一种基于非线性反馈重复控制策略的磁通切换直线电机推力波动抑制方法

针对初级永磁型磁通切换直线(LFSPM)电机,研究其定动子双凸极结构引起的与位移相关的定位力、摩擦力及参数变化等不确定性对伺服系统的影响,提出一种基于非线性反馈的重复控制策略。首先,在分析LFSPM电机定位力的基础上,通过设计重复控制器对定位力引起的推力波动进行抑制;随后设计非线性反馈控制器,对因摩擦力及参数变化等不确定性因素引起的推力波动进行补偿,同时使逼近误差随周期数的累加而呈现减小的趋势,保证了系统的全局渐近稳定性。最后,通过AD5435半实物系统搭建了控制模型,实验结果表明,该控制方案有效抑制了因定位力及其他不确定因素引起的推力波动。     

Robust stabilization of a magnetic suspension system using H∞ Control Theory

This paper presents the robust control design of a magnetic suspension system for a flexible beam which is a simplified model of an elastic rotor in a magnetic bearing system. To stabilize this magnetic suspension system which is unstable in nature, the H^infin; control theory is applied for a design of the control system. To apply the H^infin; control theory, a statespace model of an augmented plant with frequency-weighting functions is constructed. This augmented plant has two inputs which are the exogenous inputs and the control inputs, and two outputs which are the sensor outputs and the regulated outputs. Here we consider the mixed sensitivity problem. The H^infin; controller is implemented by a digital controller which is able to execute the computations very quickly. For the evaluation of the control performance, several experiments are made. The robustness of the closed-loop system is confirmed by the experimental results. The result of this study is useful for the control design of a magnetic bearing system.     

发电机自适应Terminal滑模励磁控制

建立了单机无穷大系统的励磁控制数学模型,设计了一种自适应Terminal滑模励磁控制器。通过在滑模面加入非线性函数,使得误差能够快速收敛,从而取得良好的控制效果。同时考虑了系统中存在未知上界的不确定扰动,在设计中加入了自适应环节,实时估计扰动上界,从而使控制器具有较强的鲁棒性。根据李亚普洛夫理论证明了所设计控制系统的稳定性。仿真结果表明,无论是小扰动还是大扰动下均能有效提高系统稳定性,维持机端电压,效果优于自适应逆推滑模励磁控制。     

A High-performance Speed Feed-forward Controller for Permanent Magnet Synchronous Motor Based on Control System Model

This study proposes a feed-forward controller based on a control system model that can precisely track a reference trajectory by canceling out the effects of parameter uncertainties on a surface-mounted (magnets glued to the shaft surface) permanent magnet synchronous motor. Furthermore, the speed tracking control algorithm demands rapid and accurate q-axis current command, so the feed-forward system based on the control model is used to estimate it. The stability of the proposed controller is mathematically studied. The proposed control scheme is executed on a permanent magnet synchronous motor drive using a Renesas micro-control unit (RX62TADFFM, Japan). Finally, simulation and experimental results are presented to verify that the proposed controller achieves less steady-state error, better robust performance, and faster dynamic response than the proportional–integral controllers in the presence of permanent magnet synchronous motor parameter uncertainties and external load torque disturbance.     

Robust magnetic bearing control using stabilizing dynamical compensators

This paper considers the robust control of an active radial magnetic bearing system, having a homopolar, external rotor topology, which is used to support an annular fiber composite flywheel rim. A first-order dynamical compensator, which uses only position feedback information, is used for control, its design being based on a linearized one-dimensional second-order model which is treated as an interval system in order to cope with parameter uncertainties. Through robust stability analysis, a parameterization of all first-order robustly stabilizing dynamical compensators for the interval system is initially obtained. Then, by appropriate selection of the free parameters in the robust controller, the H/sub 2/ norm of the disturbance-output transfer function is made arbitrarily small over the system parameter intervals, and the H/sub /spl infin// norm of the input-output transfer function is made arbitrarily close to a lower bound. Simulation and experimental results demonstrate both stability and performance robustness of the developed controller.     

基于DSP和CPLD的主动磁悬浮轴承数字控制器

设计了一种新型的基于DSP和CPLD的主动磁轴承控制器,它以DSP为主处理器,把所有控制电路、PWM信号等在CPLD中实现.同时,控制器软件采用改进型的PID控制算法,以提高系统控制精度和动态性能.实验结果表明,该控制器实现了磁悬浮轴承控制系统的高速率实时控制,增强了系统的鲁棒性和抗干扰能力,取得了良好的效果.     

Fully parameterized fixed‐order controller design for H∞ loop shaping method using frequency responses—extension to MIMO systems

Robust control is often applied to systems with uncertainties and disturbances. Above all, the H∞ loop shaping method is known to achieve good control performance and robustness. In this method, the final controller consists of weighting functions and a stabilizing controller. The stabilizing controller is derived for the shaped plant to suppress the H∞ norm of the transfer matrix consisting of a sensitivity function, a complementary sensitivity function, and so on. In addition, the stabilizing controller improves robust stability margin while keeping gain characteristic of the shaped plant if weighting functions are suitable. As a result, the closed‐loop system is well‐balanced between good tracking and robustness. However, a final controller tends to be high‐order. For this problem, reduction techniques are often applied to the final controller. In this case, performance and stability is not always adequately evaluated due to errors by the controller reduction. This paper proposes a fully parameterized fixed‐order controller design method using frequency responses of the plant. We formulate a design problem for multi‐input–multi‐output systems as an optimization problem. Therefore, we can directly design a low‐order controller from frequency responses using the iterative LMI optimization. Accordingly, we can avoid to deteriorate the evaluation of performance and stability.     

主动磁轴承系统的自适应滑模控制

本文针对磁轴承系统的结构参数具有时变性,为典型的复杂非线性系统的特点,将自适应控制和滑模控制相结合,设计了一种能实时跟踪系统结构参数变化的自适应滑模控制器,并应用到单自由度磁悬浮轴承控制系统,使得系统的性能达到最优或近似最优。以单自由度磁轴承控制系统为研究对象,建立了基于自适应滑模控制的仿真模型,构建了以PC为上位机,TMS320F2812型DSP为下位机的实验平台。仿真与实验结果表明,自适应滑模控制器不但能削弱常规滑模控制中的固有抖振,而且具有更好的鲁棒性和快速性,满足磁轴承系统实时控制的要求。     

基于复合控制的圆筒形永磁直线同步电机位置控制

针对圆筒形永磁直线同步电机,设计了一种位置控制系统。考虑到直线电机的推力脉动、摩擦力和系统模型的不确定性,采用干扰观测器(DOB)对其进行在线估算并进行补偿,经过补偿,系统模型近似等价其标称模型;基于标称模型设计速度前馈控制器,基于速度控制系统的模型设计位置前馈控制器,使得永磁直线同步电机控制系统的输出能够无误差地跟踪期望的速度和位置响应曲线;采用综合校正方法设计反馈控制器,保证系统的稳定性。最后给出了仿真结果。     

电力电子开关变换器的滑模控制

以电力电子开关变换器为对象,分析带有开关元件系统的数学模型,应用变结构控制方法,调制电力电子元件的开关模式,以获得预期的电压、电流波形和动态性能。为减少抖振,引入了模糊控制,对传统变结构控制加以改进,综合二者优点,使系统既具有变结构控制的优良性能,又能最大限度地减少抖振。最后仿真结果验证了文中控制算法的有效性。     

高压直流输电系统换流站鲁棒自适应输出反馈控制

针对高压直流输电系统,设计了一种鲁棒自适应输出反馈控制器.首先,将高压直流输电系统换流站动态模型转换成用输入输出表示的非线性系统.然后,利用自适应非线性阻尼项来抑制系统的非线性动态不确定性和未知有界扰动,应用Lyapunov稳定性理论构造出控制器和自适应参数的表达式.Lyapunov稳定性分析结果表明,文中所提出的控制器保证了闭环系统的稳定性.最后,将设计的控制器应用到一个3机直流输电系统中,仿真结果表明,与传统的PI控制器相比较,文中控制器可大大提高系统的稳定性和鲁棒性.     

Centralized optimal position control for active magnetic bearings: comparison with decentralized control

This paper discusses a closed-loop centralized control for a multi-input multi-output active magnetic bearing system. A genetic algorithm for design and a credible comparison of different controller structures are proposed. The evaluation of the design trade-offs of linear-quadratic and loop transfer recovery controllers are studied. The model-based controllers are compared with the classical PID controller and the cascaded PI/PD controller. The properties of the tested control configurations are examined using maximum singular values of the output sensitivity function of the closed-loop system and the tolerated disturbance at the input of the plant. Furthermore, indices such as measured peak output sensitivity, singular values of the uncertain control system, responses to the step reference position, step disturbance, and impulse force disturbance are examined. A good agreement between the simulation and the experimental results from the test-rig is shown.     

Optimal Linear Control of Modular Multi-Level Converters with a Prescribed Degree of Stability

Abstract

In this paper, a new control approach using an optimal linear control with prescribed degree of stability for modular multi-level converters (MMC) is presented and analyzed. The proposed controller relies on a linear quadratic regulator with integral action which brings the ability of state variable reference tracking for modular multi-level converters. Since MMC is a complex system with several state variables, a unified control system design for this system is vital. The proposed controller of this study is designed to obtain wider stability margin thanks to the implementation of prescribed degree of stability concept to minimize the quadratic performance index of the control structure. By means of this method, the poles of the closed-loop system will be shifted to the desired places in the left half side of the S-plane. The main advantages of this control strategy compared to previous methods are that it will be possible to control the state of energy for each phase separately, while there will be superior tolerance to nonlinearities and the enhanced stability margin with less sensitivity to plant-parameter variations. The performance of the designed controller is verified through MATLAB^TM simulations (The MathWorks, Natick, MA, USA) with the nonlinear model of MMC.     

基于FPGA的数字控制DC／DC研究

与DSP器件相比,现场可编程门阵列(Field Programmable Gate Array,简称FPGA)能够实现性能更优的数字控制DC/DC变换器.基于FPGA开发平台.研究了数字化DC/DC变换器的实现方法,介绍了电压模式数字控制器各功能模块及系统的状态机实现.实验系统的测试结果表明,采用FPGA实现数字DC/DC具有较好的性能,具体性能指标完全可以满足要求.     

H∞ control approach to a magnetic levitation system by 4-point attraction with nonlinear characteristics

An H_∞ control system design for a magnetic levitation system by 4 points attraction is presented. In the levitation system, a vehicle which runs as the secondary in a reluctance-type linear motor is levitated by four pairs of attraction forces and guided by two pairs of attraction forces. Because it has contactlessness, in the field of semiconductor products, its application is favorable for ultraclean environments in microscopic processing. In the control system design, the influence of both disturbances and uncertainties in the model is considered. The main disturbances stem from the position sensors. The uncertainties are divided into electromagnetic and mechanical ones: the former are due to the gain change in the current amplifier, the influence of leakage flux and linearization error in the magnetic circuit, and the latter are due to the changes of the mass and the moment of inertia of the vehicle. Therefore, the designed controller is indispensable to guarantee robustness of this system for both stability and performance. The controller design is based on the standard H_∞-optimal control problem. As the novel features in this paper, the low sensitivity and the robust stability for this system design is obtained. Further, there are two-poles on jω-axis in the controlled model, and an integrator is included in the controller so that equivalently there are three poles on the jω-axis in the model. Finally, several experiments, comparisons and simulations are carried out to verify the low sensitivity and robustness of the designed control system.     

一种集中式四自由度磁轴承振动抑制方法

针对磁悬浮飞轮储能中同频扰动抑制问题,建立了磁轴承转子系统数学模型,讨论了以电磁力作为控制量进行控制器设计的可行性和优越性,并从系统能量函数角度出发,提出了一种以电磁力作为控制量的集中式同频扰动抑制算法。在以电磁力作为控制量的基础上,将线性扩张状态观测器与集中式四自由度状态反馈控制器相结合,并通过李雅普诺夫定理验证了系统稳定性,使得控制算法能够对同频扰动进行主动观测和补偿。仿真结果表明该算法在宽转速范围内对于同频扰动的抑制具有明显效果。     

计及换流器间动态交互的中压直流配电系统控制参数设计

由于各换流器间存在动态交互作用,使得中压直流(MVDC)配电系统的控制参数设计比单台换流器时困难得多。首先,针对系统中换流器的电流控制环、电压控制环和下垂控制环,依次分别建立了计及换流器间动态交互的开环和闭环传递函数,并且所建传递函数零极点的个数与单台换流器独立运行时完全一致。然后,提出了一种计及换流器间动态交互的MVDC配电系统控制参数设计方法,该方法能够从系统动态稳定性的角度定性定量设计控制参数。该设计方法通过部分零极点的相互抵消,利用一对共轭主导极点准确设计系统动态特性,并在较宽频率范围(如10~50 Hz)内均有效。最后,在电力电子仿真软件PLECS中对所提传递函数和控制参数设计方法进行了仿真验证。     

计及换流器间动态交互的中压直流配电系统控制参数设计

由于各换流器间存在动态交互作用,使得中压直流(MVDC)配电系统的控制参数设计比单台换流器时困难得多。首先,针对系统中换流器的电流控制环、电压控制环和下垂控制环,依次分别建立了计及换流器间动态交互的开环和闭环传递函数,并且所建传递函数零极点的个数与单台换流器独立运行时完全一致。然后,提出了一种计及换流器间动态交互的MVDC配电系统控制参数设计方法,该方法能够从系统动态稳定性的角度定性定量设计控制参数。该设计方法通过部分零极点的相互抵消,利用一对共轭主导极点准确设计系统动态特性,并在较宽频率范围(如10~50 Hz)内均有效。最后,在电力电子仿真软件PLECS中对所提传递函数和控制参数设计方法进行了仿真验证。     

基于α逆系统理论磁轴承数学模型及控制系统

采用α阶逆系统方法,对轴向混合磁轴承这一非线性控制对象进行线性化控制研究。介绍了轴向混合磁轴承的结构并分析了其工作原理,推导出轴向混合磁轴承吸力方程。在阐述了α阶逆系统方法的基础上,针对轴向混合磁轴承动力学模型分析了基于α阶逆系统方法线性化控制的可行性,推导出基于α阶逆系统方法的线性化算法,并设计了闭环系统控制器。最后利用Matlab软件环境,构建了仿真系统,针对系统的阶跃响应、转子起浮、抗干扰性能等进行了仿真和分析。仿真试验结果表明α阶逆系统策略能够对混合磁轴承数学模型精确线性化,设计的闭环控制系统具有良好的动、静态性能。     

烧结制粒工艺模糊PID湿度控制

介绍了烧结过程中的制粒湿度控制系统，针对系统中出现的纯时滞、时变不确定性等问题，在常规PID控制的基础上，结合模糊控制理论，设计了模糊自整定PID控制器，应用模糊推理的方法实现了PID控制参数的在线自整定。仿真结果表明，模糊自整定PID控制器提高了系统的适碰能力，增强了系统的鲁棒性，改善了系统的动静态性能，具有良好的控制效果。