Dynamic feedback linearization of the induction motor

Dynamic state feedback is used to achieve feedback linearization of the induction motor. It is shown that the sixth-order nonlinear dynamical model of the induction motor consisting of rotor speed, two stator currents, two rotor fluxes and an integrator in the feedback controller can be made equivalent to two third-order decoupled linear systems by nonlinear state feedback through the stator input voltages. It is further shown that a nonsingular dynamic feedback linearizing transformation exists as long as the (electromagnetic) torque put out by the motor is nonzero     

A new non‐linear sliding‐mode torque and flux control method for an induction machine incorporating a sliding‐mode flux observer

In this paper a novel sliding‐mode control algorithm, based on the differential geometry state‐co‐ordinates transformation method, is proposed to control motor torque directly. Non‐linear feedback linearization theory is employed to decouple the control of rotor flux magnitude and motor torque. The advantages of this method are: (1) The rotor flux and the generated torque can be accurately controlled. (2) Robustness with respect to matched and mismatched uncertainties is obtained. Additionally, a varying continuous control term is proposed. As a result, chattering is eliminated without sacrificing robustness and precision. The control strategy is based on all motor states being available. In practice the rotor fluxes are not usually measurable, and a sliding‐mode observer is derived to estimate the rotor flux. The observer is designed to possess invariant dynamic modes which can be assigned independently to achieve the desired performance. Furthermore, it can be shown that the observer is robust against model uncertainties and measurement noise. Simulation and practical results are presented to confirm the characteristics of the proposed control law and rotor flux observer. Copyright © 2004 John Wiley & Sons, Ltd.     

A GLOBAL EXPONENTIAL OUTPUT‐FEEDBACK CONTROLLER FOR INDUCTION MOTORS

In this paper, we design an output‐feedback, rotor position/rotor flux controller for the full‐order, nonlinear dynamic model of an induction motor. The singularity free controller does not require measurement of rotor flux or rotor velocity and yields global exponential rotor position and rotor flux tracking. The proposed controller is termed output‐feedback due to the inexpensive/simplistic manner in which stator current measurements can be obtained (e.g., the most primitive method of measuring current can be achieved through simple voltage measurements across known resistive elements). Experimental results are included to verify the effectiveness of the proposed controller.     

Linearizing control of induction motor based on networked control systems

A new approach to speed control of induction motors is developed by introducing networked control systems （NCSs） into the induction motor driving system. The control strategy is to stabilize and track the rotor speed of the induction motor when the network time delay occurs in the transport medium of network data. First, a feedback linearization method is used to achieve input-output linearization and decoupling control of the induction motor driving system based on rotor flux model, and then the characteristic of network data is analyzed in terms of the inherent network time delay. A networked control model of an induction motor is established. The sufficient condition of asymptotic stability for the networked induction motor driving system is given, and the state feedback controller is obtained by solving the linear matrix inequalities （LMIs）. Simulation results verify the efficiency of the proposed scheme.     

基于定转子电阻误差补偿的感应电动机自适应逆解耦控制研究

对于具有多变量、非线性、强耦合、慢时变等特征的异步电动机调速系统, 实现定子磁链与电磁转矩的高精度动态解耦是提高系统性能的关键. 首先通过非线性状态反馈建立感应电动机的积分逆模型, 并在此基础上提出了一个基于定、转子电阻误差补偿的感应电动机自适应逆解耦控制方法, 将补偿后的积分逆模型串联到对象的输入端建立广义被控对象. 复杂的感应电动机调速系统被解耦成电磁转矩与定子磁链的两个独立回路, 利用线性系统理论分别对独立回路进行综合设计, 实现定子磁链和电磁转矩对各自给定值的渐近跟踪. 利用Matlab进行了仿真实验, 实验结果验证了建议方案的有效性和可行性.     

Robust output feedback learning control for induction motor servo drives

This paper addresses the output feedback tracking control problem for induction motor servo drives with mechanical uncertainties: rotor angle, rotor speed and stator currents are assumed to be available for feedback. A robust adaptive learning control is designed under the assumption that the reference profile for the rotor angle is periodic with known period: it ‘learns’ the periodic disturbance signal by identifying the Fourier coefficients of any truncated approximation; ??₂ and ??_∞ transient performances are guaranteed in the ‘learning phase’. It is shown that, for any motor initial condition belonging to an arbitrary given compact set, by properly setting the control parameters: (i) the rotor position and flux modulus tracking errors exponentially converge to residual sets, which may be arbitrarily reduced by increasing the number of terms in the truncated Fourier series; (ii) when the unknown periodic disturbance can be represented by a finite Fourier series, the rotor position and flux modulus tracking errors exponentially converge to zero. As in field oriented‐control, the control algorithm generates references for the magnetizing flux component and for the torque component of the stator current leading to significant simplifications for current‐fed motors. Copyright © 2008 John Wiley & Sons, Ltd.     

A differential-algebraic approach to speed estimation in an induction motor

This note considers a differential-algebraic approach to estimating the speed of an induction motor from the measured terminal voltages and currents. In particular, it is shown that the induction motor speed /spl omega/ satisfies both a second- and a third-order polynomial equation whose coefficients depend on the stator voltages, stator currents, and their derivatives. It is shown that as long as the stator electrical frequency is nonzero, the speed is uniquely determined by these polynomials. The speed so determined is then used to stabilize a dynamic (Luenberger type) observer to obtain a smoother speed estimate. With full knowledge of the machine parameters and filtering of the sensor noise, simulations indicate that this estimator has the potential to provide low speed (including zero speed) control of an induction motor under full rated load.     

Extended complex Kalman filter for sensorless control of an induction motor

This paper deals with the design of an extended complex Kalman filter (ECKF) for estimating the state of an induction motor (IM) model, and for sensorless control of systems employing this type of motor as an actuator. A complex-valued model is adopted that simultaneously allows a simpler observability analysis of the system and a more effective state estimation. The observability analysis of this model is first performed by assuming that a third order ECKF has to be designed, by neglecting the mechanical equation of the IM model, which is a valid hypothesis when the motor is operated at constant rotor speed. It is shown that this analysis is more effective and easier than the one performed on the corresponding real-valued model, as it allows the observability conditions to be directly obtained in terms of stator current and rotor flux complex-valued vectors. Necessary observability conditions are also obtained along with the well-known sufficient ones. It is also shown that the complex-valued implementation allows a reduction of 35% in the computation time w.r.t. the standard real-valued one, which is obtained thanks to the lower dimensions of the matrices of the ECKF w.r.t. the ones of the real-valued implementation and the fact that no matrix inversion is required. The effectiveness of the proposed ECKF is shown by means of simulation in Matlab/Simulink environment and through experiments on a real low-power drive.     

基于中立型系统理论的感应电机高精度磁链观测器研究

针对感应电机交流传动控制系统磁链观测模型不精确, 忽略控制中的延时问题, 转子磁链观测一般具有观测精度不高、易受电机参数变化影响等问题, 运用中立型理论, 建立中立型感应电机观测模型, 提出一种基于中立型的转子磁链观测方法, 设计了中立型转子磁链观测器.该磁链观测器具有观测精度高、受电机参数变化影响小、鲁棒性好的优点, 通过建立精确的观测模型, 解决控制中延时问题对磁链观测精度的影响.对感应电机中立型磁链观测模型进行了稳定性分析.仿真和实验结果证明了所设计中立型转子磁链观测器的可行性和有效性.     

感应电机二阶滑模次优算法定子磁链观测器设计

提出了基于二阶滑模次优算法的感应电机定子磁链观测方法,设计了定子磁链观测器,并应用到感应电机直接转矩控制中.本文设计的磁链观测器,通过准确的跟踪电流及其变化率,从而实现对转子磁链的准确估算,然后利用转子磁链与定子磁链的关系,估算出定子磁链.由于本文设计的定子磁链观测器是一个多输入多输出(MIMO)系统,稳定性分析非常复杂,为此将磁链估算误差的微分看作扰动处理,从而将MIMO的观测器模型分解成两个独立的单输入单输出(SISO)系统,简化了稳定性分析.将该观测器用于感应电机直接转矩控制中,达到了很好的控制效果.仿真和实验验证了该方法的有效性.     

Robust speed control of induction motors using position and currentmeasurements

A nonlinear robust output feedback control is designed for a sixth-order model of an induction motor. The control uses only measurement of the rotor position and stator currents. It contains two observers, a second-order observer to estimate the rotor flux from the stator current and a third-order high-gain observer to estimate the rotor speed and acceleration from its position. The control is robust to uncertainties in the rotor and stator resistances, and a bounded time-varying load torque. It guarantees that the speed tracking error can be made arbitrarily small by choice of certain design parameters. Moreover, when the speed reference and load torque are constant, it ensures asymptotic regulation. Simulation results agree well with the analysis     

一种用于异步电机矢量控制的新型滑模转子磁链观测器研究

针对异步电机矢量控制需要实现定、转子电路解耦的一个关键问题是准确地观测转子磁链.提出了一种以异步电机在两相同步旋转坐标系下的定子电流和转子磁链为状态变量的基于滑模变结构思想的转子磁链观测器,对滑模变结构输入控制信号的设计使得滑模运动速度与轨迹和滑模面的距离相关联,并利用李亚普诺夫理论证明了算法的收敛性.通过仿真表明,该方法具有较高的转子磁链观测准确度,对转子电阻的变化具有很强的鲁棒性,能够改善异步电机矢量控制调速系统的动静态性能.     

电机矢量控制按转子磁链定向的参数辨识方法

就异步电机旋转变换和转子磁链定向进行了分析,采用了同步旋转模型到按转予磁链定向的变换的方法,建立了新的电机旋转变换参数模型。由于这个模型包含了磁链定向的参数信息,利用该模型进行参数辨识通过计算可以得到固定的磁链定向角。分析变换和计算机仿真结果说明该方案是有效的,为交流异步电机矢量控制磁链定向实现提供了新的途径。     

一种无速度传感器矢量控制系统的研究

本文基于同步轴系下的感应电动机电压磁链方程式,提出了一种感应电动机转子磁场定向的矢量控制方法,利用在同步轴系中q轴电流的误差信号实现对电机速度的估算。在该无传感器矢量控制系统中,由于采用了经典的PI调节器,使得控制系统更为简单。最后利用MATLAB建立的该无传感器矢量控制系统的仿真模型,通过仿真验证了本文所提出的无传感器矢量控制系统具有良好的动态和静态性能。     

TORQUE AND FLUX TRACKING OF INDUCTION MOTORS

The problem of torque tracking and rotor flux norm regulation of induction motors perturbed by an unknown constant load torque was recently solved with an observer-based controller in Reference 5. In this paper we extend this result to treat the practically important case when the rotor flux norm is required to follow a time-varying reference. The controller design follows the passivity-based approach and proceeds in two steps: first, we define a target closed-loop dynamics compatible with the physical model of the motor that delivers the desired rotor flux and torque. Second, we propose a nonlinear dynamic output feedback controller that ensures this behaviour is asymptotically achieved. A proof of global tracking is given under the assumption of known motor parameters. Some key features of our physically based design are that the control law does not require measurement of rotor variables, is always well defined and does not rely on (intrinsically nonrobust) nonlinear dynamics cancellation. A corollary of our main result is the proof that a slight modification of the classical indirect field-oriented controller ensures global tracking for current-fed machines. © 1997 by John Wiley & Sons, Ltd.     

An output feedback globally stable controller for induction motors

We present a globally stable nonlinear dynamic output feedback controller for torque tracking and flux regulation of induction motors. The control law is globally defined, requires only measurement of stator variables and rotor speed, and does not rely on cancellation of the systems nonlinearities. Our work extends the result of the paper by Ortega et al.(1993), where the torque tracking problem was solved for a model and the variables are expressed in a frame rotating at an arbitrary angular frequency (dq model). First, we obviate the need to transfer the dq control signals of the paper by Ortega et al., to the physical input variables in the stator frame, hence providing a directly implementable control law. Second, besides the torque tracking objective, we include the practically important rotor flux regulation task. Third, by choosing a more suitable representation of the motor model, we simplify the controller structure and provide a better understanding of its derivation and behavior     

考虑转子磁链动态性的感应电机解耦控制

采用矢量控制的感应电机在高速运转时,d-q轴之间的电流耦合会削弱转矩控制效果;在采用反馈解耦和前馈解耦进行控制时,去耦控制效果受到电机参数估计误差的影响;该文在交流电机转子磁场定向控制的基础上,考虑到转子磁链的动态性,根据控制理论的不变性原理,把电机给定量和反馈量的偏差用于解耦项的计算,提出一种偏差解耦控制方法用于感应电机的转矩控制,并对算法进行了推导;对几种解耦方式和影响解耦的因素进行了探讨;通过计算机仿真对解耦效果进行了比较,仿真结果表明所提方法具有良好的控制效果。     

基于无源性的异步机自适应控制

对近年来出现的一种异步机控制方法--基于无源性的控制(简称PBC)进行了发 展,从理论上取消了对定子电流反馈的要求,并针对转子电阻变化,增加了参数自调整的自 适应控制和转子磁链闭环控制.该控制器保留了PBC方法的简单、无奇异点等优点,而且抑 制了由于转子电阻变化引起的转速和磁链跟踪误差.     

一种改进磁链计算模型分析

准确获取异步电动机转子磁链信号在高性能电机控制系统中具有十分重要的意义。介绍了常用转子磁链计算的电压和电流模型,针对各自存在的部分问题,提出了一种基于磁链计算方程进行组合的改进计算模型。在此基础上,根据矢量控制理论,采用Matlab／Simulink软件设计了异步电机矢量控制系统。仿真结果表明了该理论的正确性和可行性。     

五自由度无轴承异步电机α-阶逆系统解耦控制

A 5-degrees-of-freedom bearingless induction motor is a multi-variable, nonlinear and strong-coupled system. In order to achieve rotor suspension and operation steadily, it is necessary to realize dynamic decoupling control among torque and suspension forces. In the paper, a method based on α-th order inverse system theory is used to study dynamic decoupling control. Firstly, the working principles of a 3-degrses-of-frsedom magnetic bearing and a 2-degrees-of-freedom bearingiess induction motor are analyzed,the radial-axial force equations of 3-degrees-of-freedom magnetic bearing, the electromagnetic torque equation and radial force equations of the 2-degrees-of-freedom bearingless induction motor are given, and then the state equatious of the 5-degrees-of-freedom bearingless induction motor are set up. Secondly, the feasibility of decoupling control based on dynamic inverse theory is discussed in detail, and the state feedback linearization method is used to decouple and linearize the system. Finally, linear control system techniques are applied to these linearization subsystems to synthesize and simulate. The simulation results have shown that this kind of control strategy can realize dynamic decoupling control among torque and suspeusion forces of the 5-degrees-of-freedom bearingless induction motor, and that the control system has good dynamic and static performance.