The efficiency of induction motor drives operating under variable conditions can be improved by predicting the optimum flux that minimizes the losses. In this study, a Loss-Minimization Controller (LMC) and a Search Controller (SC) are combined. The output from the controllers would drive the field oriented control inverter in order to achieve the optimum flux in the motor that minimizes the losses. For this purpose, a mathematical model for calculating the total power losses as a function of magnetic flux and a factor to obtain feedback as a function of optimum flux were discussed. An LMC-SC vector-controlled induction motor drive system was modelled, simulated and tested. The results have validated the effectiveness of this system in minimizing the motor operating losses, especially at light and medium loads. The proposed controller can be implemented in adjustable speed induction motor drive systems with variable loads, operating below rated speed.

This paper has presented a mathematical-based scheme for induction motor drive system leading to efficiency optimization.The proposed scheme uses information on torque of the squirrel cage motor to generate the appropriate voltage amplitude that maximizes the motor efficiency.A constantV/f efficiency controller model has been configured and built depending on a set of experimental data, based on the motor equivalent circuit, using Matlab computer program.The model was validated by simulation using a typical induction motor drive model implemented with Matlab/Simulink.The aim of this paper is the drive system performance improvement by designing optimal efficiency controller; this will supply stator of the motor with proper voltage and frequency under different loading conditions using appropriate algorithm.

The paper considers controlling DC motor speed using LabVIEW-based frequency locked loop control algorithm which consists of a set of virtual instruments. Power interface circuit is required to supply the motor. In order to realize frequency-lock; a software digital integrator is used by implementing up-down counter. Proportional control term is included in order to control the depth of integral action. The result of the experiment shows acceptable startstop time characteristics and that motor speed is hold constant independent of motor load changes.

This paper presents Electronic Workbench (EWB) model used for parametric speed control of Separately Excited DC Motor, namely armature voltage, armature resistance and field current control methods. The speed time response and the armature current time response were investigated during start up period. The speedtorque characteristics were plotted. The study is carried out using one model contacting four functional blocks. The results should be implemented in electric drive laboratory at Al-Balqa Applied University.

Energy efficiency optimization techniques of electrical drive systems improve the overall efficiency and reduce the hardness of mechanical characteristics of the drive system. It is therefore important to reduce the slip of induction motor to maintain its stable operation at different frequencies and loads. In this paper a slip compensator, based on fuzzy logic incremental controller has been developed to improve the steady state performance of efficiency-optimized three-phase induction motor drive system. The slip control is accomplished through a fuzzy controller with 9 rules, taking speed error and speed error variation as inputs, to produce the frequency. The proposed controller reduces the slip occurring at low frequencies and light loads to certain value, and also reduces the energy efficiency of the system.

This research presents two mathematical -based optimal control systems for induction motor drives leading to stator current optimization and energy saving.The first is a classical optimal control system, which uses information on torque of the motor to generate the appropriate voltage amplitude that minimizes the induction motor stator current.The second is a genetic algorithmbased optimal control system, which uses information on torque of the motor to generate the appropriate minimum stator current according to fitness function.The constant f V optimal stator current controller models have been configured and built depending on a set of experimental data using MATLAB computer program, the models were validated by simulation using a typical induction motor drive model implemented with MATLAB/Simulink toolbox.The aim of this research is the industrial machineries performance improvement by analyzing and designing the induction motor optimal stator current controller, this will minimize the stator current under different loading conditions.Depending on the motor shaft mechanical load torque in order to minimize the stator current, the controller will supply stator of motor with proper voltage and frequency using appropriate control algorithm for industrial machinery.

This paper describes a strategy for identification and control of three-phase squirrel cage induction motors. The strategy in this work is divided into 3 stages: on-line identification, off-line controller design, and on-line control. First, the transfer function is identified online. Next, the controller design is performed in a pure simulation environment using the identified transfer function. Finally, the designed controller is applied to the real system.Simulation and experimental results are presented to show the validity of the proposed strategy. Advantages of the proposed strategy include high accuracy in the identified system, simplicity, and low cost. (C) 2009 Elsevier B.V. All rights reserved.

This paper employs a strategy based on hardware-in-the-loop (HIL) concept to control 3-phase induction motor on-line. The strategy in this work is divided into 3 stages: on-line identification, off-line controller design, and on-line control. The scope of this paper is limited to the controller part and therefore addresses the last two stages of the strategy. The implementation of the strategy was accomplished using HIL within a Simulink environment. Experimental results for different speed profiles are presented which show the validity of the proposed strategy. Advantages include optimizing time resources and minimizing the cost. This is a result of designing the controller offline and applying different virtual controllers to the system.

Induction motors are widely used in the industry. However, due to their involved mathematical models those depend on difficult to measure parameters such as leakage inductance. Therefore, simplified model approximations are usually used instead. In this paper, a system identification method based on auto regressive moving average (ARMA) models and hardware-in-the-loop (HIL) concept has been employed to identify and predict the behavior of a squirrel cage induction motor. The motor transfer function is identified online using an impulse input. Then, the identified model response is compared to the real system response with different input signals. Results show that the model used follows the real system response with good accuracy.

An inverter-three-phase squirrel-cage induction motor drive system with improved mechanical characteristics is presented. The proposed system provides mechanical characteristics with constant maximum torque or increased maximum torque and reduced slip speed at frequencies below the nominal frequency. The control algorithm is based on the constant volts per hertz principle using two improvement techniques: keeping maximum torque constant or keeping magnetic flux constant. Performance analysis of the system under different operation conditions was provided. For this purpose, a standard state-space model of three-phase squirrel-cage induction motor, with respect to a synchronously rotating d-q reference frame was derived. The correctness and validity of the derived model of induction motor was verified. The inverter was considered as a static linear element and modeled through its input-output equation based on the modulation index. Three types of controllers were modeled, simulated and experimentally tested. The results show that both suggested control methods improve the system performance. The slip speed has been decreased and the starting torque and maximum torque have been increased. Controller with constant maximum torque can be used in drive systems working with constant load, while controller with constant flux can be used in drive systems working with constant power.