Squirrel Cage Research Articles

Method to detect faults in the rotor squirrel cage with low load in permanent state using DWT

Although there are several methods that can be used, the Continuous Wavelet Transform and its discrete version have demonstrated their ability to work with these signals. This article presents a new method to help detect early faults in the rotor squirrel cage of induction motors noload and operational state, specifically in bars and rings. Using three techniques on the whole as it is the motor current signature analysis (MCSA), discrete wavelet transform (DWT) and multi-resolution analysis (MRA) with a decomposition tree reduced and apply a suitable index that determines the condition of the rotor. A brief description of the case study on which the research carried out is based is offered, which is used here successfully to generate a new alternative to determine the condition of the rotor squirrel cage. The performance of the results is get from the experimentation carried out and determined through comparison between the DWT conventional analysis and the new method, also exposing a brief comparison using the fourier transform. This new method reduces the uncertainty when performing the rotor diagnosis and improves the accuracy to differentiate the condition where it is.

Reduction and control of harmonic on three-phase squirrel cage induction motors with voltage source inverter (VSI) using ANN-grasshopper optimization shunt active filters (ANN-GOSAF)

Reduction and control of harmonic on three-phase squirrel cage induction motors with voltage source inverter (VSI) using ANN-grasshopper optimization shunt active filters (ANN-GOSAF)

An adaptive control strategy for grid-forming of SCIG-based wind energy conversion systems

One of the crucial issues in the expansion of isolated wind energy conversion systems (WECSs) is the design of a grid forming control structure that is robust to changes of the system’s operating point in the steady-state as well as transient conditions. This paper has addressed the voltage/frequency control of a local microgrid as well as flux and slip control of a squirrel cage induction generator that feeds the microgrid via a back-to-back converter in an isolated WECS. An adaptive nonlinear voltage control structure has been proposed for load side converter (LSC) consists of a constant frequency voltage regulator and a current controller based on the Lyapunov function method (LFM), which are connected in cascade. In an outer loop, the reference current of LSC is generated by the voltage regulator designated for maintaining the voltage/frequency of the microgrid. In an inner loop, the reference signals are robustly tracked by the current controller. In a novel reference frame that its angle difference with the stationary reference frame is determined by a dual loop DC link voltage controller, an LFM-based nonlinear flux controller is proposed for the machine side converter (MSC). Using the proposed flux control structure, in addition to maintaining the flux magnitude at a nominal value, by controlling the generator slip through adjusting the speed of the proposed reference frame, the power balance is established and the DC voltage is maintained at a pre-set value. The performance of the proposed controllers has been investigated through simulation in the MATLAB® software. The obtained results confirm the robustness and stability of the proposed control structure with respect to various disturbances and uncertainties.

Energy efficiency model-based Digital shadow for Induction motors: Towards the implementation of a Digital Twin

The 4th industrial revolution requires the tracking and optimization of energy consumption using an intelligent energy management system (IEMS). Such a system needs accurate real-time energy information to operate industrial machines, where Induction Motors (IMs) represent 42.2% of the global energy consumption. This paper addresses the problems of data acquisition for Induction motors in the context of Industry 4.0 (I4.0) where precision, real-time constraints, and optimal operations play a major role in decision-making. A new vision of Digital Shadow (DS) is proposed for the energy efficiency (EE) of IMs. A hybrid model consisting of a data-driven model and a physics-based model is developed to represent the machine efficiency information in real-time (RT). The proposed method is developed based on a two-stage procedure. Firstly, the IM EE model is established by considering Stator joule losses, core losses, rotor joule losses, friction, and windage losses, in addition to the stray losses to create an improved model. This was established based on the double cage model where core loss resistance is added. Secondly, the machine’s losses and efficiency are visualized using the 8 electrical circuit parameters (ECP) from the double cage model in addition to the rated speed and test temperature. The parameters estimation in RT incurred complexities and required the use of Adaptive Neuro-Fuzzy Inference System (ANFIS)-based modeling. The proposed model was developed using Fuzzy Logic Toolbox and Neuro-Fuzzy Designer app from MATLAB by training Sugeno systems. 8 ANFIS MATLAB models are trained to estimate each of the 8 ECP from the double cage model by using standard inputs. The training and testing dataset is constituted by the experimental data of the ECPs were calculated using the FSOLVE function to solve the nonlinear system formed by 60 motors from 8 manufacturers’ data such as voltage, number of pole-pairs, rated output power, rated torque, current, starting current, maximum torque and the power factor. Finally, the proposed method is validated experimentally using a 1.5 KW, 400/230 V, 50 Hz squirrel cage induction motor (SCIM) for linear speed control. The EE, Torque, and losses are visualized through the proposed model using MATLAB/SIMULINK. The mean value of the RMSE for the eight estimated ECPs are 7.57e-05, and 5.73e-01 respectively for training and testing while the mean values of the MAE are 2.06e-05, and 3.79e-01 respectively for training and testing. The errors of the EE estimation w.r.t the measured EE at rated condition, are RMSE = 0.205, and MAE = 0.1671. These results show that the proposed model can be implemented in the industry to monitor the machine EE and its losses.

Experimental investigation of a Wells turbine under dynamic stall conditions for wave energy conversion

Marine energy still plays a marginal role in the current global energy scenario, despite the incessant effort by research for more than thirty years in the exploitation of the so-called blue energy. Among the wide range of marine technologies, wave energy harvesting can play a significant role in view of its potential and Oscillating Water Column (OWC) systems, coupled with Wells turbines, can be considered among the most mature wave energy technology. Due to the oscillating nature of the flow rate in this kind of applications, Wells turbines are affected by dynamic stall, which has significant effects in terms of performance, fatigue, noise and structural integrity of the turbine.Actually, during dynamic stall, the Wells turbine experiences evident high frequency torque fluctuations which overlay on the typical hysteresis loop, mainly during flow deceleration. The amplitudes of these fluctuations are damped as the flow rate decreases toward reattachment. Often these fluctuations are not evident because hysteresis loops are usually provided with phase-averaged data, which can significantly smoothen or even conceal them. Indeed, it is difficult to find in the literature high frequency torque measurements able to show these fluctuations. With the aim to better investigate how the stall triggers this phenomenon, a monoplane Wells turbine has been manufactured in 3D printing and tested in the open wind tunnel of the Polytechnic University of Bari, Italy. The interest of the experimental campaign has been mainly focused on the effects of main parameters of the oscillating inlet flow rate (mean flow rate, amplitude and period of the oscillations, modifying the controlling parameters of the inverter driving the squirrel cage blower) on the performance of the machine. The machine has been firstly investigated under steady state inlet flow conditions, then under dynamic stall conditions. As a result, unsteady torque fluctuations occur during the flow deceleration till the flow reattachment. After the stall, the investigated Wells turbine experiences a drastic reduction of the torque coefficient of about 90%. Moreover, the torque coefficient shows a number of peaks during deceleration phases ranging from 2 to 4. Specifically, the case with the maximum period of the flow rate under investigation (i.e., T = 20 s) shows a greater number of peaks (4) than those related to the other cases (3). Moreover, it has been found that this unsteady behavior is due neither to the mass flow rate crossing the turbine, nor to the stagnation pressure drop, nor to the rotational speed control, which is correctly performed keeping the rotational speed within 1% of the target value. Hence, detecting these oscillations can be relevant in the turbine design phase to enhance the structural strength of the turbine.

A transfer learning‐based deep convolutional neural network approach for induction machine multiple faults detection

SummaryThe condition monitoring of squirrel cage induction motors (SCIMs) is vital for uninterrupted production and minimum downtime. Early fault detection can boost output with minimum effort. This article combines the application of transfer learning and convolution neural network (TL‐CNN) for developing an efficient model for bearing and rotor broken bars damage identification in SCIMs. A simple technique for the 1‐D current signal‐to‐image conversion is also proposed to provide input to the proposed deep learning‐based TL‐CNN technique. The proposed approach embodies the advantages of TL and CNN for effective fault identification in SCIMs. The developed technique has classified faults efficiently with an average accuracy of 99.40%. The complete analysis and data collection have been done on the experimental set‐up with a 5 kW SCIM and LabVIEW‐based data acquisition system. The propounded fault detection model has been created in python with the help of packages like Keras and TensorFlow.

Comparison of Eddy Current Coupling Topologies for High Efficiency Mechanical Power Transmission

The paper is an investigation into permanent magnet eddy current couplings for high efficiency power transmission. Through extensive simulation studies, the performance of radial- and axial-field topologies, employing squirrel cage and conducting sheets, are compared in terms of torque transmission density and efficiency of power transmission. It is shown, that although using a conducting sheet (as it is often the case) results in higher torque transmission density, employing a squirrel cage is more suitable for high efficiency power transmission. A prototype of the proposed radial-field single sided permanent magnet eddy current coupling employing a copper squirrel cage is developed and tested, and a good agreement between measurements and predictions is demonstrated.

Dynamic analysis of grid-connected hybrid wind farm

Since the last couple of years, the expansion of grid-connected wind farms (WFs) has increased dramatically. The wind turbine might be a fixed-speed squirrel cage induction generator (FSWT-SCIG) or a variable speed wind turbine with a doubly-fed induction generator (VSWT-DFIG). The main disadvantage of FSWT-SCIG is its lack of ability to adjust power quality. Inversely, the VSWT-DFIG is a competitive wind turbine technology that allows for the effective management of both active and reactive power outputs. Moreover, it has some extraordinary functionaries rather than FSWTSCIG. However, the major downside to this system is that it only has a partial rating AC/DC/AC power converter, which is extremely expensive. Hence, to reduce the overall cost combining the implementation of VSWT-DFIG and FSWT-SCIG in a WF could be a feasible alternative. Therefore, a novel DFIG control technique is proposed in this article, which can keep the connection point voltage of the hybrid WF stable during dynamic analysis. To evaluate the proposed controller responses PSCAD/EMTDC software has been used.

Statics analysis and strength optimization of squirrel cage elastic support structure

Statics analysis and strength optimization of squirrel cage elastic support structure

Parameter identification of squirrel cage induction machine using Linear Kalman filter

In the industrial environment, the induction machine is generally the most used, given its low cost, its efficiency, and its reliability. To obtain optimal operation, it is essential to collect values of its parameters (stator and rotor resistances and inductions). This data can be used to prevent breakdowns and ensure these machines’ rational use. In this context, this article proposes a new method to estimate the internal parameters of these machines using the KALMAN FILTER. Simulations under the MATLAB environment have been developed. Their results show that the estimated parameters are close to the nominal ones.

Implementation of Three Phase Induction Motor Pre-Design Program on Electronic Circuit

In this study, the performance analysis of a 5.5 kW, 460 V, 60 Hz, 4-pole, and 3-phase squirrel- cage induction motor (IM) has been carried out by developing a portable electronic circuit, design, and the software, independent of any commercial software. The mathematical equations used in the design steps and the preliminary design of the main dimensions of the squirrel cage IM are realized with a developed electronic circuit. To perform preliminary design calculations Nextion 7-inch touch screen, Arduino mega 2560 microcontroller is used in electronic circuit design. Briefly, IM basic data are entered from the Nextion 7 inches touch screen in the electronic circuit created and the data are sent to the Arduino Mega 2560 microcontroller card via serial communication. On the Arduino Mega 2560 microcontroller board, IM mathematical calculations are accomplished, and the calculation results are presented on the Nextion screen. It has been observed that the analytical calculations and the calculation results in the developed calculation tool have been obtained in good agreement.

TCSC Application for Transient Stabilization of Wind Turbine with Fixed Speed Induction Generator

Wind turbines (WTs) are a desirable alternative to traditional nonrenewable power resources as a result of recent environmental concerns. Some of them are fixed speed wind generator (FSWG) and have been integrated to power system by squirrel cage induction generator (SCIG). Induction machine absorbs reactive power during all operating conditions, especially at fault condition may result in severe voltage drop which can lead to generator outage. This outage disconnects a significant amount of active power and consequently leads to frequency instability. In order to prevent induction generator (IG) outages in short circuit failures, this paper investigates thyristor-controlled series capacitor (TCSC) device as a candidate solution. TCSC compensates the IG terminal voltage drop by adjusting transmission line impedance at fault condition. In the proposed method, a metaheuristic technique means that shuffled frog leaping algorithm (SFLA) has been utilized to optimize the TCSC controller gains. The proposed scheme can be applied for both SCIGs and wound rotor induction generators (WRIGs) which is another advantage of this method. Single-machine infinite bus system is considered as case study, and various operating conditions and disturbances have been considered to verify the effectiveness of the proposed method.

Üç Fazlı Bir Asenkron Motorun Çeşitli Bobin Adım Biçimi ile Performans ve Harmonik Analizi

In this work, analyses of the effect of full-, under-, and over-pitched stator winding configurations on the efficiency, output power, torque characteristics, and current and voltage harmonic components are carried out on a three-phase, squirrel cage induction motor. Performance analyses have been performed both via Ansys/RMxprt and Maxwell/2D software by modelling the stator winding with coil pitches of 100°, 120°, 140°, 160°, 180°, 200°, 220°, 240°, and 260°. Current and voltage harmonics analyses have been performed in Matlab using the data obtained from Maxwell/2D simulations. Maxwell/2D results showed that the maximum efficiency is attained at 200° over-pitched configuration, which is 0.73% higher than the efficiency when the motor is full-pitched. The maximum output power and torque are attained at 240° over-pitched configuration, which is 7.96% and 7.45% more than the power and torque obtained when the motor is full-pitched, respectively. Harmonic analysis results showed that both under-pitched and over-pitched coils can be used to eliminate harmonics in the current and voltage waveforms. However, over-pitched coils performed better in eliminating the phase current harmonics. The minimum total harmonic distortion (THD) of the phase current and induced voltage are reached at 260° over-pitched and 120° under-pitched configurations, which is 52.39% and 74.36% lower than the THD when the motor is full-pitched, respectively. Over-pitched coils provide slightly higher efficiency, output power, and torque than the under-pitched coils. There is no unique coil pitch configuration to eliminate all harmonic components. Therefore, in order to eliminate a specific harmonic component, a specific coil-pitch must be applied.

Wavelet packet analysis for rotor bar breakage in an inverter induction motor

Introduction. In various industrial processes, squirrel cage induction motors are widely employed. These motors can be used in harsh situations, such as non-ventilated spaces, due to their high strength and longevity. These machines are subject to malfunctions such as short circuits and broken bars. Indeed, for the diagnosis several techniques are offered and used. Novelty of the proposed work provides the use of wavelet analysis technology in a continuous and discrete system to detect faults affecting the rotating part of an induction motor fed by a three-phase inverter. Purpose. This paper aims to present a novel technique for diagnosing broken rotor bars in the low-load, stationary induction machine proposed. The technique is used to address the problem of using the traditional Techniques like Fourier Transforms signal processing algorithm by analyzing the stator current envelope. The suggested method is based on the use of discrete wavelet transform and continuous wavelet transform. Methods. A waveform can be monitored at any frequency of interest using the suggested discrete wavelet transform and continuous wavelet transform. To identify the rotor broken bar fault, stator current frequency spectrum is analyzed and then examined. Based on a suitable index, the algorithm separates the healthy motor from the defective one, with 1, 2 and 3 broken bars at no-load. Results. In comparison to the healthy conditions, the recommended index significantly raises under the broken bars conditions. It can identify the problematic conditions with clarity. The possibility of detecting potential faults has been demonstrated (broken bars), using discrete wavelet transform and continuous wavelet transform. The diagnostic method is adaptable to temporary situations brought on by alterations in load and speed. Performance and efficacy of the suggested diagnostic method are demonstrated through simulation in Simulink® MATLAB environment.

Bifurcation Analysis of a Rotor-Casing Coupling System with Bolted Flange Connection under the Effect of Rotor-Casing Rubbing Fault

This study mainly investigated the nonlinear vibration performance of a rotor-casing coupling system containing a bolted flange connection. The dynamic equations of the coupling system were developed while considering the radial stiffness of the bolted flange structure, which contained a spigot, squirrel cage with ball bearing, and rotor-casing coupling vibration. To study the influence of the disk casing fixed-point rubbing fault on the coupling system’s nonlinear dynamic performance, an analytical model of the nonlinear impact forces was established, which considered the contact and vibration responses of the rotor and casing. The frictional force was obtained based on the Coulomb friction law. The iterative analysis of motion equations was performed utilizing the Newmark method. Then, the nonlinear dynamic behaviors of the coupled systems were examined using data, including a bifurcation diagram, spectrum plot, greatest Lyapunov exponents, etc. The effects of rubbing fault on the dynamic properties of system were investigated in detail, indicating that there were various motion states, which were described as periodic, multi-periodic, and quasi-periodic motions. Comparing the simulation results, it was found that rubbing fault seriously affected the motion stability of the rotor system. Finally, by gathering and examining the vibration data set from a test platform for rotor-casings with bolted joints, the correctness of the numerical simulation findings was confirmed. Additionally, the results of the experimental investigation agreed with that of the simulation. The dynamic distinguishing characteristics that were noticed can be used as an indicator for determining whether the fixed-point rubbing fault between the rotor and casing has become worse.

Comparative Study of Grid Frequency Stability Using Flywheel-Based Variable-Speed Drive and Energy Capacitor System

Recently, there has been a rise in the integration of renewable energy sources into power grids. As a result of this, there is a need to carry out new studies in order to understand the dynamics of power grids during disturbances that is mainly caused by the stochastic nature of wind energy. The operation of modern power grids that are tied to wind farms follows a stipulated grid requirement or grid codes, considering the allowable threshold frequency variation during grid dynamics. This paper presents a comparative study of two frequency control schemes considering grid frequency stability using two frequency control topologies. A novel dynamic flywheel scheme with a doubly fed induction generator (DFIG) variable-speed wind turbine with the coordinated control of excess kinetic energy and mechanical torque during operation was the first scheme, and a control strategy of an energy capacitor system (ECS) with a squirrel cage induction generator fixed-speed wind turbine (FSWT) was the second scheme. The salient part of this study was that the DFIG maximum point power tracking for effective smoothing of the output of the wind generator in the first scheme was designed based on the control strategy of its reference power to achieve smoothing of the wind power at the terminals of the wind generator. The model system employed in this work was a wind farm that is tied to a conventional power grid made of steam and hydro synchronous turbines. For an effective and fair comparison of results, the same natural wind speed was used in PSCAD/EMTDC for both schemes. When no control, Scheme 1, and Scheme 2 were implemented, the frequency dips were 47.20, 49.99, and 49.99 Hz with overshoots of 50.500, 50.005, and 50.001 Hz and recovery times of over 600.00, 0.01, 0.01 s, respectively, for the frequency variable.

Development of a Novel High Strength Aluminum-Cerium Based Rotor Alloy for Electric Vehicle Induction Motor Applications

<div class="section abstract"><div class="htmlview paragraph">To increase vehicle range, light weighting of electric vehicles has been extensively researched and implemented by using aluminum intensive solutions. With regards to traction motors, aluminum alloys that have a desired combination of high electrical conductivity and strength are required for high power output and efficiency. In this research, a novel Al-Ce based alloy, with minor additions of Si and Mg for strengthening, was investigated in different heat treatment tempers to maximize mechanical properties while maintaining a high electrical conductivity. This new alloy system appears to have addressed the classic conundrum of the inverse relationship of mechanical performance verses electrical conductivity for traditional aluminum alloy systems. The results suggest that the Al-Ce-Si-Mg alloy had yield strength in excess of 120 MPa and electrical conductivity of at least 50 %IACS in the T5 and T6 conditions. Simulations of a squirrel cage induction machine show that this combination of properties resulted in similar motor performance to other rotor Al alloys. As a result, the Al-Ce-Si-Mg alloy is a promising alternative to the near pure Al or Cu-based alloys that are currently used in induction motor rotor castings.</div></div>

Improvement of power system stability in wind connected generator by using PSAT

Voltage stability in power systems is a major problem that receives international attention. An open and free source piece of software, Power System Analysis Toolbox (PSAT) is used in this study to create a model of modified IEEE 14 bus system. Models of two recently created wind turbines—the Squirrel Cage Induction Generator (SCIG) and Doubly Fed Induction Generator (DFIG)—are connected to a modified IEEE 14 bus system. The stability of the power system is examined in this work in relation to the effects of Squirrel Cage Induction Generator (SCIG) and Doubly Fed Induction Generators (DFIG). Here, both DFIG and SCIG, which have variable speeds, are regarded as wind generators. In this work, a small signal stability investigation using SCIG and DFIG wind turbine systems was carried out on a modified IEEE 14 bus system. The results of their simulation were analysed.

Optimization of a double-intake squirrel cage fan using OpenFoam and metamodels

In the present study, a powerful double-intake and rotor squirrel cage fan is designed and optimized by using a developed optimization process loop based only on open source libraries: Dakota, Salome and OpenFoam. Thirteen design parameters are selected for the trimming and in the impellers, blades and volute regions. The total efficiency and the force applied on the impeller are improved by maximizing and minimizing their values, respectively. A coupling was achieved between CFD, Latin Hypercube Sampling, Kriging metamodel and the Efficient Global Optimization to find the optimal design. Configuration 2 allows to improve the efficiency by 7.64% and to reduce the force by 33.36% compared to Configuration 1. The Kriging and the EGO models predict with accuracy the objective functions of the optimal design with a maximum error of 4.50%. Based on the optimal design of Configuration 2, a blade trimming was applied, which allows to improve the initial efficiency by 7.86%. The optimal prototype over all configurations was built and validated successfully against experimental data with a maximum error of 1.10%.

Dynamical modeling and experimental validation for squeeze film damper in bevel gears

Squeeze film damper (SFD) effectively reduces rotor motion amplitude while crossing critical speeds for vibration and noise reduction in a wide application of aero-engine rotor system. The squirrel cage elastic support (SCES) as an essential component of SFD, accurate modelling of SCES using component modal synthesis (CMS) to account for its flexibility, and calculation of nonlinear oil film forces for SFD using the finite difference method. The CMS method is also used to model the bevel gear wheel body and to establish a finite element nodal dynamics model of the gear-rotor-bearing-SFD system considering time-varying mesh stiffness, tooth clearance, gyroscopic effects, transmission error excitation and SFD oil film forces. The modal frequency of the gear shaft in aero-engine power transmission is exercised to verify the established bevel gear model. Moreover, a bevel gear test platform with SFD is established to study the vibration reduction effect of SFD. It is found that SFD can effectively improve the transmission of the bevel gear system, and the flexibility of the SCES makes the critical speed shift. Actually, the smaller the stiffness of SCES, the more the critical speed is moved to the left. By using CMS to determine the flexibility of bevel gear and SCES, it can show the complete phenomenon of the dynamic behaviors of the bevel gear system with SFD.