Three-phase Induction Machine Research Articles

Reduced Order Observer for Two-Connected Machine Drive

The paper presents a study of a reduced order observer with the vector control of a series-connected two-motor drive supplied by a single inverter. The multimachine system consists of a six-phase induction machine and a three-phase induction machine. The stators windings of both machines are connected in series in appropriate manner. The dynamic decoupling of each machine from the group is obtained using the indirect vector control algorithm. Modeling of the multi-machine system showed the possibility of independent control of each machine in the group. The independent control is demonstrated by analyzing the characteristics of the torque and speed of each machine obtained via simulation of multi-machine system under indirect vector control scheme. A reduced-order observer is applied to sensor-less control of multimachine. The simulation results show that the closed-loop system performances are satisfactory using the proposed algorithm.

Efficient feature extraction technique for diagnosing broken bars in three-phase induction machines

An original diagnostic method is proposed for identifying broken rotor bars based on a new technique for decomposing electric signals obtained by measurements, the Orthogonal Component Decomposition technique. This decomposition shows to be an efficient fault-specific feature extractor, and a broken bar simulation is used to determinate the relationships between the decomposition products and the fault phenomena. The efficiency of the information extraction is evaluated by Kruskall-Wallis variance analyses and Support Vector Machines on experimental signals, where the fault occurrence is detected, and the fault severity, given by the number of broken bars, is also diagnosed. The experimental signals are obtained by measurements from induction machines operating with different torque levels and driven either directly by the grid or frequency inverters. The proposed diagnostic method does not depend on frequency analysis and spectral resolution and comprises the Orthogonal Component Decomposition and Support Vector Machines. Furthermore, the results demonstrate the effectiveness of the information extraction since high diagnostic accuracy is achieved in low-torque situations and in a broad range of slip values. Additional analyses support that the proposed decomposition should be further investigated for many other applications on event detection.

A New Method to Estimate Induction Machine Parameters from the No-Load Startup Transient

The paper proposes a new method to estimate the electrical parameters of three-phase induction machines based only on the voltages and currents of the stator acquired during a no-load startup test. The method is based on the instantaneous impedance and on the rotor speed, both estimated according to procedures detailed in the paper. Parameter variations with the speed are determined based on the concept of data windowing and using a single-cage model. Theoretical and practical considerations are presented and discussed, with the method being validated through simulations and also through experimental results obtained for eleven machines with power from 5.5 to 75 kW. The most relevant characteristic of the proposed method is that the variation of the resistance and leakage inductance of the rotor during the transient, caused mainly by skin effect, can be effectively and systematically assessed. The practical results proved that the method has great potential to advantageously replace traditional no-load and blocked-rotor tests as it requires less time and has much lower associated costs.

Modeling and experimental analysis of grid-connected six-phase induction generator for variable speed wind energy conversion system

In this paper, an advanced control for grid-connected asymmetrical six-phase induction generator (ASIG) in variable speed wind energy conversion system (WECS) is proposed. It involves a detailed model of ASIG, a six-phase converter for machine side control, and a three-level converter for grid side control. ASIG consists of two three-phase sets spatially space shifted by thirty electrical degrees. This configuration offers higher power in the same machine frame, more reliability, and robustness when compared to the conventional three-phase induction generator (TPIG). Back to back connected voltage source converters (VSCs) are utilized for interfacing ASIG with the grid. Efficient control strategies are applied to generator side and grid side converters. Two machine side converters connected in parallel are operated with an advanced rotor field oriented control (RFOC) for maximum power point tracking (MPPT). RFOC is achieved by involving six PI controllers. It mainly focuses on removal of unbalanced currents between two sets of three-phase windings. Three-level grid side converter is controlled for maintaining DC link voltage, and to regulate the flow of reactive power between grid and generator. Experimental investigation of the proposed method is performed with 1.5-hp, six-pole, six-phase induction generator reconfigured from an existing three-phase induction machine. Generated power is supplied to the grid at unity power factor. Validating results indicating power flow, grid voltage and grid current are also exhibited. Paper also presents a comparative analysis of ASIG with conventional TPIG.

Diagnosis of the Induction Machine Using Advanced Signal Processing Methods

This work is a part of the thematic of monitoring and fault diagnosis of the squirrel cage three-phase induction machine. The choice of this type of machine is justified by the growing success it has exhibited, mainly, in the electric drives with variable speed. Signal based detection methods are presented is validated in simulation. The proposed diagnosis approach requires only little experimental data, and more importantly it provides efficient simulation tools that allow characterizing faulty behavior.In this study, the proposed approach considers the value of rotor resistance as fixed for condition monitoring. This value in the diagnostic tools which one uses is not fixed contrary to the classical approaches of control of machine.

Real-time diagnosis of three-phase induction machine using Arduino-Uno card based on park’s circle method

Real-time diagnosis of three-phase induction machine using Arduino-Uno card based on park’s circle method

Equivalent Circuit of PWM-Fed Induction Machine With Damper Winding for Noise and Vibration Reduction

This paper presents a system that enables the passive reduction of noise and vibrations in a three-phase induction machine with a stator damper winding connected to capacitors. This is a simple and effective system for reducing the flux density harmonics in an electrical machine. The theoretical study is based on the modeling of a machine equipped with the damper winding obtained from Kron's theory about equivalent circuits of electrical machinery. The analysis of the equivalent circuit allows one to identify possibilities to reduce the flux density harmonics responsible of unwanted noise and vibration components. Finally, an experimental validation is performed.

Response to Discussion of “A Modular Speed-Drooped System for High Reliability Integrated Modular Motor Drives”

The authors appreciate the interest shown in their paper. In the paper under discussion, a distributed speed control strategy suitable for multi-three-phase machines with enhanced power sharing capability is presented. The focus of the paper is on the power sharing transient controllability achieved by using a sharing regulator based on the droop controller, which was introduced for the first time by Fingas and Lehn. Galassini et al. added the outermost loop in charge of restoring the drooped output speed. The overall control strategy and the design procedure of each loop -current, sharing, and speed -is presented and validated by means of experimental results. Two off-the shelf three-phase induction machines coupled on the same shaft and controlled by a custom inverter were loaded by a third off the-shelf three-phase induction machine.

Analysis of the Impact of Stator Interturn Short-Circuit Faults on Induction Machines Driven by Direct Torque Control

This paper addresses the analysis of three-phase squirrel-cage induction machine (IM) with interturn short-circuit (ITSC) fault and its influence on direct torque control (DTC). The particularities of the DTC such as its behavior, its standard heuristic derivation, and its nature of been a nonlinear hysteresis-based predictive controller are exploited, thus allowing the improvement and development of alternative explanations to the phenomena. The understanding of DTC and the development of the current state–space model of the asymmetric IM, presented here for first time in the literature, enables the analytical treatment of the research topic and the discovery of several DTC reactions to the fault. The ITSC impact on DTC and its reaction leads to the following twofold characterizations: first, unobservable and visible effects, and second, compensation and tolerant reactions. For purposes of simulation, a plug-and-play configurable circuit-block for the asymmetric IM was developed based on Norton's equivalent circuit. Simulation and experimental results demonstrate the assertiveness of the developed analyses and theoretical findings, which allows future research in online fault diagnostics and condition monitoring of inverter-fed IM with this type of fault.

Induction machine fault detection using smartphone recorded audible noise

This study presents induction machine fault detection possibilities using smartphone recorded audible noise. Acoustic and audible noise analysis for fault detection is a well-established technique; however, specialised equipment for diagnostic purposes is often very expensive and difficult to operate. To overcome this obstacle, a simple pre-diagnostic procedure, using hand-held smartphones is proposed. Different faults of the three-phase squirrel cage induction machine such as various numbers of broken rotor bars and dynamic rotor eccentricity are inflicted to the machine and the resulting audible signals are recorded in laboratory circumstances using two widely available commercial smartphones. The analysis is performed on audible noise and compared with the results of mechanical vibrations measurements, recorded by vibration sensors. Rotational speed frequency and twice-line frequency are used as diagnostic indicators of faults. A simple neural network is composed and probabilities of fault detection using such diagnostic measures are presented. The necessity for further study as well as further implementation and method refinement necessity is pointed out.

Feasibility Analysis of the Use of the Generation of Induction in the Distributed Generation

This work presents a theoretical-experimental study in permanent regime of the three-phase induction generator of squirrel cage connected directly to the distribution network at fixed speed. With the expansion of distributed generation, the three-phase induction machine operating as a generator becomes a viable option for cost reduction in the implementation or expansion of power generation. The experimental test was performed in a laboratory with a 1-cv squirrel cage induction motor, connecting in the electrical network through a transformer. When the motor is driven above the synchronous speed (1800 rpm) by means of a primary mover it acts as a generator. The induction generator with squirrel cage has great robustness, requires no maintenance in the excitation system, nor synchronization system for use in distributed generation and is cheaper in front of the synchronous generator. The induction generator does not need a synchronization system because it is sufficient to set it as the empty motor and accelerate it to about 5% of the synchronous speed to operate as a generator.

A Hierarchical Approach for the Recognition of Induction Machine Failures

Due to its sturdiness, low cost and ease of implementation, the induction machine is one of the most common electrical motors used in industry. However, this machine still concedes failures leading to unplanned shutdowns, sources of significant financial losses. For this reason, induction machine failure diagnosis has become an ordinary task, where some ameliorations have to be achieved in order to improve the efficiency of maintenance programs by minimizing the number and the time period of unexpected shutdowns. In this paper, we address the recognition of inter-turn short circuit (ITSC) in the stator windings and broken rotor bars (BRBs) in the three-phase squirrel cage induction machine by proposing a new approach. This approach relies on the three-phase current analysis method to extract features and a new hierarchical recognition algorithm based on an ensemble of three different classifiers. In addition, the present work studies the failures recognition of the induction machine operating with a torque and speed control. The proposed approach is a major advanced for the induction machine diagnosis research because it recognizes correctly (detects, localizes and estimates the degree of severity) ITSC and (detects and estimates) BRB faults with an accuracy of 93.36% and with a great robustness compared to a classical machine learning algorithm.

Steady state and dynamic performance of self-excited induction generator using FACTS controller and teaching learning-based optimization algorithm

PurposeThe paper aims to present an application of teaching learning-based optimization (TLBO) algorithm and static Var compensator (SVC) to improve the steady state and dynamic performance of self-excited induction generators (SEIG).Design/methodology/approachThe TLBO algorithm is applied to generate the optimal capacitance to maintain rated voltage with different types of prime mover. For a constant speed prime mover, the TLBO algorithm attains the optimal capacitance to have rated load voltage at different loading conditions. In the case of variable speed prime mover, the TLBO methodology is used to obtain the optimal capacitance and prime mover speed to have rated load voltage and frequency. The SVC of fixed capacitor and controlled reactor is used to have a fine tune in capacitance value and control the reactive power. The parameters of SVC are obtained using the TLBO algorithm.FindingsThe whole system of three-phase induction generator and SVC are established under MatLab/Simulink environment. The performance of the SEIG is demonstrated on two different ratings (i.e. 7.5 kW and 1.5 kW) using the TLBO algorithm and SVC. An experimental setup is built-up using a 1.5 kW three-phase induction machine to confirm the theoretical analysis. The TLBO results are matched with other meta heuristic optimization techniques.Originality/valueThe paper presents an application of the meta-heuristic algorithms and SVC to analysis the steady state and dynamic performance of SEIG with optimal performance.

Active-Phase Converter for Operation of Three-Phase Induction Motors on Single-Phase Grid

The operation of a three-phase induction machine on single-phase supply has been an approach used for electromechanical energy conversion in rural communities with limited or no access to the three-phase grid. Such single-phase to three-phase conversion can be achieved by passive and active means. In passive methods, fixed capacitors are used for starting and running the motor. Single-phase to three-phase conversion with reduced switch count is desirable, as this leads to a lower cost. However, it is a challenge to start an induction motor using such a power converter and to maintain balanced three-phase voltage under all loading conditions. It is shown in this work that balanced excitation cannot be achieved under all conditions with variable capacitor emulation method. An active phase-converter configuration and its control that ensures balanced three-phase power supply at the motor terminals under all operating conditions is proposed. Also, this approach has the ability to soft-start the motor. It is shown that this can be done without drawing excessive currents from the power converter or from the single-phase grid. A design methodology is presented for the selection of the autotransformer taps to limit startup transient currents to the desired level, based on the analytical results. Simulation and experimental results are presented that validate the proposed topology and control.

A General Analytical Three-Phase Induction Machine Core Loss Model in the Arbitrary Reference Frame

An analytical three-phase induction machine model is proposed, derived, and validated in this paper. This model is capable for arbitrary qd0-frame analysis and core loss estimation at both line-fed and inverter-fed situations. Detailed model-based machine copper and core loss estimations are presented. A simulation verification of the model consistency is given under a changing load profile in MATLAB/Simulink. Then, the model is verified comprehensively using three induction machines (1.5 HP, 3 HP, and 10 HP), where the model is proved to be scalable, and to provide excellent machine loss estimation in line-fed situation and inverter-fed situation with machine input line filters, as well as in the flux-weakening region. Finally, a series of sensitivity tests of the model parameters are performed and the effects of the parameters on the machine losses are discussed. It is believed that the proposed model will be beneficial for various qd0-frame model-based research works of three-phase induction machines.

Study and comparison between two DTC strategies of induction machine fed by direct matrix converter

This work aims to study, analyze, and compare two direct torque control (DTC) methods of induction machine fed by [3 × 3] direct matrix converter (MC). The first method, DTC, uses the direct model of the matrix converter, whereas the second method, direct torque control indirect (DTCI), uses its indirect model, which describes MC as a combination of a four-quadrant rectifier with a two-level inverter. The two methods are simulated with the same parameters and references of speed and flux. An experimental validation is performed on a prototype of a [3 × 3] direct matrix converter realized in the laboratory, which feeds a three-phase induction machine coupled with a brake. These tests allowed us to demonstrate the practical feasibility of these control schemes. The algorithms are implemented on a dSPACE 1104 controller board. The input power factor is fixed to 1. A comparison between the two algorithms results based on several criteria (power quality, static and dynamic performance of the system, and maintenance of the unity power factor) is presented, and the results are discussed.

Prediction of Losses and Efficiency for Three-Phase Induction Machines Equipped With Combined Star–Delta Windings

Combined star–delta windings in electrical machines result in a higher fundamental winding factor and cause a smaller spatial harmonic content. This leads to lower I 2 R losses in the stator and the rotor windings, and thus to an increased efficiency. However, compared with an equivalent six-phase winding, additional spatial harmonics are generated due to the different magnetomotive forces in the star and the delta parts of the winding. In this paper, a complete theory and analysis method for the analytical calculation of the efficiency for induction motors equipped with combined star–delta windings is developed. The method takes into account the additional harmonic content due to the different magnetomotive forces in the star and delta parts. To check the analysis’ validity, an experimental test is reported both on a cage induction motor equipped with a combined star–delta winding in the stator and on a reference motor with the same core, but with a classical three-phase winding.

Analysis and MPPT control of a wind‐driven three‐phase induction generator feeding single‐phase utility grid

In this study, a three-phase diode bridge rectifier and a single-phase voltage source inverter topology has been proposed for feeding single-phase utility grid employing a three-phase induction generator fed from wind energy. A self-excited induction generator configuration has been chosen for wide speed operation of wind turbine system, which gives the scope for extracting maximum power available in the wind. In addition to maximum power point tracking (MPPT), the generator can be loaded to its rated capacity for feeding single-phase utility grid using a three-phase induction machine, whereas it is not possible with existing configurations because of the absence of power converters. For the proposed system, MPPT algorithm has been devised by continuously monitoring the grid current and a proportional resonant controller has been employed for grid synchronisation of voltage source inverter with single-phase grid. A MATLAB/Simulink model of the proposed system has been developed to ascertain its successful working by predetermining the overall performance characteristics. The present proposal has also been tested with sag, swell and distortion in the grid voltage. The control strategy has been implemented using field programmable gate array (FPGA) controller with modularised programming approach. The efficacy of the system has been demonstrated with the results obtained from an experimental set-up in the laboratory.

Complex-Vector Model of Interturn Failure in Induction Machines for Fault Detection and Identification

This paper presents an improved complex-vector dynamic model for a three-phase induction machine (IM) with stator interturn short-circuit fault. The paper proposes an accurate and meaningful approach to the faulty stator leakage inductance and describes a nonlinear phenomenon in the faulty circuit. The asymmetric model is developed in detail and represented in state-space (SS) form with the flux-linkages as the SS variable. Based on the proposed model, steady-state complex-vector, operational, and sequence component equivalent circuits are derived for fault detection and identification purposes. For reasons of verification, the model is simulated in MatLab environment and experimentally corroborated for a 1HP three-phase squirrel-cage IM. The simulations and experiments are compared at no-load and loading condition for both transient and steady-state response. The permanent regime analysis studies the model with respect to the fault severity factor, fault resistance, and load variation. The proposed model shows high correlation with the experimental results.

A Diagnostic Space Vector-Based Index for Rotor Electrical Fault Detection in Wound-Rotor Induction Machines Under Speed Transient

This paper investigates a new approach for the detection of rotor electrical faults in three-phase wound-rotor induction machines. The method is assessed in a wind energy conversion system, where the rotor side of the wound-rotor induction machine is supplied by a static converter for the control of active and reactive power flows from the generator to the electrical grid. Here, a diagnostic space vector is presented that sensibly improves the rotor fault detection in wound-rotor induction machine by combining the spectral signatures of both rotor current and voltage space vectors. The dc component of this diagnostic space vector, that is equal to zero in healthy conditions and different from zero under rotor asymmetry, is adopted as rotor fault index. The main advantages of the proposed technique are the implementation simplicity and the capability to operate even during speed transients. The technique is also validated by means of simulation and laboratory scale experimental tests.