A robust sliding mode flux and speed observer for speed sensorless control of an indirect field oriented induction motor drives

In this paper a new sliding mode flux and speed observer is proposed for indirect field oriented induction motor drive system. The error between the actual and observed currents converges to zero, which guarantees the accuracy of the flux observer. The rotor speed and the rotor time constant are estimated based on the estimated stator currents and rotor flux. The estimated rotor time constant is used in slip calculation and observer structures and the estimated speed is used as feedback to the speed regulation. Computer simulation and experimental results of the speed control verify the validity of the proposed speed estimation algorithm. The experimental results show the robustness and performance of the proposed observer structure. Experimental results have been realized without load, with load and with external disturbances.     

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.     

Very low speed and zero speed estimations of sensorless induction motor drives

Recently, speed sensorless control of induction motor drives received great attention to avoid the different problems associated with direct speed sensors. However, low speed operation with robustness against parameter variations remains an area of research for sensorless systems. Stator resistance is of utmost importance for good operation of speed sensorless systems in low speed region. In this paper, a sliding mode current observer for an induction motor is presented. An estimation algorithm based on this observer in conjunction with Popov's hyper-stability theory is proposed to calculate the speed and stator resistance independently. The proposed speed observer with parallel stator resistance identification is first verified by simulation. Experimental results are included as well as to demonstrate the good performance of the proposed observer and estimation algorithms at very low and zero speeds.     

感应电机无速度传感器控制自适应速度观测器

理论与实践证明自适应速度观测器是实现高性能的感应电动机无速度传感器控制系统的有效方法之一。由于该系统的非线性性质,在观测器设计以及系统应用中还有许多有待解决的问题。针对此类问题,从理论联系实际的角度,分析现有的电机磁链、速度观测器理论的要点及其成果,如建模的条件、自适应速度估计算法及其物理性质、系统稳定性分析、线性化方法、以及观测器参数的辨识等。同时,给出了实验结果、指出了这些内容中尚存的相关问题。     

Analysis of rotor slotting saliency in induction motor sensorless control

This paper deals with induction machines study by Finite Element Analysis (FEA) for position sensorless control drives based on rotating voltage carrier injection. It focuses the analysis of the rotor slotting saliency, under the variations of: (1) supply of the machine (both the high frequency rotating voltage carrier and the fundamental frequency supply), (2) reference flux of the drive, (3) load torque, and (4) rotor geometry design. The relative spatial harmonic of the stator inductance space-vector responsible for the rotor slotting effect has been chosen as an index for evaluating the response to the high frequency carrier. A methodology for retrieving the stator inductance space-vector from a FEA is proposed as well. Results of the variation of the rotor slotting spatial harmonic of the stator inductance with the carrier frequency, the rotor flux linkage, the load torque and the rotor geometry are presented.     

基于改进滑模观测器的SPMSM无位置传感器矢量控制系统

将用于预测永磁同步电机转子位置和转速的滑模观测器进行了改造,并构建了无位置传感器的矢量控制系统;并在此基础上提出了一种用于补偿转子位置角预测误差的改进方法。最后用Matlab仿真验证了算法的有效性,对结果进行了分析讨论。     

MRAS-based sensorless control of a vector controlled five-phase induction motor drive

Multi-phase ac motor drives are nowadays considered for various applications, due to numerous advantages that they offer when compared to their three-phase counterparts. In principle, control methods for multi-phase machines are the same as for three-phase machines. Variable speed induction motor drives without mechanical speed sensors at the motor shaft have the attractions of low cost and high reliability. To replace the sensor, information of the rotor speed is extracted from measured stator currents and voltages at motor terminals. Vector controlled drives require estimating the magnitude and spatial orientation of the fundamental magnetic flux waves in the stator or in the rotor. Open-loop estimators and closed-loop observers are used for this purpose. They differ with respect to accuracy, robustness, and sensitivity against model parameter variations. This paper analyses operation of an open-loop and model reference adaptive system (MRAS)-based sensorless control of vector controlled five-phase induction machine with current control in the stationary reference frame. The MRAS-based sensorless operation of a three-phase induction machine is well established and the same principle is extended in this paper for an IRFOC five-phase induction machine. Performance, obtainable with hysteresis current control, is illustrated for a number of operating conditions on the basis of simulation results. Full decoupling of rotor flux control and torque control is realised. Dynamics, achievable with a five-phase vector controlled induction machine, are shown to be essentially identical to those obtainable with a three-phase induction machine. Experimental verification is also provided.     

一种异步电机无速度传感器间接磁场定向控制策略

针对无速度传感器异步电机,提出了一种新的滑模磁通和速度观测方法。实际电流和观测电流之间的误差收敛到零,保证磁通观测器的精确性。根据估计的定子电流和转子磁链来估计转子的转速和转子时间常数。估计的转子时间常数用于滑模计算和观测器结构中,估计的转速用来作为转速调节的反馈。仿真结果证明所提出的速度估算方法有效以及所提出的观测器结构具有鲁棒性。     

Validation of an integral sliding mode control for optimal control of a three blade variable speed variable pitch wind turbine

Reduction in cost of wind energy requires most efficient control technology which can able to extract optimum power from the wind. This paper mainly focuses on the control of variable speed variable pitch wind turbine (VSVPWT) for maximization of extracted power at below rated wind speed (region 2) and regulation of extracted power when operating at above rated wind speed (region 3). To extract maximum power at below rated wind speed torque control is used whereas to regulate rated power at above rated wind speed pitch control is used. In this paper a nonlinear control i.e. integral sliding mode control (ISMC) is proposed for region 2 whereas a conventional proportional–integral (PI) control is adapted for region 3 of a VSVPWT. The proposed controller is combined with modified Newton Raphson (MNR) wind speed estimator to estimate the wind speed. The stability of the proposed ISMC is analyzed using Lyapunov stability criterion and the control law is derived for region 2 which is also adapted for the transition period between region 2 and region 3 (region 2.5). The dynamic simulations are tested with nonlinear FAST (Fatigue, Aerodynamics, Structures, and Turbulence) wind turbine (WT). The simulation results of ISMC are presented and the control performance is compared with conventional SMC and existing controllers such as aerodynamic torque feed forward control (ATF) and Indirect speed control (ISC). It is seen that especially in region 2.5, ISMC gives better performance compared to all other controllers.     

Artificial intelligence-based speed control of DTC induction motor drives—A comparative study

The design of the speed controller greatly affects the performance of an electric drive. A common strategy to control an induction machine is to use direct torque control combined with a PI speed controller. These schemes require proper and continuous tuning and therefore adaptive controllers are proposed to replace conventional PI controllers to improve the drive's performance. This paper presents a comparison between four different speed controller design strategies based on artificial intelligence techniques; two are based on tuning of conventional PI controllers, the third makes use of a fuzzy logic controller and the last is based on hybrid fuzzy sliding mode control theory. To provide a numerical comparison between different controllers, a performance index based on speed error is assigned. All methods are applied to the direct torque control scheme and each control strategy has been tested for its robustness and disturbance rejection ability.     

Sensorless vector control of a Permanent magnet synchronuous motor with fuzzy logic observer

In this paper, a new method for sensorless vector control of a permanent magnet synchronous motor (PMSM) using a fuzzy logic observer is developed. This method is based on determination of rotor position and thereby speeds by estimating back-emf components which result from fuzzy logic observers. The rotor position angle and rotating speed are estimated by evaluating the instantaneous values of stator voltages and currents. The estimators are two fuzzy logic observers. They have two inputs: the estimated stator currents and the difference between the measured and estimated stator currents. In addition, the outputs of the fuzzy logic observers are the back-emf components in an – reference frame. The proposed method was implemented using a MATLAB/Simulink software package program. The obtained results are within acceptable error limits for a wide speed range, from 40 rad/s up to 500 rad/s.     

MRAS-based speed sensorless control scheme with stator resistance identification function for vector-controlled induction motor drives

This paper describes a new scheme for the speed sensorless control of the vector-controlled induction motor drive. Based on the model reference adaptive system (MRAS) theory, the rotor speed of the induction machine is estimated with a full-order adaptive observer. The estimated speed then is used as the signal for the vector control and the speed control. To accurately estimate the speed at the lower speed range, the value of the stator resistance also is identified at the same time and then is used to modify the resistance value set in the observer. The resulting system is verified to be hyperstable with Popov's criterion. As a result, this drive can operate stably in a wide range of speed even at zero speed. Also, it is shown theoretically that neither speed nor resistance of the rotor can be identified at the same time because these two parameters are dependent on each other. Simulation results and experiments also show that the scheme is effective.     

Design of an adaptive observer for sensorless vector control of induction machines under regenerating conditions

The objective of this investigation is to stabilize a sensorless vector control system of induction motors by means of an adaptive observer in regenerating mode at very low speed. The adaptive observer gain is designed by means of the Routh–Hurwitz criterion. It is verified by simulation and experiment that the proposed system is stable. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(4): 78–87, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10202     

Application of reaching law approach to the position control of a vector controlled induction motor drive

In this paper, a new position control method based on the reaching law control (RLC) approach is proposed for the robust position control of electrical drive systems. The main aim of this study is to investigate the robustness of the RLC approach under inertial-frictional variations and external disturbances and to address the application problems of the RLC approach for position control systems. New components are added to the controller in order to improve the robustness. The control method is applied to a vector-controlled induction motor drive system. It is shown in the paper that the practical constraints such as torque limitation, and the demand of high control performance, i.e., high bandwidth, result in undesirable overshoots. The performance of the control method is shown by simulation and experimental results.List of symbols X, X _k Continuous and discrete-time state vectors - x ₁, x ₂ State variables (the shaft position and speed of the rotor) - , _re Position and reference angles (rad) - Angular velocity (rad/s) - A,A _n State variable matrix with true and nominal parameters - B,B _n Control input matrix, with true and nominal parameters - u,u _max Control signal, and its maximum value - A,B Uncertain parts of the state matrix and the control input matrix - Equivalent terms of A, B uncertainties referred to matching condition - C Gain vector of switching function - s _k Switching function - q A constant used in the reaching law - A constant used in the reaching law - A constant used in the chattering reduction approach - T sampling period - J,J _n True and nominal inertia coefficient (kg m²) - B,B _n True and nominal friction coefficient (kg m²/s) - J,B The uncertain parts of the inertia and friction coefficients - T _e Produced (electrical) torque (control signal) (Nm) - Load torque (Nm) - Equivalent term of A referred to matching condition and scalar component - Equivalent term of B referred to matching condition - All uncertainties and disturbances referred to matching condition - J₀,B₀ The variation ratios of the inertia and friction coefficients - G State variable matrix in discrete-time model - H Control input matrix in discrete-time model - Slope of the sliding line (surface) - a Mechanical time constant - v _sd, v _sq Stator voltages in d-q axis (V) - i _sd, i _sq Stator currents in d-q axis (A) - L _s, L _R Stator and rotor self inductances (H) - L _m Mutual inductance (H) - Leakage factor - _e, _sl Stator and slip angular velocity (rad/s) - _r Rotor time constant - P Number of poles     

Observer-based nonlinear control of power system using sliding mode control strategy

This paper presents a new transient stabilization with voltage regulation analysis approach of a synchronous power generator driven by steam turbine and connected to an infinite bus. The aim is to obtain high performance for the terminal voltage and the rotor speed simultaneously under a large sudden fault and a wide range of operating conditions. The methodology adopted is based on sliding mode control technique. First, a nonlinear sliding mode observer for the synchronous machine damper currents is constructed. Second, the stabilizing feedback laws for the complete ninth order model of a power system, which takes into account the stator dynamics as well as the damper effects, are developed. They are shown to be asymptotically stable in the context of Lyapunov theory. Simulation results, for a single-Machine-Infinite-Bus (SMIB) power system, are given to demonstrate the effectiveness of the proposed combined observer-controller for the transient stabilization and voltage regulation.     

PMSM扩展状态滑模观测器及转子位置和速度估算

针对永磁同步电机(PMSM)反电势滑模观测器抖振问题,提出一种基于电流和磁链为变量的 PMSM扩展状态方程的自适应滑模观测器.以实际电流与观测电流之差构成滑模面,当滑模运动发生时,电流观测误差为零,等效控制信号包含磁链误差相关信息.通过反馈矩阵将等效信号输入到磁链观测方程中,磁链观测误差渐进收敛到零.在磁链观测结果中,抖振现象被很好的抑制,转子角度可以由磁链直接计算.分析了速度估计误差对磁链观测影响,并以此为基础进行反馈矩阵的计算.建立了速度自适应率,并采用Lyapunov方法证明了算法的收敛性.仿真和实验结果表明,通过该观测器和速度辨识方法能够准确计算出电机角度和速度,具有良好的稳态精确度和动态性能.     

异步电机无速度传感器矢量控制系统的研究

为了实时辨识电动机的转子转速,提出利用在异步电机端测量得到的电压和电流来估算电机转速,以实现无速度传感器矢量控制的模型参考自适应方法.在MATLAB/Simulink中,建立了一个基于该方法的无速度传感器矢量控制系统,并进行了仿真实验,仿真结果表明该系统具有良好的动静态特性和稳定性.     

基于二阶滑模观测器的感应电机转子磁链观测

实现矢量控制的基础是准确获得转速和转子磁链信息,本文提出了一种基于二阶滑模观测器的转子磁链观测方法。将构造的滑模观测器作为模型参考自适应系统(MRAS)的参考模型,将磁链的电流模型改造为该中间变量的可调模型,且其可调量为转速变量,进而构造出MRAS,实现对转速的观测。在此基础上,完成转子磁链的计算,并得到转子磁链角度,实现基于直接磁场定向的感应电机矢量控制。中间量的构造有效避免了传统MRAS中的纯积分问题,便于算法的实施;二阶滑模观测器有效地削弱了一阶滑模观测器存在的抖振扰动,并且参数具有较强的鲁棒性。仿真结果表明该转子磁链观测器具有较高的观测精度,且对外部扰动和转子电阻变化具有较强的鲁棒性,提高了系统的动稳态性能。     

三电平扩展卡尔曼滤波异步电机滑模控制

传统异步电机闭环控制中转速和磁链外环采用比例积分(PI)控制,针对其有超调和动态响应慢等问题,提出了一种新型的滑模控制器用于外环转速和磁链控制,改善了动态性能.采用五阶扩展卡尔曼滤波(EKF)来估计转速和磁链并用于闭环反馈,进一步研究了引入转矩观测后的六阶EKF,考察了转动惯量对速度估计的影响,在三电平逆变器驱动异步电机平台上进行了各种实验.结果表明,基于EKF和滑模控制的无速度传感器控制系统在较宽的速度范围内具有良好的动静态性能.     

永磁同步电机滑模调速控制及其实现

永磁同步电机（PMSM）的模型是一个多变量,非线性,强耦合的系统,而滑模变结构控制（SMC）具有快速响应,对参数变化及扰动不灵敏,算法简单,易于工程实现等优点,这为复杂工业控制问题提供了一种很好的解决途径。本文中的PMSM调速系统,以TMS320F2812为主控芯片,利用指数趋近律法下的滑模变结构控制器进行控制,给出了滑模控制器的位置式和增量式表达式。并将推导出的算法以增量式的形式编写进程序,作为调速系统的软件。最后通过MATLAB仿真和具体实验证明了该系统具有动态响应速度快,电磁转矩脉动小,稳定等众多优点,使系统具有更好的鲁棒性。