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Showing papers on "Induction motor published in 2007"


Journal ArticleDOI
TL;DR: A detailed overview of the state-of-the-art in multiphase variable-speed motor drives can be found in this article, where the authors provide a detailed survey of the control strategies for five-phase and asymmetrical six-phase induction motor drives, as well as the approaches to the design of fault tolerant strategies for post-fault drive operation.
Abstract: The area of multiphase variable-speed motor drives in general and multiphase induction motor drives in particular has experienced a substantial growth since the beginning of this century. Research has been conducted worldwide and numerous interesting developments have been reported in the literature. An attempt is made to provide a detailed overview of the current state-of-the-art in this area. The elaborated aspects include advantages of multiphase induction machines, modelling of multiphase induction machines, basic vector control and direct torque control schemes and PWM control of multiphase voltage source inverters. The authors also provide a detailed survey of the control strategies for five-phase and asymmetrical six-phase induction motor drives, as well as an overview of the approaches to the design of fault tolerant strategies for post-fault drive operation, and a discussion of multiphase multi-motor drives with single inverter supply. Experimental results, collected from various multiphase induction motor drive laboratory rigs, are also included to facilitate the understanding of the drive operation.

1,445 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a control scheme that allows doubly fed induction wind generators (DFIWG) to participate effectively in system frequency regulation. But, the control strategy defined at the wind generator to supply primary frequency regulation capability exploits a combination of control of the static converters and pitch control, adjusting the rotor speed and the active power according to the deloaded optimum power extraction curve.
Abstract: This paper proposes a control scheme that allows doubly fed induction wind generators (DFIWG) to participate effectively in system frequency regulation. In this control approach, wind generators operate according to a deloaded optimum power extraction curve such that the active power provided by each wind turbine increases or decreases during system frequency changes. The control strategy defined at the wind generator to supply primary frequency regulation capability exploits a combination of control of the static converters and pitch control, adjusting the rotor speed and the active power according to the deloaded optimum power extraction curve. Results obtained in a small isolated system are presented to demonstrate the effectiveness of the approach.

571 citations


Journal ArticleDOI
TL;DR: This paper presents a DFIG control strategy that enhances the standard speed and reactive power control with controllers that can compensate for the problems caused by an unbalanced grid by balancing the stator currents and eliminating torque and reactivePower pulsations.
Abstract: Wind energy is often installed in rural, remote areas characterized by weak, unbalanced power transmission grids. In induction wind generators, unbalanced three-phase stator voltages cause a number of problems, such as overcurrent, unbalanced currents, reactive power pulsations, and stress on the mechanical components from torque pulsations. Therefore, beyond a certain amount of unbalance, induction wind generators are switched out of the network. This can further weaken the grid. In doubly fed induction generators (DFIGs), control of the rotor currents allows for adjustable speed operation and reactive power control. This paper presents a DFIG control strategy that enhances the standard speed and reactive power control with controllers that can compensate for the problems caused by an unbalanced grid by balancing the stator currents and eliminating torque and reactive power pulsations

333 citations


Journal ArticleDOI
15 Oct 2007
TL;DR: In this paper, the authors discussed the problem concerning the determination of some thermal parameters which are very complex to compute, such as the equivalent thermal resistance between external frame and ambient, equivalent thermal conductivity between winding and lamination, forced convection heat transfer coefficient between end winding and end-caps, radiation heat transfer ratio between external frames and ambient and interface gap between lamination and external frame, air cooling speed, and the bearings effective thermal resistance.
Abstract: In this paper, the authors discuss the problem concerning the determination of some thermal parameters which are very complex to compute. These parameters play an important role in thermal networks usually adopted for electrical machine thermal analysis. In particular, in this paper, the following thermal parameters are analyzed: equivalent thermal resistance between external frame and ambient, equivalent thermal conductivity between winding and lamination, forced convection heat transfer coefficient between end winding and end-caps, radiation heat transfer coefficient between external frame and ambient, interface gap between lamination and external frame, air cooling speed, and the bearings effective thermal resistance. While the information given in this paper is mainly related to induction motors, it is also of general use for the designers of other types of machine. The reported results have been validated using induction motors with power ranges from a few kilowatts up to 1 MW.

314 citations


Journal ArticleDOI
TL;DR: Extended-Kalman-filter-based estimation algorithms that could be used in combination with the speed-sensorless field-oriented control and direct-torque control of induction motors (IMs) are developed and implemented experimentally and motivated by the lost coupling effect at very low and zero speed.
Abstract: In this paper, extended-Kalman-filter-based estimation algorithms that could be used in combination with the speed-sensorless field-oriented control and direct-torque control of induction motors (IMs) are developed and implemented experimentally. The algorithms are designed aiming minimum estimation error in both transient and steady state over a wide velocity range, including very low and persistent zero-speed operation. A major challenge at very low and zero speed is the lost coupling effect from the rotor to the stator, which makes the information on rotor variables unobservable on the stator side. As a solution to this problem, in this paper, the load torque and the rotor angular velocity are simultaneously estimated, with the velocity taken into consideration via the equation of motion and not as a constant parameter, which is commonly the case in most past studies. The estimation of load torque, on the other hand, is performed as a constant parameter to account for Coulomb and viscous friction at steady state to improve the estimation performance at very low and zero speed. The estimation algorithms developed based on the rotor and stator fluxes are experimentally tested under challenging variations and reversals of the velocity and load torque (step-type and varying linearly with velocity) over a wide velocity range and at zero speed. In all the scenarios, the current estimation error has remained within a very narrow error band, also yielding acceptable velocity estimation errors, which motivate the use of the developed estimation method in sensorless control of IMs over a wide velocity range and persistent zero-speed operation

304 citations


Journal ArticleDOI
TL;DR: In this paper, a reduced-order DFIG model is developed that restricts the calculation to the fundamental frequency component and allows the consideration of the alternating components of the rotor current as well, which is necessary for triggering the crowbar operation.
Abstract: This paper deals with modeling of the doubly-fed induction generator (DFIG) and the corresponding converter for stability studies. To enable efficient computation, a reduced-order DFIG model is developed that restricts the calculation to the fundamental frequency component. However, the model enhancement introduced in this paper allows the consideration of the alternating components of the rotor current as well, which is necessary for triggering the crowbar operation. Suitable models are presented for the rotor and grid side converters as well as the dc-link, taking into account all four possible operating modes. The proposed model for speed and pitch angle control can be used when wind and rotor speed variations are significant. Simulation results are presented for model verification purposes and also for demonstrating the dynamic behavior of a large offshore wind farm connected through a long undersea cable to the high voltage grid.

275 citations


Journal ArticleDOI
TL;DR: The accuracy of the estimated speed achieved experimentally, without the speed sensor clearly demonstrates the reliable and high-performance operation of the drive.
Abstract: This paper presents a new method of online estimation for the stator and rotor resistances of the induction motor for speed sensorless indirect vector controlled drives, using artificial neural networks. The error between the rotor flux linkages based on a neural network model and a voltage model is back propagated to adjust the weights of the neural network model for the rotor resistance estimation. For the stator resistance estimation, the error between the measured stator current and the estimated stator current using neural network is back propagated to adjust the weights of the neural network. The rotor speed is synthesized from the induction motor state equations. The performance of the stator and rotor resistance estimators and torque and flux responses of the drive, together with these estimators, are investigated with the help of simulations for variations in the stator and rotor resistances from their nominal values. Both resistances are estimated experimentally, using the proposed neural network in a vector controlled induction motor drive. Data on tracking performances of these estimators are presented. With this speed sensorless approach, the rotor resistance estimation was made insensitive to the stator resistance variations both in simulation and experiment. The accuracy of the estimated speed achieved experimentally, without the speed sensor clearly demonstrates the reliable and high-performance operation of the drive

265 citations


Journal ArticleDOI
TL;DR: An analytical redundancy method using neural network modeling of the induction motor in vibration spectra is proposed for machine fault detection and diagnosis and it is shown that a robust and automatic induction machine condition monitoring system has been produced.
Abstract: Condition monitoring is desirable for increasing machinery availability, reducing consequential damage, and improving operational efficiency. Model-based methods are efficient monitoring systems for providing warning and predicting certain faults at early stages. However, the conventional methods must work with explicit motor models, and cannot be applied effectively for vibration signal diagnosis due to their nonadaptation and the random nature of vibration signal. In this paper, an analytical redundancy method using neural network modeling of the induction motor in vibration spectra is proposed for machine fault detection and diagnosis. The short-time Fourier transform is used to process the quasi-steady vibration signals to continuous spectra for the neural network model training. The faults are detected from changes in the expectation of vibration spectra modeling error. The effectiveness of the proposed method is demonstrated through experimental results, and it is shown that a robust and automatic induction machine condition monitoring system has been produced

260 citations


Journal ArticleDOI
TL;DR: It is observed from the simulation results that the five input parameter system predicts more accurate results.
Abstract: The positive features of neural networks and fuzzy logic are combined together for the detection of stator inter-turn insulation and bearing wear faults in single-phase induction motor. The adaptive neural fuzzy inference systems (ANFISs) are developed for the detection of these two faults. These faults are created experimentally on a single-phase induction motor in the laboratory. The experimental data is generated for the five measurable parameters, viz, motor intakes current, speed, winding temperature, bearing temperature, and the noise of the machine. Earlier, the ANFIS fault detectors are trained for the two input parameters, i.e., speed and current, and the performance is tested. Later, the three remaining parameters are added and the five input ANFIS fault detector is trained and tested. It observed from the simulation results that the five input parameter system predicts more accurate results

250 citations


Journal ArticleDOI
15 Oct 2007
TL;DR: In this article, a wavelet-based method for broken-bar detection in squirrel-cage induction machines is presented, which consists in the energy evaluation of a known bandwidth with time-scale analysis using the discrete wavelet transform.
Abstract: The aim of this paper is to present a wavelet-based method for broken-bar detection in squirrel-cage induction machines. The frequency-domain methods, which are commonly used, need speed information or accurate slip estimation for frequency-component localization in any spectrum. Nevertheless, the fault frequency bandwidth can be well defined for any squirrel-cage induction machine due to numerous previous investigations. The proposed approach consists in the energy evaluation of a known bandwidth with time-scale analysis using the discrete wavelet transform. This new technique has been applied to the stator-current space-vector magnitude and the instantaneous magnitude of the stator-current signal for different broken-bar fault severities and load levels.

241 citations


Journal ArticleDOI
TL;DR: In this paper, an indirect-rotor-field-oriented-control scheme for sensorless speed control of a PMSM is proposed, in which the rotor-flux position is estimated by direct integration of the estimated rotor speed to reduce the effect of the system noise.
Abstract: Efficient and precise sensorless speed control of a permanent-magnet synchronous motor (PMSM) requires accurate knowledge of rotor flux, position, and speed. In the literature, many sensorless schemes have been presented, in which the accurate estimation of rotor flux magnitude, position, and speed is guaranteed by detecting the back electromotive force (EMF). However, these schemes show great sensitivity to stator resistance mismatch and system noise, particularly, during low-speed operation. In this paper, an indirect-rotor-field-oriented-control scheme for sensorless speed control of a PMSM is proposed. The rotor-flux position is estimated by direct integration of the estimated rotor speed to reduce the effect of the system noise. The stator resistance and the rotor-flux speed and magnitude are estimated adaptively using stable model reference adaptive system estimators. Simple stability analysis and design of the estimators are performed using linear-control theory applied to an error model of the PMSM in a synchronous rotating reference frame. The convergence of rotor position- and speed-estimation errors to zero is guaranteed. Experimental results show excellent performance

Journal ArticleDOI
TL;DR: An automatic algorithm based an unsupervised neural network for an on-line diagnostics of three-phase induction motor stator fault is presented and the obtained experimental results show the effectiveness of the proposed method.
Abstract: In this paper, an automatic algorithm based an unsupervised neural network for an on-line diagnostics of three-phase induction motor stator fault is presented. This algorithm uses the alfa-beta stator currents as input variables. Then, a fully automatic unsupervised method is applied in which a Hebbian-based unsupervised neural network is used to extract the principal components of the stator current data. These main directions are used to decide where the fault occurs and a relationship between the current components is calculated to verify the severity of the fault. One of the characteristics of this method, given its unsupervised nature, is that it does not need a prior identification of the system. The proposed methodology has been experimentally tested on a 1kW induction motor. The obtained experimental results show the effectiveness of the proposed method

Journal ArticleDOI
Kouro, Bernal, Miranda, Silva, Rodriguez 
TL;DR: This paper presents a high-performance torque and flux control strategy for high-power induction motor drives that uses the torque error to control the load angle, obtaining the appropriate flux vector trajectory from which the voltage vector is directly derived based on direct torque control principles.
Abstract: This paper presents a high-performance torque and flux control strategy for high-power induction motor drives. The control method uses the torque error to control the load angle, obtaining the appropriate flux vector trajectory from which the voltage vector is directly derived based on direct torque control principles. The voltage vector is then generated by an asymmetric cascaded multilevel inverter without need of modulation and filter. Due to the high output quality of the inverter, the torque response presents nearly no ripple. In addition, switching losses are greatly reduced since 80% of the power is delivered by the high-power cell of the asymmetric inverter, which commutates at fundamental frequency. Simulation and experimental results for 81-level inverter are presented.

Journal ArticleDOI
TL;DR: Simulation results show the global effectiveness of the proposed approaches, particularly the one based on modern and intelligent control techniques in terms of speed and torque smoothness.
Abstract: This paper describes active fault-tolerant control systems for a high-performance induction-motor drive that propels an electrical vehicle (EV) or a hybrid one (HEV). The proposed systems adaptively reorganize themselves in the event of sensor loss or sensor recovery to sustain the best control performance, given the complement of remaining sensors. Moreover, the developed systems take into account the controller-transition smoothness, in terms of speed and torque transients. The two proposed fault-tolerant control strategies have been simulated on a 4-kW induction-motor drive, and speed and torque responses have been carried to evaluate the consistency and the performance of the proposed approaches. Simulation results, in terms of speed and torque responses, show the global effectiveness of the proposed approaches, particularly the one based on modern and intelligent control techniques in terms of speed and torque smoothness

Journal ArticleDOI
TL;DR: The average efficiencies of both the inverter drive and the induction traction motor are evaluated and summarized under city as well as highway driving conditions and the overall traction motor drive system efficiency is estimated.
Abstract: Extensive research done in the recent past has proven that power electronic converters and electric propulsion motors are extremely critical components for modern hybrid electric vehicle (HEV) propulsion applications. Therefore, it is essential that both the traction motor and the associated drive operate at their optimal efficiencies throughout the driving schedule. In typical HEV propulsion applications, the traction motor and the drive are used over the entire torque/speed operational range. In view of this fact, this paper aims at modeling the inverter and motor losses/efficiencies over typical city and highway driving schedules. The noteworthy losses within a typical three-phase dc/ac traction inverter, such as the switching and conduction losses for both the insulated-gate bipolar transistors and the antiparallel diodes, are modeled and simulated over the city and highway driving patterns. An induction motor (IM) is used for a medium-sized sport utility vehicle, which was modeled in the advanced vehicle simulator (ADVISOR) software. The significant IM losses that were considered in the study include the stator copper losses, rotor copper losses, and core losses. Thus, the average efficiencies of both the inverter drive and the induction traction motor are evaluated and summarized under city as well as highway driving conditions. Finally, based on the individual-model-based efficiency analysis, the overall traction motor drive system efficiency is estimated.

Journal ArticleDOI
TL;DR: In this paper, bearing defect is detected using the stator current analysis via Meyer wavelet in the wavelet packet structure, with energy comparison as the fault index, and the presented method is evaluated using experimental signals.

Journal ArticleDOI
TL;DR: In this paper, a defect in the outer race of an induction motor ball bearing was detected by using vibration, stator current, acoustic emission and shock pulse (SPM) measurements at different loads.

Journal ArticleDOI
TL;DR: The experimental results for the V/f control of 3-hp induction motor drives controlled by a digital signal processor TMS320C31 chip have verified the effectiveness of the proposed PWM converter topology.
Abstract: This paper proposes a novel control scheme of single-phase-to-three-phase pulsewidth-modulation (PWM) converters for low-power three-phase induction motor drives, where a single-phase half-bridge PWM rectifier and a two-leg inverter are used. With this converter topology, the number of switching devices is reduced to six from ten in the case of full-bridge rectifier and three-leg inverter systems. In addition, the source voltage sensor is eliminated with a state observer, which controls the deviation between the model current and the system current to be zero. A simple scalar voltage modulation method is used for a two-leg inverter, and a new technique to eliminate the effect of the dc-link voltage ripple on the inverter output current is proposed. Although the converter topology itself is of lower cost than the conventional one, it retains the same functions such as sinusoidal input current, unity power factor, dc-link voltage control, bidirectional power flow, and variable-voltage and variable-frequency output voltage. The experimental results for the V/f control of 3-hp induction motor drives controlled by a digital signal processor TMS320C31 chip have verified the effectiveness of the proposed scheme

Journal ArticleDOI
Yi Li1, Zi-Qiang Zhu1, D. Howe1, Chris Bingham1, David A. Stone1 
15 Oct 2007
TL;DR: In this paper, an improved signal-injection-based sensorless-control method for permanent-magnet brushless AC (BLAC) motors, accounting for the influence of cross-coupling magnetic saturation between the d- and q-axes, is presented.
Abstract: This paper presents an improved signal-injection-based sensorless-control method for permanent-magnet brushless AC (BLAC) motors, accounting for the influence of cross-coupling magnetic saturation between the d- and q -axes. The d- and q -axis incremental self-inductances, the incremental mutual inductance between the d-axis and q -axis, and the cross-coupling factor are determined by finite-element analysis. An experimental method is proposed for measuring the cross-coupling factor which can be used directly in the sensorless-control scheme. Both measurements and predictions show that a significant improvement in the accuracy of the rotor-position estimation can be achieved under both dynamic and steady-state operation compared with that which is obtained with the conventional signal-injection method.

Journal ArticleDOI
TL;DR: In this paper, a methodology for constructing a state-variable model, based on a magnetic equivalent circuit of the motor, is described, which is an excellent compromise between the speed of lumped parameter models and the ability of finite element methods to capture spatial effects.
Abstract: Finite element models are invaluable for determining expected machine performance. However, finite element analysis can be computationally intense; particularly if a large numbers of studies or high bandwidth studies are required. One method to avoid this difficulty is to extract machine parameters from the finite element model and use the parameters in lumped parameter models. While often useful, such an approach does not represent space harmonics or asymmetries in the motor. A methodology for constructing a state-variable model, based on a magnetic equivalent circuit of the motor is described herein. In addition, the parameters for this model are based solely on geometrical data. This approach is an excellent compromise between the speed of lumped parameter models and the ability of finite element methods to capture spatial effects. Experimental validation of the model is provided.

Journal ArticleDOI
TL;DR: A fourth-order sliding-mode flux observer is developed and the equivalent values of the switching functions are proven to be the rotor resistance and the inverse of the rotor time constant.
Abstract: Field orientation techniques without flux measurements depend on the parameters of the motor, particularly on the rotor resistance or rotor time constant (for rotor field orientation). Since these parameters change continuously as a function of temperature, it is important that the value of rotor resistance is continuously estimated online. A fourth-order sliding-mode flux observer is developed in this paper. Two sliding surfaces representing combinations of estimated flux and current errors are used to enforce the flux and current estimates to their real values. Switching functions are used to drive the sliding surfaces to zero. The equivalent values of the switching functions (low-frequency components) are proven to be the rotor resistance and the inverse of the rotor time constant. This property is used to simultaneously estimate the rotor resistance and the inverse of the time constant without prior knowledge of either the rotor resistance or the magnetizing inductance. Simulations and experimental results prove the validity of the proposed approach

Journal ArticleDOI
TL;DR: The proposed control strategy, which is based on a direct flux and torque control scheme, utilizes the stator flux as a control variable, and the flux level is selected in accordance with the torque demand of the EV to achieve the efficiency-optimized drive performance.
Abstract: This paper proposes a strategy to minimize the losses of an induction motor propelling an electric vehicle (EV). The proposed control strategy, which is based on a direct flux and torque control scheme, utilizes the stator flux as a control variable, and the flux level is selected in accordance with the torque demand of the EV to achieve the efficiency-optimized drive performance. Moreover, among EV's motor electric propulsion features, the energy efficiency is a basic characteristic that is influenced by vehicle dynamics and system architecture. For this reason, the EV dynamics are taken into account. Simulation tests have been carried out on a 1.1-kW EV induction motor drive to evaluate the consistency and the performance of the proposed control approach

Journal ArticleDOI
TL;DR: In this paper, the effect of several potential rotor faults on the current spectrum of brushless dc motors with a view to develop an effective condition-monitoring scheme is investigated. But the authors do not consider the impact of load unbalances, misalignments, and varying load torques on the diagnosis of such machines.
Abstract: Brushless dc (BLDC) machines are finding increasing use in applications that demand high and rugged performance. Automotive and aerospace are some such areas where these machines may be used. In this context, condition monitoring of these machines would provide added value. This paper investigates the effect of several potential rotor faults on the current spectrum of BLDC motors with a view to develop an effective condition-monitoring scheme. The effect of load unbalances, misalignments, and varying load torques on the diagnosis of such machines is investigated. A method to estimate the strength of the rotor magnets is also provided. Simulation and experimental results are presented to substantiate that current signature analysis could be a viable tool for diagnosing the condition of BLDC machines.

Journal ArticleDOI
TL;DR: The experimental results of the proposed technique to compensate the effects of dead time in sinusoidal pulsewidth-modulated voltage-source inverters that is applied in a three-phase induction motor drive system are presented.
Abstract: This paper proposes a technique to compensate the effects of dead time in sinusoidal pulsewidth-modulated voltage-source inverters. The compensation is implemented by adjusting the switching frequency to avoid unfeasible pulsewidths of the gating signals, as well as to minimize the total harmonic distortion of the inverter output voltage. The technique can be used at any switching frequency, but the best results are obtained in the high-frequency range. The experimental results of the proposed technique that is applied in a three-phase induction motor drive system are presented.

Journal ArticleDOI
TL;DR: An inverter control scheme with common-mode voltage (CMV) elimination, along with a simple DC link voltage control, is developed by using only switching states with zero CMV for the entire modulation range.
Abstract: The paper presents a five-level inverter scheme with reduced power circuit complexity for an induction motor drive. The scheme is realized by cascading conventional two-level and three-level neutral point clamped inverters in conjunction with an open-end winding three-phase induction motor drive. An inverter control scheme with common-mode voltage (CMV) elimination, along with a simple DC link voltage control, is developed by using only switching states with zero CMV for the entire modulation range. Theoretical considerations are experimentally verified for a variety of operating conditions.

Journal ArticleDOI
TL;DR: A new concept for control of induction machines by generating the torque at the end of the sampling interval, using the predictive algorithm and can be split into two parts, to predict the reference flux vector corresponding to the reference torque.
Abstract: This paper proposes a new concept for the control of voltage-source inverter (VSI)-fed induction machines. The method uses a predictive algorithm and can be split into two parts. The purpose of the first part, i.e., predictive torque control (PTC), is to predict the stator reference flux vector corresponding to the reference torque at the end of the sampling interval. The second part of the method provides accurate tracing of the stator reference flux by selecting either an active or a zero voltage vector. This approach is called immediate flux control (IFC), where two possible variants are suggested. In the first variant, a simple and fast algorithm obtains minimal stator flux error by impressing either an active or a zero voltage vector throughout the entire sampling interval. Consequently, the switching frequency becomes very low, but current and torque ripple are considerable. The second IFC variant generates the stator flux more accurately by applying an active voltage vector only throughout a calculated time slot within a sampling interval, whereas, during the remaining time of the sampling interval, a zero voltage vector is impressed. As a result, higher switching frequency arises, but it is still lower than that with space vector modulation. Both IFC variants, together with PTC, require minimal processing time and were efficiently implemented in a digital signal processor, which controlled a 3-kW induction machine drive. The obtained experimental results confirm the validity of the proposed approach.

Journal ArticleDOI
15 Oct 2007
TL;DR: In this article, a sensorless on-line monitoring technique for detecting and classifying stator turn faults and high-R electrical connections in induction machines based on the zero sequence voltage or negative sequence current measurements is proposed.
Abstract: The goal of stator winding turn fault detection is to detect the fault at an early stage, and shut down the machine immediately to prevent catastrophic motor failure due to the large fault current. A number of turn fault detection techniques have been proposed; however, there is currently no method available for distinguishing turn faults from high-resistance(R) connections, which also result in 3 phase system asymmetry. It is important to distinguish the two faults since a high-R connection does not necessarily require immediate motor shutdown. In this paper, new sensorless on-line monitoring techniques for detecting and classifying stator turn faults and high-R electrical connections in induction machines based on the zero sequence voltage or negative sequence current measurements are proposed. An experimental study on a 10 hp induction motor performed under simulated turn faults and high-resistance circuit conditions verifies that the two faults can be reliably detected and classified. The proposed technique helps improve the reliability, efficiency, and safety of the motor system and industrial plant, and also allows maintenance to be performed in a more efficient manner since the course of action can be determined based on the type and severity of the fault.

Journal ArticleDOI
15 Oct 2007
TL;DR: In this article, a self-tuning fuzzy controller is proposed for variable-speed induction machines, which can adjust its parameters online according to the error between actual machine speed and a model reference.
Abstract: The field-oriented control of induction machines is widely used in high-performance applications. However, detuning caused by parameter disturbances still limits the performance of these drives. In order to accomplish variable-speed operation, conventional PID-like controllers are commonly used. These controllers provide limited good performance over a wide range of operation, even under ideal field-oriented conditions. An alternate approach is to use the so-called ldquofuzzyrdquo controller. In this paper, a self-tuning fuzzy controller is implemented. The proposed controller has the ability to adjust its parameters online according to the error between actual machine speed and a model reference. The scheme is compared to the conventional proportional-integral control and validated by simulation and experimental tests of both control techniques.

01 Jan 2007
TL;DR: In this article, a fuzzy logic approach is used to diagnose stator winding faults in an induction motor based on monitoring the line/terminal current amplitudes, and the fuzzy system is able to identify the motor stator condition with high accuracy.
Abstract: The online monitoring of induction motors is becoming increasingly important. The main difficulty in this task is the lack of an accurate analytical model to describe a faulty motor. A fuzzy logic approach may help to diagnose induction motor faults. This work presents a reliable method for the detection of stator winding faults (which make up 38% of induction motor failures) based on monitoring the line/terminal current amplitudes. In this method, fuzzy logic is used to make decisions about the stator motor condition. The fuzzy system is based on knowledge expressed in rules and membership functions, which describe the behaviour of the stator winding. The finite element method (FEM) is utilised to generate virtual data that support the construction of the membership functions and give the possibility to online test the proposed system. The layout has been implemented in MATLAB/SIMULINK, with both data from a FEM motor simulation program and real measurements. The proposed method is simple and has the ability to work with variable speed drives. The fuzzy system is able to identify the motor stator condition with high accuracy. This work is an example of the fusion between soft and hard computing.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the performance of a three-phase induction machine with nonuniform static eccentricity along axial direction or inclined SE, and the relationship between the number of rotor bars and poles and the existence of fault-related current harmonics was discussed.
Abstract: Fault diagnosis is gaining more attention for electric machines running critical loads, whose sudden breakdown can result in unpredictable revenue losses. Consequently, the motor drive systems with fault diagnostic and prediction features are of great concern and are becoming almost indispensable. Among all kinds of common faults, quite a few have relationship with unequal air gap. So far, work on detection of eccentricity-related faults in induction and synchronous machines has been well documented. However, a few are reported on faults resulting from axial nonuniform air gap. This paper investigates the performance of a three-phase induction machine with nonuniform static eccentricity (SE) along axial direction or inclined SE. A variant of modified winding function approach is applied to study this fault. The relationship between the number of rotor bars and poles, and the existence of fault-related current harmonics is discussed. It is shown that inclined eccentricity also demonstrates similar characteristics such as circumferential nonuniform air gap (SE). More importantly, it has been proved conclusively that inclined eccentricity symmetric to the midpoint of the machine shaft cannot be recognized from the current spectrum and would therefore require some other form of detection. Finite-element results to verify the inductance values used in simulation are also presented. The analysis is supplemented by the stator current spectra obtained from simulated results for different load and fault conditions. Finally, a four-pole 45-rotor-bar 2-kW induction motor is used to validate the theoretical and simulation results experimentally. Both current as well as vibration spectra are presented