Extended disturbance observer for nonlinear system with time-varying disturbance gain

In control engineering, the disturbance is a major problem that deteriorates system robustness. To address this problem, a disturbance observer (DOB) has been proposed and developed. In particular, a general method of estimating high-order disturbance, expressed as a time series expansion, was studied (H-DOB). However, systems to which H-DOB are applicable are limited to those in which disturbance gain is constant. This constraint degrades the generality of H-DOB because applicable systems are limited. Therefore, by expanding to a system with a time-varying disturbance gain, we propose a more general H-DOB. The DOB proposed in this paper redesigns the dynamics of the observer based on the structure of the H-DOB. The proposed DOB is applicable even if the system is highly nonlinear. This paper verifies the convergence of the proposed DOB through proof. Using this proof, the same characteristic error dynamics can be obtained, so the same design method can be applied. The simulation for the verification of the proposed method performs disturbance estimation of the extension system. This simulation proves that, compared to H-DOB, the proposed DOB has good disturbance estimation performance.     

双重化PWM整流器自抗扰模型预测直接功率控制

针对车载双重化脉宽调制(pulse width modulation,PWM)整流器控制性能易受到模型不确定性和列车运行条件(输入电压、功率等级、电路参数等)变化影响的问题,提出一种基于自抗扰控制(active disturbance rejection control,ADRC)和模型预测直接功率控制(model predictive direct power control,MPDPC)的双闭环控制算法。其中,外环基于自抗扰控制理论,构建了基于误差驱动的ADRC(error-based ADRC,EADRC)控制器调节直流侧电压;内环结合基于内模原理的功率补偿方案使用两步MPDPC算法实现电流信号的控制。仿真和实验将所提自抗扰模型预测直接功率控制(ADRC-MPDPC)算法与传统基于比例积分的直接功率控制(proportional integral-based direct power control,PI-DPC)算法和PI-MPDPC方法进行对比,结果表明所提策略在系统启动、负载变化及工况切换等场景表现出更优的动态特性和鲁棒性能。     

Robust design of vibration suppression control system for crane using sway angle observer considering friction disturbance

It is desirable for a container crane to operate smoothly and quickly. For this purpose, the control system of a container crane should be capable of antisway control for suppressing vibrations. A vision sensor system is often used to detect the sway angle. However, since a control system with a vision sensor has a delay time when determining the angle, it sometimes leads to deterioration of control performance owing to the delay time. In order to overcome this problem, this paper proposes a new antisway crane control system based on a dual‐state observer with sensor‐delay correction. However, because of nonlinear friction in the crane, the estimation accuracy achieved by using the observer is poor. To overcome this problem, this paper proposes a disturbance observer considering friction disturbance. The control performance and e?ectiveness of the proposed robust control system based on the estimated information are shown to be satisfactory by experimental results. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(3): 36–46, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22412     

Speed control system and design of resonant system with disturbance observer

In industrial motor drive systems such as industrial plants and industrial robots, a torsional vibration often is generated because of the elastic elements in torque transmission. This vibration makes it difficult to achieve quick responses of speed and may result in damage to the plant. Such systems simply are modeled as a two mass system. The shaft torque feedback system with the disturbance observer, which is called “resonance ratio control,” is proposed to suppress the vibration for the two-mass system. In this paper, the design of controller gains in the shaft torque feedback system is examined considering not only the control performance such as the vibration suppression and dynamic responses, but also the robust stability against the noise and the model uncertainties. This paper shows the validity of the control system and the examinations by several experiments.     

具有扰动观测及实时补偿的大型光电望远镜主轴控制技术

为了降低各种内外干扰对大型光电设备成像精度的影响,对控制回路进行了扰动观测补偿器设计。首先,通过开环实验方法估计出设计观测器所需要的控制量增益b;其次,通过仿真建模给出控制器的参数设计,并进行性能分析。结果表明,该控制方法能够在不增加系统闭环带宽的前提下,将系统在中低频段的扰动抑制能力提高10dB。最后,在直流有刷力矩转台上进行了性能对比实验。实验结果表明,与PI控制器相比,系统性能在低、中、高速3种状态下都得到了明显改善。0.1°/s的阶跃响应下调节时间减少3.7s;1°/s的阶跃响应下调节时间减少0.25s,且稳态误差从0.025 7°/s减小至0.018 9°/s;10°/s的阶跃响应下稳态误差从0.113°/s减小至0.061 7°/s。可见,使用同一组控制参数,该控制方法能实现在中低、中、高速运行下的高性能控制,且只需调试2个参数,简单易实现。     

微型燃气轮发电机系统的自抗扰控制方法研究

微型燃气轮机是一个复杂的热能动力系统,它的不确定性与非线性特性使得难以对其实现高精度控制,为了实现对微型燃气轮机的稳定控制,充分发挥微型燃气轮机在分布式发电中的优越性,引入自抗扰控制器,以转速为输入设计扩张观测器,利用前馈环节予以补偿,同时通过非线性组合抑制转速偏差,实现整个微型燃气轮机控制的优化.论文详细介绍了微型燃气轮机的模型及ADRC控制策略,通过负荷波动仿真及鲁棒性仿真来研究自抗扰控制器在提高微型燃气轮机系统稳定性上的优势.仿真结果表明,基于自抗扰控制器的微型燃气轮机表现出良好的动态性能,具有较强的鲁棒性能.     

Sliding mode control for a class of uncertain nonlinear system based on disturbance observer

In this paper, a sliding mode control (SMC) scheme is proposed for a class of nonlinear systems based on disturbance observers. For a nonlinear system, the disturbance that cannot be directly measured is estimated using a nonlinear disturbance observer. By choosing an appropriate nonlinear gain function, the disturbance observer can well approximate the unknown disturbance. Based on the output of the disturbance observer, an SMC scheme is presented for the nonlinear system, and the stability of the closed‐loop system is established using Lyapunov method. Finally, two simulation examples are presented to illustrate the features and the effectiveness of the proposed disturbance‐observer‐based SMC scheme. Copyright © 2009 John Wiley & Sons, Ltd.     

微型燃气轮发电机系统的自抗扰控制方法研究

微型燃气轮机是一个复杂的热能动力系统,它的不确定性与非线性特性使得难以对其实现高精度控制,为了实现对微型燃气轮机的稳定控制,充分发挥微型燃气轮机在分布式发电中的优越性,引入自抗扰控制器,以转速为输入设计扩张观测器,利用前馈环节予以补偿,同时通过非线性组合抑制转速偏差,实现整个微型燃气轮机控制的优化。论文详细介绍了微型燃气轮机的模型及ADRC控制策略,通过负荷波动仿真及鲁棒性仿真来研究自抗扰控制器在提高微型燃气轮机系统稳定性上的优势。仿真结果表明,基于自抗扰控制器的微型燃气轮机表现出良好的动态性能,具有较强的鲁棒性能。     

一种改进线性扩张状态观测器的自抗扰控制宽频带振荡抑制方法研究

针对自抗扰控制策略在并网系统参数变化时能否维持逆变器接入弱电网的稳定性展开了进一步研究。首先,建立了计及频率耦合的自抗扰控制型并网逆变器等效单输入单输出序阻抗模型,并采用Nyquist稳定判据定量分析逆变器输出功率、电网短路比、锁相环以及自抗扰控制器参数变化对并网系统稳定性的影响。其次,针对上述参数变化所导致的弱电网下自抗扰控制型逆变器稳定性降低、宽频带振荡等问题,提出了一种改进线性扩张状态观测器(enhanced linear expansion state observer, e-LESO)的自抗扰控制宽频带振荡抑制方法。通过在传统一阶自抗扰控制器中LESO内部增添比例支路和滤波环节,重塑自抗扰控制型并网逆变器输出阻抗,拓宽其中频段(100 Hz~1 kHz)内呈正阻尼特性的频率范围,从而增强自抗扰型并网逆变器鲁棒性,实现宽频带振荡抑制。最后,通过仿真验证了所提方法的有效性。     

双极性直流微电网的改进型高阶滑模自抗扰控制

针对双极性直流微电网中分布式新能源的系统功率波动、负载侧负荷频繁投切等不确定因素所引起母线电压波动问题,以基于风光互补含混合储能的双极性直流微电网为研究对象,提出一种双闭环改进型高阶滑模自抗扰控制策略。首先,依据自抗扰理论将控制系统拟合为一阶系统模型,转化为自抗扰控制系统范式。其次,设计了改进型超螺旋滑模控制器代替传统自抗扰控制中的线性控制器,引入了具有快速收敛性的级联有限时间扩张状态观测器代替线性扩张状态观测器,既能通过高阶滑模控制算法抑制抖振,又能提高对系统集总扰动的估计精度,从而利用非线性控制策略的优势改善系统动态响应过程及抗扰性能。然后,通过Lyapunov理论证明控制系统的稳定性。最后,基于Matlab/Simulink仿真软件以及搭建实验平台对3种不同控制策略进行对比验证,实验表明所提控制能够很好地抵抗扰动和提高系统的暂态性能。     

利用扩张状态观测器的交流永磁同步电机控制

为了提高交流永磁同步电机控制系统的控制品质,保证系统在内外各种扰动的影响下仍能保持快速、无超调、高精度的控制品质,提出了一种改进的控制方式。首先,根据电机模型的特点,分析了影响系统控制品质的因素,包括电流环的动态耦合、速度环的未知扰动等。然后,在介绍扩张状态观测器的原理及功能的基础上,设计了三个扩张状态观测器分别估计速度环和电流环的总扰动,进而设计出具有扰动前馈补偿和误差反馈律相结合的复合控制器。最后仿真和实验均证明了改进的控制策略的有效性。实验结果表明,使用同一组控制器参数,改进的控制策略能够同时实现高低速的高品质动态响应。设定速度为600 r/min时,与传统PI控制器相比,调节时间从0.54 s缩短为0.09 s,速度稳态误差RMS值从2.2 r/min降为1.6 r/min;设定速度为0.01 r/min时,改进的控制策略仍能够保持电机平稳运行,且位置误差在±1码。该控制策略能够满足交流永磁同步电机高精度控制的要求。     

Measurement of mechanical parameters in two-mass resonant system using disturbance observer

In application fields for two-mass resonant system, control theory-based various techniques that use feed-forward/feedback control have been proposed to achieve high performance motion control. Although these schemes effectively suppress resonant vibration, they are quite sensitive to system parameters because the design of such controllers basically relies on system mechanical parameters. This paper presents a disturbance observer-based novel mechanical parameter measurement scheme for a two-mass resonant system. In the proposed measurement, load inertia and torsional constant of the resonant system can be measured by using error components of the estimated disturbance torque due to setting errors of the parameters in the observer. With this measurement algorithm no additional tool other than the observer is required for parameter measurement. The effectiveness of the proposed measurement scheme is verified by experimental results that are obtained by a prototype. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (2): 19–29, 1997     

Improving transparency of bilateral control system by sliding mode assist disturbance observer

Transparency is an important indicator to evaluate the performance of a bilateral control system. Uncompensated disturbances in high frequency degrade the transparency in the traditional disturbance observer (DOB) based bilateral control. This paper analyzes the influence of the uncompensated disturbances, and proposes a sliding mode assist disturbance observer (SMADO) to solve the problem. The sliding mode technique helps the original DOB to estimate the disturbances in high frequency by making use of a rapid switching control value. The required switching gain is small in the proposal, which is good for alleviating the chattering. Moreover, to avoid conservative and arbitrary design of the switching gain, a reasonable benchmark is proposed by employing the estimation error between the original DOB and another parallel DOB with a different cutoff frequency. The validity of the proposal is confirmed by experiments. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于自抗扰控制技术的发电机励磁控制方法

采用合理的发电机励磁控制方案对改善电力系统扰动稳定性有着重要的作用.探讨了二阶自抗扰控制器,并将其技术应用于发电机励磁系统.经同步发电机自抗扰励磁控制仿真验证,设计的自抗扰励磁控制器,对不确定的模型和系统的内外扰表现出更强的适应性和鲁棒性,能快速抑制发电机端电压的大幅振荡,有效地改善系统的动态品质,提高系统的稳定水平.     

永磁直驱风力发电系统最大功率跟踪非线性抗扰控制

针对永磁同步发电机的非线性、内部参数不确定以及外部扰动等问题,提出了一种直驱式永磁同步风力发电系统最大功率跟踪的非线性抗扰控制方法。该方法使用一种非线性光滑函数来设计非线性扩张状态观测器(NLESO)和非线性抗扰控制律。由NLESO来实现系统扰动及不确定性的估计,前馈到控制输入端对扰动进行补偿,从而有效提高了系统的抗扰能力。分析了NLESO的收敛性。仿真结果表明了该控制方法不仅具有响应速度快、控制精度高的特点,而且无超调无抖振现象,因而在风力发电系统最大功率跟踪控制领域具有较大应用价值。     

基于降阶线性扩张状态观测器的风电并网逆变器线性自抗扰控制*

针对风电并网逆变器直流母线电压易受电网电压波动和负载扰动影响的问题,文中提出了一种电压外环改进型线性自抗扰控制(LADRC)。首先建立了风电并网逆变器在d-q旋转坐标系下的数学模型,在此基础上,设计了基于降阶线性扩张状态观测器的线性自抗扰控制,减小了观测器的相位滞后,提高了系统的扰动观测精度;然后在观测器总扰动通道上增加了一个超前滞后的校正环节以减弱观测器的噪声放大效应;最后对改进型LADRC控制策略进行了频域特性分析。仿真结果表明,相比于传统LADRC控制策略,文中所提的控制策略对并网逆变器直流母线电压具有更好的控制效果。     

基于级联型扩张状态观测器的直流微电网低压负载接口变换器自抗扰稳压研究

直流微电网负载侧供压稳定是实现新能源电力高水平消纳的重要前提。为维持低压负载侧电压稳定,利用级联型扩张状态观测器提高扰动的估计重构精度与速度,将二阶自抗扰控制技术引入低压侧稳压控制。首先,在考虑扰动存在的低压接口变换器动态模型基础上实现对于稳压控制策略的系统设计。之后,在时域上分析级联型扩张状态观测器对于扰动重估精度的提升效果,利用线性等效框架在复频域上分析系统对于总扰动的抑制性能,以及系统模型不确定下对于动态性能的影响。此外,将Lyapunov理论运用于分析所提稳压控制策略的稳定性,表明该系统在工程上稳定。最后仿真实验验证了所提出稳压策略的正确性与有效性,且对于扰动具有较好的抑制性。     

电动变桨伺服系统的自抗扰控制研究

针对变桨伺服系统非线性、多变量、数学模型难以建立的特性,在电流环和速度环设计了自抗扰控制器,有效解决了传统PI调节器的快速性与超调之间的矛盾。仿真结果表明,电动变桨伺服系统采用以上控制方法,可以保证伺服系统有较强的抗扰性能,同时实现了无超调、响应快,具有良好的动态控制性能。     

基于自抗扰控制的交联电缆悬垂控制系统

交联悬垂控制系统是一个非线性、时变、强耦合多干扰的复杂控制系统,为提高悬垂控制系统的抗干扰能力和鲁棒性。提出一种基于自抗扰的悬垂控制策略。文中分别针对下牵引交流异步电机的速度环、电流环以及磁链还进行自抗扰控制器的设计,通过所设计的自抗扰控制器有效地提高了系统的悬垂控制精度。考虑到悬垂控制系统是一个非线性时延系统,时延的存在一定程度上降低了系统的控制性能。本文将史密斯预估技术引入到自抗扰控制器的设计中,设计了一种基于史密斯预估器的输出预估自抗扰控制器,有效地降低了时延的影响,提高了系统的鲁棒性和抗干扰性能。文中最后给出了仿真分析,仿真结果验证了所设计的复合控制器的有效性。     

Adaptive neural prescribed performance output feedback control of pure feedback nonlinear systems using disturbance observer

In this study, an adaptive output feedback control with prescribed performance is proposed for unknown pure feedback nonlinear systems with external disturbances and unmeasured states. A novel prescribed performance function is developed and incorporated into an output error transformation to achieve tracking control with prescribed performance. To handle the unknown non-affine nonlinearities and avoid the algebraic loop problem, the radial basis function neural network (RBFNN) is adopted to approximate the unknown non-affine nonlinearities with the help of Butterworth low-pass filter. Based on the output of the RBFNN, the coupled design between sate observer and disturbance observer is presented to estimate the unmeasured states and compounded disturbances. Then, the adaptive output feedback control scheme is proposed for unknown pure feedback nonlinear systems, where a first-order filter is introduced to tackle with the issue of “explosion of complexity” in the traditional back-stepping approach. The boundedness and convergence of the closed-loop system are proved rigorously by utilizing the Lyapunov stability theorem. Finally, simulation studies are worked out to demonstrate the effectiveness of the proposed scheme.