Induction Motor System Research Articles

ROTOR RESISTANCE IDENTIFICATION IN AN IRFO SYSTEM OF A SATURATED INDUCTION MOTOR

This paper presents a novel method for the rotor resistance identification of an indirect rotor field oriented (IRFO) control system of a saturated induction motor. A saturated induction motor is an induction motor with a variable (saturable) mutual inductance. Saturation of the mutual inductance appears in operating conditions with variable rotor flux levels in the IRFO control system of an induction motor. The rotor resistance identification is based on an inverse rotor time constant identification, which is based on the model reference adaptive system (MRAS) principle. The magnitude of the rotor flux has been estimated in the stationary reference frame by the voltage model (reference model) and by the current model (adaptive model). The error signal of the rotor flux magnitude of the two estimators is applied to drive a PI mechanism that provides a correction to the inverse rotor time constant. This paper presents an original analysis of the IRFO system stability by taking small deviations of mutual inductance and rotor resistance at a steady-state operating point. The effectiveness of the proposed method for rotor resistance identification has been verified by digital simulation and experimentation.

INDUCTION MOTOR DRIVE SYSTEM WITH ADAPTIVE FUZZY LOGIC CONTROLLER

Abstract The aim of this paper is to present a control system for a squirrel cage three-phase induction motor with an adaptive speed controller. The adaptive speed controller is based on fuzzy logic theory and is applied for nonlinear sensorless control. A multiscalar model of induction motor is used for machine control, while an adaptive fuzzy controller is supposed to provide better machine response for different operating points than the conventional PI one. A comparative study of Fuzzy based controller with the PI type of controller is done. Simulation and experimental results are provided to validate the proposed concept.

ANN based real time incipient fault detection and protection system for induction motor

Artificial neural network (ANN) has its unique advantage in the area of incipient faults detection. This article presents an ANN based real time fault detection and protection system for two types of incipient faults viz. inter-turn insulation failure and bearing wear in single-phase induction motor. The ANN fault detection (ANNFD) program is developed in C++ and implemented using a PC based DSP controller board. The ANN is trained and tested by collecting the online experimental data for five input parameters viz. motor intake current, rotor speed, winding temperature, bearing temperature and noise. The results are compared with the signature of measurable parameters. The results of evaluation indicate that the system produces satisfactory performance for the fault detection as well as for the protection of motor.

Fuzzy-Expert Diagnostics for Detecting and Locating Internal Faults in Three Phase Induction Motors

Internal faults in three phase induction motors can result in serious performance degradation and eventual system failures if not properly detected and treated in time. Artificial intelligence techniques, the core of soft-computing, have numerous advantages over conventional fault diagnostic approaches; therefore, a soft-computing system was developed to detect and diagnose electric motor faults. The fault diagnostic system for three-phase induction motors samples the fault symptoms and then uses a fuzzy-expert forward inference model to identify the fault. This paper describes how to define the membership functions and fuzzy sets based on the fault symptoms and how to construct the hierarchical fuzzy inference nets with the propagation of probabilities concerning the uncertainty of faults. The designed hierarchical fuzzy inference nets efficiently detect and diagnose the fault type and exact location in a three phase induction motor. The validity and effectiveness of this approach is clearly shown from obtained testing results.

Experimental verification for stability improvement of sensorless vector control system of induction motor using real‐time tuning of observer gain

AbstractThis paper proposes a method for the design of the adaptive rotor flux observer gain to improve stability at low speed and in regenerating mode. The method is based on stability analysis, which utilizes a linearized model considering all systems, including each control loop. Therefore, the proposed method considers the effects of motor constants and control circuit constants. The stability analysis using the transfer function for the rotor speed considers the arrangement of poles and zeros and the steady‐state error. The rotor flux observer gain which improves the stability for each operating condition is ascertained. This paper also proposes a real‐time tuning method for the observer gain. The validity of the proposed method was confirmed by simulation using Matlab Simulink and by experiment. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(1): 67–81, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20715

The Effects of Structural and Localized Resonances on Induction Motor Performance

Troubleshooting resonance problems within alternating current induction motor systems has always presented difficult challenges for motor manufacturers and end users alike. Often, the changes in structural stiffness from a motor manufacturer's rigid foundation to a less stiff field base can produce drastically different vibration performance. In most cases, a structural natural frequency of a motor or foundation that coincides with a motor forcing function will provide detrimental results to the motor vibration. Many times the effects of undesirable system resonances may be detected after the motor has been installed, causing costly down time, or even motor failure if the problem remains undetected. Additionally, natural frequencies of motor components, such as fans, may cause a catastrophic fatigue failure when the motor is subjected to forcing functions with frequencies in the vicinity of these localized resonances. This paper will provide insight on motor system resonances and localized resonances that may be damaging to an induction motor's operation.

On-line broken-bar fault diagnosis system of induction motor

Induction motor faults including mechanical and electrical faults are reviewed. The fault diagnosis methods are summarized. To analyze the influence of stator current, torque, speed and rotor current on faulted bars, a time-stepping transient finite element (FE) model of induction motor with bars faulted is created in this paper. With wavelet package analysis method and FFT method, the simulation result of finite element is analyzed. Based on the simulation analysis, the on-line fault diagnosis system of induction motor with bars faulted is developed. With the speed of broken bars motor changed from 1 478 r/min to 1 445 r/min, the FFT power spectra and the wavelet package decoupling factors are given. The comparison result shows that the on-line diagnosis system can detect broken-bar fault efficiently.

Neural-Network-Based Parameter Estimations of Induction Motors

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The goal of this paper is to use artificial neural networks (ANNs) for online identification of induction-motor parameters. ANNs such as feedforward and recurrent networks will be used to develop an ANN as a memory for remembering the estimated parameters and for computing the parameters during transients. Simulations and experimental results will be presented for a nonlinear control system of induction motors. A digital signal processor will be used for the experimental investigation. </para>

Development of a finite element solution module for the analysis of the dynamic behavior and balancing effects of an induction motor system

The study developed a multipurpose finite element solution module with the theoretical groundwork originated from principles of rotordynamics. This module is capable of solving many of the related rotating machine problems such as of the high speed gas bearing spindles and the electric machines. The goal of this paper is to utilize the developed solution module in investigating various aspects of the vibration behavior of an induction motor system for solving its failure problem of the shaft. Some of the crucial factors to the quality and performance of the motor, such as the vibration amplitude as resulted from the bearing wear, damping effects, mass unbalance, and the passing of system resonance critical speeds, are all investigated in the study. An efficient dual-rotor model is verified to have excellent accuracy when comparing the calculated frequency response function (FRF) with that from modal testing. The results of the transient orbit analysis indicate that the bearing stiffness and damping dominates the vibration amplitude remarkably. The effects both from the bearing damping as well as from the clamping–damping between the silicon steel core and the rotating shaft are all examined. It is noticed that the bearing damping plays the major role in the restraint of the vibration amplitudes of the rotor. For the analysis of vibration suppression with different eccentricities of the unbalanced masses, it is found that the adding of balance masses will normally suppress the vibration amplitude effectively until the point where an optimum amount that causes the minimum balanced vibration amplitudes is observed. Both the qualitative and quantitative analyses for the effectiveness of the balance mass added with different eccentricity ratios are studied. Thus, the critical adding mass ratio (i.e. the adding mass ratio at the minimum balanced amplitude factor) can also be predicted through its linear relationship with the eccentricity ratio. Based on all the findings through the study, it is concluded that the approach not only can solve the realistic shaft vibration failure problems of a motor and the demonstrated processes are also believed to be able to help the designers to have better command of motor performance at the system design stage.

A DSP-based modified slip energy recovery drive using a 12-pulse converter and shunt chopper for a speed control system of a wound rotor induction motor

This paper introduces a modified slip energy recovery drive system for speed control of a wound rotor induction motor offering improvement of drive performance, particularly line power factor and overall system efficiency. A 12-pulse line commutated thyristor converter operating in an inverter mode in conjunction with an additional IGBT shunt chopper is employed to transfer slip energy back to ac mains supply via three phase transformers. This approach offers motor speed control by varying the duty cycle of the chopper instead of changing the inverter firing angle. As a consequence, supply power factor can be improved. The servo state feedback designed by linear quadratic regulator (LQR) with observer is also included in order to keep motor speed to be constant over a certain range of operating conditions by using the estimated dc link current derived from motor speed. The advantage of this technique is absence of current transducers for current feedback control loop. The overall control system is implemented on DSP, DS1104’TMS320F240 controller board. Experimental results are illustrated in order to validate performance of the proposed system.

Reduced Harmonic Pollution: Intelligent Switching Strategy for Matrix Converter

This paper proposes a neural-network current-regulated switching strategy for a matrix converter induction motor drive system. In this paper, the design and implementation of the induction motor system has been investigated. This paper has provided a systematic and analytic approach for designing a high performance matrix converter induction motor drive system. All the control algorithms, which include switching strategy, current regulation, are executed by a digital signal processor TMS320C6711. By using this new switching strategy, the current harmonics of the system are effectively reduced. Several experimental results are shown to validate the theoretical analysis.

Feature‐based fault diagnosis system of induction motors using vibration signal

Purpose – The purpose of this paper is to identify the efficiency of vibration signals for fault diagnosis system of induction motors.Design/methodology/approach – A fault diagnosis system for induction motors using vibration signals is designed based on pattern recognition. Genetic algorithm is used for feature reduction and neural network tuning.Findings – The usage of genetic algorithm improves the system performance through selecting significant features and optimizing network structure. The efficiency of vibration signals is demonstrated.Practical implications – Condition monitoring and fault diagnosis for induction motors is one of the main industry maintenance parts. Motors faults usually result in whole production line breakdown. In this paper, one fault diagnosis system is proposed for induction motors based on feature recognition through combination of feature extraction, genetic algorithm and neural network techniques. From the paper, one can learn practically the whole procedure of feature‐bas...

계층구조의 분류기에 의한 유도전동기 고장진단

In this paper, we propose a fault diagnosis scheme tor induction motor by adopting a hierarchical classifier consisting of k-Nearest Neighbors(k-NN) and Support Vector Machine(SVM). First, some motor conditions are classified by a simple k-NN classifier in advance. And then, more complicated classes are distinguished by SVM. To obtain the normal and fault data, we established an experimental unit with induction motor system and data acquisition module. Feature extraction is performed by Principal Component Analysis(PCA). To show its effectiveness, the proposed fault diagnostic system has been intensively tested with various data acquired under the different electrical and mechanical faults with varying load.

Design of a Robust Stable Flux Observer for Induction Motors

This paper presents a robustly adaptive flux observer for speed-sensorless induction motor control. The proposed approach employs additional robustifying signals to cope with the parametric uncertainties instead of designing an estimator, which has been normally used in power electronic drives. For that, the sliding-mode like adaptive controls are designed and their gain parameters are determined so that the observer dynamics are stable in the sense of Lyapunov, and furthermore they can guarantee the robustness against parametric uncertainties in induction motor systems. Estimated rotor speed is to be used to generate feedback control signal for the speed sensorless vector control system. To show the validity and efficiency of the proposed system, simulation results are presented.

Fuzzy Sliding-Mode Control Using Adaptive Tuning Technique

This study mainly deals with the key problem of chattering phenomena on the conventional sliding-mode control (SMC) and investigates an adaptive fuzzy sliding-mode control (AFSMC) system for an indirect field-oriented induction motor (IM) drive to track periodic commands. First, an indirect field-orientation method for an IM drive is introduced briefly. Moreover, a fuzzy logic inference mechanism is utilized for implementing a fuzzy hitting control law to remove completely the chattering phenomena on the conventional SMC. In addition, to confront the uncertainties existed in practical applications, an adaptive algorithm, which is derived in the sense of Lyapunov stability theorem, is utilized to adjust the fuzzy parameter for further assuring robust and optimal control performance. The indirect field-oriented IM drive with the AFSMC scheme possesses the salient advantages of simple control framework, free from chattering, stable tracking control performance, and robust to uncertainties. Furthermore, numerical simulation and experimental results due to periodic sinusoidal commands are provided to verify the effectiveness of the proposed control strategy, and its advantages are indicated in comparison with the conventional SMC system and the SMC system with a boundary layer

Study of Drive System for Linear Induction Motor Using Magnetic Energy Recovery Switch

This paper proposes a suitable power supply for driving linear induction motors. The power supply consists of a voltage source inverter (VSI) and a magnetic energy recovery switch (MERS). Circuit configuration and operation principles of the power supply are described. Power factor correction by MERS can cause an increase of the output power. Technical advantages of using MERS compared with increasing voltage rating of VSI are discussed. Some experiments with a linear induction motor were conducted. The results confirms that MERS can reduce capacity of the VSI or increase output with the same VSI capacity. The number of devices and losses are evaluated on large scale drive system. A half-bridge type of MERS is proposed and discussed. The half-bridge MERS improves disadvantages of using MERS.

EMTP를 이용한 멀티레벨 인버터 구동 고압유도전동기에서 발생하는 과도과전압 저감필터의 효과분석

본 논문에서는 인버터 구동 고압유도전동기 운전시 스위칭 서지로 인하여 고압유도 전동기 단자에서 발생하는 과도과전압을 저감하기 위한 필터로 인버터 출력단자에서 dv/dt를 저감하는 LCR 필터와 전동기 입력단자에서 케이블과 유도전동기 특성임피던스를 매칭시키는 RC필터에 대한 과도과전압 저감특성을 분석하였다. 이 필터를 고압에 대용량 유도전동기에 적합하도록 EMTP(ElectroMagnetic Transients Program)를 이용하여 모델링 및 케이블 영향에 의한 필터의 과도과전압 저감효과를 전압파형과 고조파 스펙트럼으로 비교분석하고, 이를 토대로 고압 대용량 유도전동기에 사용될 필터를 제시하였다. 인버터 스위칭 서지에 의한 과도과전압은 유도전동기 고정자 권선에 심각한 전압 스트레스를 발생시켜 절연파괴를 일으키는 주요원인이 된다. 이러한 과도과전압을 저감위한 필터설계는 고압유도전동기 시스템에서 필수적인 요소임을 보였다. 또한 제시된 필터는 과도과전압을 효과적으로 저감시키는 것을 EMTP 시뮬레이션을 통하여 입증하였다.

High-performance speed servo system considering Voltage saturation of a vector-controlled induction motor

Generally, a speed servo system of a vector-controlled induction motor has limitations of motor voltage and current. When the speed servo system has a large torque reference, the output of its PI controller is often saturated. In this case, the conventional servo system stops the integral calculation of its PI controller. However, this system often has a large overshoot and/or an oscillated response caused by both a windup phenomenon and phase error on the vector control condition. This paper proposes a new speed servo system considering voltage saturation for the vector-controlled induction motor. The proposed control method compensates the phase error on vector control condition quickly, and always keeps the vector control condition. The experimental results show that the proposed system well regulates the motor speed and the secondary magnetic flux for a large torque reference without a windup phenomenon.

발전소 대형 입형펌프 전동기의 전류/진동신호 특성 분석

Induction motors are the workhorse of our industry because of their versatility and robustness. The diagnosis of mechanical load and power transmission system failures is usually carried out through mechanical signals such as vibration signatures, acoustic emissions, motor speed envelope. The motor faults including mechanical rotor imbalances, broken rotor bar, bearing failure and eccentricities problems are reflected in electric, electromagnetic and mechanical quantities. The recent research has been directed toward electrical monitoring of the motor with emphasis on inspecting the stator current of the motor, The stator current spectrum has been widely used for fault detection in induction motor systems. The motor current signature analysis is the useful technique to assess machine electrical condition. This paper describes the motor condition detected by the current signatures Paralleled with vibration signatures analysis of induction motors with the roller bearing and the journal bearing type for large vertical pumps in power plant as examples to discuss for motor fault detection and diagnosis.

Adaptive enhanced fuzzy sliding-mode control for electrical servo drive

The design and properties of an adaptive enhanced fuzzy sliding-mode control (AEFSMC) system for an indirect field-oriented induction motor (IM) drive to track periodic commands are addressed in this study. A newly designed EFSMC system, in which a translation-width idea is embedded into the FSMC, is introduced initially. Moreover, to confront the uncertainties existed in practical applications, an adaptive tuner, which is derived in the sense of the Lyapunov stability theorem, is utilized to adjust the EFSMC parameter for further assuring robust and optimal control performance. The indirect field-oriented IM drive with the AEFSMC scheme possesses the salient advantages of simple control framework, free from chattering, stable tracking control performance, and robust to uncertainties. In addition, numerical simulation and experimental results due to periodic sinusoidal commands are provided to verify the effectiveness of the proposed control strategy, and its advantages are indicated in comparison with FSMC and EFSMC systems.