A sensorless variable structure control of induction motor drives

In this paper, an indirect field-oriented induction motor drive with a sliding-mode controller is presented. The design includes rotor speed estimation from measured stator terminal voltages and currents. The estimated speed is used as feedback in an indirect vector control system achieving the speed control without the use of shaft mounted transducers. Stability analysis based on Lyapunov theory is also presented, to guarantee the closed loop stability. The high performance of the proposed control scheme under load disturbances and parameter uncertainties is also demonstrated via simulation examples.     

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.     

Decentralized model predictive‐based load‐frequency control in an interconnected power system concerning wind turbines

This paper presents a load‐frequency control (LFC) design using the model predictive control (MPC) technique in a multi‐area power system in the presence of wind turbines (WTs). In the studied system, the controller of each local area is designed independently such that the stability of the overall closed‐loop system is guaranteed. A frequency response model of the multi‐area power system including WTs is introduced, and physical constraints of the governors and turbines are considered. The model was employed in the MPC structures. Digital simulations for a two‐area power system are provided to validate the effectiveness of the proposed scheme. The results show that with the proposed MPC technique the overall closed‐loop system performance shows robustness in the face of uncertainties due to governor and turbine parameter variation and load disturbances. A performance comparison between the proposed controller with WTs and MPC without WTs and a classical integral control scheme is carried out, confirming the superiority of the proposed MPC technique with WTs. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

麻雀搜索算法的 PMSM 固定时间无模型滑模控制

针对永磁同步电机(permanent magnet synchronous motors, PMSM)调速系统的易受外部负载扰动的影响,提出了一种基于改进麻雀搜索算法的PMSM固定时间无模型滑模控制策略。在转速环输入输出超局部模型的基础上构建了固定时间滑模速度控制器,设计了固定时间扰动观测器估计超局部模型的未知扰动,并通过前馈补偿的方式削弱未知扰动对调速系统带来的不利影响,提高调速系统的抗干扰能力,利用李雅普诺夫函数证明了速度控制器和观测器的固定时间收敛性。由于控制器参数较多且会影响系统性能,为了准确获取参数,提出了改进的麻雀搜索算法对控制器的参数进行优化。实验结果显示,本文提出的控制方案与PI控制相比较,有效解决了超调问题,稳定时间加快了22.8%,加载时转速变化减少了75%,表明本文提出控制方案的有效性。     

Nonlinear reference tracking control of a gas turbine with load torque estimation

Input–output linearization‐based adaptive reference tracking control of a low‐power gas turbine model is presented in this paper. The gas turbine is described by a third‐order nonlinear input‐affine state‐space model, where the manipulable input is the fuel mass flowrate and the controlled output is the rotational speed. The stability of the one‐dimensional zero dynamics of the controlled plant is investigated via phase diagrams. The input–output linearizing feedback is extended with a load torque estimator algorithm resulting in an adaptive feedback scheme. The tuning of controller parameters is performed considering three main design goals: appropriate settling time, robustness against environmental disturbances and model parameter uncertainties, and avoiding the saturation of the actuator. Simulations show that the closed‐loop system is robust with respect to the variations in uncertain model and environ‐mental parameters and its performance satisfies the defined requirements. Copyright © 2007 John Wiley & Sons, Ltd.     

Sliding mode control with integral augmented sliding surface: design and experimental application to an electromechanical system

In this study, an integral augmented sliding mode control (SMC + I) has been proposed to improve control performance of systems. Stability of the closed-loop system is guaranteed in the sense of Lyapunov stability theorem. The effectiveness of the control solution is established by the stability analysis of the closed-loop system dynamics. The proposed controller is adopted to control speed of an electromechanical system. The experimental set-up reflects the emphasis on the practicability of the proposed sliding mode controller. The experimental results are presented and compared with the results obtained from conventional sliding mode control and Proportional + Integral + Derivative (PID) control. The experimental results verify that the proposed controller provides favorable tracking performance, faster and smoother speed regulation with regard to parameter variations and disturbances. The present study shows that the proposed controller, with its straightforward solution, is easily applicable to industrial problems and an alternative to conventional PID and sliding mode controllers.     

Adaptive under-voltage load shedding scheme using model predictive control

Recent system wide disturbances have demonstrated the need for automatic system protection schemes to prevent such cascading disturbances. In this paper, an adaptive under-voltage load shedding scheme using model predictive control is proposed to protect power system against voltage instability. The proposed scheme calculates the criticality of the system based on the measurements of voltage magnitudes and reactive power generations and then in case of voltage instability a model predictive based step-sized load shedding scheme will be triggered. The speed and amount of load shedding steps are adapted to the severity of contingency in the affected region. By devising the grid into the separate regions the proposed scheme acts as a distributed controller without having a central dispatching center. The performance of the proposed model predictive based scheme is verified over a 10-bus dynamic test case. The proposed model predictive control will be solved using sequential quadratic programming technique.     

基于模型参考神经网络的异步电机鲁棒速度控制方法

提出一种新型的基于模型参考神经网络的异步电机驱动系统鲁棒速度控制方法。由带负载转矩观测器的两层神经网络对象辨识器(NNPI)对未知的电机动态参数进行实时的自适应辨识与估计。由双层神经网络PI控制器(NNC)对异步电机转子速度进行鲁棒控制。神经网络使用学习算法以自动调节NNPIC的参数并有效地降低系统对参数变化以及负载扰动的敏感度。仿真结果表明该方法对于参数变化和负载转矩扰动具有很强的自适应能力,能够提高异步电机的性能,并减小其对参数变化、非线性影响以及负载扰动的敏感度。     

基于H∞/m方法的永磁直线同步电机鲁棒二自由度控制

针对永磁直线同步电机(PMLSM)直接驱动伺服系统易受负载扰动、测量噪声及参数变化影响的特点，基于H￥/m方法设计了一个鲁棒二自由度速度控制器，解决了传统单自由度控制器在满足系统跟踪性能和抗干扰性能要求方面存在的矛盾。由于在求解m控制器时应用了标准H￥控制理论，大大提高了m控制器的获得速度。该速度控制器克服了标准H￥控制器保守性的缺点，并且对负载扰动、测量噪声和参数不确定性等干扰的抑制方面也比标准H￥控制器更具鲁棒性。仿真结果及分析表明，所提基于H￥/m方法二自由度速度控制器，满足高精度永磁直线同步电机伺服系统对鲁棒性和快速性的要求。     

Precision motion control of a small launching platform with disturbance compensation using neural networks

A kind of launching platform driven by two permanent magnet synchronous motors which is used to launch kinetic load to hit the target always faces strong parameter uncertainties and strong external disturbance such as the air current impulsion which would degrade their tracking accuracy greatly. In this paper, a practical method which combines adaptive robust control with neural network‐based disturbance observer is proposed for high‐accuracy motion control of the launching platform. The proposed controller not only accounts for the parametric uncertainties but also takes the external disturbances into account. Adaptive control is designed to compensate the former, while neural network‐based disturbance observer is designed to compensate the latter respectively and both of them are integrated together via a feedforward cancellation technique. A new kind of parametric adaptation and weight adaptation strategy is designed by using the linear combination of the system's tracking error and the weight estimation error as a driving signal for parametric adaptation and disturbance approximation. The stability of the novel control scheme is analyzed via a Lyapunov method and this method presents a prescribed output tracking performance in the presence of both parameter uncertainties and unmodeled nonlinearities. Extensive comparative simulation and experimental results are obtained to verify the high‐performance of the proposed control strategy. Copyright © 2016 John Wiley & Sons, Ltd.     

基于滑模模糊方法的变速风电系统的最大风能捕捉控制器设计

针对具有不确定参数和强干扰的变速风力发电系统,提出一种积分滑模模糊自适应控制器。该控制策略基于带积分补偿的滑模控制器,并利用自适应模糊控制方法,把滑模控制器中的不确定项进行模糊逼近,同时对其中的切换项也进行模糊自适应逼近,从而有效降低变结构控制固有的抖振现象。利用李亚普诺夫函数证明了控制器的稳定性。采用此控制策略,对变速风力发电系统的风轮转速进行跟踪控制,仿真结果显示此控制方法具有较强的鲁棒性和良好的跟踪性能。     

Robust nonlinear controller based on control Lyapunov function and terminal sliding mode for buck converter

This paper studies the sliding mode control (SMC) and terminal SMC (TSMC) techniques of output voltage regulation in dc–dc buck converters. In this paper, the conventional terminal sliding manifold (TSM), fast terminal sliding manifold, and adaptive terminal sliding manifold are investigated by using hysteresis‐modulated control. In addition, proportional‐integral‐derivative‐shaped TSM, PI‐shaped TSM, and proportional‐integral‐derivative‐integral‐shaped TSM are proposed in order to overcome the problems of conventional TSMs. Furthermore, a new continuous controller based on control Lyapunov function (CLF), with pre‐settable‐fixed switching frequency, is suggested. CLF‐based controller (CLF‐bC) is also adapted to the discontinuous digital input of the buck converter. In the proposed CLF‐bC, the switching frequency is completely independent and pre‐settable. Stabilization, reference tracking, high performance dynamic response, robustness against parameter uncertainties, and rejection of disturbances (e.g., input voltage changes and load variations) are some advantages of the proposed controllers. Impact of the controllers' parameters on the performance of the system is also summarized. Finite‐time stability of TSMs and proposed CLF‐bC, and the robustness of CLF‐bC against parameter variations and disturbances are mathematically proved. Performance of the proposed Adaptive TSMC (ATSMC), proportional‐integral‐derivative‐TSMC, and CLF‐bC has been verified through matlab simulations and compared with the conventional SMC and TSMC strategies. Copyright © 2016 John Wiley & Sons, Ltd.     

直接驱动环形永磁力矩电机m-H∞速度控制器设计

针对直接驱动数控转台用环形永磁力矩电机易受负载扰动及参数变化影响的特点，将去除正交性假设的H∞控制器设计方法与m综合中的m-K迭代法相结合，设计了一个m-H∞速度控制器。除去正交性假设可以大幅度压缩m值上界，减少搜寻时间与范围。与纯H∞控制器相比，该速度控制器对负载扰动和参数不确定性更具鲁棒性，且控制器的获取也比m控制器快。仿真结果及分析表明，所提出的m-H∞速度控制器满足高精度直接驱动数控转台用环形永磁力矩电机伺服系统对鲁棒性和快速性的要求。     

基于遗传算法的永磁同步直线电机PID控制研究

由于永磁同步直线电机系统运行过程中参数摄动和负载扰动等问题的存在,传统 PID控制器无法满足高精度伺服控制系统的要求。设计出一种基于遗传算法(GA)优化的 PID 控制器,并通过 Simulink 对永磁同步直线电机控制系统进行建模和仿真实验。仿真和实验表明,采用 GA优化的PID控制器与传统的 PID控制器在指定速度和负载扰动条件下相比,具有更好的动态稳定性和跟踪性能,能有效抑制参数摄动的影响并对负载扰动具有较强的鲁棒性,实验结果也证明了方案的有效性和可行性。     

异步电机转动惯量在线辨识与自适应控制的研究

小型异步电机在应用中受电机参数及负载扰动的影响很大。本文提出了一种基于模型参考自适应理论的电机转动惯量辨识算法,以及一种基于系统频域分析的速度调节器自整定算法。仿真和实验证实了其有效性。     

为提高轮廓加工精度采用DOB和ZPETC的直线伺服鲁棒跟踪控制

为了提高轮廓加工精度,本文针对高精度直线伺服系统,提出了一种将零相位误差跟踪控制器(ZPETC)和干扰观测器(DOB)相结合的鲁棒跟踪控制策略.ZPETC作为前馈跟踪控制器,保证了快速性,使系统实现准确跟踪;基于DOB的鲁棒反馈控制器补偿了外部扰动、未建模动态、系统参数变化和机械非线性等,保证了系统的强鲁棒性能.仿真结果表明了所提出的控制方案是有效的,既能实现完好跟踪,又有较强的鲁棒性能.从而有效地减小了轮廓误差,提高了轮廓加工精度.     

Robust speed control method for dc servomotors using adaptive gain law

The speed control ability of dc servomotors is affected by parameter variations and disturbance torque. In this paper, a robust speed control method for dc servomotors with a disturbance torque observer and a feedback controller is proposed. The disturbance torque observer is used for the compensation of parameter variations and disturbance. The feedback gain is adjusted in the aspect of stability by an adaptive gain law based on Lyapunov's direct method and is used to restrain the influence of estimation error for the disturbance observer. A robust current control scheme for a voltage source PWM inverter with disturbance observer is also presented, since current control ability affects the control performance of dc servomotors. The validity of this control scheme is verified by numerical simulations and experiments. © 1999 Scripta Technica, Electr Eng Jpn, 126(3): 30–40, 1999     

Performance improvement of repetitive controlled PWM inverters: A phase‐lead compensation solution

The compensation of the phase lag plays an important role in the improvement of convergence rate, tracking accuracy, and robustness of repetitive controller. However, it is often difficult to compensate the system phase lag exactly due to variation of the load and unknown disturbances. An alternative way is to provide a simple but effective phase compensation to compensate the phase lag in a frequency band that contains the major tracking error components. With this motivation, a repetitive control scheme with a linear phase‐lead compensator is proposed and applied to the control of constant‐voltage constant‐frequency pulse‐width modulated DC–AC inverters. Detailed analysis of phase compensation on system stability is provided, and conditions for the design of phase compensation are derived. The experimental results under different loads and load changes show that the proposed scheme can achieve high tracking accuracy, low total harmonic distortion, and fast dynamic response. Copyright © 2008 John Wiley & Sons, Ltd.     

Mismatched disturbance attenuation control for static var compensator with uncertain parameters

The use of a static var compensator (SVC) as a component of flexible alternating current transmission system (FACTS) devices to control power systems has been investigated for decades. Its aim is to regulate the system voltage and improve the stability and loadability of power systems. A typical assumption in such a system is that the parameters of the controlled system are known accurately, which is rarely satisfied in practice. This paper explores the development of a simple but effective controller for a single-machine infinite-bus power system with SVC subjected to both matched and mismatched disturbances where the controller derivation is based on the assumption that all parameters used in the system modeling are unknown, but bounded in size. The research in this paper illustrates how an indirect robust control can be incorporated with a modified disturbance observer-based feedforward term to attenuate the influence of parameter variations and disturbances from the outputs of the system. Simulation results are presented to confirm the effectiveness of the proposed scheme.     

Robust decentralized neural networks based LFC in a deregulated power system

In this paper, a decentralized radial basis function neural network (RBFNN) based controller for load frequency control (LFC) in a deregulated power system is presented using the generalized model for LFC scheme according to the possible contracts. To achieve decentralization, the connections between each control area with the rest of system and effects of possible contracted scenarios are treated as a set of input disturbance signals. The idea of mixed H₂/H_∞ control technique is used for the training of the proposed controller. The motivation for using this control strategy for training the RBFNN based controller is to take large modeling uncertainties into account, cover physical constraints on control action and minimize the effects of area load disturbances. This newly developed design strategy combines the advantage of the neural networks and mixed H₂/H_∞ control techniques to provide robust performance and leads to a flexible controller with simple structure that is easy to implement. The effectiveness of the proposed method is demonstrated on a three-area restructured power system. The results of the proposed controllers are compared with the mixed H₂/H_∞ controllers for three scenarios of the possible contracts under large load demands and disturbances. The resulting controller is shown to minimize the effects of area load disturbances and maintain robust performance in the presence of plant parameter changes and system nonlinearities.