Nonlinear sliding-mode torque control with adaptive backsteppingapproach for induction motor drive

In this paper, the nonlinear sliding-mode torque and flux control combined with the adaptive backstepping approach for an induction motor drive is proposed. Based on the state-coordinates transformed model representing the torque and flux magnitude dynamics, the nonlinear sliding-mode control is designed to track a linear reference model. Furthermore, the adaptive backstepping control approach is utilized to obtain the robustness for mismatched parameter uncertainties. With the proposed control of torque and flux amplitude, the controlled induction motor drive possesses the advantages of good transient performance and robustness to parametric uncertainties, and the transient dynamics of the induction motor drive can be regulated through the design of a linear reference model which has the desired dynamic behaviors for the drive system. Finally, some experimental results are demonstrated to validate the proposed controllers     

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     

Sensorless speed tracking of induction motor with unknown torque based on maximum power transfer

In this paper, the authors first derive the maximum power transfer theorem for an induction motor. Then, a nonlinear indirect adaptive sensorless speed tracking controller for the motor with the maximum power transfer is proposed. In this controller, only the stator currents are assumed to be measurable. The rotor flux and speed observers are designed to relax the need of flux and speed measurement. In addition, the rotor resistance estimator is also designed to cope with the problem of the fluctuation of rotor resistance with temperature. Stability analysis based on Lyapunov theory is also performed to guarantee that the controller design here is stable. Finally, the computer simulations and experiments are conducted to demonstrate the satisfactory tracking performance of the authors' design subject to maximum power transfer.     

Nonlinear observer-based adaptive tracking control for inductionmotors with unknown load

In this paper, we propose a nonlinear observer-based adaptive controller for induction motors with unknown load. With the use of the skew-symmetric property of induction motors, a two-stage design technique is applied to construct an observer-based controller for velocity tracking control. To demonstrate the effectiveness of the proposed scheme, a voltage-control type of drive system is set up to perform the task of velocity tracking. The main computing facility consists of two personal computers, PC 486 and PC 286, of which one is to perform the calculation of the control law and the other is to provide the function of pulse width modulation (PWM) and to generate the gating pulses. Satisfactory experimental results are shown in the paper     

无轴承异步电机无速度传感器控制

为解决无轴承异步电机运行中转速辨识问题,提出了一种可以同时在线估计转子电阻和转速的方法。该方法首先通过电压型转子磁链模型估计出转子磁链,然后根据静止坐标系下的无轴承异步电机模型和电压型转子磁链模型推出包含转子电阻和转速的表达式,再将这两个表达式看作一个二元一次方程组并求解,最终得到转子电阻跟转速的解析表达式。最后应用这种转速估计方法构建无轴承异步电机无速度传感器控制系统,并开展仿真研究。仿真结果表明:所提方法能够实现无轴承异步电机转子电阻和转速的准确估计,并保证无轴承异步电机的稳定悬浮运行。     

Nonlinear adaptive torque control of electro-hydraulic load system with external active motion disturbance

This paper develops a high performance nonlinear adaptive control method for electro-hydraulic load simulator (EHLS). The tracking performance of EHLS is mainly affected by the following factors: actuator’s active motion disturbance, flow nonlinear and parametric uncertainties, etc. Most previous studies on EHLS pay too much attention on actuator’s active motion disturbance, while deemphasize the other two factors. This paper concerns EHLS as a motion loading system. Besides actuator’s motion disturbance, both the nonlinear characteristics and parametric uncertainties of the loading system are addressed by the present controller. First, the nonlinear model of EHLS is developed, and then a Lyapunov-based control algorithm augmented with parameters update law is developed using back-stepping design method. The stability of the developed control algorithm is proven via Lyapunov analysis. Both the co-simulation and experiment are performed to validate the effectiveness of the developed algorithm.     

Model reference adaptive speed control for induction motor driveusing neural networks

A model reference adaptive speed control scheme using neural networks is presented. The robust observer-based model reference tracking control technique is used to establish the training patterns. Then, the trained neural networks are used as an adaptive speed controller to robustly track a reference model for an induction motor drive     

Robust speed control of IM with torque feedforward control

The authors describe a digital signal processor-based (DSP-based) robust speed control for an induction motor (IM) with the load-torque observer and the torque feedforward control. In the proposed system, the load torque is estimated by the minimal-order state observer based on the torque component of a vector-controlled IM. Using the load-torque observer, a speed controller can be provided with a torque feedforward loop, thus realizing a robust speed control system. The control system is composed of a DSP-based controller, a voltage-fed pulsewidth modulated (PWM) transistor inverter and a 3.7 kW IM system. An eccentric load with an arm and a weight is coupled to the IM and it generates the sinusoidal gravitational fluctuating torque. Experimental results show robustness against disturbance torque and system parameter change     

An effective method for rotor resistance identification forhigh-performance induction motor vector control

An effective method for rotor resistance identification is presented for the purpose of improving the performance of vector control of induction motor drives. The method is mathematically derived from proper selection of coordinate axes and utilization of the steady-state model of the induction motor. The major advantages of the method lie in its simplicity and accuracy. A series of computer simulations has been performed with very satisfactory results     

Nonlinear speed observer for high-performance induction motorcontrol

In this paper, we consider the problem of estimating the angular velocity of an induction motor using encoder measurements. Two methods are compared. In the first method, the speed is found by calculating the backward difference of the position measurement and low-pass filtering the result. In the second method, the velocity is estimated using a nonlinear observer constructed using the known dynamic model of the induction motor. The performance of the two methods is evaluated in the context of their use for velocity feedback in a high-performance field-oriented control law. Experimental results demonstrate that the speed observer leads to a smoother operation of the motor in closed-loop. With the estimator based on differentiation, either the delay imposed by the low-pass filter is too large to maintain high bandwidth feedback, or the fluctuations in the estimated speed are so large that much more energy ends up being dissipated to achieve the same control task     

Estimation of induction machine inverse rotor time constant using torque angle tangent calculation

A new inverse rotor time constant estimation scheme for an induction machine is presented. For high performance induction machine control, indirect rotor flux oriented vector control is the most commonly applied control technique. It requires that an accurate estimate of the inverse rotor time constant is obtained to ensure correct orientation of the current vector with the rotor flux vector. An incorrect estimate will result in an incorrect flux level, reduced dynamic torque performance and reduced maximum available torque. A novel parameter estimation scheme is presented, based on the calculation of the tangent of the torque angle. The effectiveness of the technique is demonstrated through simulation and practical results.     

Speed-sensorless sliding-mode torque control of an induction motor

Novel induction motor control optimizing both torque response and efficiency is proposed in the paper. The main contribution of the paper is a new structure of rotor flux observer aimed at the speed-sensorless operation of an induction machine servo drive at both low and high speed, where rapid speed changes can occur. The control differs from the conventional field-oriented control. Stator and rotor flux in stator fixed coordinates are controlled instead of the stator current components in rotor field coordinates i_sd and i_sq. In principle, the proposed method is based on driving the stator flux toward the reference stator flux vector defined by the input command, which are the reference torque and the reference rotor flux. The magnitude and orientation angle of the rotor flux of the induction motor are determined by the output of the closed-loop rotor flux observer based on sliding-mode control and Lyapunov theory. Simulations and experimental tests are provided to evaluate the consistency and performance of the proposed control technique     

Direct torque control of induction machines with constant switching frequency and reduced torque ripple

Direct torque control (DTC) of induction machines is known to have a simple control structure with comparable performance to that of the field-oriented control technique. Two major problems that are usually associated with DTC drives are: switching frequency that varies with operating conditions and high torque ripple. To solve these problems, and at the same time retain the simple control structure of DTC, a constant switching frequency torque controller is proposed to replace the conventional hysteresis-based controller. In this paper, the modeling, averaging, and linearization of the torque loop containing the proposed controller followed by simulation and experimental results are presented. The proposed controller is shown to be capable of reducing the torque ripple and maintaining a constant switching frequency.     

Adjustable speed control of ultrasonic motors by adaptive control

The driving principle of the ultrasonic motor (USM) is different from those of the electro-magnetic type motors. Some mathematical models for the USM have been reported; however, these models are very complex to apply for speed control of the USM. Therefore, the speed controllers have been designed using PI controllers or fuzzy controllers and it is necessary to develop a simple and convenient mathematical model for the USM in order to achieve a high-performance speed control. In this paper, a mathematical model for the USM is proposed which is simple and useful for speed control. The speed controller is designed based on the model using adaptive control theory. Adaptive control is attractive for control of the USM because the speed characteristics of the USM vary with drive conditions. The application of this control scheme to speed control for the USM is attempted first. The effectiveness of proposed control is demonstrated by experimental     

Band-constrained technique for direct torque control of induction motor

In this paper, a novel technique for the direct torque control (DTC) of an induction motor is proposed, which overcomes the trouble of high torque ripple afflicting the conventional DTC technique. With the novel technique, the inverter voltage vector selected from the switching table is applied for the time interval needed by the torque to reach the upper (or the lower) limit of the band, where the time interval is calculated from a suitable modeling of the torque dynamics. By this approach, the control system emulates the operation of a torque hysteresis controller of analog type since the application time of the inverter voltage vector is dictated by the allowed torque excursion and not by the sampling period. It is shown by experimental results that the technique yields a considerable reduction of the torque ripple. A further and ultimate reduction is obtained by compensating for the delay inherent in the discrete-time operation of the control system. The outcome is that the torque ripple of the motor is constrained within the hysteresis band of the torque controller, for a band of customary value. An ancillary merit of the technique is the almost full elimination of the average torque error inherent in the conventional technique. If the hysteresis band is shrunk, the torque ripple is bound to swing out the band limits. Under this circumstance, an extension of the technique is developed, which helps keep the torque ripple at minimum. To assess the characteristics of the proposed DTC technique, the following quantities: average torque error, rms value of the torque ripple, and inverter switching frequency are measured for different stator flux angular speeds and hysteresis bands of the torque and flux controllers. As a comparison, the same quantities are given for the conventional DTC technique.     

Minimum-time minimum-loss speed control of induction motors underfield-oriented control

A new minimum-time minimum-loss speed control algorithm for induction motors is suggested to obtain high performance, as well as high efficiency, under field-oriented control with practical constraints on voltage and current. This algorithm utilizes a two-stage control. In the transient stage, a maximum torque control algorithm is utilized to get the minimum-time response. In the steady state, a minimum-loss control algorithm is applied to improve the efficiency. Simulation studies show the performance of the proposed minimum-time minimum-loss control algorithm under field-oriented control     

A modular control scheme for PMSM speed control with pulsating torque minimization

In this paper, a modular control approach is applied to a permanent-magnet synchronous motor (PMSM) speed control. Based on the functioning of the individual module, the modular approach enables the powerfully intelligent and robust control modules to easily replace any existing module which does not perform well, meanwhile retaining other existing modules which are still effective. Property analysis is first conducted for the existing function modules in a conventional PMSM control system: proportional-integral (PI) speed control module, reference current-generating module, and PI current control module. Next, it is shown that the conventional PMSM controller is not able to reject the torque pulsation which is the main hurdle when PMSM is used as a high-performance servo. By virtue of the internal model, to ify the torque pulsation it is imperative to incorporate an internal model in the feed-through path. This is achieved by replacing the reference current-generating module with an iterative learning control (ILC) module. The ILC module records the cyclic torque and reference current signals over one entire cycle, and then uses those signals to update the reference current for the next cycle. As a consequence, the torque pulsation can be reduced significantly. In order to estimate the torque ripples which may exceed certain bandwidth of a torque transducer, a novel torque estimation module using a gain-shaped sliding-mode observer is further developed to facilitate the implementation of torque learning control. The proposed control system is evaluated through real-time implementation and experimental results validate the effectiveness.     

感应电机直接转矩控制系统中的模糊控制研究

对模糊控制在直接转矩控制系统中的应用做了全面分析和总结,重点讨论了各种模糊直接转矩控制方案的特点和不足之处.最后指出,这些方案都能改善系统性能,但无疑增加了系统的复杂性.     

感应电机直接转矩控制系统中的模糊控制研究

对模糊控制在直接转矩控制系统中的应用做了全面分析和总结,重点讨论了各种模糊直接转矩控制方案的特点和不足之处。最后指出,这些方案都能改善系统性能,但无疑增加了系统的复杂性。     

Synthesis of direct torque and rotor flux control algorithms by means of sliding-mode theory

This paper is an attempt to synthesize the direct torque and rotor flux control (DTRFC) algorithms of induction motor using sliding-mode theory. The choice of the sliding-mode theory has been motivated by the presence of switches in the voltage-source inverter (VSI). Changes in the state of the switches cause the variation in the topology of the controlled system. In addition, this theory offers a mathematical process that allows rigorous procedures of analysis and synthesis. The developed voltage vector is generated by two methods: direct control of the VSI (hysteresis VSI control), and indirect control of the VSI using space-vector modulation. In addition, taking into account the complementarity of the advantages of each VSI control algorithm, the high dynamic performance of the direct control and the smoothness of the indirect control, the idea of the dynamic reconfiguration of DTRFC algorithms is proposed.