Induction Machine Parameters Research Articles

Improved performance of linear induction motors based on optimal duty cycle finite-set model predictive thrust control

Linear induction machines (LIMs) find widespread adoption in various applications, owing to their inherent advantages such as low noise, compact turning radius, and excellent climbing capability. LIMs are extensively utilized in linear metro applications. However, in practical operations, the output thrust shrinks with the increase in speed, which is attributed to end effects. This phenomenon leads to a reduction in efficiency. In addition, fluctuations in the normal force impact system stability, posing disturbances to the suspension system. To address these challenges, this paper suggests a finite-set model predictive thrust control (FS-MPTC) for a drive system employing a linear induction motor (LIM). The FS-MPTC optimizes the duty cycle for the active voltage vector and allocates the remaining period to one of the zero voltage vectors. The selected zero voltage vector reduces the switching transition between it and the active voltage vectors. The duty cycle is calculated for the six voltage vectors by incorporating the deadbeat concept and the derivative value for the electromagnetic thrust. In the prediction stage of the FS-MPTC, the computed duty cycle and the corresponding voltage vector are used simultaneously and repeated for the six voltage vectors. The cost function comprises two terms: the error between the reference thrust and predicted thrust value as the first term and the error between the rated primary flux linkage and its predicted value as the second term. The reference thrust is generated from the outer speed control loop. To validate the effectiveness of the proposed control approach, Japanese 12000 linear induction machine parameters are employed for verification. Comparative analysis of the performance between the suggested control method with the optimal duty cycle and the same process with a fixed duty cycle demonstrates superior performance when utilizing the optimal duty cycle. Finally, the proposed FS-MPTC with the optimal duty cycle offers a promising solution to enhance the operational efficiency of the LIM-based drive systems.

New Speed Control Scheme for a Three-Phase Induction Machines - (3~IM) Based on Sine Duty Cycle Modulation (SDCM)

This paper proposes a new control scheme for three-phase induction machines based on the sinusoidal duty cycle modulation control strategy combined with V/f control. This technique allows efficient open-loop control of inverter switches. The proposed diagram shows the main characteristics:1 0.1   ,0 50 ,Hzf 21.44 ,base KHzf  2 ,12ref V Vu  . In addition, it guarantees optimum operation of the inverter with the torque and speed parameters of the three-phase induction machine complying with current requirements:10rC Nmmax 6,5A/50Hz/ THD=1,2%

New identification of induction machine parameters with a meta-heuristic algorithm based on least squares method

PurposeThe great value of offline identification of machine parameters is when the machine manufacturer does not provide its parameters. Most machine control strategies require parameter values, and some circumstances in the industrial sector only require offline identification. This paper aims to present a new offline method for estimating induction motor parameters based on least squares and a salp swarm algorithm (SSA).Design/methodology/approachThe central concept is to use the classic least squares (LS) method to acquire the majority of induction machine (IM) constant parameters, followed by the SSA method to obtain all parameters and minimize errors.FindingsThe obtained results showed that the LS method gives good results in simulation based on the assumption that the measurements are noise-free. However, unlike in simulations, the LS method is unable to accurately identify the machine’s parameters during the experimental test. On the contrary, the SSA method proves higher efficiency and more precision for IM parameter estimation in both simulations and experimental tests.Originality/valueAfter performing a primary identification using the technique of least squares, the initial intention of this study was to apply the SSA for the purpose of identifying all of the machine’s parameters and minimizing errors. These two approaches use the same measurement from a simple running test of an IM, and they offer a quick processing time. Therefore, this combined offline strategy provides a reliable model based on the identified parameters.

An enhanced control strategy based imaginary swapping instant for induction motor drives

<p>The main aim of this paper is to present a novel control approach of an induction machine (IM) using an improved space vector modulation based direct torque control (SVM-DTC) on the basis of imaginary swapping instant technique. The improved control strategy is presented to surmount the drawbacks of the classical direct torque control (DTC) and to enhance the dynamic performance of the induction motor. This method requires neither angle identification nor sector determination; the imaginary swapping instant vector is used to fix the effective period in which the power is transferred to the IM. Both the classical DTC method and the suggested adaptive DTC techniques have been carried out in MATLAB/SimulinkTM. Simulation results shows the effectiveness of the enhanced control strategy and demonstrate that torque and flux ripples are massively diminished compared to the conventional DTC (CDTC) which gives a better performance. Finally, the system will also be tested for its robustness against variations in the IM parameters.</p>

Parameter Estimation and Online Adaptation of Rotor Time Constant for Induction Motor Drive

The performance of a sensor-based rotor flux-oriented vector control induction machine drive is highly influenced by the estimated value of the rotor time constant/rotor resistance which varies continuously with temperature when it is driven with the variable loads. Therefore, to achieve accurate torque control, online tunning of the rotor time constant is necessary. This article proposes a novel and simple adaption technique to estimate the rotor time constant. In this proposed method, the reference model of the rotor flux vector is derived using the voltage model of the induction machine, which is independent of the rotor time constant. The current controller uses the model of the rotor flux vector that is derived using the current model of the induction machine. This current model is dependent on the rotor time constant. The error between the rotor flux vectors derived using the current model and the voltage model is minimized using the least-squares method. In this process, the rotor time constant is always tuned to its actual value. The article also presents a simple approach to estimate the parameters of induction machine like the stator resistance, the net leakage inductance, and the initial value of the rotor time constant in an offline mode at a standstill condition. To validate the proposed algorithm, two experimental prototypes are developed for two different power ratings of 3.7 and 67 kW. Experimental results from these prototypes confirm the effectiveness, reliability, and stability of the proposed algorithm both in the motoring and regenerative modes of operation. This method of the adaptation of the rotor time constant is simple and, therefore, useful for practicing engineers.

Effects of induction machine parameters on its performance as a standalone self excited induction generator

A squirrel cage induction machine (SCIM) when aggregated with relevant capacitances and a prime mover, acts as self-excited induction generator (SEIG). As it hosts energy conversion the parameters of SCIM have considerable impact on the power extraction capability of SEIG. An aspect which is missing from the available research on SEIGs is evaluation of the affects of its rotor’s moment of inertia (J) and per-phase stator winding resistance (Rs) on performance indices. This work investigates the impacts of these factors on a SCIM’s performance as series compensated, short shunt SEIG. The study considers two distinctly designed SCIMs, in terms of J and Rs, operated as SEIG. In order to simulate their performance a stationary reference frame dq model including non-linear saturation and cross coupling effects is developed and verified experimentally. Several key investigations based on series capacitance selection, losses and efficiency, on-load performance with different power factor loads, transient performance with load perturbation and variable speed operation are carried out. The study reveals that SEIG with high J and lower Rs gives considerably better performance than its counterpart. The conclusions reported in the study are important especially for standalone/off grid application of SEIGs.

Parametric Regression Applied for Determination of Electrical Parameters of Synchronous and Induction Generators Operating in Parallel on the Electrical Energy Repowering System

The purpose of this work is to determine the values of electrical parameters of synchronous and induction machines to validate electrical interactions between an induction generator and a synchronous generator. The generators are connected in two ways: (i) isolated from the common bus and (ii) parallel to the common bus in steady state, subject to nonlinear load. They are old and refurbished machines; thus, the parametric regression methodology is used to determine the electrical parameter values. After the computational model validation, analyses are performed by various system configurations to confirm the repowering and to analyze the system harmonic current flow. The results obtained comparing the computer simulation and experimental tests prove that the validated model represents the real system. With an experimentally validated computational model, it is possible to verify the occurrence of system repowering and the increased value of harmonic distortions in the induction generator terminals, acting as a preferential path for harmonic currents.

Air-Cored Resonant Induction Machines: Comparison of Capacitor Tuning Criteria and Experimental Validation

The operation of air-cored resonant induction machines is very sensitive to the tuning of the capacitors. By using the equivalent circuit equations, this article explores in detail the machine performances under four different tuning criteria: (a) both stator and rotor capacitors resonating with the stator and rotor self-inductances; (b) both capacitors resonating with the leakage inductances; (c) stator capacitors tuned to compensate for the overall stator terminal reactance and no rotor capacitors; (d) stator capacitors only to cancel out the machine ideal input reactance neglecting resistances, which is the new option introduced in this article. Extensive comparisons of all tuning options in torque, efficiency, power factor, capacitor size, and feasibility are presented and their performances are compared with a pure air-cored induction machine without capacitors. Analytic expressions for the maximum efficiency and maximum torque and related slip values are also derived as functions of the machine parameters, which provides a valuable tool for design optimization. A numerical case study based on parameters of a real air-cored induction machine is discussed and the article includes the first experimental validation to be carried out on a spinning air-cored resonant induction machine prototype. Results show that using only stator capacitors to compensate for the machine equivalent terminal reactance can be a practical choice to achieve both high torque and high efficiency and avoid rotor capacitors.

A method to estimate parameters of five-phase induction machines including the third-harmonic airgap field

We propose a method to estimate all electrical parameters of five-phase induction motors based on a new concept of instantaneous impedance. Only stator voltages and currents acquired during no-load startup tests are required to determine the parameters of the fundamental and third-harmonic equivalent circuits. Additional quantities, such as rotor speed and electromagnetic torque, are also estimated from measurements. Unlike similar procedures, the parameters of the third-harmonic circuit are estimated separately from the parameters of the fundamental circuit, thus making the estimation more accurate. To experimentally validate the method, we tested a 4.5-kW and a 5.5-kW prototype using sinusoidal as well as trapezoidal voltages generated by a static converter. One of the main advantages of the proposed procedure is the possibility of using data acquired also with a static converter. Besides, to validate the method as well as to assess the accuracy of the estimated parameters, we first simulated the machine behavior using the estimated parameters and the measured stator voltages as input and subsequently compared the simulated currents with those acquired during no-load startup and load tests. Furthermore, we implemented a closed-loop Rotor Field Oriented Control (RFOC) scheme using both calculated and estimated parameters and then compared the controller performance with both sets of parameters. The practical results demonstrate not only that the method provides accurate estimates for all parameters but also that the use of the estimated parameters can improve the performance of the controller.

SENSORLESS VECTOR CONTROLLED THREE-PHASE PWM INVERTER-FED INDUCTION MOTOR DRIVE SYSTEM WITH AUTO-TUNING ESTIMATION OF MACHINE PARAMETER APPROACH

This paper deal with a practical development technology on a highly accurate faster response adjustable speed drive implementation for the three-phase sinewave fed general purpose induction motor system which is based upon sensorless slip frequency type vector control scheme with an automatic auto-tuning machine parameter estimation strategy. The essential procedure and considerations to measure and estimate the exact stator and cage rotor circuit parameters of the induction motor treated here are discussed under its operating conditions. The speed regulation characteristics of the induction motor is illustrated and evaluated for the induction machine parameter variations under the actual operating conditions ranging from a low frequency to a high frequency for various specified load torque setting. The variable speed induction motor drive system employing sensorless slip frequency-based vector control scheme which incorporates the current controlled three-phase high frequency carrier PWM switching inverter with automatic auto-tuning estimation strategy on the temperature-dependent and -independent machine circuit parameters is practically implemented using DSP-based vector controller. The dynamic speed response performances under essentially changed load torque disturbances as well as steady state speed against torque characteristics of the proposed variable speed drive control and implementations are illustrated and discussed from an experimental point of view.

ОБЗОР МЕТОДОВ ОЦЕНИВАНИЯ ПАРАМЕТРОВ СХЕМЫ ЗАМЕЩЕНИЯ АСИНХРОННОЙ ЭЛЕКТРИЧЕСКОЙ МАШИНЫ ДЛЯ ОРГАНИЗАЦИИ ВЕКТОРНОЙ СИСТЕМЫ УПРАВЛЕНИЯ

Relevance Today, due to the well-known and proven by many years of positive qualities of successful operation, induction machines (IM) have found wide application in various industries [1, 2], as part of motor [3–5] and generator sets [6–8]. The main advantages of an IM include simplicity of design, relatively low cost, the ability to withstand short-term current overloads, the absence of a brush-collector unit and expensive rare-earth magnets [9–14]. The relevance of the use of IM, which has not lost over the years, is confirmed, in particular, by modern manufacturers of electric vehicles [15], for which the issue of the most rational use of electricity is in the first place. The development of the principles of the theory of control of asynchronous controlled electric drives led to the emergence of various IM control methods, implemented in modern microprocessor-based frequency converters. These control methods include U/f control, field oriented control and direct torque control in various modifications and combinations [16–18]. The listed control methods have their own areas of application and are, to varying degrees, demanding on the availability of the parameters of the IM equivalent circuit used as part of the electric drive [19, 20]. Setting incorrect settings of the control system, based to the greatest extent on the parameters of the IM equivalent circuit, can lead to deterioration in the quality of regulation, as well as to a decrease in the energy efficiency of the electric drive [21–24]. It should be noted that the most acute problem with the availability of correct estimates of IM parameters arises when constructing sensorless control systems for electric drives [25]. Aim of research Review and compare the main methods estimation of induction motor equivalent circuit parameters used to organize a closed-loop control system of an electric drive. Research methods In this study, the following methods were used: study of scientific literature, study and generalization of information, comparison. Results The need to find estimations of IM equivalent circuit parameters for organizing a field oriented control system for an electric drive. A comparative analysis is carried out, the advantages and disadvantages of the main groups of methods for finding estimates of the parameters of an IM are described.

Design, Analysis and Validation of a Six-Phase Induction Machine from a Commercial Three-Phase for Academic Research

Multiphase machines have been reemerged for high-power as well as fault-tolerant applications such as electric vehicles and wind turbines. Nevertheless, these types of machines are typically built only for industries for specific purposes. Therefore, the availability of multiphase machines in the market for academic research work, for instance at universities, is limited due to they require special construction processes and involve high initial costs for the companies. For that reason, the aim of this paper is to present a step-by-step design of a multiphase winding of an induction machine (IM) from a commercial three-phase IM for academic research use. The obtained results will be first analyzed by using the ANSYS Maxwell simulation environment. Then, a model-based current controller will be performed to validate the proposed design and the electric parameters of the six-phase IM.

Model reduction based on sparse identification techniques for induction machines: Towards the real time and accuracy-guaranteed simulation of faulty induction machines

The development of condition monitoring (CM) systems of induction machines (IMs) is essential for the industry because the early fault detection would help engineers to optimise maintenance plans. However, the use of several IMs to test and validate the fault diagnosis methods developed requires also costly test benches that, anyway, often face limitations in the range of faults and operating conditions to be tested. To avoid it, the use of accurate models such as those based on finite element method (FEM) would reduce the major drawbacks of test benches but their inability to execute FEM models in real time largely reduces their application in the development of on-line continuous monitoring systems. To alleviate this problem a hybrid FEM-analytical model has been proposed. It uses an analytical model that can be run in real-time in a hardware in the loop (HIL) system, after its parameters have been computed through FEM simulations. In this way, the proposed model provides high accuracy but at the cost of long simulation times and high computational costs (both computing power and memory resources) to compute the IM parameters. This work aims at reducing these drawbacks. In particular, a model based on sparse identification techniques is proposed. The method balances complexity and accuracy by selecting a sparse model that reduces the number of FEM simulations to accurately compute the coupling parameters of an IM model with different fault severity degrees. Particularly, the proposed methodology has been applied to develop models with abnormal eccentricity levels as this fault is related to development of mechanical faults that produce most of IM breakdowns.

Theoretical method for determination of the impact of parasitic torques from the equivalent scheme of induction machines fed by PWM inverter

This paper presents a theoretical method for determining the impact of parasitic induction torques analyzing the quantities and parameters of equivalent schemes of induction machines fed by PWM inverter. Tested are three-pased and one-phase induction machines of different parameter and power types. For the fundamental values of power supply from PWM invertor and for important parameters of tested induction machines, comparation of results has been made, of simulation of electrical (stator and rotor current) and mechanical sizes (number of rotation and parasitic torque) of equivalent schemes of induction machines with squirrel cage and wound (phase) rotor are adopted. Theoretic model contains a correction factor, defined as relation of supply power and electro-engine force of induction machine when the rotor is stable. Comparing the real values of resistance parameters of induction machines and values obtained, taking into account a correction factor, certain discrepancies could be observed between values calculated by equivalent T and Г scheme for both groups of machines which do not exceed a value of 5%. Obtained formulas calculated according to equivalent Г schemes could be used for determination of short circuited currents. They are also used for analysis of properties of electric motors, usually for determination of currents that electric motors in the case of short circuits inject into electric network, as well as for the calculation of operating, mechanical and electrical characteristics of induction machines. Adapted simulation in the software package Matlab-Simulink in the sub-program psbupwm.mdl, replaced missing laboratory equipment, which has been used to perofm comparing of results of matematical method of such a system.

Offline method for experimental identification of load‐dependentsaturation of induction motor taking into account variation of inverse rotortime constant

Accurate knowledge of induction machine parameters has a direct impact on the overall performance of field-oriented control strategies. In the case of rotor flux oriented control, parameter mismatch causes a discrepancy in the estimated rotor flux position and amplitude. Magnetising inductance is one of the parameters whose detuning has a direct impact on the setpoints of the control loops and estimation of hardly or non-measurable quantities. Conventional iron saturation, which can be obtained by a standard no-load test, is not the only type of saturation occurring in the machine. Depending on the rotor design, the magnetising inductance and the rotor leakage inductance may also strongly saturate as a function of load and, thus, rotor current. Based on the authors’ previous work, a new, improved experimental method for identifying the load-dependent saturation of induction motor, which takes into account variation of the inverse rotor time constant, is proposed. Experimental results conducted on 12 kW motor show improved static and dynamic behaviour of the drive compared to the constant parameter model.

Parameter Estimation of Induction Machine Single-Cage and Double-Cage Models Using a Hybrid Simulated Annealing–Evaporation Rate Water Cycle Algorithm

This paper presents the usage of the hybrid simulated annealing—evaporation rate water cycle algorithm (SA-ERWCA) for induction machine equivalent circuit parameter estimation. The proposed algorithm is applied to nameplate data, measured data found in the literature, and data measured experimentally on a laboratory three-phase induction machine operating as an induction motor and as an induction generator. Furthermore, the proposed method is applied to both single-cage and double-cage equivalent circuit models. The accuracy and applicability of the proposed SA-ERWCA are intensively investigated, comparing the machine output characteristics determined by using SA-ERWCA parameters with corresponding characteristics obtained by using parameters determined using known methods from the literature. Also, the comparison of the SA-ERWCA with classic ERWCA and other algorithms used in the literature for induction machine parameter estimation is presented. The obtained results show that the proposed algorithm is a very effective and accurate method for induction machine parameter estimation. Furthermore, it is shown that the SA-ERWCA has the best convergence characteristics compared to other algorithms for induction machine parameter estimation in the literature.

Influence of Design Parameters on the Airgap Induction of Five-Phase Induction Machines Operating With One Phase Opened

This paper addresses the relation between some constructive parameters of five-phase induction machines and the airgap induction distribution under operation with one phase opened; we focus on the impact of design parameters on the airgap induction and the Joule losses. The influence of design parameters of the rotor and the stator is assessed using three distinct machines as a case study: two with identical stator but different rotors, and one with a distinct stator and also a distinct rotor. The results from the case study show that the characteristics of the stator windings, such as the number of slots per pole and phase and the number of layers, have less impact on the airgap induction under fault than under healthy operation. Besides, the case study shows that a decrease in the number of rotor bars contributes to an increase in the amplitude of the third harmonic component of the airgap induction. Finally, theoretical results are validated through analysis with the finite element method.

Speed Observer Structure of Induction Machine Based on Sliding Super-Twisting and Backstepping Techniques

This article presents an analysis of the two speed observer structures which are based on the backstepping and sliding super twisting approach. The observer stabilizing functions result from the Lyapunov theorem. To obtain the observer tuning gains the observer structure is linearized near the equilibrium point. The rotor angular speed is obtained from nonadaptive dependence. In the sensorless control system structure the classical PI controllers and transformation to the multiscalar variables are applied. The theoretical derivations are verified in experimental waveforms. Comparison of both speed observer structures is presented for nominal speed, load torque injections while regenerating mode, very low speed range and the uncertainties of nominal parameters of induction machine.

Optimization Procedure for Computing Sampling Time for Induction Machine Parameter Estimation

This paper presents a method for selecting the sampling time for induction machine parameter estimation from the machine line start measurements. the metaheuristic optimization method is used to find the optimal Prony exponential series approxiamtion of the line start transient current. From the optimal approximation, poles of the linearized induction machine model are computed and used to determine the optimal sampling time. the results show that sampling frequencies needed for parameter estimation are much lower than 1–15 kHz commonly used today. This reduces the necessary amount of collected data and the computing power needed for the estimation. the optimal sampling time is computed for the simulated and for the measured data. Referenced parameter estimation technique is tested for the measured transient showing benefits of using the optimal sampling time.

A comparative study on parameters estimation of squirrel cage induction motors using neural networks with unmemorized training

Induction machines are often preferred in industrial applications at present. Therefore, it is an important problem to know the electrical parameters of induction machines correctly. Electrical parameters of induction motors can be obtained experimentally by performing DC test, no-load rotor test, and locked rotor test. Furthermore, equivalent circuit parameters of the induction machines can be estimated with high accuracy using the data from machine manufacturers. In this study, equivalent circuit parameters of squirrel-cage induction motors have been successfully estimated by using Feed Forward Neural Network (FFNN) for single-cage and double-cage models. Although there is a feed forward neural network study in the literature, the training process of the neural network structures was carried out with unmemorized training. In addition to FFNN, an unmemorized Elman Neural Network (ENN) structure has been proposed to solve this problem. The proposed methods were compared with the literature for both models, and their performances were examined. The obtained FFNN results suggest that the proposed method performed better results than both adaptive neuro fuzzy inference system (ANFIS) and artificial neural network (ANN) for the single-cage model. In the double-cage model, FFNN performed better than ANN but relatively weaker than ANFIS. The results of the ENN structure are close to ANFIS for both single-cage and double-cage models.