Robust nonlinear receding-horizon control of induction motors

Nonlinear robust receding-horizon control is designed and applied to fifth-order model of induction motor in cascade structure. The controller is based on a finite horizon continuous time minimization of the predicted tracking errors and no online optimization is needed. The initial system is decomposed into two sub-systems (mechanical and electromagnetic sub-systems) in cascade form. An integral action is incorporated in external loop to increase the robustness of the controller with respect to unknown time-varying load torque and mechanical parameters uncertainties. The control uses only measurement of the rotor speed and stator currents. The rotor flux is estimated by Kalman filter. The proposed nonlinear controller permits to achieve asymptotic speed and flux tracking in presence of mechanical parameters uncertainties, unknown variable load torque and resistances variations. In addition, it assures asymptotic decoupling of the speed and flux subsystems. The controller is applied, via simulation, to a benchmark example.     

感应电动机系统的变结构反推控制研究

感应电动机系统的矢量控制为了进行电流(或电压)的3/2(或2/3)坐标变换需要进行转子转差或磁链角的计算，转子转差的计算容易受转子电阻变化的影响，而磁链角的直接计算容易受定子电阻变化的影响，因此避免转子转差或磁链角的计算对于感应电动机系统的控制是非常有意义的。文中把变结构反推控制运用于感应电动机系统的转矩和磁链控制，设计方法避开了转子转差或转子磁链角的计算，通过一定的坐标变换，基于定子侧的静止坐标系实现转矩和磁链的解耦控制。变结构反推控制设计能够实现快速的速度、转矩和磁链的渐近跟踪，同时系统控制器能够保证系统性能在电动机参数和外部负载变化时具有强的鲁棒性，通过Matlab仿真验证了系统设计的有效性和可行性。     

Adaptive non-linear speed control of induction motors

In this paper we present two adaptive non-linear speed control algorithms for induction motors. They employ input-output linearization techniques for the motor model in the stator fixed reference frame. The first control algorithm directly tracks speed and rotor flux. The second is designed using torque and rotor flux tracking and is extended for speed control. A key point is that this algorithm ensures exact current limitation in the known parameter case. The adaptation based on Lyapunov design can cope with rotor and stator resistance variations. Significant simulations using sampled controllers are presented emphasizing adaptation and current limitation effects.     

直接转矩控制永磁同步发电机相位自校正型定子磁链观测器

直接转矩控制永磁同步发电具有电磁转矩和直流电压输出动态响应快等优点,但这些优点的实现需要准确的定子磁链。实际发电机参数在一定范围内随工作点变化而变化,这就要求定子磁链观测器对这些参数变化具有很强的鲁棒抑制特性。该文提出一种新型定子磁链观测器,该观测器借助有效磁链概念计算出转子磁极位置角观测值,基于此将定子磁链电压模型和电流模型联系起来,无需转子速度信息;为了进一步降低观测的定子磁链相位误差,将观测的定子电流矢量与实际定子电流矢量乘积结果送给PI调节器,利用PI输出值对转子位置角观测值进行校正。实验结果表明,采用该文提出的定子磁链观测器在无需转子速度及参数辨识情况下,对电机参数变化及模拟量采样误差具有很强的鲁棒抑制特性,可以获得准确的磁链观测值,实现电磁转矩和直流发电电压的快速而平稳控制。     

Robust sliding mode control and flux observer for induction motor using singular perturbation

This paper proposes a sequential methodology for designing a robust adaptive sliding mode observer for an induction motor drive using a two-time-scale approach. This approach is based on the singular perturbation theory. The two-time-scale decomposition of the original system of the observer error dynamics into separate slow and fast subsystems permits a simple design and sequential determination of the observer gains. In the proposed method, the stator currents and rotor flux are observed on the stationary reference frame using the sliding mode concept. The control algorithm is based on the indirect field oriented sliding mode control with an on-line adaptation of the rotor resistance to keep the machine field oriented. The control–observer scheme seeks to provide an asymptotic tracking of speed and rotor flux in spite of the presence of an uncertain load torque and an unknown value of rotor resistance. The validity for practical implementation has been verified through computer simulations.     

Adaptive control for speed‐sensorless induction motors with uncertain load torque and rotor resistance

The problem of controlling a speed‐sensorless induction motor is addressed. Smooth reference signals for rotor speed and flux modulus are required to be tracked for any unknown constant values of load torque and rotor resistance within known bounds. A fourth order non‐linear adaptive tracking control is presented which is based on a novel rotor speed observer and on two identifiers for the uncertain parameters; it guarantees asymptotic rotor speed tracking and exponential rotor flux modulus tracking with an explicitly computed domain of attraction. The closed‐loop performances are illustrated by simulation. Copyright © 2005 John Wiley & Sons, Ltd.     

基于模型参考自适应律的无速度传感器交流异步电动机矢量控制仿真

针对异步电动机矢量控制中对定子电阻和转子时间常数等参数的依赖性,设计了一种基于模型参考自适应律(MRAS)的参数辨识器。该辨识器同时还可以观测定子磁链及转子速度,并以此为基础,利用MATLAB/Simulink构建了以定子磁场定向的无速度传感器矢量控制系统。仿真结果表明:该方法实时辨识电机参数的变化,提高了控制系统的准确性和鲁棒性。     

基于模型参考自适应律的无速度传感器交流异步电动机矢量控制仿真

针对异步电动机矢量控制中对定子电阻和转子时问常数等参数的依赖性，设计了一种基于模型参考自适应律（MRAS）的参数辨识器。该辨识器同时还可以观测定子磁链及转子速度，并以此为基础，利用MATLAB／Simulink构建了以定子磁场定向的无速度传感器矢量控制系统。仿真结果表明：该方法实时辨识电机参数的变化，提高了控制系统的准确性和鲁棒性。     

Identification of the machine parameters in a vector-controlledinduction motor drive

High dynamic performance of pulse-width-modulated (PWM) inverter-fed induction motor drives was achieved by using the method of field-oriented control. This method requires the actual value of the rotor time constant as essential system information, based on how the magnitude and the position of the rotor flux are calculated. An online identification technique for the rotor time constant and for other machine parameters is described. The identification is based on an evaluation of the stator current trajectory, which is the dynamic response of the induction motor to the PWM-switching sequence. An analytical machine model is operated in parallel to the actual machine, having the stator voltages and the mechanical speed of the induction motor as input signals. The coincidence of the two stator current trajectories of the model and the machine serves as an error indicator for the parameter identification scheme, permitting repetitive updates of the model parameters     

基于精确线性化解耦的永磁同步电机空间矢量调制系统

从永磁同步电机的定子磁链模型出发，应用精确线性化理论，实现永磁同步电机输入输出线性化与解耦。将永磁同步电机动态解耦成二阶线性转速子系统和一阶线性磁链子系统，结合磁链扇区判断方法和线性化解耦后的实际系统输入来确定目标空间电压矢量，实现了永磁同步电机调速系统的转速和磁链动态解耦控制。仿真和实验结果表明，基于精确线性化解耦的永磁同步电机空间矢量调制系统具有理想的速度跟踪性、良好的鲁棒性和低速性。     

基于定子电流矢量定向的异步电机转子磁链估计器及其应用研究

异步电机矢量控制的关键问题在于精确地估计转子磁链。然而，传统的磁链估计器的精度会因定子或转子电阻的摄动而降低。文中提出了一种基于定子电流矢量定向的转子磁链估计器。该新型估计器不包含定转子电阻，可以避免电阻参数摄动对估计精度的影响。开环和闭环的仿真结果表明，该估计器具有相当高的精度，并且在定转子电阻大幅度摄动时，估计结果几乎不受影响，显示出比传统的磁链估计器更强的抗扰动能力。     

Online tuning method of stator and rotor resistances in both motoring and regenerating operations for vector‐controlled induction machines

The vector control of induction motors is widely used. This method needs accurate motor parameter but the stator and rotor resistance vary due to motor temperature variation. If the value of resistance in the controller can be set up accurately at first, there must be a difference between the reference and real value of torque because of drift of the resistance. It is necessary to adapt the resistance value. The indirect field‐oriented control of an induction motor requires the value of rotor resistance only, but the direct field‐oriented control method with rotor flux observer requires the value of not only rotor resistance but also stator resistance in the controller. Consequently, it is necessary to adapt both stator resistance and rotor resistance. A parameter adaptation scheme has previously been proposed for the direct field‐oriented control method with rotor flux observer, but this method cannot be used when the motor is in regenerating operation. In this paper, a new stator and rotor resistance adaptation scheme is proposed, which can be applied when the motor is in regenerating operation. The usefulness of the proposed adaptation scheme is confirmed by simulation. © 2001 Scripta Technica, Electr Eng Jpn, 135(1): 56–64, 2001     

基于区域极点配置理论的定子磁链全阶观测器

以定子电流和定子磁链为状态变量,设计了一个定子磁链观测器。为了克服定、转子电阻和转速变化对观测测性能的不良影响,基于区域极点配置理论,根据实际工程需要构造具有一定自由度观测器的增益矩阵,使得对电机定转子电阻变化、转速变化等不确定性,观测器系统矩阵的极点都被配置到指定的稳定区域内。为了验证方案的有效性,进行了仿真研究,仿真结果表明磁链观测器对电机本身的参数不确定性、负载突变和转速突变都具有较强的鲁棒性。     

Adaptive sliding mode observer for induction motor using two-time-scale approach

This paper presents an original method for the design of a robust adaptive sliding mode current and flux observer for induction motor drive using two-time-scale approach. This approach, based on the singular perturbation theory, decomposes the original system of the observer error dynamics into separate slow and fast subsystems of lower dimensions and permits a simple design and sequential determination of the observer gains. For the proposed observer, the rotor speed signal is assumed to be available. The stator currents and rotor flux are observed on the stationary reference frame using sliding mode concept, and the adaptive rotor time-constant is derived from Lyapunov stability theory using measured and estimated currents and estimated rotor flux. The control algorithm is based on the indirect field-oriented sliding mode control to keep the machine field oriented. The control-observer scheme seeks to provide asymptotic tracking of speed and rotor flux in spite of the presence of an uncertain load torque and unknown value of the rotor resistance. The effectiveness of this control algorithm has been successfully verified through computer simulations.     

Nonlinear adaptive state-feedback speed control of a voltage-fed induction motor with varying parameters

An adaptive nonlinear-state-feedback speed control scheme of a voltage-fed induction motor has been developed in which the control of torque and flux is decoupled. The inputs to the control algorithm are the reference speed, the reference flux, the measured stator currents, the measured rotor speed, the estimated rotor flux, and estimates of the rotor resistance, stator resistance, and load torque, which may vary during operation. The controller outputs are the reference stator voltages in rotor-flux rotating reference frame. An accurate knowledge of the rotor flux and machine parameters is the key factor in obtaining a high-performance and high-efficiency induction-motor drive. The rotor flux is estimated using the induction-motor rotor-circuit model. Although the estimated rotor flux is insensitive to the stator-resistance variation, it does depend on the rotor resistance. A stable model reference adaptive system (MRAS) rotor-resistance estimator insensitive to stator-resistance variation has been designed. Stable stator-resistance and load-torque MRAS estimators have also been developed. These estimators have been developed to constitute a multi-input-multi-output (MIMO) decoupled-cascade structure control system. This simplifies the design problem of the estimators for a stable operation from a MIMO design problem to a single-input-single-output (SISO) design problem. The continuous adaptive update of the machine parameters and load torque ensures accurate flux estimation and high-performance operation. Simulation and experimental results are presented to verify the stability of the induction-motor drive in various operating modes.     

A nonlinear tracking control for sensorless induction motors with uncertain load torque

We propose a novel nonlinear tracking control algorithm for induction motors with uncertain load torque in which only stator currents are used for feedback: rotor speed and flux sensors are not required; no open‐loop integration of flux dynamics is used. For a class of reference signals, for sufficiently small computable time‐varying load torque uncertainty and for any initial condition belonging to an explicitly computed region, closed‐loop boundedness is guaranteed while, under persistency of excitation, local exponential rotor speed and flux modulus tracking are achieved in the case of constant load torque. Copyright © 2007 John Wiley & Sons, Ltd.     

Global adaptive linear control of the permanent‐magnet synchronous motor

We contribute with a linear time‐varying controller for the permanent magnet synchronous motor. We solve the open problem of speed‐tracking control by measuring only stator currents and the rotor angular positions, under parametric uncertainty. Integral action is used to compensate for the effects of the unknown load‐torque, and adaptation is employed to estimate the unknown parameters. In the case that parameters are known (except for the load), we show that the origin of the closed‐loop system is uniformly globally exponentially stable. For the case of unknown parameters, we prove uniform global asymptotic stability; hence, we establish parametric convergence. In contrast to other adaptive control schemes for electrical machines, we use a reduced‐order adaptive controller. Indeed, adaptation is used only for the electrical dynamics equations. Moreover, not surprisingly, the closed‐loop system has a structure well‐studied in adaptive‐control literature. Performance is illustrated in a numerical setting. Copyright © 2013 John Wiley & Sons, Ltd.     

High-quality torque control at zero and very high speed operation

This article focuses on the design and analysis of a direct field orientation (DFO) approach based upon a closed-loop loop rotor flux observer. The approach is ideally suited for applications requiring both zero and very high (i.e., several times base) speed operation. Such applications are common in manufacturing automation where both zero speed position control and high traverse rates with controlled position trajectories are required. Examples include robot motion control systems as used for assembly and the more traditional machining center axis control. The quality of the proposed approach is largely based on the unique structure of its flux observer. The observer effectively combines the best accuracy attributes of rotor flux indirect (feedforward) field orientation (IFO) and stator flux DFO. The parameter sensitivity is similar to IFO at low and zero speeds and to stator flux DFO at high speeds. The closed-loop structure of the observer provides a smooth transition between two open-loop rotor flux observers referred to as the current and voltage models in a deterministic manner set by the closed-loop bandwidth (eigenvalues). The proposed DFO approach is analytically evaluated in comparison with both IFO and stator flux DFO. Experimental results verify the viability of this approach     

感应电机无源性分析及自适应控制

感应电机由于其变量非线性耦合、转子电量难以测量、电机参数时变性这3方面的问题，导致交流调速控制复杂。无源性控制理论应用于感应电机控制是一种全新的方法，其控制律是全局定义的，无输入输出线性化解耦奇点问题，是间接磁场定向控制。证明了感应电机转子磁链子系统的无源性，找到系统能量耗散特性方程中的无功力，它不会影响系统的稳定性，得出无需转子磁链观测反馈即能稳定跟踪转子磁链的参考值，同时考虑电机转子电阻在运行中发生未知变化，设计自适应调节器使系统对转子电阻呈现鲁棒性，构建了带电流内环速度控制系统。该方案保证转矩、转子磁链及转速的渐进跟踪，使调速系统具有良好的动静态性能，易于实现。仿真验证了设计的控制系统的有效性和先进性。     

A robust air‐gap flux estimation for speed sensorless vector control of double‐star induction machine

The paper presents a new direct field‐oriented control (DFOC) for double‐star induction machine (DSIM) drives using the stator currents. First, we propose a new algorithm to estimate air‐gap flux for speed sensorless air‐gap flux orientation control. Compared to the previous DFOC schemes the new one is independent from any motor parameter variation, specially on the stator resistance. Then, the DFOC is associated with a low pass filter (LPF) to solve the dc drift problems caused by the pure integration of air‐gap flux. In the present paper, the rotor resistance is estimated by an algorithm using Lyapunov theory. Good results have been obtained in the benchmark simulations. Copyright © 2004 John Wiley & Sons, Ltd.