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.     

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     

A nonlinear tracking control for sensorless induction motors

We propose a novel tracking control for induction motors in which only stator currents are used for feedback. Local exponential rotor speed and flux modulus tracking are achieved for any constant reference value and for restricted time-varying reference signals; any known motor parameters values (including constant load torque) and any initial condition, including rotor speed and fluxes, belonging to an explicitly computed domain of attraction are allowed.     

A semiglobally stable adaptive field-oriented controller for current-fed induction motors

In this short paper we propose a procedure to adjust on-line the rotor time constant estimate of an indirect field-oriented control law for current-fed induction machines. The resulting scheme is shown to be semiglobally exponentially stable provided the load torque on the motor is zero and the a priori uncertainty on the range of variation of the rotor time constant is smaller than 100%. The latter is a reasonable assumption in many practical cases. We also show that, when the load torque is different from zero, the speed error enters in finite time a residual set whose size is proportional to the load torque.     

Automatic differentiation and nonlinear controller design by exact linearization

Various modern algorithms for controller design are based on differential-geometric concepts. A method of particular importance is called exact linearization via feedback. In this case, the implementation of the controller requires the computation of Lie derivatives, which have been computed symbolically. This can be very time consuming. We present a new computation method relying on automatic differentiation.     

A new nonlinear multivariable control strategy of induction motors

A new real-time control strategy for induction motors is introduced. This paper shows that rotor speed and rotor flux magnitude reference tracking of an induction machine can be originally obtained. The proposed control law is based on two points: an open-loop reference control which allows to obtain perfect tracking since outputs are planned and on a closed-loop strategy based on PI controllers for the stabilization around the desired trajectories. This innovative structure ensures rotor speed and rotor fluxes tracking despite uncertainties on rotor resistance and load torque variations. Simulation and experimental results, including an estimation of the rotor flux norm, are given to illustrate the originality and effectiveness of this control law.     

A global adaptive link position-tracking controller for robot manipulators driven by induction motors

We present an adaptive, partial-state feedback, link position tracking controller for robot manipulators driven by induction motors. The proposed controller compensates for parametric uncertainty in the mechanical subsystem while yielding global asymptotic link position tracking. The proposed controller does not require measurement of rotor flux; furthermore, the controller does not exhibit any singularities. Preliminary experimental and simulation results are provided to illustrate the effectiveness of the proposed controller.     

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 predictive controller for induction motors using an unknown input observer for online rotor resistance estimation and an update technique for load torque

This paper deals with the design of an output feedback predictive controller for induction motors. The fundamental interest of the proposed controller is the capability of decoupling the mechanical speed and the rotor fluxes, without degradation against the variation of rotor resistance and load torque. Hence, the contribution is to apply two estimation procedures in order to achieve this goal. Namely, an unknown input observer (UIO) is used for the constant time estimation whereas a heuristic solution is exploited for the load torque update. Moreover, rotor flux components are recovered as an unavailable state of the system. Effectiveness of the proposed observers and the performance of the controller are confirmed by simulation results.     

Design of an adaptive terminal sliding‐function controller for nonlinear multivariable systems

This paper presents an adaptive terminal sliding‐function controller approach for controlling a class of nonlinear multivariable systems with uncertainty. An appropriate terminal sliding function (TSF) is designed and then applied to the control law. Based on the Lyapunov stability theory, the adaptive terminal sliding‐function controller for nonlinear multivariable systems guarantees that the TSF is asymptotically convergent. Different from classical terminal sliding mode control, which uses a discontinuous switching control law, the TSF control uses a continuous TSF and thus avoids the chattering problem. The simulation results demonstrate that the proposed method achieves satisfactory stability. Copyright © 2013 John Wiley & Sons, Ltd.     

Design of an adaptive self-organizing fuzzy neural network controller for uncertain nonlinear chaotic systems

Though the control performances of the fuzzy neural network controller are acceptable in many previous published papers, the applications are only parameter learning in which the parameters of fuzzy rules are adjusted but the number of fuzzy rules should be determined by some trials. In this paper, a Takagi–Sugeno-Kang (TSK)-type self-organizing fuzzy neural network (TSK-SOFNN) is studied. The learning algorithm of the proposed TSK-SOFNN not only automatically generates and prunes the fuzzy rules of TSK-SOFNN but also adjusts the parameters of existing fuzzy rules in TSK-SOFNN. Then, an adaptive self-organizing fuzzy neural network controller (ASOFNNC) system composed of a neural controller and a smooth compensator is proposed. The neural controller using the TSK-SOFNN is designed to approximate an ideal controller, and the smooth compensator is designed to dispel the approximation error between the ideal controller and the neural controller. Moreover, a proportional-integral (PI) type parameter tuning mechanism is derived based on the Lyapunov stability theory, thus not only the system stability can be achieved but also the convergence of tracking error can be speeded up. Finally, the proposed ASOFNNC system is applied to a chaotic system. The simulation results verify the system stabilization, favorable tracking performance, and no chattering phenomena can be achieved using the proposed ASOFNNC system.     

无轴承异步电机悬浮系统的非线性滤波器自适应逆控制

讨论了基于非线性自适应滤波器的无轴承异步电机(bearlngless induction motor,BIM)悬浮系统自适应逆解耦控制问题.利用非线性自适应滤波器,建立系统模型和逆模型.复制逆模型,将其串联在悬浮系统之前作为逆控制器,并采用改进的最小均方(least mean square,LMS)算法在线调整权值,从而实现转子的悬浮控制.相比于传统的控制方法,此方法不必依靠转矩系统来传递磁链信息,从而避免了各自的控制策略之间的相互制约问题.仿真结果验证了该方法的有效性,完成了系统模型和逆模型的建立,并且能够实现两自由度径向悬浮力之间解耦.     

Method of magnetic circuits for nonlinear magnetostatic fields in polyphase induction motors at no-load

The nonlinear magnetostatic field in polyphase induction motors at no-load is solved by the finite difference method based on the method of magnetic circuits.     

含静止同步串联补偿器的单机系统非线性综合控制器设计

本文考虑含静止同步串联补偿器(SSSC)的单机无穷大系统、汽门、励磁各变量间的相互作用建立了4阶多变量3输入3输出非线性模型, 在此模型基础上, 运用动态逆系统方法完成解耦和线性化, 构造出3个单输入单输出的伪线性系统, 并采用变结构控制理论分别设计控制器. 根据MATLAB仿真结果验证了该控制方法对发电机功角, 机端电压和传输功率这3个控制指标有很好的控制效果.     

非线性时滞系统鲁棒L2控制器设计

本文针对带有不确定性的非线性时滞系统,基于系统耗散的定义,讨论了其鲁棒L2控制器设计问题,通过设计一个新的李雅普诺夫泛函,得到了系统稳定且满足耗散的充分必要条件,在此基础上设计满足L2性能指标的控制器,所得结果通过线性矩阵不等式给出.     

A nonlinear robust PI controller for an uncertain system

This paper presents a smooth control strategy for the regulation problem of an uncertain system, which assures uniform ultimate boundedness of the closed-loop system inside of the zero-state neighbourhood. This neighbourhood can be made arbitrarily small. To this end, a class of nonlinear proportional integral controllers or PI controllers was designed. The behaviour of this controller emulates very close a sliding mode controller. To accomplish this behaviour saturation functions were combined with traditional PI controller. The controller did not need a high-gain controller or a sliding mode controller to accomplish robustness against unmodelled persistent perturbations. The obtained closed-solution has a finite time of convergence in a small vicinity. The corresponding stability convergence analysis was done applying the traditional Lyapunov method. Numerical simulations were carried out to assess the effectiveness of the obtained controller.     

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.     

基于滑模与自适应观测器的感应电机非线性控制新策略

提出一种结合滑模变结构和自适应观测技术的感应电机非线性控制新方法. 以定子电流与定子磁链为状态变量建立感应电机模型, 采用非线性分析方法建立转矩与磁链误差方程, 使用自适应滑模技术设计转矩与磁链控制器, 推导出定子电压控制量. 基于模型参考技术设计自适应观测器, 向控制器提供准确的转速辨识与磁链观测值,并给出了控制系统的稳定性证明. 该方法具有转矩脉动小、定子磁链畸变不明显的优点, 低速时也具有良好的控制性能, 且对参数与负载变化有较强的鲁棒性. 仿真与实验结果证明了该控制策略的正确性与有效性.     

基于两时间尺度模型的直升机非线性控制器设计

提出一种基于两时间尺度模型的直升机非线性控制方法. 该方法利用直升机不同状态达到稳定的时间不同的特点, 将直升机模型分为快速和慢速两种模型. 反步控制方法和逆动力学控制方法分别被用于进行快慢两种模型控制器的设计, 并在控制过程中采用了不同的控制周期. 仿真结果表明, 利用上述方法设计的控制器, 对于阶跃变化和正弦变化的速度轨迹具有良好的跟踪效果.

     

异步电机反馈线性化二阶滑模定子磁链观测器设计

为了提高异步电机定子磁链的观测精度,提出了基于反馈线性化的二阶滑模磁链观测方法,设计了定子磁链观测器,并应用到异步电机直接转矩控制中.为更准确的观测磁链,选取转子磁链为系统输出,运用微分几何理论将异步电机系统的输入/输出线性化,得到以转子磁链为输出的异步电机反馈线性化模型.在此基础上设计基于Super-twisting算法的二阶滑模转子磁链观测器,实现对转子磁链的准确估算,并对所设计的观测器进行稳定性分析.然后再利用转子磁链与定子磁链的关系,估算出定子磁链.将该观测器用于异步电机直接转矩控制中,达到了很好的控制效果.仿真与实验结果验证了该方法的可行性和有效性.