Global adaptive output feedback control of induction motors withuncertain rotor resistance

The authors design a global adaptive output feedback control for a fifth-order model of induction motors, which guarantees asymptotic tracking of smooth speed references on the basis of speed and stator current measurements, for any initial condition and for any unknown constant value of torque load and rotor resistance. The proposed seventh-order nonlinear compensator generates estimates both for the unknown parameters (torque load and rotor resistance) and for the unmeasured state variables (rotor flux); they converge to the corresponding true values under persistency of excitation which actually holds in typical operating conditions. The control algorithm generates references for the magnetizing flux component and for the torque component of stator current which lead to significant simplification for current-fed motors. Simulations show that the proposed controller is suitable for high dynamic performance applications     

多机传动机械系统的同步控制

本文提出通过磁场定向控制分别控制多个感应电动机跟踪同一个指令性速度的多机驱动机械系统的同步控制方案,通过建立全维转子状态估计器,辩识感应电动机的转子速度,定子和转子电阻,瞬时外负载,根据外负载辩识结果与速度ＰＩＤ控制器确定感应电动机的转矩电流,实现感应电动机的无速度传感器控制,计算机仿真结果表明了该控制方案的有效性。     

Further results on nonlinear tracking control and parameter estimation for induction motors

The original contribution of this paper, which concerns induction motors with uncertain constant load torque and rotor/stator resistances, is twofold. The first innovative contribution relies on the experimental analysis of the latest theoretically-based sensorless/output feedback solutions to the problem of tracking rotor speed and flux modulus reference signals with the simultaneous estimation of the uncertain parameters. The second novel contribution is constituted by the proof of existence for a new adaptive local flux observer from rotor speed and stator currents/voltages, which, in its full-order or reduced-order-like versions, involves neither over-parameterizations nor non-a priori verifiable first order stator resistance identifiability conditions at steady-state.     

A rotor speed estimation algorithm in variable speed permanent magnet synchronous generator wind energy conversion system

A rotor speed estimation algorithm in a direct vector controlled permanent magnet synchronous generator wind energy conversion system is proposed. The proposed method is based on a simple equation obtained from the flux model of the machine and contains only stator flux and current. Constant gain recursive least squares estimator is used for implementing the speed estimation algorithm. Rotor position information used for coordinate transformation is computed using the estimated speed. Stator flux information required by the speed estimator is obtained using the stator voltage equation by implementing a programmable low pass filter. The estimated speed is used as the feedback signal for the speed control loop of the vector controlled machine side converter control system whose command speed is obtained from a wind speed sensorless maximum power point tracking controller, thus, we obtain a complete rotor speed and wind speed sensorless permanent magnet synchronous generator wind energy conversion system. Simulation is carried out to validate the performance of the proposed method. Copyright © 2012 John Wiley & Sons, Ltd.     

基于EKF和SMC的永磁同步电机无传感器矢量控制

采用扩展卡尔曼滤波(EKF)算法估计永磁同步电机(PMSM)转速和转子位置,构成转速、电流双闭环的无传感器矢量控制系统.针对扩展卡尔曼滤波为有偏估计、对模型误差鲁棒性差等问题,提出了基于指数趋近律的滑模转速控制器.为提高转速环抗负载转矩扰动能力,设计负载转矩观测器并将观测结果引入到电流控制器的输入端,作为速度控制器前馈补偿的控制输入.仿真实验结果表明,与传统采用PI(proportional-integral)转速控制器的系统相比,文中所提控制策略具有转速跟踪误差小、响应快、无超调、抗负载扰动能力强等优点.     

利用插入高频电流进行异步机转速辨识方法的研究

本文描述了一种异步电动机无速度传减速矢量控制系统转速辨识的新方法,它利用在ｄ轴插入的高频电流在矢量控制未完全解耦时产生的转矩纹波,估算转子磁链角速度。     

An adaptive tracking control from current measurements for induction motors with uncertain load torque and rotor resistance

The problem of controlling sensorless induction motors with uncertain constant load torque and rotor resistance on the basis of stator current measurements only is addressed. A new eighth-order dynamic nonlinear adaptive control algorithm is designed, which relies on a closed loop adaptive observer for the unmeasured state variables (rotor speed and fluxes) and for the uncertain parameters and is not based on non-robust open loop integration of flux dynamics. Local exponential stability of the closed loop tracking and estimation error dynamics is achieved under persistency of excitation conditions which restrict the reference signals and may be interpreted in terms of motor observability and rotor resistance identifiability.     

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.     

Nonlinear predictive controller for a permanent magnet synchronous motor drive

A nonlinear predictive controller (NPC) for a permanent magnet synchronous motor (PMSM) is proposed in this paper. Its objective is high performance tracking of the rotor speed trajectory while maintaining the d-axis component of the armature current at zero. The load torque and the mismatched parameters are considered to be unknown perturbations. To ensure robustness against these perturbations, a disturbance observer is designed using a new gain function, and integrated into the control law. The combination of the nonlinear predictive controller and the disturbance observer works as a nonlinear controller. The overall closed-loop system is proved to be globally asymptotically stable depending on the design parameters. The validity of the proposed controller was tested by simulations. Satisfactory results were obtained with respect to the tracking of the speed trajectory and disturbance rejection.     

A Robust Backstepping Sensorless Control for Interior Permanent Magnet Synchronous Motor Using a Super‐Twisting Based Torque Observer

In order to achieve high‐performance speed regulation for sensorless interior permanent magnet synchronous motors (IPMSMS), a robust backstepping sensorless control is presented in this paper. Firstly, instead of a real mechanical sensor, a robust terminal sliding mode observer is used to provide the rotor position. Then, a new super‐twisting algorithm (STA) based observer is designed to obtain estimates of load torque and speed. The proposed observer ensures finite‐time convergence, maintains robust to uncertainties, and eliminates the common assumption of constant or piece‐wise constant load torque. Finally, a sensorless scheme is designed to realize speed control despite parameter uncertainties, by combining the robust backstepping control with sliding mode actions and the presented sliding mode observers. The stability of the observer and controller are verified by using Lyapunov's second method to determine the design gains. Simulation results show the effectiveness of the proposed approach.     

An asymptotically stable sensorless speed controller for non‐salient permanent magnet synchronous motors

A solution to the longstanding problem of sensorless control of an electrical machine is provided in this paper. That is, the construction of an asymptotically stable controller that regulates the mechanical speed of the motor, measuring only the electrical coordinates. The result is presented for a non‐salient permanent magnet synchronous motor perturbed by an unknown constant load torque. The proposed scheme is a fourth order nonlinear observer‐based controller that does not rely on—intrinsically nonrobust—operations like open‐loop integration of the systems dynamical model nor signal differentiation and can be easily implemented in real time. The controller is easy to commission, with the tuning gains directly determining the convergence rates of the position, speed, and load torque observers. Simulation and experimental results are presented. In particular, a comparison with a sensorless field‐oriented controller, recently proposed in the drives literature, is carried out. Copyright © 2012 John Wiley & Sons, Ltd.     

Sensorless fault tolerant control for induction motors

In this paper, a sensorless fault tolerant controller for induction motors is developed. In the proposed approach, a robust controller based on backstepping strategy is designed in order to compensate for both the load torque disturbance and the rotor resistance variation caused by the broken rotor bars faults. The proposed approach needs neither fault detection and isolation schemes nor controller re-design. Moreover, to avoid the use of speed and flux sensors, a second order sliding mode observer is introduced to estimate the flux and the speed. The observer converges in a finite time and leads to good estimates of the flux and the speed even in the presence of the rotor resistance variation and the load torque disturbance. Since the observer converges in the finite time, the stability of the closed-loop system (controller with observer) is shown in two steps. First, the boundedness of the closed-loop system trajectories before the convergence of the observer is proved. Second, the convergence of the closed-loop system trajectories is proved after the convergence of the observer. To highlight the efficiency and applicability of the proposed control scheme, simulation and experimental results are conducted for a 1.5 kW induction motor.     

感应电动机的无速度传感控制

提出了一种简洁快速的感应电动机的无速度传感控制方法. 该方法利用一种新型的观测器获得精确的速度与磁通的模的估计, 然后设计了二阶控制器. 在不考虑同步转速为零且负载转矩不可测的个别工程条件下, 证明了该方法能够全局稳定的跟踪转子的给定参考速度和参考磁通. 数值仿真进一步验证了所提出控制方法的有效性.     

Adaptive speed control for induction motors based on a semi-current-fed model

This paper presents a semi-current-fed concept and a virtual desired variable synthesis for induction motor control. First, the traditional ideal current-loop assumption is relaxed. The relaxed assumption, considering more practical situations, allows a bounded stator voltage and a finite absolute-integral of current tracking error. From this novel concept, a semi-current-fed model for induction motors is used for the design. Both unknown rotor resistance and torque load are considered along with immeasurable rotor flux. To cope with the problems, we use a virtual desired variable approach to synthesize the control law. In the absence of a flux sensor and not using a flux observer, the asymptotic speed tracking is ensured without needing the persistent excitation condition. However, if the controlled system is persistently excited, an optimal torque control is additionally achieved. In addition to the theoretical proof, experimental results show the expected tracking performance.     

三维多层仿形织造过程多机协同智能控制技术

三维多层仿形织造过程多机同步协同控制是其关键技术之一。本文通过对三维多层仿形织造工艺技术的研究,依据磁场磁链定向控制作用机理,提出了一种对磁场磁链定向和变力矩控制的方法,来分别对多个感应电动机进行速度和力矩跟踪智能控制。依据控制方法,通过建立全维转子状态估计器,来辨识感应电动机的转子速度、定子和转子电阻、瞬时外负载等参数。由外负载辨识结果与速度、力矩PID控制器来确定感应电动机的转矩电流,实现感应电动机速度与力矩控制。仿真实验与三维多层仿形织造工程试验结果表明了该智能控制方法的先进性和实用性。     

磁链跟踪PWM感应电机矢量控制系统

PWM调制方式及控制器参数对感应电机矢量控制系统性能有较大影响,使电机在低速时电流脉动和转矩脉动较大。以磁链、转矩闭环的电机矢量控制方法为基础,提出了磁链跟踪控制(Space Vector PWM,SVPWM)的感应电机矢量控制系统仿真模型及低速变控制器参数的控制方法,高度模拟实际系统,并考虑逆变器死区时间的影响,在不同的调速范围下,进行了系统性能分析。在转子磁链定向准确,转子磁链构造准确的前提下,仿真结果表明磁链跟踪控制的矢量控制系统跟踪磁链为准圆形,在低速下,电机电流脉动和转矩脉动都比较小,使系统能够稳定运行,对于解决感应电机高性能调速的低速问题给出了可行的途径。     

A globally stable discrete-time controller for current-fed induction motors

In this short paper we present a discrete-time field oriented controller (FOC) for current-fed induction motors which insures global asymptotic speed regulation as well as rotor flux norm tracking. To the best of our knowledge, this is the first time such a result is rigorously established for a controller implemented in discrete-time. To insure global stability a condition on the reference for the rotor flux norm, which is time-varying, is imposed. This condition disappears as the sampling period goes to zero, hence allowing for independent speed regulation and rotor flux norm tracking. One important feature of our scheme is that, compared with the first-difference approximation of the classical indirect FOC, the additional computational burden is negligible. It is also shown that the result can easily be extended to the case of tracking time-varying references in speed or position.     

异步电机的非线性自适应反步控制器设计

针对描述异步电机的动态特性方程,在一些系统参数未知的情况下,应用分离子系统的方法和反向递推技术,设计了非线性自适应控制器.实现了电机对给定转速信号和磁通量信号的输出渐近跟踪控制,保证了整个系统的全局有界稳定性.仿真结果验证了该自适应控制策略的有效性.     

Hybrid control for speed sensorless induction motor drive

The dynamic response of a hybrid-controlled speed sensorless induction motor (IM) drive is introduced. First, an adaptive observation system, which comprises speed and flux observers, is derived on the basis of model reference adaptive system (MRAS) theory. The speed observation system is implemented using a digital signal processor (DSP) with a high sampling rate to make it possible to achieve good dynamics. Next, based on the principle of computed torque control, a computed torque controller using the estimated speed signal is developed. Moreover, to relax the requirement of the lumped uncertainty in the design of a computed torque controller, a recurrent fuzzy neural network (RFNN) uncertainty observer is utilized to adapt the lumped uncertainty online. Furthermore, based on Lyapunov stability a hybrid control system, which combines the computed torque controller, the RFNN uncertainty observer and a compensated controller, is proposed to control the rotor speed of the sensorless IM drive. The computed torque controller with RFNN uncertainty observer is the main tracking controller and the compensated controller is designed to compensate the minimum approximation error of the uncertainty observer instead of increasing the rules of the RFNN. Finally, the effectiveness of the proposed observation and control systems is verified by simulated and experimental results     

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