±Vdc/6之内,而且可以减小电流的总谐波畸变率。仿真和实验结果验证了该方法的有效性。     

基于双PWM变换器的永磁直驱风电系统控制策略研究

针对基于双PWM变换器的永磁直驱风电系统的控制问题,对该风电系统电机侧变换器、电网侧变换器的控制策略进行了详细的分析,提出了一种桨距角控制策略,并基于Matlab/Simulink对永磁直驱风电系统进行了仿真。仿真结果表明,永磁直驱风电系统能够在不同风速下稳定运行,在额定风速以下可实现风能的最大功率跟踪,在额定风速以上通过桨距角控制能将风机系统的功率输出限制在额定值附近。研究结果验证了所提出的桨距控制策略的可行性。     

Hierarchical control strategy for a three-phase 4-wire microgrid under unbalanced and nonlinear load conditions

This paper proposes an improved hierarchical control strategy consists of a primary and a secondary layer for a three-phase 4-wire microgrid under unbalanced and nonlinear load conditions. The primary layer is comprised of a multi-loop control strategy to provide balanced output voltages, a harmonic compensator to reduce the total harmonic distortion (THD), and a droop-based scheme to achieve an accurate power sharing. At the secondary control layer, a reactive power compensator and a frequency restoration loop are designed to improve the accuracy of reactive power sharing and to restore the frequency deviation, respectively. Simulation studies and practical performance are carried out using the DIgSILENT Power Factory software and laboratory testing, to verify the effectiveness of the control strategy in both islanded and grid-connected mode. Zero reactive power sharing error and zero frequency steady-state error have given this control strategy an edge over the conventional control scheme. Furthermore, the proposed scheme presented outstanding voltage control performance, such as fast transient response and low voltage THD. The superiority of the proposed control strategy over the conventional filter-based control scheme is confirmed by the 2 line cycles decrease in the transient response. Additionally, the voltage THDs in islanded mode are reduced from above 5.1% to lower than 2.7% with the proposed control strategy under nonlinear load conditions. The current THD is also reduced from above 21% to lower than 2.4% in the connection point of the microgrid with the offered control scheme in the grid-connected mode.     

基于PLC和直流电机的风力发电模拟平台试验研究

为解决风力发电中的风能利用问题,以直流电机为原动机,搭建了基于BECKHOFF PLC的永磁直驱风力发电模拟试验平台,并使用KingView组态软件开发了人机交互界面。风力发电模拟平台采用DC Driver来实现直流电动机模拟风机的转矩控制,采用下位机控制软件TwinCAT PLC集成的PID算法实现永磁同步发电机的转速控制,从而实现风力机的转矩特性模拟和永磁同步发电机的最佳转速追踪控制。最后,在所搭建的实验平台上对基于最佳叶尖速比的最大风能捕获控制方案进行了试验研究。研究结果表明,模拟风机可以动态地追踪最大功率点,验证了风机模拟平台的有效性。     

APF空间矢量预测电流控制策略研究

影响有源电力滤波器性能的两个关键环节是无功谐波电流检测环节和电流跟踪控制环节。本文先阐述APF的原理与系统结构,然后对基于ip-iq运算方法的谐波电流的实时检测方法进行论述。为提高APF的电流跟踪性能,采用电压空间矢量预测电流控制方法。最后仿真实验表明,该方法具有更好的电流控制效果。     

Model predictive control based on reduced order models applied to belt conveyor system

In the paper, a model predictive controller based on reduced order model is proposed to control belt conveyor system, which is an electro-mechanics complex system with long visco-elastic body. Firstly, in order to design low-degree controller, the balanced truncation method is used for belt conveyor model reduction. Secondly, MPC algorithm based on reduced order model for belt conveyor system is presented. Because of the error bound between the full-order model and reduced order model, two Kalman state estimators are applied in the control scheme to achieve better system performance. Finally, the simulation experiments are shown that balanced truncation method can significantly reduce the model order with high-accuracy and model predictive control based on reduced-model performs well in controlling the belt conveyor system.     

永磁同步电机模型预测控制的现状与发展

模型预测控制是一种优化控制算法,近年来已经成为电机控制领域研究的热点。模型预测控制根据过去和现在的信息,对系统的状态量进行预测,并综合考虑控制对象的预期值和控制量的变化等评价指标,得到最优的控制量。该文综述了基于线性模型预测的永磁同步电机的直接转矩控制、矢量控制、直接电流控制、混合控制等算法的特点,以及基于非线性模型预测的永磁同步电机控制的研究现状,阐述了模型预测控制理论与应用方面有待进一步研究的几个主要问题。     

基于扩充虚拟矢量的永磁同步电动机模型预测直接转矩控制

针对传统模型预测直接转矩控制策略存在的计算效率低、电压跳变过高、稳态特性较差等问题，提出一种改进模型预测直接转矩控制策略。为提升电动机的稳态特性，基于最近三矢量原则构建36个虚拟电压矢量，并结合无差拍原理调节虚拟电压矢量中冗余矢量的作用时间；为防止逆变器输出线电压跳变过高以对电动机产生不良影响，仅选取电压跳变不超过U_dc/2的电压矢量作为备选电压矢量。同时，结合模型通过无差拍原理预测出参考电压矢量，选取与参考电压矢量位于同一扇区的电压矢量作为最终备选矢量集。实验结果证明了在额定工况下改进控制策略较传统控制策略的电磁转矩、定子磁链幅值误差和电流谐波畸变率分别减少了37.42%、32.00%和44.52%,程序执行时间减少了约11.52%。     

Application of multi-model switching predictive functional control on the temperature system of an electric heating furnace

A method of multi-model switching based predictive functional control is proposed and applied to the temperature control system of an electric heating furnace. The control strategies provide the effective and independent control modes of the electric heating furnace temperature in order to obtain improved control performance. The method depends on conventional implementation of the multi-model switching state, which requires some endeavors to tune the switching model in the model predictive control and allows a reduction of the calculation compared with the weighted multiple model algorithms. In order to test the advantage of the proposed method, experimental equipment is set up and experiments are done on the temperature process of a heating furnace, which verify the validity and effectiveness of the proposed algorithm.     

Fuel cell starvation control using model predictive technique with Laguerre and exponential weight functions

Fuel cell system is a complicated system that requires an efficient controller. Model predictive control is a prime candidate for its optimization and constraint handling features. In this work, an improved model predictive control (MPC) with Laguerre and exponential weight functions is proposed to control fuel cell oxygen starvation problem. To get the best performance of MPC, the control and prediction horizons are selected as large as possible within the computation limit. An exponential weight function is applied to place more emphasis on the current time and less emphasis on the future time in the optimization process. This leads to stable numerical solution for large prediction horizons. Laguerre functions are used to capture most of the control trajectory, while reducing the controller computation time and memory for large prediction horizons. Robustness and stability of the proposed controller are assessed using Monte-Carlo simulations. Results verify that the modified MPC is able to mimic the performance of the infinite horizon controller, discrete linear quadratic regulator (DLQR). The controller computation time is reduced approximately by one order of magnitude compared to traditional MPC scheme. Results from Monte-Carlo simulations prove that the proposed controller is robust and stable up to system parameters uncertainty of 40%.     

直驱永磁同步风电机组不对称故障穿越的研究

在分析不对称电网电压条件下直驱永磁风力发电机组并网逆变器数学模型的基础上,提出了正负序双电流闭环控制策略,完成风力发电机组在电网发生不对称故障下的不脱网运行.在PSCAD/EMTDC环境下建立基于IGBT背靠背变频器的1.5 MW永磁直驱风力发电系统仿真模型,仿真结果证明该控制策略的可行性.     

Move Suppression Calculations for Well-Conditioned MPC

Several popular tuning strategies applicable to Model Predictive Control (MPC) schemes such as GPC and DMC have previously been developed. Many of these tuning strategies require an approximate model of the controlled process to be obtained, typically of the First Order Plus Dead Time type. One popular method uses such a model to analytically calculate an approximate value of the move suppression coefficient to achieve a desired condition number for the regularized system dynamic matrix; however it is not always accurate and tends to under-estimate the required value. In this paper an off-line method is presented to exactly calculate the move suppression coefficient required to achieve a desired condition number directly from the unregularized system dynamic matrix. This method involves an Eigendecomposition of the system dynamic matrix - which may be too unwieldy in some cases –and a simpler analytical expression is also derived. This analytical expression provides a guaranteed tight upper bound on the required move suppression coefficient yielding a tuning formula which is easy to apply, even in on-line situations. Both methods do not require the use of approximate or reduced order process models for their application. Simulation examples and perturbation studies illustrate the effectiveness of the methods in both off-line and on-line MPC configurations. It is shown that accurate conditioning and improved closed loop robustness can be achieved.     

永磁直驱风电系统建模及其机电暂态模型参数辨识

针对基于双脉宽调制(PWM)变换器的永磁直驱风电系统的运行特性,分析了风力机特性、电机侧变换器和电网侧变换器的控制策略,利用Matlab/Simulink建立了反映电力电子开关动作的永磁直驱风电系统详细模型,并在此基础上根据同步电机3阶暂态模型,建立了直驱风机的机电暂态数学模型,采用粒子群算法(PSO)对模型进行了参数辨识。仿真结果表明,该详细模型能够描述永磁直驱风电系统对不同风速的响应,实现风能的最大功率跟踪;机电暂态数学模型与详细模型特性接近,能够从总体上反映永磁直驱风电系统对端电压变化的有功、无功响应,PSO参数辨识有效。研究结果表明,所建立的详细模型能够用于控制方式的研究以改善输出特性,机电暂态模型能够用于研究电网与永磁直驱风电系统的相互影响。     

产品质量智能预测控制研究

介绍了质量预测控制的研究现状,提出了基于质量特征参数序列的质量智能预测控制系统模型,分析了系统的稳定性.根据提出的系统模型利用动态神经网络对加工过程质量特征参数的变化进行了跟踪实验,效果良好.     

Design of a new PID controller using predictive functional control optimization for chamber pressure in a coke furnace

An improved proportional-integral-derivative (PID) controller based on predictive functional control (PFC) is proposed and tested on the chamber pressure in an industrial coke furnace. The proposed design is motivated by the fact that PID controllers for industrial processes with time delay may not achieve the desired control performance because of the unavoidable model/plant mismatches, while model predictive control (MPC) is suitable for such situations. In this paper, PID control and PFC algorithm are combined to form a new PID controller that has the basic characteristic of PFC algorithm and at the same time, the simple structure of traditional PID controller. The proposed controller was tested in terms of set-point tracking and disturbance rejection, where the obtained results showed that the proposed controller had the better ensemble performance compared with traditional PID controllers.     

基于最优控制的新型非线性预测仿真研究

首先设计出基于输出反馈的最优控制 ,在此基础上 ,给出连续域的预测控制设计方法 ,把预测控制参数设计问题简化为积分增益ks、预测时域M、补偿增益km的选择问题。用模型预测替代在最优控制中所必需的多微分环节的作用 ,实现超前调节。给出针对非线性对象的预测控制方法。经仿真研究证明 ,这种方法是合理、有效的     

基于双阵元超声波接收阵列的风矢量测量

针对当前超声波测风仪测量精度不高及抑制噪声干扰能力不强的问题,提出了一种双阵元超声波接收阵列结构及基于该结构的风矢量测量方法。首先,设计了一种基于超声波测风原理的风速风向测量系统结构,该结构中包含一个超声波发射阵元和两个超声波接收阵元;然后,依据该系统结构给出了一种基于相关方法的超声波时延估计算法,根据超声波传输时间与风矢量之间的关系可直接获得风速风向值。最后,通过仿真实验对所提方法的可行性与有效性进行了验证,且通过搭建的双阵元超声波阵列测风系统对所提方法进行了实测数据验证。实验结果表明:设计的结构简单易实现,算法稳定计算复杂度低,并且具有较高的噪声抑制能力。实测环境下风速测量的最大相对误差为2.3%、风向角测量的最大测量误差为-1.5°,基本达到了风矢量测量仪的技术要求。     

基于ANFIS及MPC的车辆转向换道控制系统设计

为提高智能车辆在高速工况下进行转向换道避撞时的行驶稳定性,设计了一种基于ANFIS及MPC的车辆转向换道控制系统。车辆转向换道控制系统是以模型预测控制(Model Predictive Control, MPC)算法为基础,结合五阶多项式换道路径和最小车距安全模型搭建的;以理想横摆角速度与实际横摆角速度的偏差及其变化率为双输入,利用自适应神经模糊系统(Adaptive Network-based Fuzzy Inference System, ANFIS)规则输出所需的附加横摆力矩,对车轮进行差动制动,以修正车身姿态,实现行车稳定。仿真结果对比表明,此车辆转向换道控制系统可显著提高车辆在高速工况下进行转向换道避撞时的行驶稳定性。