Deadbeat flux level control of direct-field-oriented induction motor

A method for the deadbeat flux level control of a direct-field-oriented induction motor with position control loop has been developed that employs an adaptive rotor flux observer. The observer is a full-order type and is used not only in the direct-field-oriented controller, but also to identify stator and rotor resistances of the motor. The observer reduces the sensitivity of a deadbeat controller to fluctuations in the motor parameters. The main advantage of this method is that it improves the efficiency of an induction motor without sacrificing dynamic performance. This paper describes the method as well as the fundamental characteristics of the system derived from experimental and simulation results.     

High-response flux control of direct-field-oriented induction motorwith high efficiency taking core loss into account

Stator core loss has significant adverse effects when an induction motor is controlled by the conventional field-oriented method. Therefore, taking core loss into account should make it possible to control the torque very precisely. In this paper, a direct-field-oriented induction motor with a deadbeat rotor flux controller was developed. The method ensures maximum efficiency in the steady state without degradation of the dynamic response. Simulation and experimental results have demonstrated that this method has higher efficiency and good speed response without any degradation in the transient characteristics     

Digital current regulation of field-oriented controlled inductionmotor based on predictive flux observer

A new technique based on deadbeat control theory is proposed to control induction motor stator currents under field-oriented control. Stator currents and motor speed were measured. Rotor fluxes are predicted using a state observer with variable poles selection. Then, the pulse-width-modulated (PWM) pattern of the inverter is controlled such that the stator currents are exactly equal to the reference currents at every sampling instant. From the theoretical analysis, digital simulations, and experimental results, the following conclusions were made. The deadbeat controller permitted low current ripple with lower switching frequency, which, in turn, resulted in low torque ripple. The predictive state observer made possible the estimation of rotor flux with very low sensitivity to parameter variation and then contributed to performance improvement of conventional vector control     

A speed-sensorless vector control of induction motor operating athigh efficiency taking core loss into account

This paper proposes a speed-sensorless vector control method for an induction motor operating at high efficiency and high response, in which core loss is taken into account, and discusses the system's performance. The proposed vector control system consists of a speed-adaptive rotor-flux observer which takes core loss into account and employs a direct-field-oriented control scheme which compensates for the influence of core loss. On the basis of simulation and experimental results, we show that the proposed system can estimate motor speed even when the rotor flux is changed     

基于改进混合模型转子磁链观测器的异步电机无速度传感器控制

针对异步电机无速度传感器控制由于估计转子磁链不准确导致控制精度不佳的问题,提出了一种改进的混合模型转子磁链观测器设计方法。首先,介绍了常规的异步电机磁链观测方法,并借助异步电机的复矢量模型和特征函数详细分析了常规Gopinath型转子磁链观测器存在的主要问题。其次,为了解决常规磁链观测器存在的缺点,提出了一种改进的特征函数设计方法,进而得到了一种改进的混合模型转子磁链观测器。再次,基于特征函数和频率响应函数,进一步对比研究了常规Gopinath型转子磁链观测器和所提改进的混合模型转子磁链观测器的参数灵敏性。最后,利用所提混合模型转子磁链观测器的磁链观测结果和锁相环,实现了异步电机的无速度传感器控制。基于StarSim和YXSPACE-SP2000平台的对比实验结果,验证了所提混合模型转子磁链观测器的参数鲁棒性,同时也验证了所提无速度传感器控制策略的有效性。     

DSP-based speed adaptive flux observer of induction motor

A method for estimating the rotor flux and speed of an induction motor based on adaptive control theory is presented. The method is applied to a direct field-oriented induction motor control without speed sensors. The influence of the parameter variation on the speed estimation can be removed by the proposed parameter adaptive scheme. The validity of the adaptive flux observer is verified experimentally     

Robust direct torque and flux control of adjustable speed sensorless induction machine drive based on space vector modulation using a PI predictive controller

A Direct torque and flux control design for a sensorless induction motor, following a Lyapunov-based stator flux observer is presented. In this control scheme, the torque error signal and the amplitude of the stator flux reference vector are delivered to a PI predictive controller. The predictive controller also uses information on the amplitude and position of the actual stator flux vector and measured stator currents to determine the voltage command vector for space vector modulation inverter. In addition, a conventional PI speed controller is used to generate the torque reference signal. Using the fifth order model of the three-phase induction machines in a stationary two axes reference frame, a nonlinear stator flux observer is developed in order to estimate the rotor speed, rotor and stator resistances simultaneously. The stability of this observer is proved by Lyapunov theory. It is shown that if the persistancy of excitation condition is satisfied, the estimated quantities converge to their real values. The effectiveness of the proposed control scheme is verified by computer simulation and experimental results.     

基于正交反馈双补偿方法的转子磁链观测器

在异步电机矢量控制中,转子磁链观测的准确程度直接关系着控制的性能,因此要获得高性能的控制效果,必须构建一个精确的磁链观测器。针对异步电机转子磁链观测的电压模型积分饱和漂移、补偿量难以确定等不足,提出了一种基于正交反馈双补偿的转子磁链观测方法,根据磁链与反电动势的矢量正交程度,通过非线性正交法动态进行误差补偿,并调整补偿与低通滤波顺序,以提升频率突变时磁链的观测响应。仿真结果表明,本方法能够改善磁链观测波形,实现对磁链准确、迅速跟踪。     

感应电机全阶状态观测器及其无源性转速控制

为了实现感应电机的高动态调速性能,针对电机的非线性本质,提出了一种基于全阶状态观测器及其转速自适应估算的感应电机无源性转速控制方案。在基于感应电机无源性与稳定性分析的基础上,设计了渐近稳定转矩跟踪无源性控制器。针对无源控制律所需转子电流难以观测的问题,提出了一种旋转坐标系下以转子电流和转子磁链为状态变量的全阶状态观测器,并应用该观测器对转速进行估算,实现了感应电机无速度传感器的无源性转速控制。仿真结果表明该控制方法易于实现,采用全阶观测器观测转子电流值和估算转速值更为准确,显著提高了感应电机的动静态性能。     

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     

Design and implementation of a closed-loop observer and adaptivecontroller for induction motor drives

This paper discusses the implementation and experimental results of a closed-loop rotor flux observer and model reference adaptive system (MRAS) of a direct field-oriented control (FOC) of an induction motor drive. The motor was supplied from a high-frequency (20 kHz) AC resonant link via a MOS-controlled-thyristor (MCT)-based bidirectional converter. Hardware and software implementations of the various motor control functions are presented. The closed-loop observer combines the current and voltage models via a speed-dependent gain (SDG). The current model was formulated to operate in the rotor reference frame and requires only an encoder angle and not the actual rotor speed for implementation. The closed-loop observer permits the use of a pure analog integrator to calculate an adequate stator flux. The use of an AC resonant link further complicated an all-digital calculation of the stator flux. The observer and adaptive controller were tested on a 400-Hz 2-hp induction motor for low and high speeds. The closed-loop observer showed sensitivity at low speeds to the rotor circuit time constant which attributed to the current model rotor flux estimation. At high speed, the closed-loop observer followed the voltage model rotor flux estimation attributes. The MRAS was able to improve the complete speed response by correcting the current model rotor flux observer for errors in estimation of its parameters     

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.     

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。     

一种用于异步电机无速度传感器控制的自适应滑模观测器

针对异步电机无速度传感器中存在的对参数变化鲁棒性差的问题,研究了一种基于自适应滑模观测器的异步电机无速度传感器的矢量控制方案。自适应滑模观测器根据电机静止坐标系下的数学模型构造了转子磁链观测器,定子电流观测值与实际值的误差构成观测器的滑模面,在滑模运动下该观测器的观测值最终趋近于实际值,从而实现转子磁链的估计。电机转速由自适应方法估算得到,滑模观测器的稳定性可由李雅普诺夫稳定性证明。与其他方案相比,该方法的优点在于实现简单,对参数变化具有鲁棒性。仿真和实验对控制方案的正确性和可行性给出了验证,该观测器可以实现对转子磁链和转速的观测,且在负载扰动和给定转速变化的情况下该滑模观测器具有鲁棒性。     

A speed-sensorless vector control method of parallel-connected dual induction motor fed by a single inverter

The purpose of this paper is to present the speed-sensorless vector control method of the torque production from each rotor of two induction motors with parallel-connected stator windings fed by a single inverter. In this paper, an adaptive rotor flux observer is applied to the method in order to eliminate a flux sensor, and an adaptive scheme for rotor speed is added to the adaptive rotor flux observer in order to eliminate a speed sensor. The experimental results show that the proposed method is useful under the condition that the ratings of each induction motor are different.     

感应电动机非线性解耦控制的动态性能分析

在借鉴国内外相关研究的基础上,对感应电动机非线性解耦控制系统的动态性能进行了深入分析.经过分析发现,在非线性解耦控制器的作用下,感应电动机的转速、磁链控制误差及转子磁链估计误差可以指数收敛至零,但负载力矩估计误差只能是渐近有界的.对感应电动机的仿真结果表明,上述理论分析是正确的.     

Manipulation of rotor flux for time-optimal single-step velocityresponse of field-oriented induction machines

A single-step time-optimal velocity response control of an induction motor by manipulation of rotor flux is proposed as a control strategy that maintains fast velocity response, even if the flux level is reduced, to attain high efficiency of low acoustic noise drives. This control scheme includes minimization of startup time from standstill and recovery time against impact load. However, the final value of rotor flux is unconstrained, and the proposed control scheme could not be implemented with a field-oriented controller, which accommodates the dynamically changing rotor flux. Introduction of the variable-flux concept causes the induction motor to be nonlinear. Therefore most of the optimal control problems are discussed only numerically. Saturation of the flux has also been treated and the analytical results show that the optimal solution is uniquely defined, being independent of the mechanical load conditions     

基于电流模型的Kalman滤波转子磁链观测器

为了研究异步电机矢量控制系统,本文提出了应用电流模型设计Kalman滤波转子磁链观测器的新思路。为一台模型样机设计了基于电流模型的Kalman滤波转子磁链观测器,并设计了基于异步电机全阶模型的Kalman滤波转子磁链观测器,还迚行了对比研究,结果表明,两者的估计精度相当。可见,本文所提的基于电流模型的Kalman滤波转子磁链观测器是有效的、可行的。由于其状态方程的维数降低,它比基于全阶方程的Kalman滤波转子磁链观测器更适宜于在线观测。     

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.     

一种用于无速度传感器异步电机控制的自适应滑模观测器

研究了一种用于异步电机控制的自适应滑模观测器。该观测器由两个滑模电流观测器、转子磁链观测器和速度估计部分组成。转子磁链观测器以两个电流观测器和速度观测器的输出作为输入,估计转速反馈到第二个电流观测器和转子磁链观测器。采用Lyapunov理论和Popov超稳定性理论对该方法的稳定性进行验证。该观测器具有设计新颖、对参数变化具有很强的鲁棒性等特点。通过Simulink仿真验证了该观测器的有效性。