A start-up method for a speed sensorless stator-flux-orientedvector-controlled induction motor drive

This paper describes a zero-speed start-up method of a speed sensorless stator-flux-oriented direct vector-controlled induction motor drive with the help of a machine current model that does not use any speed signal. The machine starts smoothly with vector control at finite developed torque and then transitions to the standard direct vector-control mode with the voltage model signals as the speed begins to develop. The direct vector-control mode with voltage model uses programmable cascaded low-pass filters for flux-vector synthesis and enables the drive to operate from zero speed to field-weakening mode. As the drive speed falls to zero, the drive again transitions to start-up mode, so that it can be smoothly started again. The performance of the start-up scheme has been verified on a 100 kW electric vehicle drive     

A simple approach to flux and speed observation in induction motordrives

The stator-flux orientation concept allows very good transient and steady-state performances in induction motor drives. However, this control strategy can be conveniently implemented only if the stator flux is correctly observed in the entire speed range. The authors have developed a simple flux observer that gives very satisfactory results, especially near zero speed, and the approach which has been followed also allows a good speed estimation. The observer has been both simulated and implemented on an experimental system that uses a single chip to control the whole drive system. The experimental results show excellent performances, despite the low computational load     

基于滑模控制的异步电机无速度传感器DTC研究

建立了一种滑模速度观测器,用于电机转速的精确观测。该观测器充分利用电机状态方程具有的结构特点,设计出简单有效的速度估算方法,在转子磁链的估算中无须用到转子时间常数和转速等信息,提高了观测器对于参数误差的鲁棒性。将所建立的观测器和空间电压矢量脉宽调制技术(SVPWM)结合对电机进行控制,进一步提高了系统的调速性能。仿真结果验证了基于滑模控制理论的异步电机无速度传感器直接转矩控制系统的可行性以及对参数误差的鲁棒性。     

Sliding-mode MRAS speed estimators for sensorless vector control of induction Machine

This paper presents two novel sliding mode (SM) model reference adaptive system (MRAS) observers for speed estimation in a sensorless-vector-controlled induction-machine drive. Both methods use the flux estimated by the voltage model observer as the reference and construct SM flux observers that allow speed estimation. Stability and dynamics of the two proposed SM flux observers are discussed. The observers are compared with the classical MRAS observer. The proposed estimators seem very robust and easy to tune. Unlike the classical MRAS, the speed-estimation process is based on algebraic calculations that do not exhibit underdamped poles or zeros on the right-hand plane. Simulations and experimental results on a 1/4-hp three-phase induction machine confirm the validity of the approaches.     

Low-frequency signal-demodulation-based sensorless technique for induction motor drives at low speed

The paper presents a method to compute the air-gap flux position in induction motors at very low including zero-stator frequency. A low-frequency (50 /spl divide/ 100 Hz) sinusoidal stationary signal is added to the normal stator variables to provide the machine with a suitable permanent excitation. Such an additional excitation modulates the saturation level of the magnetic core of the machine according to the angular position of the air-gap flux. As a result, a new zero-sequence stator-voltage component is generated that contains useful information about the position of the air-gap flux unaffected by load variation. Such a zero-sequence voltage can be easily employed to provide a wide bandwidth measurement of the air-gap flux position. A key feature of the proposed approach is that a low-frequency (0 /spl divide/ 5 Hz) signal is demodulated, thus avoiding any drawback featured by previous sensorless techniques operating with high-frequency signal injection.     

An optimal speed controller for permanent-magnet synchronous motordrives

An optimal control system synthesis method which can achieve vector and speed control simultaneously for permanent-magnet synchronous motor (PMSM) drives is proposed in this paper. A state-space multiple-input-multiple-output (MIMO) model for PMSM is first developed and the compensation for the nonlinearities in this model is discussed. A pseudo-linearized PMSM model is dynamically constructed through the state detection, and subsequently an optimal speed controller is developed based on this linearized model. The integral control technique is incorporated to eliminate possible speed offsets. A speed observer is further developed to eliminate the speed sensor from the drive     

An improved sensorless vector-control method for an induction motor drive

In the present paper, a new improved sensorless vector-control method for an induction motor drive is presented. The proposed method is based on an improved closed-loop stator-flux estimator, based on the dynamic model of the asynchronous motor, which achieves precise stator-flux estimation over a wide area of operation. This new stator-flux estimator ensures stability of the overall control scheme in a very-wide-speed operation area, as it will be shown in this paper. The rotor-speed-estimation method is based on an observer based on the model reference adaptive systems (MRAS) theory. The control scheme is based on a stator-flux-oriented direct vector-control method, where both flux and speed controllers are optimal tuned. In addition, implementation of the proposed method is based on a simplified algorithm capable of running in a low-cost microcontroller, which is discussed in detail. Also, the motor-drive system, including the stator-flux estimator, the speed estimator, and the control logic are simulated and some characteristic simulation results are presented. These results reveal that the proposed method is able to obtain precise flux and speed control over a wide operation area, including very low operating frequencies.     

新型异步电机无速度传感器低速控制算法

基于数学模型的速度估算是异步电机无速度传感器控制的核心。目前,围绕速度估算这个问题,在电机控制领域已出现模型参考自适应、自适应观测器以及扩展卡尔曼滤波等多种方法。无论采用哪种速度估算技术,速度估算系统的动静态性能、低速性能、对参数的敏感性、算法的复杂程度及实现难度都是工程师必须考虑的几个重要性能指标。文中针对低速条件下的异步电机速度估算及控制提出了一种基于无功功率闭环的异步电机无速度传感器矢量控制算法,并探讨了该方法的一些性能指标问题。     

An improved stator flux estimation for speed sensorless stator fluxorientation control of induction motors

This paper proposes a programmable low pass filter (LPF) to estimate stator flux for speed sensorless stator flux orientation control of induction motors. The programmable LPF is developed to solve the DC drift problem associated with a pure integrator and a LPF. The pole of the programmable LPF is located far from the origin in order to decrease the time constant with the increasing speed. In addition, the programmable LPF has a phase/gain compensator to estimate exactly stator flux in a wide speed range. Consequently, the drift problem is much improved and the stator flux is exactly estimated in the wide speed range. The validity of the proposed programmable LPF is verified by speed sensorless vector control of a 2.2 kW three-phase induction motor     

Lyapunov-function-based flux and speed observer for AC induction motor sensorless control and parameters estimation

AC induction motors have become very popular for motion-control applications due to their simple and reliable construction. Control of drives based on ac induction motors is a quite complex task. Provided the vector-control algorithm is used, not only the rotor speed but also the position of the magnetic flux inside the motor during the control process should be known. In most applications, the flux sensors are omitted and the magnetic-flux phasor position has to be calculated. However, there are also applications in which even speed sensors should be omitted. In such a situation, the task of state reconstruction can be solved only from voltage and current measurements. In the current paper, a method based on deterministic evaluation of measurement using the state observer based on the Lyapunov function is presented. The method has been proven in testing on a real ac induction machine.     

A new current model flux observer for wide speed range sensorless control of an induction machine

A new closed loop current model flux observer is designed to estimate the rotor flux, position and velocity of an induction machine. The current observer includes carefully designed sliding mode functions which are derivative of the fluxes along the /spl alpha/ and /spl beta/ axes. Therefore, when the estimated current converges to the measured one, the flux estimation is a mere integration of the sliding mode function. The rotor speed can then be derived from the sliding mode functions and the estimated flux. In the current and flux observers all of the terms that contain the rotor time constant and the rotor speed have been replaced by the sliding mode functions, thus making the proposed current and flux estimations completely insensitive to the rotor time constant variation and any error in the estimated speed. Simulations and experiments are performed under a variety of conditions to validate the effectiveness of the proposed algorithm.     

Novel wide range speed control of permanent magnet brushless motordrives

This paper presents a novel approach for the wide range speed control of a permanent magnet (PM) brushless motor drive, including both sinewave and squarewave versions. As compared with conventional flux-weakening control, the approach has definite advantages in that it can be applied to the squarewave PM brushless motor drive directly, and even to the motor drive with negligible mutual inductances between phase windings. Moreover, it is easier to implement than flux-weakening control because no coordinate transformation is needed. The key of this approach is to make use of the transformer EMF in such a way that it weakens the rotational EMF when the motor operates above the base speed, leading to the achievement of constant-power operation. Computer simulation and experimental results show that the proposed approach works well     

永磁同步电机的零低速无传感器控制研究

文中介绍了基于高频注入法的无位置传感器控制实现了永磁同步电机初始位置的估计,控制系统采用了先进的控制策略:矢量控制策略和SVPWM(电压空间矢量脉宽调制技术),基于MATLAB/SIMULINK搭建了仿真模型,结果证明了基于高频注入法实现永磁同步电机无位置传感器控制系统算法上的有效性。     

Online rotor resistance estimation using the transient state underthe speed sensorless control of induction motor

In the speed sensorless control of the induction motor, the machine parameters (especially rotor resistance R₂) have a strong influence on the speed estimation. It is known that the simultaneous estimation of the rotor speed and R₂ is impossible in the slip frequency type vector control, because the rotor flux is constant. But the rotor flux is not always constant in the speed transient state. In this paper, the R₂ estimation in the transient state without signal injection to the stator current is proposed. This algorithm uses the least mean square algorithm and the adaptive algorithm, and it is possible to estimate R₂ exactly. This algorithm is verified by the digital simulations and experiments     

Extreme learning machine approach for sensorless wind speed estimation

Precise predictions of wind speed play important role in determining the feasibility of harnessing wind energy. In fact, reliable wind predictions offer secure and minimal economic risk situation to operators and investors. This paper presents a new model based upon extreme learning machine (ELM) for sensor-less estimation of wind speed based on wind turbine parameters. The inputs for estimating the wind speed are wind turbine power coefficient, blade pitch angle, and rotational speed. In order to validate authors compared prediction of ELM model with the predictions with genetic programming (GP), artificial neural network (ANN) and support vector machine with radial basis kernel function (SVM-RBF). This investigation analyzed the reliability of these computational models using the simulation results and three statistical tests. The three statistical tests includes the Pearson correlation coefficient, coefficient of determination and root-mean-square error. Finally, this study compared predicted wind speeds from each method against actual measurement data. Simulation results, clearly demonstrate that ELM can be utilized effectively in applications of sensor-less wind speed predictions. Concisely, the survey results show that the proposed ELM model is suitable and precise for sensor-less wind speed predictions and has much higher performance than the other approaches examined in this study.     

A new method for impedance control of induction motor speed

A novel induction machine with continuous speed control is found possible. This motor may be regarded as an inverted version of a Schrage motor in construction in that the tertiary winding is placed along with the secondary (on the stator) rather than with the primary (on the rotor). Hence a static commutator connected to the tertiary winding with the brushes placed over it at the appropriate places helped in injecting an EMF (of slip frequency) at various angles with respect to the secondary EMF induced by brush rotation. This has resulted in speed control of the induction motor. The performance characteristics of the new motor resemble those of a series-regulated induction machine in contrast to the shunt characteristics of a Schrage motor.     

Low-speed sensorless control of induction Machine

Induction motor (IM) speed sensorless control, allowing operation at low and zero speed, optimizing torque response and efficiency, will be presented in this paper. The magnitude and the orientation angle of the rotor flux of the IM are determined by the output of the closed-loop rotor-flux observer based on the calculation of the extended electromotive force of the machine. The proposed rotor-flux-oriented control scheme is robust to parameter variations and external disturbances. Both observer and controller utilize the continuous sliding mode and Lyapunov theory. A smooth transition into the field-weakening region and the full utilization of the inverter current and voltage capability are thus possible. The produced torque is a continuous output variable of control. The performance of the proposed method is investigated and verified experimentally on a digital signal processor.     

New observer-based DFO scheme for speed sensorless field-orienteddrives for low-zero-speed operation

This paper describes a new direct field orientation (DFO) scheme based on a modified flux observer using measured stator voltages and currents. The proposed approach addresses the problem of torque control of speed sensorless drives at low-zero speed, where rapid speed changes do not occur and signal frequency can approach zero. The scheme can maintain field orientation and stable torque control with simultaneous resistance and speed tuning taking place. Simulations and locked rotor experiments with torque measurements are used for verification     

Extended-range PMSM sensorless speed drive based on stochasticfiltering

The paper describes the design of a high-performance sensorless permanent magnet synchronous motor (PMSM) drive, capable of starting at full torque even from standstill and able to deliver full torque in 1:12 speed range. Experimental setup, hardware circuitry and software implementation are described into details. Particular emphasis is given to the software control algorithms, that were specifically studied to enhance the overall system performance