RFNN controlled sensorless induction spindle motor drive

A sensorless induction spindle motor drive using synchronous PWM (SPWM) and dead-time compensator with recurrent fuzzy-neural network (RFNN) speed controller is proposed in this study for advanced spindle motor applications. First, the operating principles of a new type SPWM technique and the circuit of dead-time compensator using field-programmable gate arrays (FPGA) are described. Then, a speed observer based on a modified Luenberger observer is adopted to estimate the rotor speed. Moreover, since the control characteristics and motor parameters for a high-speed induction spindle motor drive are time-varying, an RFNN speed controller is developed to reduce the influence of parameter uncertainties and external disturbances. In addition, the RFNN is trained on-line using a delta adaptation law. Finally, the performance of the proposed sensorless induction spindle motor drive system is demonstrated using some simulated and experimental results.     

电流控制电压源逆变器驱动的感应电机逆解耦控制

在转子磁链坐标系下,以电流控制电压源逆变器供电驱动电机运行.通过在电流内环采用高增益控制器,感应电机模型中的2个定子电流分量可近似为定子参考电流,从而可忽略定子电流动态特性的影响,将以定子电压为控制量的感应电机四阶模型降阶成以定子电流为控制量的二阶模型.采用状态反馈线性化方法求得感应电机的逆系统,将多变量、非线性、强耦合的感应电机动态解耦成转速与转子磁链2个一阶子系统.在此基础上,设计一种积分比例(IP)控制器对解耦子系统进行闭环控制.电流内环采用滞环比较器,直接获得PWM信号,控制逆变器实现电流跟踪,从而使调速系统具有快速的动态响应性能.仿真结果验证所提控制方案的有效性和优越性.     

Quasi-resonant inverter-fed direct torque controlled induction motor drive

A quasi-resonant inverter-fed induction motor operated under direct torque control (DTC) scheme is modeled and analyzed with SABER simulator. The dc link voltage is clamped to source voltage. All the devices in the resonant link and inverter except auxiliary switch in the resonant link are operated soft under zero-voltage switching (ZVS). The auxiliary switch is turned on under zero-current switching (ZCS), but turned off hard. This scheme has been implemented on a laboratory-sized experimental setup. A comparison of simulation and experimental results under identical operating conditions were presented.     

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     

An improved CSI fed induction motor drive

Current source inverter (CSI) drives are preferred over voltage source inverter (VSI) drives in high power applications where fast dynamic response is not required. Conventional CSI drives have drawbacks such as resonance, instability at low speeds and high torque ripple, due to which their applications are restricted. This paper presents an improved CSI fed drive configuration that addresses these major drawbacks, as well as other power quality issues associated with the conventional drives. Two active power filters (APFs) are used in the proposed drive. The drive ensures sinusoidal waveforms at both the input and the output terminals. A simple CSI power circuit switching at fundamental frequency is used. Further, the use of a standard six-pulse SCR based rectifier eliminates the bulky and expensive input transformer, thus reducing the overall system cost. The proposed configuration is verified for a high power rating vector controlled induction motor drive. The design of the controllers and operation of the APFs are explained. Simulation results for the entire operating region of the drive including low speed operation and the field weakening region are presented. Finally, an important result regarding the presence of undesired circulating currents with the common DC bus for the two APFs, is also reported. The solution to avoid this problem is presented.     

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.     

双模糊神经网络的滑模控制感应电动机伺服驱动研究

根据感应电动机伺服驱动系统高性能的要求,设计了一种基于双模糊神经网络的滑模控制的感应电动机伺服驱动系统.控制策略具有设计过程简单、意义清晰、鲁棒性好等优点,对于参数未知、时变、负载扰动大的伺服系统,它是一种有效的实时控制策略.仿真和实验结果表明:该控制策略大大提高了系统的高速响应能力,鲁棒性强,系统具有较好的动、静态性能和抗干扰能力,是开发高精度、高性能交流伺服系统的一条有效途径.     

Variable speed drive with current source inverter supply and permanent magnet synchronous motor compared with cage induction motor

Contents Industrial drives with adjustable speed and a progressive torque speed characteristic may be built with a considerably higher efficiency by using the permanent magnet excited synchronous motor instead of the squirrel cage induction motor. To prove the benefit, the power losses of two experimental drive systems were determined by calculation and measurement as well. The air gap damper losses of the synchronous machine induced by the commutations of the stator current and the slot and winding harmonics of the air gap field are calculated by solving the 2-dimensional diffusion equation using harmonic series and by applying the Poynting-vector method. It turns out that the power losses of the drive are reduced by 44%.

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Drehzahlstellbarer Antrieb mit stromeinprägendem Frequenzumrichter und permanentmagnetisch erregtem Synchronmotor im Vergleich mit dem Käfigläufermotor

Übersicht Industrieantriebe mit stellbarer Drehzahl und progressiver Drehmoment-Drehzahl-Kennlinie können mit wesentlich besserem Wirkungsgrad gebaut werden, wenn anstatt eines Asynchron-Käfigläufermotors ein permanent erregter Synchronmotor verwendet wird. Um den Nutzen nachzuweisen, werden die Leistungsverluste von zwei experimentellen Antriebssystemen durch Berechnung und Messung bestimmt. Die Verluste des Luftspaltdämpfers der Synchronmaschine, die durch die Kommutierung des Ständerstromes und die Nut- und Wicklungsoberwellen des Luftspaltfeldes entstehen, werden durch Lösung der zweidimensionalen Diffusionsgleichung mit harmonischen Reihen und mit dem Poynting-Vektor berechnet. Es stellt sich heraus, daß die Leistungsverluste des Antriebs um 44% reduziert werden.

     

Analysis of PWM current source GTO inverter with PWM-controlledthyristor rectifier for induction motor drive

With the application of an energy rebound circuit for the pulsewidth modulation (PWM)-controlled rectifier, an improved current source gate turn-off thyristor (GTO) inverter system capable of producing sinusoidal inputs and outputs is presented. The energy rebound circuit in the inverter is used to turn off the thyristors in the rectifier for applying PWM control techniques and also to clamp the spike voltage produced in the inverter circuit. The principles and circuit operations of this system are described in detail, and requirements for PWM control of the rectifier are investigated. The conditions for satisfying the requirements of the energy rebound circuit are analyzed by experimental and theoretical methods. The PWM-controlled current source GTO inverter system is used to drive an eight-pole 400 Hz 5.5 kW induction motor. Analytical and experimental results, as well as the characteristics of the motor drives, are given     

Calculation method of linear induction motor supplied from symmetrical voltage source

Contents A finite length of the primary part of a linear induction motor (LIM) contributes to nonuniform magnetic field distribution in an airgap. It causes the current asymmetry if the primary winding is supplied from a symmetrical voltage source. This paper presents a calculation method of the LIM performance. The method is based on Fourier series technique and takes into account the current asymmetry caused by the end effects. In order to illustrate an influence of current asymmetry the calculation results of electromechanical characteristics of a flat single-sided LIM are presented.

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Die Berechnungsmethode eines linearen Induktionsmotors (LIM) der aus einer symmetrischen Spannungsquelle gespeist wird

Übersicht Die endliche Länge des Primärsteils eines linearen Induktionsmotors (LIM) ruft die ungleichmäßige Verteilung des magnetischen Feldes im Luftspalt hervor. Es bewirkt die Asymmetrie der Ströme, wenn die Wicklung des Primärsteils aus der symmetrischen Spannungsquelle gespeist wird. Dieser Beitrag stellt die Berechnungsmethode der Leistungen von LIM dar. Diese Methode beruht auf der Berücksichtigt der Asymmetrie der Ströme, die von Rand-effekten bewirkt wird. Die Ergebnisse der Berechnungen der elektromechanischen Charakteristiken des einseitigen flach LIM wurden dargestellt, um den Einfluß der Asymmetrie der Ströme zu illustrieren.

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List of symbols and abbreviations B magnetic flux density - b slot opening - d conducting plate thickness - E electric field intensity - E e.m.f. - F force - |I _r | phase current - J current density - imaginary unit - K _t finite primary width correction factor - K _C Carter's coefficient - k, l, i harmonic and wave number - L primary length - P ₁ input power - P _m mechanical power - q number of slots per pole per phase - s slip - |U _r | phase voltage - v secondary speed relative to primary - W primary width - w _c number of wire per coil - w _s secondary width - X reactance - P power losses - Z impedance - conductivity - modified airgap length - _r actual airgap length - permeability - LIM efficiency - ( _s –L) distance between adjacent primaries - _i tooth pitch - _x pole pitch - Q=Q _m exp (jt) Q _m =|Q _m| exp (j) - Q ^* conjugate value ofQ - r number of phase - angular frequency - f frequency     

PWM-CSI induction motor drive with phase angle control

The authors describe a pulse-width-modulated current-source inverter drive system using an induction motor. Its dominant feature is that it provides adequate control of either torque or speed over a wide range without requiring a shaft position or speed sensor. The capacitor-loaded current-source invertor system has the advantages of simplicity, low switching frequency, four-quadrant operation, overcurrent protection, and low harmonic content in the motor current and voltage. The choice of maximum value for the capacitor depends on the degree of nonlinearity that can be tolerated in the torque-stator current relation, whereas its minimum value depends on the need for a low impedance path for inverter current harmonics. The control strategy is based on the concept of controlling the stator phase angle of the induction motor. The stator voltage is sensed, and the current-source inverter is used to inject current into the motor with the desired phase angle     

Lower speed range drive for sensorless vector controlled induction machines with stator voltage offset compensation method

The vector control method is widely used for induction machine drives. Recently, sensorless vector control for induction machines has been investigated and proposed. The speed range for the drives is limited to about 1:100 in industry. The main reason for this limitation is the inaccuracy of stator voltage measurement. The lower the rotor speed is, the lower the stator voltage. Therefore, it is difficult to detect the stator voltage accurately in the lower speed region, and difficult to control motor speed and motor torque precisely. This paper presents a method of improving the lower speed performance of sensorless vector controlled induction machine drives using offset compensation of stator voltage. The offset is compensated by using the fluctuation of the estimated rotor flux. The validity of the proposed method is verified by experimentation. © 2000 Scripta Technica, Electr Eng Jpn, 133(1): 79–86, 2000     

Neural network-based stator voltage compensator for low-frequency operation of a vector-controlled induction motor drive

The stator field-oriented sensorless vector control method is receiving wide attention from the standpoints of being sensorless and less dependent on the motor parameters. However, this method has a problem at low speeds because actual stator voltage does not coincide with the corresponding reference voltage owing to the quantization error in the controller, the discrete-time process, the forward voltage drop of switching devices, and the dead time of the inverter. In this study, an artificial neural network-based voltage compensator is proposed to reduce the voltage error between the reference and the actual voltages. The proposed method was performed on an experimental system and the results were found to be excellent.     

新型感应电机V/F控制系统稳定性方法

针对感应电机V/F控制系统在空载或轻载时存在一个持续振荡的稳定性问题,提出一种改善感应电机V/F控制系统稳定性的方法.根据感应电机的数学模型,研究了系统振荡与无功电流波动之间的关系.并基于定子电压定向对电流进行分解,通过控制无功电流恒定调节输出电压来抑制电机振荡,提高系统的稳定性.实验结果表明:该方法不依赖电机参数,鲁棒性高,使系统在0～50 Hz内都能平稳运行.电机的振荡得到了抑制,有效地提高了系统的稳定性.     

Application of type-2 fuzzy logic controller to an induction motor drive with seven-level diode-clamped inverter and controlled infeed

This paper describes a new control method for the integrated of six current rectifiers—seven-level diode-clamped inverter feeding induction motor considering dc-link capacitors voltage balancing problem. The proposed controller uses type-2 fuzzy systems to compensate the fluctuations of capacitors voltage, draw a sinusoidal line current with nearly unity power factor, and ensure the motor speed control. The performance of dc-link voltages control is evaluated in comparison to the conventional PI control scheme. The overall system and the control algorithm are presented and a set of simulations is carried out in order to prove the good performances of the proposed solution.     

A single phase induction motor drive with improved performance

This paper presents a new method to improve the efficiency and torque characteristics of a single phase induction motor. First, the mathematical model of the motor is analyzed. Next, a method which uses power electronic technology to improve the efficiency and starting torque of the motor is proposed. The starting capacitor and the centrifugal switch can be eliminated here. Only a running capacitor is used. A prototype system which consists of some simple hardware circuits and a TMS320C40 digital signal processor system has been implemented. Several experimental results can validate the simulated waveforms. This paper proposes a new direction in improving the performance of the single phase induction motor system.