Energy Efficient Control of Three-Phase Induction Motor - A Review
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paper_title: Robust DSP-based efficiency optimization of a variable speed induction motor drive

paper_content:

This paper proposes a practical digital-signal-processor (DSP)-based algorithm for the online efficiency optimization of induction motor drives. The algorithm combines good features of the search control and loss-model-based control, while simultaneously eliminating their major drawbacks. It ensures very fast convergence without the need for any a priori knowledge of the motor loss-related parameters. The minimum loss operating point is decided from a functional approximation of the motor and the power converter losses, in the form of a suitably defined loss function. The loss function parameters are obtained online from input power measurement and a dedicated identification routine acting in conjunction with the common drive control functions. Proposed online identification of the loss function parameters relies upon the signals and states readily available within the drive controller memory and does not involve the user entry nor the initialization procedure. The proposed controller is coded into a conventional low-cost 16-bit DSP and verified on a 2.2-kW induction motor drive prototype.
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paper_title: A neuro-fuzzy-based on-line efficiency optimization control of a stator flux-oriented direct vector-controlled induction motor drive

paper_content:

Fuzzy logic-based online efficiency optimization control has been described previously for an indirect vector-controlled induction motor drive. The purpose of this paper is to extend the same control to a stator flux-oriented electric vehicle induction motor drive and then implement the fuzzy controller by a dynamic back propagation neural network-based controller. The principal advantage of fuzzy control, i.e., fast convergence with adaptive step size of the control variable, is retained. The neural network adds the advantage of fast control implementation, either by a dedicated hardware chip or by digital signal processor (DSP)-based software.
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paper_title: Performance optimization of induction motors during Voltage-controlled soft starting

paper_content:

This paper deals with the performance optimization of medium/high-power induction motors during soft starting by eliminating the supply frequency torque pulsations, and by keeping the line current constant at the preset value. Starting torque pulsations are eliminated by triggering back-to-back-connected thyristors at proper points on the first supply voltage cycle. Line current during starting can be kept constant at any preset value by a simple strategy composed of successive cosinusoidal and constant function segments of the triggering angle. These strategies are implemented by the use of an 8-b microcontroller. Transient performance analyses of the system are carried out by means of a hybrid ABC/dq machine model which takes into account the three-phase, two-phase, and disconnected modes of operation in terms of actual stator variables. Experimental results obtained on a custom-design test bed are found to be in good agreement with the theoretical ones.
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paper_title: Differential Evolution based Optimal control of Induction Motor Serving to Textile Industry”, Int

paper_content:

This paper illustrates the importance of controllers on energy saving opportunity of partial loaded three-phase induction motor in textile mill (ring spinning frame) applications. The economics of a scalar controlled 100 HP induction motor is investigated with three topologies namely star-delta (S/D) connection, constant Volt/frequency (V/f) controller and Differential Evolution (DE) controller in steady-state conditions. In this study, the flux level in a machine has been considered to adjust to give minimum operating cost for the textile mill load. The flux controller improves the economics in terms of operating cost (energy cost and demand charge cost) and the test results show that the flux level in the most economic motor will be adjusted according to load and speed, particularly at light load. Standard benchmark problems (Rastingin and Griewank) have been considered for validation of the proposed DE controller for induction motor operating cost minimization. Case study also presented in this paper.
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paper_title: Energy saving operation of induction motors by voltage reduction at no and low partial-load

paper_content:

An investigation of the electrical energy savings obtained by reducing the terminal voltage of induction motors when they are not loaded or only partially loaded is presented. The purpose is to obtain information to help decide whether to install an energy saving device in plants using induction motors. At no-load operation, the saving can be as high as 50%. The saving decreases with the increase of load. Switching-off one phase of the three-phase supply during no-load operation does not contribute to energy saving. Intermittent disconnection of the supply voltage can lead to considerable energy saving, if the interruption interval is sufficiently long. This method is recommended for small motors. >
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paper_title: Energy optimization of induction motor drives

paper_content:

This paper deals with energy optimization of induction motor drives. In many applications, efficiency optimization of induction motors represents an important factor of control especially for autonomous electrical traction. In this paper different approaches to improve efficiency in vector controlled induction motor drives at steady state condition are compared. Three methods are possible to control the excitation: Methods based on induction motor losses, methods based on the use of look-up table and methods based on search controllers of minimum. We expose in this paper some methods, which use the search controller techniques. These techniques consist in changing flux level in small steps to keep the output power of the motor constant and find the minimum of input power. These controllers are efficient at steady state condition and do not require knowledge of motor and converter parameters. However, the search controller using the stator current instead of power give similar results to their using power. This technique is less complex and doesn't need measurement of PWM quantities. The proposed search controller is based on fuzzy algorithm. The advantages of this controller are compared with others known as Rosenbrock method and Golden section. Fuzzy search controller presents a good trade off between convergence time and oscillations of stator current ripple.
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paper_title: Efficiency optimizing control of induction motor using natural variables

paper_content:

This paper presents a new approach of optimizing the efficiency of induction motor drives through minimizing the copper and core losses. The induction machine model which accounts for the varying core loss resistance and saturation dependent magnetizing inductance uses natural and reference frame independent quantities as state variables. Utilization of the nonlinear geometric control methodology of input-output linearization with decoupling, permits the implementation of the control in the stationary reference frame. This approach eliminates the need of synchronous reference transformation and flux alignment required in classical vector control schemes. The new efficiency optimizing formulation yields a reference rotor flux which ensures minimum loss and yields an improved efficiency of the drive system especially when driving part-load. The proposed scheme and their advantages are demonstrated both by computer simulations and some experimental results for motor speed control.
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paper_title: THREE-PHASE INDUCTION MOTOR DESIGN OPTIMIZATION USING THE MODIFIED HOOKE-JEEVES METHOD

paper_content:

ABSTRACT A new method of computer-aided design optimization of a three-phase induction motor is proposed. Due to the highly non-linear nature of the design optimization problem an approach using the modified Hooke-Jeeves method is employed. The optimization of the objective function (motor efficiency) is deduced in terms of eight independent motor design variables which are then used to predict seven performance indices and the cost index of the machine. The method is applied to optimize the design of a 5-HP motor. The results obtained are compared with those of an optimally designed motor [3].
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paper_title: Minimizing Induction Motor Losses by Excitation Control in Variable Frequency Drives

paper_content:

For a given induction motor under a specified load condition, a combination of stator voltage and frequency exists which results in minimum power losses. This optimal operating point is calculated over the complete speed and torque range using a model of the induction machine including saturation, stray losses, and skin effect. It is shown that substantial power savings can be achieved compared to conventional programmed volts/hertz control and that main flux saturation has a dominant role in determining the optimal operating condition. A detailed analysis of the mechanisms yielding power savings is presented as well as an experimental confirmation of the theoretical results. These results are utilized to study thetinfluence of machine size, rated slip, and other factors on the optimal performance.
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paper_title: Efficiency optimization of a vector controlled induction motor drive using an artificial neural network

paper_content:

This paper presents an approach for efficiency optimization of a vector controlled induction motor drive. The optimum flux-producing current is obtained using an artificial neural network. The artificial neural network model is established using Matlab/Simulink and based on the load torque and speed data of an indirect vector-controlled induction motor drive. The change of iron core loss resistance due to flux and frequency variation is taken into consideration. Simulation results of the proposed approach show a significant improvement in energy saving and efficiency optimization.
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paper_title: Induction motor optimum flux search algorithms with transient state loss minimization using a fuzzy logic based supervisor

paper_content:

A review of different optimum flux search algorithms for loss minimization in a vector-controlled induction motor drive is presented. A fuzzy logic controller, actuating as a supervisor, is proposed to work with reduced flux levels during transients and also to optimize efficiency in dynamic modes. Experimental results demonstrate the validity of the proposed methods.
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paper_title: Microprocessor-Based Optimal-Efficiency Drive of an Induction Motor

paper_content:

A method for improving the efficiency of a slightly loaded induction motor is suggested. It is based upon the optimal-efficiency slip tracking by adjusting the voltage to frequency ratio (V/f). It has adopted the converter-inverter fed induction motor drive system. All the control loops are implemented by the Z-80 microprocessor. By this method, 10 percent or more improvement is obtained at a quarter of the full load.
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paper_title: Multiobjective optimal design of three-phase induction motor using improved evolution strategy

paper_content:

This paper presents the multiobjective optimal design of induction motor for Electric Vehicle (EV) using a modified evolution strategy (ES). The Optimization process is performed by using (1+1) evolution strategy (ES). The conventional ES algorithm falls into a trap of local minima with high probability in solving the optimization problem that has many design variables. To overcome this problem, ES algorithm is modified by introducing shaking technique. To verify its validity, the proposed method is applied to an induction motor design.
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paper_title: Application of soft computing techniques to induction motor design

paper_content:

Purpose – The purpose of this paper is to present a comparative study of the various soft computing techniques and their application to optimum design of three‐phase induction motor design.Design/methodology/approach – The need for energy conservation is increasing the requirements for increased efficiency levels of induction motor. It is therefore important to optimize the efficiency of induction motor in order to obtain significant energy savings. To optimize the efficiency, design of the induction motor has to be chosen appropriately. In this paper, computational intelligence techniques such as artificial neural network, fuzzy logic, genetic algorithm, differential evolution, evolutionary programming, particle swarm optimization, simulated annealing approach, radial basis function, and hybrid approach are applied to solve the induction motor design optimization problem.Findings – These methods are tested on two sample motors and the results are compared and validated against the conventional Modified H...
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paper_title: DESIGN OPTIMIZATION OF INDUCTION MOTOR BY GENETIC ALGORITHM AND COMPARISON WITH EXISTING MOTOR

paper_content:

This paper presents an optimal design method to optimize three-phase induction motor in manufacturing process. The optimally designed motor is compared with an existing motor having the same ratings. The Genetic Algorithm is used for optimization and three objective functions namely torque, efficiency, and cost are considered. The motor design procedure consists of a system of non-linear equations, which imposes induction motor characteristics, motor performance, magnetic stresses and thermal limits. Computer simulation results are given to show the effectiveness of the proposed design process.
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paper_title: Loss minimization control of induction motor drives based on genetic algorithms

paper_content:

In this paper, a new approach using a floating point genetic algorithm (GA) is applied to minimize induction motor (IM) electric losses. The maximum efficiency is obtained by the online evaluation of the optimal magnetization flux. The loss model approach used is based on the steady state mathematical model of the IM. Some simulation results are given to validate this new approach. It is shown that this approach gives good results both in the steady state and dynamic operations.
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paper_title: Optimization of Three-Phase Induction Motor Design Using Simulated Annealing Algorithm

paper_content:

Three-phase induction motors are designed to meet various special requirements. Irrespective of these requirements, the basic conditions to be fulfilled are (1) The starting torque must be high, and (2) Operating efficiency and power factor must be as high as feasible. This article discusses the formulation of design optimization of three-phase induction motor as a nonlinear multivariable programming problem to meet the above requirements. Three different objective functions were considered. The simulated annealing algorithm was used to obtain an optimum design. The algorithm was implemented on three test motors and the results indicate that the method has yielded a global optimum. The proposed algorithm results are compared with the conventional design results to select a suitable optimal design of the induction motor. The performance of the motor is found to improve with application of this algorithm.
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paper_title: Digital Implementation of DTC Based on PSO for Induction Motors

paper_content:

A novel scheme for direct torque control (DTC) using particle swarm optimization (PSO) was proposed. The PSO was used to adjust the parameters (Kp, Ki, Kd) of PID controller. The scheme improves the adjustive capability of PID controller. PSO-PID controller decreases the torque ripple and rotor speed ripple, and increases system rapidity and stability. Finally, the strategy was implemented using TMS320F240 digital signal processor on a 370W induction motor drive. Experimental results illustrate that the system has a better dynamic and steady characteristics
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paper_title: A genetic algorithms approach for adaptive field oriented control of induction motor drives

paper_content:

In this paper an adaptive field oriented control of induction motor drive is proposed. The adaptive scheme uses a genetic algorithm for the identification of the rotor time constant, which is used to adjust the estimate of the slip angular speed. The identification method is presented as an optimization problem where the objective function is the total square error between the motor and the commanded stator currents. Computer simulation results are obtained and the performance of the resulting field oriented controller is analyzed. Further, this paper indicates that the genetic algorithm approach amounts to a promising methodology to handle adaptive control of indirect field oriented induction motors.
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paper_title: Motor design features for adjustable-frequency drives

paper_content:

The advantages of having a motor specifically designed for adjustable-frequency drive systems are listed. Some of the design parameters that can be changed to make motors more compatible with the nonsinusoidal current and voltage waves generated by these drive systems are detailed. It is suggested that users and the motor industry combine to encourage these improvements. >
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paper_title: Optimal design of three phase induction motors and their comparison with a typical industrial motor

paper_content:

Abstract Three optimally designed three-phase squirrel-cage induction motors are compared with an industrial (conventional) motor having the same ratings. The Hooke–Jeeves search routine is used for optimization and three objective functions, namely efficiency, efficiency–cost and cost, are considered. Comparison of the optimum designs with the initial and industrial design reveals that better than the proposed performance can be obtained by a simple optimization method. It is interesting to note that the industrial design satisfies some performance of the cost optimum design, and efficiency optimum design, of course with a lower efficiency. The most desirable variation of motor performance with line voltage and output power is due to the efficiency optimum design.
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paper_title: Induction motor design optimization using constrained Rosenbrock method (hill algorithm)

paper_content:

Abstract In the present work an optimum design of polyphase cage induction motor using Rosenbrock's method is put forth. The optimization programme considers the cost of active materials as an objective function and temperature rise and other performance items as constraints. The variables chosen are ampere conductors/m, ratios of stack length to pole pitch and stator slot depth to width, stator core depth (cm), average air gap flux density (wb/m 2 ) and stator and rotor winding current densities (A/mm 2 ).
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paper_title: No tooling cost process for induction motors energy efficiency improvements

paper_content:

In This work the analysis of some possibilities for increasing the induction motor efficiency using production technological process modifications is reported. This approach is known as "No Tooling Cost" (NTC) strategy because it does not require a complete redesign of new laminations and a consistent cost increment in terra of investments. The paper shows the results obtained by a full experimental approach, using "ad hoc" prototypes. The NTC design modification and the technological processes analyzed in This work have been done on TEFC standard induction motors. The original motors have been compared from the energetic point of view with these prototypes. The energetic performances have been measured in accordance with the IEEE Std.112-96 method B. In particular, the following modifications, for getting an efficiency increase, have been taken into consideration: rotor with copper bar included in the slot before the aluminum die cast process, increase of the core axial length and annealing of the stator core.
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paper_title: Energetic parameters of induction motors as the basis of energy saving in a variable speed

paper_content:

The purpose of the given paper is to consider energy saving with the help of an induction motor for a vari- able speed drive modernization. Realization possibility of energy saving ways at the expense of induction motor mod- ernization without transversal section change has been shown. Carried out economical calculations allow to note that ob- tained electrical losses cost decreases by 10 %, but the in- creased motor cost as the result of modernization will cover the expenses for less than five months.
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paper_title: A new global optimization approach for induction motor design

paper_content:

This paper proposed a new global optimization approach for electric machine design problems. Its algorithm uses the error function between the actual cost function at a given computational step, and its limit value which is lower than the desired global minimum. The error function provides a good indication of how far or close the cost function is approaching its limit solution. This method may be considered to be self adaptive in a sense that the higher the error is, the higher the step size of the variables will be. This feature will help the function to escape local solutions and tend to reach the targeted solution. The proposed approach has been tested on various typical multimodal functions and particularly, applied to induction motor design optimization problems. The algorithm of this method is very simple and easy to implement but yet powerful and effective as highlighted in the test results.
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paper_title: Optimal stator slot design of inverter-fed induction motor in consideration of harmonic losses

paper_content:

This paper proposes optimal design method of stator slot for three-phase cage induction motor fed by six-step inverter output voltage by using proposed analysis method. The finite-element method (FEM) on one phase band stator periodic condition is coupled with harmonic equivalent circuit. Using the FEM, the stator slot is optimally designed and the result is presented. Stator core loss and copper loss including harmonic loss are reduced by the proposed optimum slot design method. The analysis result is verified by experimental measurement.
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paper_title: Multiobjective optimal design of three-phase induction motor using improved evolution strategy

paper_content:

This paper presents the multiobjective optimal design of induction motor for Electric Vehicle (EV) using a modified evolution strategy (ES). The Optimization process is performed by using (1+1) evolution strategy (ES). The conventional ES algorithm falls into a trap of local minima with high probability in solving the optimization problem that has many design variables. To overcome this problem, ES algorithm is modified by introducing shaking technique. To verify its validity, the proposed method is applied to an induction motor design.
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paper_title: Application of soft computing techniques to induction motor design

paper_content:

Purpose – The purpose of this paper is to present a comparative study of the various soft computing techniques and their application to optimum design of three‐phase induction motor design.Design/methodology/approach – The need for energy conservation is increasing the requirements for increased efficiency levels of induction motor. It is therefore important to optimize the efficiency of induction motor in order to obtain significant energy savings. To optimize the efficiency, design of the induction motor has to be chosen appropriately. In this paper, computational intelligence techniques such as artificial neural network, fuzzy logic, genetic algorithm, differential evolution, evolutionary programming, particle swarm optimization, simulated annealing approach, radial basis function, and hybrid approach are applied to solve the induction motor design optimization problem.Findings – These methods are tested on two sample motors and the results are compared and validated against the conventional Modified H...
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paper_title: An evolutionary algorithm for the optimal design of induction motors

paper_content:

This paper describes the application of an evolutionary algorithm to the design of induction motors. It is shown that the use of an evolutionary algorithm offers advantages over other approaches. These include a high rate of global convergence and the ability to handle discrete variables.
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paper_title: DESIGN OPTIMIZATION OF INDUCTION MOTOR BY GENETIC ALGORITHM AND COMPARISON WITH EXISTING MOTOR

paper_content:

This paper presents an optimal design method to optimize three-phase induction motor in manufacturing process. The optimally designed motor is compared with an existing motor having the same ratings. The Genetic Algorithm is used for optimization and three objective functions namely torque, efficiency, and cost are considered. The motor design procedure consists of a system of non-linear equations, which imposes induction motor characteristics, motor performance, magnetic stresses and thermal limits. Computer simulation results are given to show the effectiveness of the proposed design process.
---
paper_title: Optimization of Three-Phase Induction Motor Design Using Simulated Annealing Algorithm

paper_content:

Three-phase induction motors are designed to meet various special requirements. Irrespective of these requirements, the basic conditions to be fulfilled are (1) The starting torque must be high, and (2) Operating efficiency and power factor must be as high as feasible. This article discusses the formulation of design optimization of three-phase induction motor as a nonlinear multivariable programming problem to meet the above requirements. Three different objective functions were considered. The simulated annealing algorithm was used to obtain an optimum design. The algorithm was implemented on three test motors and the results indicate that the method has yielded a global optimum. The proposed algorithm results are compared with the conventional design results to select a suitable optimal design of the induction motor. The performance of the motor is found to improve with application of this algorithm.
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paper_title: Control Means for Minimization of Losses in AC and DC Motor Drives

paper_content:

Motor drive losses can be reduced considerably by independently controlling the voltage and frequency for ac motors, and the field current and armature voltage for dc motors for any torque and speed operating point. The quantities to be controlled are already accessible in inverter ac power supplies and phase-controlled rectifier dc power supplies. The control signals can be supplied by an open- loop controller which solves the loss minimization equations using preset drive parameters, or by an optimizing controller that measures or calculates the losses and finds the combination of quantities that minimizes the losses.
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paper_title: Numerical approach to loss minimization in an induction motor

paper_content:

This paper describes a numerical approach to power-loss minimization in a fractional hp induction motor driven by a voltage-source inverter. The motor parameters are obtained from a genetic algorithm search. Optimum voltage and frequency excitations are arranged as a table for an energy-saving controller. The proposed method is useful under variable-torque load conditions. Simulation and experimental results are presented.
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paper_title: An efficient controller for an adjustable speed induction motor drive

paper_content:

The induction motor (IM) is a high-efficiency machine when working close to its rated operating point. However, at torques and/or speeds far from the rated values the efficiency is greatly reduced. In this work a new approach is proposed that minimizes the total copper and iron losses in a variable speed and/or torque IM drive, while keeping a good dynamic response. This method is based on a simple IM model that includes iron losses. The model, which only requires the knowledge of conventional IM parameters, is referred to a field-oriented frame. Using this model, the IM losses are quantified and an algorithm, based on a field-oriented scheme, is deduced. Simulation and experimental results are presented to validate the proposed method. >
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paper_title: Differential Evolution based Optimal control of Induction Motor Serving to Textile Industry”, Int

paper_content:

This paper illustrates the importance of controllers on energy saving opportunity of partial loaded three-phase induction motor in textile mill (ring spinning frame) applications. The economics of a scalar controlled 100 HP induction motor is investigated with three topologies namely star-delta (S/D) connection, constant Volt/frequency (V/f) controller and Differential Evolution (DE) controller in steady-state conditions. In this study, the flux level in a machine has been considered to adjust to give minimum operating cost for the textile mill load. The flux controller improves the economics in terms of operating cost (energy cost and demand charge cost) and the test results show that the flux level in the most economic motor will be adjusted according to load and speed, particularly at light load. Standard benchmark problems (Rastingin and Griewank) have been considered for validation of the proposed DE controller for induction motor operating cost minimization. Case study also presented in this paper.
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paper_title: Robust torque control design for induction motors: The minimum energy approach

paper_content:

Abstract This paper presents two different aspects concerning the control design laws for induction motors: (1) it derives state operating points (steady-state values for currents and fluxes) parameterized in terms of the desired motor torque, defining minimum-energy operation conditions for the electrical motor. (2) It gives a state-space feedback control design methodology based on Lyapunov analysis which renders the minimum-energy operating points invariant. Several controllers are proposed: P-type control, observer-based P-type control, PI-type control and observer-based PI-type control. The PI-structure and the observer-based control are introduced to deal with motor parameter uncertainties, and the absence of flux measurements, respectively. Stability of all these control schemes is studied. Experimental results are also presented.
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paper_title: Optimal efficiency analysis of induction motors fed by variable-voltage and variable-frequency source

paper_content:

The authors discuss the efficiency analysis and experimental data for an induction motor fed by a variable-voltage and variable-frequency (VVVF) source. Nonideal factors (core saturation, source harmonics, and skin effect) affecting the efficiency are included in the analysis to yield practical results from computer simulation. Based on the simulated results, an experimental system, composed of a DC link power converter with a VVVF feature, a dynamometer and a PC/AT, was developed to evaluate the efficiencies of the induction motor from low to rated speed and torque. Both analysis and experimental results indicate that the efficiency with VVVF is superior to that of constant flux operation. Experimental results showed that 10-15% improvement in the efficiency of a 2 hp induction motor at 0.4 per unit load using VVVF can be achieved as compared to the constant flux operation. >
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paper_title: A novel technique for optimal efficiency control of current source inverter fed induction motor

paper_content:

A technique that optimizes flux level to improve the efficiency of an induction motor is discussed. When harmonics and saturation effects are considered, the slip of minimum loss, or optimal slip, depends on both the speed and the load torque. The measurements of speed and torque are achieved without conventional torque and speed sensors, using motor terminal quantities. The control strategy is divided into two stages. First, the optimal slip is searched by trial and error, and the results are tabulated in microprocessor memory. Then the motor is operated at optimal efficiency by simply tracking the optimal slip given in the table. Experimental results show good performance in energy saving and dynamic responses. >
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paper_title: Neural network flux optimization using a model of losses in induction motor drives

paper_content:

This paper focuses on loss minimization in induction motor (IM) drives. In many applications Induction Motor drives work below the nominal torque most of the time. In these circumstances the IM efficiency can be improved lowering the flux. For a given torque, this decreases iron looses and increases copper losses. With appropriate algorithms an optimum point for the flux can be achieved in order to minimize IM total power losses. Using an IM model, a neural network (NN) based approach is used to improve efficiency in a vector control of the induction motor drive. A complex loss model of the motor, including magnetic and thermal deviations of its parameters, is used to estimate losses. Based on this model, the neural network is trained to estimate the optimum rotor flux. Inputs to the NN are torque, speed and rotor resistance of the IM and the output is the rotor flux. Analysis, modeling and simulation results are presented to demonstrate the validity of the proposed method. method.
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paper_title: Optimal Characteristics of a Variable-Frequency Centrifugal Pump Motor Drive

paper_content:

Efficient variable-frequency control of the centrifugal pump drive motor is preferable to fluid control by a throttling valve or a bypass valve in many applications. The properties of the centrifugal pump as a motor load are discussed and the implications for the drive design. Also discussed are other properties of the motor drive in a pumping system such as startup behavior, response to pump overload, and loss of priming fluid as well as its characteristics as a control system element. Since fans and centrifugal blowers are similar in operation to centrifugal pumps, much of this discussion is also applicable to them. The aim is to give the specifier of pumping system components a set of criteria with which to judge the suitability of a given motor drive algorithm for his pumping application.
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paper_title: Loss minimization in induction motor adjustable-speed drives

paper_content:

A loss model controller (LMC) for determining the optimal air-gap flux that minimizes the losses in scalar controlled induction motor drives is presented. The suggested LMC is simple, and its implementation does not affect significantly the cost and the complexity of the drive. Although the conception of the suggested LMC is based on the loss model of the induction motor, it is shown that its realization does not require knowledge of the loss model.
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paper_title: Control Means for Minimization of Losses in AC and DC Motor Drives

paper_content:

Motor drive losses can be reduced considerably by independently controlling the voltage and frequency for ac motors, and the field current and armature voltage for dc motors for any torque and speed operating point. The quantities to be controlled are already accessible in inverter ac power supplies and phase-controlled rectifier dc power supplies. The control signals can be supplied by an open- loop controller which solves the loss minimization equations using preset drive parameters, or by an optimizing controller that measures or calculates the losses and finds the combination of quantities that minimizes the losses.
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paper_title: Loss minimization in induction motor adjustable-speed drives

paper_content:

A loss model controller (LMC) for determining the optimal air-gap flux that minimizes the losses in scalar controlled induction motor drives is presented. The suggested LMC is simple, and its implementation does not affect significantly the cost and the complexity of the drive. Although the conception of the suggested LMC is based on the loss model of the induction motor, it is shown that its realization does not require knowledge of the loss model.
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paper_title: Numerical approach to loss minimization in an induction motor

paper_content:

This paper describes a numerical approach to power-loss minimization in a fractional hp induction motor driven by a voltage-source inverter. The motor parameters are obtained from a genetic algorithm search. Optimum voltage and frequency excitations are arranged as a table for an energy-saving controller. The proposed method is useful under variable-torque load conditions. Simulation and experimental results are presented.
---
paper_title: An efficient controller for an adjustable speed induction motor drive

paper_content:

The induction motor (IM) is a high-efficiency machine when working close to its rated operating point. However, at torques and/or speeds far from the rated values the efficiency is greatly reduced. In this work a new approach is proposed that minimizes the total copper and iron losses in a variable speed and/or torque IM drive, while keeping a good dynamic response. This method is based on a simple IM model that includes iron losses. The model, which only requires the knowledge of conventional IM parameters, is referred to a field-oriented frame. Using this model, the IM losses are quantified and an algorithm, based on a field-oriented scheme, is deduced. Simulation and experimental results are presented to validate the proposed method. >
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paper_title: Differential Evolution based Optimal control of Induction Motor Serving to Textile Industry”, Int

paper_content:

This paper illustrates the importance of controllers on energy saving opportunity of partial loaded three-phase induction motor in textile mill (ring spinning frame) applications. The economics of a scalar controlled 100 HP induction motor is investigated with three topologies namely star-delta (S/D) connection, constant Volt/frequency (V/f) controller and Differential Evolution (DE) controller in steady-state conditions. In this study, the flux level in a machine has been considered to adjust to give minimum operating cost for the textile mill load. The flux controller improves the economics in terms of operating cost (energy cost and demand charge cost) and the test results show that the flux level in the most economic motor will be adjusted according to load and speed, particularly at light load. Standard benchmark problems (Rastingin and Griewank) have been considered for validation of the proposed DE controller for induction motor operating cost minimization. Case study also presented in this paper.
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paper_title: High performance induction motor drive with optimized excitation current control

paper_content:

A high performance induction motor drive is presented in this paper. The drive has two important features: (a) it can produce a highest possible starting/braking torque to improve the dynamic performance of the drive; and (b) it can maximize the energy efficiency when the motor operates in steady state. Both features are achieved by optimizing the excitation current (rotor flux) of the motor. A nonlinear model for the induction motor in the MT synchronous rotating frame is derived, based on which the magnetic saturation of the motor can be accurately taken into account. The principle of optimized excitation current control is elaborated. The nonlinear motor model is integrated into the indirect field oriented vector control. The control algorithm is implemented by a multi-processor digital controller. It is demonstrated through computer simulation and experiments that the drive dynamic performance is optimized and the energy efficiency is maximized. The proposed drive is particularly suitable for electric vehicle and traction applications.
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paper_title: Robust torque control design for induction motors: The minimum energy approach

paper_content:

Abstract This paper presents two different aspects concerning the control design laws for induction motors: (1) it derives state operating points (steady-state values for currents and fluxes) parameterized in terms of the desired motor torque, defining minimum-energy operation conditions for the electrical motor. (2) It gives a state-space feedback control design methodology based on Lyapunov analysis which renders the minimum-energy operating points invariant. Several controllers are proposed: P-type control, observer-based P-type control, PI-type control and observer-based PI-type control. The PI-structure and the observer-based control are introduced to deal with motor parameter uncertainties, and the absence of flux measurements, respectively. Stability of all these control schemes is studied. Experimental results are also presented.
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paper_title: Optimal efficiency analysis of induction motors fed by variable-voltage and variable-frequency source

paper_content:

The authors discuss the efficiency analysis and experimental data for an induction motor fed by a variable-voltage and variable-frequency (VVVF) source. Nonideal factors (core saturation, source harmonics, and skin effect) affecting the efficiency are included in the analysis to yield practical results from computer simulation. Based on the simulated results, an experimental system, composed of a DC link power converter with a VVVF feature, a dynamometer and a PC/AT, was developed to evaluate the efficiencies of the induction motor from low to rated speed and torque. Both analysis and experimental results indicate that the efficiency with VVVF is superior to that of constant flux operation. Experimental results showed that 10-15% improvement in the efficiency of a 2 hp induction motor at 0.4 per unit load using VVVF can be achieved as compared to the constant flux operation. >
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paper_title: A novel technique for optimal efficiency control of current source inverter fed induction motor

paper_content:

A technique that optimizes flux level to improve the efficiency of an induction motor is discussed. When harmonics and saturation effects are considered, the slip of minimum loss, or optimal slip, depends on both the speed and the load torque. The measurements of speed and torque are achieved without conventional torque and speed sensors, using motor terminal quantities. The control strategy is divided into two stages. First, the optimal slip is searched by trial and error, and the results are tabulated in microprocessor memory. Then the motor is operated at optimal efficiency by simply tracking the optimal slip given in the table. Experimental results show good performance in energy saving and dynamic responses. >
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paper_title: Efficiency optimized control of medium-size induction motor drives

paper_content:

The efficiency of a variable speed induction motor drive can be optimized by adaptation of the motor flux level to the load torque. In small drives (<10 W), this can be done without considering the relatively small converter losses, but for medium-size drives (10-1000 kW) the losses cannot be disregarded without further analysis. The importance of the converter losses on efficiency optimization in medium-size drives is analyzed in this paper. Based on the experiments with a 90-kW drive, it is found that it is not critical if the converter losses are neglected in the control, except that the robustness toward load disturbances may unnecessarily be reduced. Both displacement power factor and model-based efficiency-optimizing control methods perform well in medium-size drives. The last strategy is also tested on a 22-kW drive with good results.
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paper_title: Neural network flux optimization using a model of losses in induction motor drives

paper_content:

This paper focuses on loss minimization in induction motor (IM) drives. In many applications Induction Motor drives work below the nominal torque most of the time. In these circumstances the IM efficiency can be improved lowering the flux. For a given torque, this decreases iron looses and increases copper losses. With appropriate algorithms an optimum point for the flux can be achieved in order to minimize IM total power losses. Using an IM model, a neural network (NN) based approach is used to improve efficiency in a vector control of the induction motor drive. A complex loss model of the motor, including magnetic and thermal deviations of its parameters, is used to estimate losses. Based on this model, the neural network is trained to estimate the optimum rotor flux. Inputs to the NN are torque, speed and rotor resistance of the IM and the output is the rotor flux. Analysis, modeling and simulation results are presented to demonstrate the validity of the proposed method. method.
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paper_title: Minimum-time minimum-loss speed control of induction motors under field-oriented control

paper_content:

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.
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paper_title: Optimal Characteristics of a Variable-Frequency Centrifugal Pump Motor Drive

paper_content:

Efficient variable-frequency control of the centrifugal pump drive motor is preferable to fluid control by a throttling valve or a bypass valve in many applications. The properties of the centrifugal pump as a motor load are discussed and the implications for the drive design. Also discussed are other properties of the motor drive in a pumping system such as startup behavior, response to pump overload, and loss of priming fluid as well as its characteristics as a control system element. Since fans and centrifugal blowers are similar in operation to centrifugal pumps, much of this discussion is also applicable to them. The aim is to give the specifier of pumping system components a set of criteria with which to judge the suitability of a given motor drive algorithm for his pumping application.
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paper_title: Asynchronous motor drive loss optimization

paper_content:

Abstract This paper presents a methodology for determination of harmonic iron losses in laminated iron cores under non sinusoidal excitation. The methodology adopted is based on a particular 3D finite element model by using a reduced scalar potential formulation. Eddy currents in iron laminations are considered by means of convenient surface current densities. Experimental verification is performed by comparing computed and measured leakage field in an E-shape laminated core case. A convenient modification of induction motor equivalent circuit parameters is proposed enabling consideration of switching frequency iron losses in case of inverter supply.
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paper_title: A Simple but Reliable Loss Model for Inverter-Supplied Induction Motors

paper_content:

A semiempirical induction motor loss model is developed as a function of motor power rating. The aim is the estimation of losses caused by harmonic-distorted (e.g., PWM) current and voltage supplies. The model may consider harmonics between about 100 and 20 000 Hz and is constructed for power ratings between 1 and 1000 kW. Losses in rotor, stator, and iron (including most important stray losses) are separately estimated and suitably combined. This leads to a simple penalization factor for the time-harmonic currents, which is a function of motor size and which is quasi-linearly depending on harmonic frequency. Total losses are then calculated by the superposition of separate harmonic current or voltage effects. The penalization factor is experimentally verified. The importance of iron (plus stray) losses has been clearly shown. The model predictions are in close agreement with loss measurements on inverter-fed induction motors.
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paper_title: A modified particle swarm optimizer with roulette selection operator

paper_content:

In this paper, a novel particle swarm optimizer combined with the roulette selection operator is proposed, which provides a mechanism to restrain the predominating of super particles in early stage and can effectively avoid the premature problem. We conduct variety experiments to test the proposed algorithm and compare it with other published methods on several test functions taken from the literature. The computational results demonstrate that this revised algorithm is promising to achieve faster convergence and better solutions, especially for multimodal function optimization.
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paper_title: Full Load Range Neural Network Efficiency Optimization of an Induction Motor with Vector Control using Discontinuous PWM

paper_content:

Model-based efficiency controllers of induction motors (IM) are known to considerably reduce power losses for loads under 0.50 p.u. by correctly setting the flux under rated value. However, for loads higher than 0.5 p.u., their performance is approximately the same as rated flux vector controllers. It has been recently shown that switching losses and harmonic losses reduction for voltage source inverter (VSI) fed IM can be done by using a discontinuous PWM strategy (DPWM). Hence, this paper proposes a full load range efficiency optimization controller by using an artificial neural network (ANN)-based flux optimizer and a DPWM strategy for both low and high loads. The controller is validated by using a simulation model and comparing its performance with a conventional rated flux controller with space vector PWM (SVPWM). Full load range optimization is achieved with a reduction of fundamental losses of 27% at light load and a 47% reduction of switching and time harmonics losses at high load.
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paper_title: Loss minimization control of induction motor drives based on genetic algorithms

paper_content:

In this paper, a new approach using a floating point genetic algorithm (GA) is applied to minimize induction motor (IM) electric losses. The maximum efficiency is obtained by the online evaluation of the optimal magnetization flux. The loss model approach used is based on the steady state mathematical model of the IM. Some simulation results are given to validate this new approach. It is shown that this approach gives good results both in the steady state and dynamic operations.
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paper_title: Efficiency optimization of a vector controlled induction motor drive using an artificial neural network

paper_content:

This paper presents an approach for efficiency optimization of a vector controlled induction motor drive. The optimum flux-producing current is obtained using an artificial neural network. The artificial neural network model is established using Matlab/Simulink and based on the load torque and speed data of an indirect vector-controlled induction motor drive. The change of iron core loss resistance due to flux and frequency variation is taken into consideration. Simulation results of the proposed approach show a significant improvement in energy saving and efficiency optimization.
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paper_title: A genetic algorithms approach for adaptive field oriented control of induction motor drives

paper_content:

In this paper an adaptive field oriented control of induction motor drive is proposed. The adaptive scheme uses a genetic algorithm for the identification of the rotor time constant, which is used to adjust the estimate of the slip angular speed. The identification method is presented as an optimization problem where the objective function is the total square error between the motor and the commanded stator currents. Computer simulation results are obtained and the performance of the resulting field oriented controller is analyzed. Further, this paper indicates that the genetic algorithm approach amounts to a promising methodology to handle adaptive control of indirect field oriented induction motors.
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paper_title: Fuzzy logic based on-line efficiency optimization control of an indirect vector-controlled induction motor drive

paper_content:

Improvement of adjustable speed drive system efficiency is important not only from the viewpoints of energy saving and cooling system operation, but also from the broad perspective of environmental pollution. The paper describes a fuzzy logic based on-line efficiency optimization control of a drive that uses an indirect vector controlled induction motor speed control system in the inner loop. At steady-state light-load condition, a fuzzy controller adaptively decrements the excitation current on the basis of measured input power such that, for a given load torque and speed, the drive settles down to the minimum input power, i.e., operates at maximum efficiency. The low-frequency pulsating torque due to decrementation of rotor flux is compensated in a feedforward manner. If the load torque or speed command changes, the efficiency search algorithm is abandoned and the rated flux is established to get the best transient response. The drive system with the proposed efficiency optimization controller has been simulated with lossy models of the converter and machine, and its performance has been thoroughly investigated. An experimental drive system with the proposed controller implemented on a TMS320C25 digital signal processor, has been tested in the laboratory to validate the theoretical development. >
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paper_title: On-Line Efficiency Optimization of a Variable Frequency Induction Motor Drive

paper_content:

The problems associated with the implementation of an optimal efficiency controller in variable frequency induction motor drives are examined. A simple method for minimizing, on-line, the global system losses is presented. This method is based on the adaptive control of the rotor flux in a field-oriented drive system. The effectiveness of this control strategy is verified using digital simulation.
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paper_title: Loss minimization in scalar-controlled induction motor drives with search controllers

paper_content:

Loss minimization in scalar-controlled induction motor drives (IMD) with search controllers (SC) is investigated. The problems arising when the input power is used as the controlled variable are described. It is proved that better results are achieved if the stator current is used as the controlled variable.
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paper_title: Loss minimization control of an induction motor drive

paper_content:

A practical method is presented for operation of an inverter-fed induction motor drive at the point of maximum efficiency while maintaining any particular torque-speed load point. The design and operation of an economical, microprocessor-based adaptive controller used to modify a commercially available six-step inverter for minimum loss operation of an induction motor are described. Experimental results are presented in graphical form, making it possible to compare the overall drive system efficiencies of loss minimization control and constant volts/hertz control operation for a standard-efficiency induction motor of 10 hp rating. The greatest potential for energy savings is found to exist for the case of loads with nonlinear torque-speed characteristics, such as a fan or pump load. >
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paper_title: Control of induction motors for both high dynamic performance and high power efficiency

paper_content:

The authors attempt to control induction motors with maximum power efficiency as well as high dynamic performance by means of decoupling of motor speed (or motor torque) and rotor flux. For maximum power efficiency, the squared rotor flux is adjusted according to a minimum power search algorithm until the measured power input reaches the minimum. Since the motor speed is dynamically decoupled from the rotor flux, this can be done successfully without any degradation of motor speed responses. The controller depends on rotor resistance but not on stator resistance. However, the performance of the control scheme is robust with respect to variations in rotor resistance because an identification algorithm for rotor resistance is employed. The identification algorithm for rotor resistance has some advantages over the previous methods. To demonstrate the practical significance of the results, some experimental results are presented. >
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paper_title: A continuous efficiency optimization controller for induction motor drives

paper_content:

In this paper, an on-line efficiency optimization controller is proposed for induction motor drives after a detailed analysis of motor losses. The controller searches for a minimum motor drive input power by continuous variation of a control variable, resulting in a smooth system performance, which is not possible by the conventional stepwise change of the control variable. The search period is short. Thus, the controller can be applied effectively to applications with frequent changes of speed and load. Also, under the proposed controller, more energy saving is achieved. Extensive simulation is performed for the induction motor under the proposed and conventional efficiency optimization controllers. The results prove the superiority of the proposed controller.
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paper_title: On-Line Efficiency Optimization of a Variable Frequency Induction Motor Drive

paper_content:

The problems associated with the implementation of an optimal efficiency controller in variable frequency induction motor drives are examined. A simple method for minimizing, on-line, the global system losses is presented. This method is based on the adaptive control of the rotor flux in a field-oriented drive system. The effectiveness of this control strategy is verified using digital simulation.
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paper_title: Steady-state optimization of induction motor drives operating in the field weakening region

paper_content:

The steady-state performance optimization of vector-controlled induction motor drives operating in the field-weakening region above base speed is discussed. Three indirect vector control schemes, stator flux field-orientation control (SFOC), rotor flux field-orientation control (RFOC), and airgap flux field orientation control (AFOC), are considered for maximum torque and maximum motor efficiency operation. The optimization of a weighted function comprising the torque and efficiency is also considered. The three field orientation schemes give the same maximum torque while the RFOC has the best optimal efficiency. >
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paper_title: Induction motor optimum flux search algorithms with transient state loss minimization using a fuzzy logic based supervisor

paper_content:

A review of different optimum flux search algorithms for loss minimization in a vector-controlled induction motor drive is presented. A fuzzy logic controller, actuating as a supervisor, is proposed to work with reduced flux levels during transients and also to optimize efficiency in dynamic modes. Experimental results demonstrate the validity of the proposed methods.
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paper_title: Fuzzy logic approach for energy efficient voltage controlled induction motor drive

paper_content:

The tracking of maximum efficiency point of a lightly loaded induction motor is generally obtained using the search technique which is time consuming and the machine is subjected to many step changes of voltage which is undesirable. This paper presents a novel technique for energy efficient operation of voltage controlled induction motor drive using fuzzy logic principles. In the proposed method, the time required to converge to the best efficiency point of the drive is minimum and the machine is subjected only to one step change of voltage, irrespective of load change. The fuzzy logic variables and the fuzzy rules are formulated based on experimental investigations. The rule base for the optimum voltage identification is generated in the entire operating range of the motor with a no priori knowledge of the machine parameters. The fuzzy logic estimator is then used for performance optimization of induction motor and the simulation results are presented. The simulation results demonstrate the efficiency of the fuzzy logic estimator based voltage controller.
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paper_title: Fuzzy logic based on-line efficiency optimization control of an indirect vector-controlled induction motor drive

paper_content:

Improvement of adjustable speed drive system efficiency is important not only from the viewpoints of energy saving and cooling system operation, but also from the broad perspective of environmental pollution. The paper describes a fuzzy logic based on-line efficiency optimization control of a drive that uses an indirect vector controlled induction motor speed control system in the inner loop. At steady-state light-load condition, a fuzzy controller adaptively decrements the excitation current on the basis of measured input power such that, for a given load torque and speed, the drive settles down to the minimum input power, i.e., operates at maximum efficiency. The low-frequency pulsating torque due to decrementation of rotor flux is compensated in a feedforward manner. If the load torque or speed command changes, the efficiency search algorithm is abandoned and the rated flux is established to get the best transient response. The drive system with the proposed efficiency optimization controller has been simulated with lossy models of the converter and machine, and its performance has been thoroughly investigated. An experimental drive system with the proposed controller implemented on a TMS320C25 digital signal processor, has been tested in the laboratory to validate the theoretical development. >
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paper_title: Robust DSP-based efficiency optimization of a variable speed induction motor drive

paper_content:

This paper proposes a practical digital-signal-processor (DSP)-based algorithm for the online efficiency optimization of induction motor drives. The algorithm combines good features of the search control and loss-model-based control, while simultaneously eliminating their major drawbacks. It ensures very fast convergence without the need for any a priori knowledge of the motor loss-related parameters. The minimum loss operating point is decided from a functional approximation of the motor and the power converter losses, in the form of a suitably defined loss function. The loss function parameters are obtained online from input power measurement and a dedicated identification routine acting in conjunction with the common drive control functions. Proposed online identification of the loss function parameters relies upon the signals and states readily available within the drive controller memory and does not involve the user entry nor the initialization procedure. The proposed controller is coded into a conventional low-cost 16-bit DSP and verified on a 2.2-kW induction motor drive prototype.
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paper_title: Fast search controllers for efficiency maximization of induction motor drives based on DC link power measurement

paper_content:

This paper presents three new techniques for the efficiency optimization of vector controlled induction motor drives. The flux producing current is controlled till the power at the DC link is minimum. Of the three techniques, the first method is based on the power-flux gradient and the second method reduces the flux producing current in a smooth manner till the DC link power shows an upward trend. The third technique combines loss model and search approaches in a unique manner to propose a hybrid method, where the first estimate is from loss model approach and the subsequent adjustment of the flux is through the search technique. All three methods are faster than the available methods. Also smooth control of the flux offers excellent dynamic performance. A comparative assessment shows that the hybrid method is the best, even if only a rough estimation of the induction motor parameters are available. The close agreement between the simulation and the experimental results confirms the validity and usefulness of the proposed techniques.
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paper_title: Energy optimization of induction motor drives

paper_content:

This paper deals with energy optimization of induction motor drives. In many applications, efficiency optimization of induction motors represents an important factor of control especially for autonomous electrical traction. In this paper different approaches to improve efficiency in vector controlled induction motor drives at steady state condition are compared. Three methods are possible to control the excitation: Methods based on induction motor losses, methods based on the use of look-up table and methods based on search controllers of minimum. We expose in this paper some methods, which use the search controller techniques. These techniques consist in changing flux level in small steps to keep the output power of the motor constant and find the minimum of input power. These controllers are efficient at steady state condition and do not require knowledge of motor and converter parameters. However, the search controller using the stator current instead of power give similar results to their using power. This technique is less complex and doesn't need measurement of PWM quantities. The proposed search controller is based on fuzzy algorithm. The advantages of this controller are compared with others known as Rosenbrock method and Golden section. Fuzzy search controller presents a good trade off between convergence time and oscillations of stator current ripple.
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paper_title: Performance optimization of induction motors during Voltage-controlled soft starting

paper_content:

This paper deals with the performance optimization of medium/high-power induction motors during soft starting by eliminating the supply frequency torque pulsations, and by keeping the line current constant at the preset value. Starting torque pulsations are eliminated by triggering back-to-back-connected thyristors at proper points on the first supply voltage cycle. Line current during starting can be kept constant at any preset value by a simple strategy composed of successive cosinusoidal and constant function segments of the triggering angle. These strategies are implemented by the use of an 8-b microcontroller. Transient performance analyses of the system are carried out by means of a hybrid ABC/dq machine model which takes into account the three-phase, two-phase, and disconnected modes of operation in terms of actual stator variables. Experimental results obtained on a custom-design test bed are found to be in good agreement with the theoretical ones.
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paper_title: Efficiency optimization techniques via constant optimal slip control of induction motor drives

paper_content:

The paper proposes a novel control technique that is able to optimize the efficiency in scalar controlled induction motor drives. The proposed strategy is based on a constant-optimal slip control and is able to modify the magnetizing flux value increasing the efficiency at light loads. Differently from the optimization methods present in the literature, the proposed approach does not require the model of the machine, does not solve any losses minimization equation and is not based on a minimum losses or minimum power search algorithm. The presented technique is based on an intuitive adaptation of the well known maximum torque per ampere (MTA) algorithm to a new version for scalar control, ensuring a constant-optimal slip. A key point is the possibility to achieve the efficiency optimization by using the same hardware as in standard adjustable speed drives operated by V/f or conventional slip control. An experimental evaluation has been accomplished on a 1,5 Hp induction motor drive to measure the losses minimization and verify the dynamic performance of the proposed method
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paper_title: Energy saving operation of induction motors by voltage reduction at no and low partial-load

paper_content:

An investigation of the electrical energy savings obtained by reducing the terminal voltage of induction motors when they are not loaded or only partially loaded is presented. The purpose is to obtain information to help decide whether to install an energy saving device in plants using induction motors. At no-load operation, the saving can be as high as 50%. The saving decreases with the increase of load. Switching-off one phase of the three-phase supply during no-load operation does not contribute to energy saving. Intermittent disconnection of the supply voltage can lead to considerable energy saving, if the interruption interval is sufficiently long. This method is recommended for small motors. >
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paper_title: Terminal-impedance control for energy-saving in induction motors at no and partial loads using microprocessor

paper_content:

A theoretical actual nonlinear mathematical model for induction motor running at no and partial loads and fed from a thyristorized AC voltage controller, was introduced to determine optimum slips required for energy-saving achievement when running at maximum efficiency and power factor (PF), minimum active and reactive power, minimum stator current and losses. A software package in BASIC was introduced to determine the net energy saving when using the controller, the critical value for the load torque at which the net energy equals zero, and the control parameters required for optimum-slip detection. Finally, the open-loop control technique was implemented to check the computed results required for the terminal-impedance closed-loop control system. A comparison study between experimental and computed results was introduced. Finally, experimental open-loop control parameters were tabulated in the look-up table to drive the implemented closed-loop technique that include the current limiting loop required through starting.
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paper_title: Energy saving work of frequency controlled induction cage machine

paper_content:

Abstract Energy saving work, understood as lowering the supply voltage when load torque is much less than rated, is one way of reducing power losses in an induction cage machine working with a variable load. Reduction in power losses also affects the thermal properties of an induction machine because the energy saving work allows the temperature rise of the windings to decrease. Thanks to a lower temperature of the windings, the same load torque can be carried by a machine of less rated power. The ability of energy saving work to reduce the temperature of windings depends on the thermal properties of an induction machine, which are different in the case of a machine with foreign ventilation and its own ventilation. This paper deals with the thermal effect of energy saving work on a frequency controlled induction cage machine. A comparison of the properties of a machine with its own and outside ventilation is presented. The results of the investigations are shown for a 3 kW induction cage machine with the two previously mentioned ways of ventilation: one provided with a fan placed on a shaft and the other provided with a fan driven by an auxiliary motor.
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paper_title: Efficiency optimizing control of induction motor using natural variables

paper_content:

This paper presents a new approach of optimizing the efficiency of induction motor drives through minimizing the copper and core losses. The induction machine model which accounts for the varying core loss resistance and saturation dependent magnetizing inductance uses natural and reference frame independent quantities as state variables. Utilization of the nonlinear geometric control methodology of input-output linearization with decoupling, permits the implementation of the control in the stationary reference frame. This approach eliminates the need of synchronous reference transformation and flux alignment required in classical vector control schemes. The new efficiency optimizing formulation yields a reference rotor flux which ensures minimum loss and yields an improved efficiency of the drive system especially when driving part-load. The proposed scheme and their advantages are demonstrated both by computer simulations and some experimental results for motor speed control.
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Title: Energy Efficient Control of Three-Phase Induction Motor - A Review

Section 1: INTRODUCTION
Description 1: This section introduces the importance of efficiency in induction motors, particularly under varying load conditions, and outlines the goals and approaches of the paper.

Section 2: OPTIMIZATION TECHNIQUES
Description 2: This section explains various optimization techniques used for improving induction motor efficiency, including conventional, AI-based, and NIA-based methodologies.

Section 3: Conventional Optimization Techniques
Description 3: This subsection details traditional optimization methods such as statistical methods, MONTE CARLO, and various other numerical methods applied to motor design.

Section 4: AI Based Optimization Techniques
Description 4: This subsection focuses on artificial intelligence methods like Fuzzy logic and ANN used in the optimization of induction motors.

Section 5: NIA Based Optimization Techniques
Description 5: This subsection discusses Nature Inspired Algorithms such as Genetic Algorithms, Particle Swarm Optimization, and Evolutionary Algorithms used in motor design optimization.

Section 6: OPTIMAL CONTROL OF INDUCTION MOTOR THROUGH LOSS MODEL
Description 6: This section describes the application of loss model controllers for optimizing motor efficiency by controlling the air gap flux and other parameters.

Section 7: Scalar Controlled Drives
Description 7: This subsection explores scalar-controlled drives for induction motors and methods to minimize losses through optimal flux control.

Section 8: AI and NIA Based Controllers
Description 8: This subsection presents various AI and NIA-based controllers for enhancing the performance and efficiency of induction motors.

Section 9: Vector Controlled Drives
Description 9: This subsection focuses on vector-controlled drives, detailing their methods for efficiency optimization by considering both magnitude and phase of the control variables.

Section 10: OPTIMAL CONTROL OF INDUCTION MOTOR THROUGH SEARCH CONTROL
Description 10: This section covers the implementation of search control techniques to optimize induction motor efficiency without requiring loss model knowledge.

Section 11: Scalar Controlled Drives
Description 11: This subsection examines scalar-controlled drives utilizing search control methods for efficiency optimization through periodic power input measurement.

Section 12: Vector Controlled Drives
Description 12: This subsection highlights the role of vector control in search control-based efficiency optimization of induction motors.

Section 13: AI and NIA Based Controllers
Description 13: This subsection discusses the use of AI and NIA approaches in combination with search control for achieving optimal efficiency in induction motors.

Section 14: Both LMC and Search Control
Description 14: This subsection compares the use of both Loss Model Control and Search Control methods for optimizing induction motor efficiency.

Section 15: Other controls
Description 15: This subsection briefly describes other control methods and strategies to improve induction motor efficiency.

Section 16: CONCLUSION
Description 16: This section summarizes the findings of the review, emphasizing the importance of efficiency optimization in induction motors and the effectiveness of various techniques discussed throughout the paper.