Field-oriented Induction Machine Research Articles

Assessment of field oriented induction machine control strategy using new generation of inverters in BB36000 locomotive

Due to their excellent characteristics; Reaching high voltage inverters by using lower voltage switches, reduced output current distortion, dv/dt, and switching losses decrease, efficiency rise, multilevel inverters are an interesting alternative to the two-level inverters especially in traction applications. Many studies compared both topologies, but this work compare performances of Field oriented control strategy using two levels and neutral point piloted three levels inverter supplied by space pulse width modulation. Based on real parameters, this work shows that this efficient multilevel inverter reduces current distortion and torque ripples in a manner to reduces the size and cost of all railway traction systems chosen for this work

Transient Energy Efficiency Analysis of Field Oriented Induction Machines

An open loop control law for stator $d$ - and $q$ -axis currents in a rotor field oriented induction machine are derived in the form of analytical functions of time and used to study how energy losses during speed transients can be minimized. The trajectories due to the developed functions are inspired by the numerical solution of the induction machine optimal control problem. It is found that transient energy efficiency of the machine depends primarily on the initial rotor flux at the beginning of the transient interval. The influences of change in the rotor speed, rotor moment of inertia, and rotor time constant on optimal transient energy efficiency are analyzed and results are discussed.

Robust On-line Rotor Time Constant Estimation for Induction Machines

This paper proposes an on-line rotor time constant estimation strategy for indirect field oriented induction machines. The performance of the indirect field oriented control is dependent especially on the rotor time constant whose value varies according to the temperature. The proposed method calculates the difference between the nominal rotor time constant and the real value from the d- and q-axis integration terms of a proportional integral (PI) current regulator and the demanded voltages of the induction machine to regulate the current in the steady state. Because the proposed strategy has a simple structure and is available in wide speed and torque ranges, the proposed method can be easily used in the industrial field. The effectiveness of proposed strategy is verified with simulations and a 7.5kW experimental setup.

Two-motor single-inverter field-oriented induction machine drive dynamic performance

Multi-machine, single-inverter induction motor drives are attractive in situations in which all machines are of similar ratings, and operate at approximately the same load torques. The advantages include small size compared to multi-inverter system, lower weight and overall cost. However, field oriented control of such drives is a challenge since no two motors will have exactly the same operating conditions at any time. In general, at least some motors in the system will operate away from perfect field orientation. It is therefore important to analyse their torque dynamics carefully. This paper discusses existing multi-machine field-oriented control methods, and analyses and compares them from the viewpoint of dynamic performance. For this, an analytical framework based on small-signal analysis is developed to compare multi-machine control methods. This analysis is verified by simulations and experiments.

Speed Control of field oriented induction motor using DsPIC Controller

The paper entitled Control of field oriented induction machine using dsPIC review for field oriented control (FOC) induction machine. In this paper Closed loop control of adjustable speed drive is presented. DSPIC30F4011 Controller is a new platform for motor control application. In recent years, the use of ASD with advanced control technique is important for automation process for the application of industrial drives. This controller based, PWM-output, variable frequency drives provide the user with a tremendous variety of features and functions which allow accurate control and monitoring in nearly every 3-phase induction motor application. In this project,a proxy sensor or IR sensor is used to measure the speed of the motor and its given to the controller. The controller generates the pulses to drive the motor.

Fuzzy Tracking Control for Indirect Field-oriented Induction Machine Using Integral Action Performance

This paper deals with the synthesis of fuzzy controller applied to the induction motor with a guaranteed H∞ tracking performance. First, the Takagi-Sugeno fuzzy model is employed to approximate a nonlinear system in the synchronous d-q frame rotating with electromagnetic field-oriented. Next, a fuzzy observer-based fuzzy tracking controller is designed to stabilize the induction motor and guaranteed a minimum disturbance attenuation level for the closed-loop system. The rotor flux is unavailable for measurement and it is estimated by a fuzzy observer. An integral action is added to the new parallel distributed compensation fuzzy controller related to the tracking to avoid static errors. The gains of fuzzy control and fuzzy observer are obtained by solving a set of Linear Matrix Inequality. Finally, simulation result is given to demonstrate the controller’s effectiveness.

Increase in the efficiency of the speed controller of an induction machine drive by means of artificial intelligence

This paper describes the application of artificial intelligence to the synthesis of an efficient speed controller for an indirect field-oriented induction machine drive. In this case, two methods of artificial intelligence are proposed to reproduce the characteristics of a fuzzy controller with the maximum number of fuzzy sets. The first method is the adaptive network-based fuzzy inference system (ANFIS) structure by Sugeno and the second is the artificial neural network (ANN) structure. The resulting characteristics of each controller are presented.

A fuzzy learning—Sliding mode controller for direct field-oriented induction machines

This paper presents a direct field-oriented induction motor drive system with two distinct features: a sliding mode voltage mode flux observer (SMVMFO) and a fuzzy model reference learning controller (FMRLC). The speed of the induction motor is regulated using an FMRLC, which does not require rigorous tuning of the controller's parameters. The rotor flux estimation for the direct field orientation (DFO) is realized by a newly proposed SMVMFO, which is insensitive to the stator resistance variation. The complete drive system is shown to have very good speed tracking performance, accurate flux estimation and field orientation, and high robustness to stator resistance variation, which has been a long-standing problem in the area of motor drives. Extensive simulations are presented for performance evaluation and validation of the proposed control scheme.

Design and implementation of a new sliding-mode observer for speed-sensorless control of induction machine

In this letter, a new sliding-mode-sensorless control algorithm is proposed for the field-oriented induction machine drive. In the proposed algorithm, the terms containing flux, speed, and rotor time constant, which are common in both current and flux equations, in the current model of the induction machine are estimated by a sliding function. The flux and speed estimation accuracy is guaranteed when the error between the actual current and observed current converges to zero. Hence, the fourth-order system is reduced to two second-order systems, and the speed estimation becomes very simple and robust to the parameter uncertainties. The new approach is verified by simulation and experimental results.

Robust intelligent control of a speed sensorless induction motor

AbstractThis paper reports results of recent applications of intelligent control techniques to a field oriented induction machine. Induction motors are characterised by complex, highly non‐linear and time‐varying dynamics and inaccessibility of some states and outputs for measurements. The advent of vector control techniques has partially solved induction motor control problems because they are sensitive to drive parameter variations and performance may deteriorate if conventional controllers such as PID are used. With fuzzy logic and neural networks based control‐lers, uncertainties in the plant parameters and non‐linearities can be dealt with more efficiently than model‐based techniques. However, a commonly known disadvantage of these methods is the lack of systematisarion and rigorous design tools. Hybrid control architectures, combining control theory with artificial intelligent tools can solve efficiently complex control problems. Three control approaches are developed and applied to adjust the speed of the drive system. The first control design combines the variable structure theory with fuzzy logic concept. In the second approach neural networks are used in an internal model control structure. Finally, a fuzzy state feedback controller is developed based on pole placement technique. A simulation study of these methods is presented. The effectiveness of these controllers is demonstrated for different operating conditions of the drive system.

A PLUG-IN ROBUST COMPENSATOR FOR IFOC INDUCTION MACHINE DRIVES

It is well-known that the system performance for an indirect field-oriented control (IFOC) induction motor drive degrades under parameter variations and in the presence of external load torque. In this paper, a novel plug-in robust compensator for position control enhancement of an indirect field-oriented induction machine drive is developed. This plug-in compensator, designed using the ℋ∞ loop shaping techniques, can be plugged into the existing controller without affecting the already satisfactory nominal tracking performance of the existing closed loop system, but can improve the system performance under plant parameter variations and in the presence of external disturbances.

Fuzzy learning enhanced speed control of an indirect field-oriented induction machine drive

Indirect field orientation (IFO) induction machine drives are increasingly employed in industrial drive systems, but the drive performance often degrades due to machine parameter variations. In this paper, a fuzzy model reference learning control technique is applied to an IFO induction machine drive, such that the machine can follow a reference model (an ideal field oriented machine) to achieve the desired speed performance. Experimental results are presented to verify the effectiveness of the proposed control scheme.

Cascade sliding mode control of a field oriented induction machine drive

This study deals with the application of sliding mode control theory to induction machine fed by a PWM voltage source inverter in which the system operates in the field oriented control. Thus, after determining the decoupled model of the machine, a set of simple surfaces have been applied to a cascade structure and the associated control laws have been synthesized. Furthermore, in order to reduce chattering phenomenon, smooth control functions with appropriate threshold have been chosen. Simulation study is conducted to show the effectiveness of the proposed method and then validated by an experimental prototype.

On-line fuzzy tuning of indirect field-oriented induction machine drives

This paper presents an on-line fuzzy tuning scheme for indirect field-orientation (IFO)-controlled induction machine drives. A fuzzy controller is used to regulate the speed, and another two fuzzy compensators are combined to correct detuning of field orientation. Since detuning effects of the IFO induction machine drive is minimized by the new fuzzy control scheme, the induction machine can achieve good performance in terms of overshoot, steady-state error, torque disturbance, and variable-speed tracking. Efficiency and torque/ampere capability are also enhanced. The results obtained by laboratory implementation are presented to verify the effectiveness of the proposed on-line fuzzy-tuning scheme.

Stator resistance tuning in a stator-flux field-oriented drive using an instantaneous hybrid flux estimator

A self-tuning control scheme for stator-flux field-oriented induction machine drives in electric vehicles operating over a wide speed range is discussed in this paper. The stator flux can be determined accurately from the terminal voltage when the machine is operating at high speed. However, at low speed, the stator resistance must be known to calculate the stator flux. The problem of calculating the stator flux accurately over the entire speed range is addressed. The rotor flux can be found from the machine speed and rotor time constant. The stator flux, at low speed, is then calculated directly from the rotor flux. By alternating between these two methods of determining the stator flux, a self-tuning operation is achieved, wherein the stator and rotor resistances are periodically updated. Since both methods of determining the stator flux are forced to track one another, a smooth transition between flux estimators is obtained. The torque and flux are then controlled in a deadbeat fashion. Good torque control over a wide speed range can therefore be obtained. With the proposed scheme, the advantages of direct torque control are obtained over the entire speed range with the addition of a speed sensor.

Fuzzy logic enhanced speed control of an indirect field-oriented induction machine drive

Field orientation control (FOC) of induction machines has permitted fast transient response by decoupled torque and flux control. However, field orientation detuning caused by parameter variations is a major difficulty for indirect FOC methods. Traditional probability density function (PID) controllers have trouble meeting a wide range of speed tracking performance even when proper field orientation is achieved. PID controller performance is severely degraded when detuning occurs. This paper presents a fuzzy logic design approach that can meet the speed tracking requirements even when detuning occurs. Computer simulations and experimental results obtained via a general-purpose digital signal processor (DSP) system are presented.

Field-oriented control of an induction machine in the field-weakening region with DC-link and load disturbance rejection

A method of actively maintaining voltage margin in field-oriented induction machine controllers is proposed. A voltage-margin controller is developed that rejects DC-link and load disturbances, such that current regulation and field orientation is maintained. In addition, the voltage-margin controller coupled with rotor-flux-oriented control is shown to provide maximum torque capability equivalent to stator-flux-oriented control.

A physically insightful approach to the design and accuracy assessment of flux observers for field oriented induction machine drives

Rotor flux observers can provide an attractive means for achieving direct field oriented control of induction machines. This paper presents a physics-based design methodology and uses it to evaluate open-loop observers and to develop a new closed-loop flux observer. It is shown that the new flux observer is a straightforward structure with properties that combine the best features of known methods. A distinction is made between observers, which use only integration and feedback summation operations, and those estimation methods requiring approximate differentiation which are, in essence, "cancellation" methods. Furthermore, a clear distinction is made between accuracy and dynamic robustness of the observer. This distinction is important because the accuracy of flux observers for induction machines is inherently parameter sensitive, whereas robustness of observers, in a controls sense, is not parameter sensitive. Moreover, it is shown how flux observers can provide robust field oriented control because the flux angle is substantially more correct than the flux magnitude. A distinctive form of frequency response function (FRF) analysis similar to that used in classical control engineering is demonstrated to be a useful and insightful tool even though flux observers are multiple-input, multiple-output systems. Finally, the limits of such flux observers are experimentally evaluated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

ROTOR FLUX COMPUTATION IN SATURATED FIELD-ORIENTED INDUCTION MACHINES

ABSTRACT The paper discusses effects of main flux saturation in field–oriented induction machines and proposes improved schemes for rotor flux space vector calculation. Field–oriented control with rotor flux computation out of the measured quantities is elaborated. Two rotor flux computer structures are analyzed. The first one is based on stator voltages and currents as measured variables, while the second scheme carries out calculations on the basis of sensed stator currents and rotor speed (position). The sensitivity of the constant parameter rotor flux computers to saturation degree variation is investigated in detail. Modified structures of the computing schemes are then proposed, which account for change in saturation level in the machine. The modified rotor flux calculators are derived from flux state–space model of a saturated induction machine. Accurate computation of rotor flux space vector is enabled in this way, irrespective of the actual saturation level in the machine. Verification of the dev...

A simple and robust adaptive controller for detuning correction in field-oriented induction machines

A novel adaptive controller for correcting the rotor time constant estimate used in the slip frequency calculator of indirect field-oriented controllers (IFOCs) is presented. The controller possesses near digital deadbeat performance and simultaneously maintains its correctness down to zero speed. The robust controller dynamics are based on an operating-point form of digital deadbeat control. The correctness down to zero rotor speed is based on the determination of the rotor flux from an accurate air-gap flux estimate obtained from the third harmonic stator phase voltage component introduced by the saturation of the machine stator teeth. The proposed controller is implemented using a digital signal processor, and the experimental results demonstrate its excellent performance for a wide range of rotor speeds, including locked rotor conditions. >