Cage Rotor Research Articles

Condition monitoring of cage rotor induction motor using electrical exogenous variables

Cage rotor induction motors are brushless singly excited very commonly used most reliable and low cost motor. It is extremely rugged in construction and most reliable and low cost motor. These moto...

Fractional kVA Rating PWM Converter Doubly Fed Variable Speed Electric Generator Systems: An Overview in 2020

Variable speed generator systems (VSGs) are at work in the now 600 GW installed wind power plants (parks). Also, they are used as vehicular and on ground stand-alone generators. VSGs imply full kVA rating PWM converters in permanent magnet (PM) or in electrically excited synchronous or in cage rotor inductance generators. But, to reduce cost in absence of PMs at a reasonable initial cost (weight) and efficiency, the fractional kVA PWM converter doubly fed induction generators (DFIG) cover now about 50% of all installed power in wind generators. The present paper reviews recent progress in DFIG and various forms of brushless DFGs (doubly fed generators) characterized in terms of topology, design, performance and advanced control for healthy and faulty load conditions in the hope of inspiring new, hopefully ground breakings, progress for wind and hydro energy conversion and in vehicular and on the ground stand-alone generator applications.

Topology Optimization of Rotor Bars Geometry and Arrangement for a Line-Start Permanent Magnet Synchronous Machine

An optimally designed line-start permanent magnet synchronous machine may require a different squirrel-cage design than traditional induction machines. The objective of this paper is to apply topology optimization based on the normalized Gaussian network in order to find the optimal shape of the rotor bars for a line-start permanent magnet synchronous machine. This approach facilitates optimizing the shape of the bar, without the limitation of a predefined bar geometry and arrangement, as is usually considered for classic induction machine design. For this study, a previously designed four-pole line-start permanent magnet synchronous machine with a rated power of 1.5kW is used as an initial design. To verify the accuracy of performance evaluation by utilizing finite-element methods, a prototype of this machine was built and tested. Then, verified model of line-start permanent magnet machine is used for topology optimization of its rotor cage area. The outcome of the optimization is the Pareto front, from which three optimized designs are selected. Finally, these designs are analyzed and proved to have better steady-state performance than the initial machine. The results provide new insights for the design of squirrel-cage bars for line-start permanent magnet synchronous machines.

Induction Motor Fault Diagnosis Based on Zero-Sequence Current Analysis

This paper presents some considerations regarding the application of the stator zero-sequence current component (ZSC) in the fault detection of cage induction machines, including the effects of magnetic core saturation. Faults such as rotor cage asymmetry and static, dynamic, and mixed eccentricity were considered. The research started by developing a harmonic motor model, which allowed us to obtain a voltage equation for the zero-sequence current component. The equation allowed us to extract formulas of typical frequencies for particular fault types. Next, in order to verify the effectiveness of ZSC in induction motor fault diagnosis, finite element calculations and laboratory tests were carried out for the previously mentioned faults for delta and wye connections with neutral wire stator winding configurations.

Dış Kafesinde Kırık Bar Arızası Olan Çift Kafesli Asenkron Motorun Performans Analizi

Induction motors are one of the most commonly used motor in the industry. For this reason, a fault (electrical or mechanical) inside or outside of the motor can cause the motor to go out of power and even cause the production losses inside the factory. Although there are many studies on single-cage induction motor failures in the literature, double cage motor failures are not a frequent subject of study. Therefore, in this study, it was investigated how the outer cage slot faults in a double cage induction motor affect the motor performance. Analyses were performed using Finite Element Method (FEM). 1, 2, 3 and 4 outer cage broken bars in the rotor slot were investigated. Rotor currents, magnetic vector potential values, magnetic flux distributions, current densities, radial forces and torque-speed graphs of the motor models were obtained and compared for both healthy and failure motors. The results show that as the number of broken bar in the rotor increased, a significant reduction was observed in all three torque (starting, maximum and nominal) values. It has been observed that the starting torque decreased by 13.77% for the 4 broken outer cage rotor bars motor according to the healthy motor.

Reliable Airgap Search Coil Based Detection of Induction Motor Rotor Faults Under False Negative Motor Current Signature Analysis Indications

Rotor cage damage in induction motors must be detected and repaired to prevent costly in-service failures that can occur due to broken cage fragments or arcing. Motor current signature analysis (MCSA) has become the most widespread test in the field for detecting these faults as it can provide remote, online monitoring using current sensors available in the motor control center. Although MCSA has been successful in detecting broken rotor bars, many cases of false indications have been reported in the field. False negative indications, where MCSA fails to detect the fault due to load variation, low slip operation, error in speed estimate, and nonadjacent broken bars, is considered serious as it can lead to unexpected motor failure. This has triggered research on alternative monitoring techniques for reliable detection of rotor faults with flux monitoring being one of them, as it can be implemented with low cost search coils. In this article, a new test method based on time–frequency analysis of the airgap flux is proposed and verified. It is shown that the second rotor rotational frequency (2×) upper sideband can provide reliable detection of rotor faults. Experimental test results are given under load variation, low slip, and nonadjacent broken bar conditions to support the claims on the reliability of the proposed method for cases where MCSA produces false negative indications.

Mathematical Modeling and Current-Oriented Control of Double-Inverter-Fed Wound Rotor IM Emulated as Two Virtual Cage Rotor IMs

Stator- and rotor-side voltage source inverters (VSIs) (VSI-S and VSI-R) of a double-inverter-fed wound rotor induction machine (DI-WRIM) drive individually feed 1-p.u. power each, to extract 2-p.u. power at a 2-p.u. speed. This feature of the DI-WRIM drive is explored, in this article, to model this drive as two virtual cage rotor induction machines (CRIMs). The VSI-S connected to the stator is emulated as one VSI-fed CRIM with the rotor short circuited, while the VSI-R connected to the rotor is emulated as another VSI-fed CRIM with the stator short circuited. The mathematical modeling of the DI-WRIM drive as two virtual CRIMs, in the synchronous reference frame, is presented by considering the angle between the stator and rotor currents (γ) as a medium of coupling between the two virtual CRIMs. The proposed mathematical model of the DI-WRIM is used to demonstrate the performance of the drive in a current-oriented control (COC) technique. In the COC technique, the VSI-S is controlled in the stator current-oriented frame and the VSI-R is controlled in the rotor current-oriented frame. The proposed model and technique is tested on a 4-hp WRIM drive and the experimental results are also presented to demonstrate the satisfactory performance of the drive.

Ring-Shaped Baffle Effect on Separation Performance of Lithium Carbonate Micro Particles in a Centrifugal Classifier.

In this work, a centrifugal classifier for separating lithium carbonate particles, used as a cathode material for lithium-ion batteries, was investigated. This work numerically evaluates the internal flow and particle separation performance of the centrifugal classifier. The complex turbulent flow field in the classifier is key to understanding particle motion. A Reynolds stress model, to describe air flow field, and a discrete phase model, to track particle motion, were applied to a numerical simulation. Design parameters such as mass flow rate and rotor speed were investigated, and a ring-shaped baffle, in particular, was designed to investigate the effects of flow and particle separation in the centrifugal classifier. The simple geometry of the baffle changes the movement direction of unseparated particles to the rotor cage region, and increases the local air velocity in the separation zone. The numerical analysis results were verified through a baffle experiment.

Kinerja Motor Induksi 1-fasa Disain 4 Kumparan dengan Kapasitansi Kapasitor Jalan Terkendali

Single phase induction motor usually has two windings. Because of that, the motor usually operated at lower efficiency than the poly-phase induction motor. A new design had been developed by using poly-phase winding to improve motor efficiency, but characteristic of the current winding at low load condition is not good. So that, this study was aimed to design a 4 phase windings construction of a single phase induction motor that using capacitance control of the run capacitor on auxiliary winding. This design was focused for capacitor-start capacitor-run induction motor that had 4 windings, one winding act as the main winding and the other three windings act as the auxiliary windings. The main and the auxiliary windings current rating of the proposed motor were 2.74A and 3.15A, respectively. The auxiliary winding current of the proposed motor was controlled by the ‘Arduino Uno’ control system. To get the best control system of the proposed motor, the performances of the proposed motor were compared to the performances of a conventional single-phase induction motor that had the same current rating, stator and rotor construction. The single-phase comparator motor used in this study was a conventional single-phase induction motor of 220V, 50 Hz, 1 HP, 8.3A, 4 poles, 1400 RPM cage rotor. The result showed that the proposed motor with capacitance control in auxiliary winding had better performances than the conventional induction motor.

Analysis of stator and rotor currents and torque of induction machine with rotor-bar faults

The paper analyzes a case of the induction motor in which one or more rotor bars in the rotor cage are broken. The method of space vectors and symmetrical components of instantaneous values of currents and voltages is used in the analysis. The solution obtained makes it possible to determine the currents in each of the healthy rotor bars, the stator currents, and the electromagnetic torque of the machine for any number and arbitrary combination of broken rotor bars. The calculations are made for an induction motor with 17 rotor bars. The theoretical results are compared with experimental measurements.

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

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

An Analytical-Numerical Approach to Model and Analyse Squirrel Cage Induction Motors

Nowadays, finite element analysis represents the most accurate tool to analyse electrical machines. However, the time domain resolution of electromagnetic problem, in some cases, requires long simulation time due to the induced nature of the currents. The computational burden increases when the machine features a skewed layout on the stator or rotor structures, since this requires 2D multi-slices approximated analysis or even a full 3D model. In this paper, a general analytical method to model electromagnetic devices is applied to a squirrel cage induction motor featuring a skewed rotor structure. The modelling approach is wisely implemented and adapted to pursue a fair balance between accuracy of the analysis and computational burden, taking advantage of all the symmetries existing in the rotor cage of the machine, aiming to minimize the model complexity. A comparative analysis in term of the inductances between analytical and finite element is proposed. The results provided by the model developed are compared with respect to the corresponding values provided by both finite element and experimental test performed on the reference machine. Such comparisons show that the proposed model is actually able to achieve a pretty good balance between accuracy and computational efficiency.

Efficient Estimator of Rotor Temperature Designing for Electric and Hybrid Powertrain Platform

This paper presents an efficient method of estimation of rotor cage temperature for induction machine design, applied for electric and hybrid vehicles. This factor influences the torque produced by the induction machine with a field-oriented control algorithm. Equipping sensors to measure the temperature of a rotation component is expensive and is not representative of mass production. The approach of estimation of rotor cage temperature is based on the good knowledge of motor parameters and the estimation of the flux of the machine. For an accuracy inductance taking account of the saturation, the no-load test can be performed. The machine flux will be estimated taking account of the voltage drop of the system on the test-bench. The rapid prototyping in a real-time motor control platform will be presented that integrates this estimator of rotor temperature. We finally show the experimental testing results compared to the measurement of the rotor cage on a prototype asynchronous low-cost motor designing for battery electric city cars.

Effect of rotor cage's outer and inner radii on the inner flow field of the turbo air classifier

AbstractThe effects of rotor cage's outer and inner radii on flow field of the turbo air classifier are comparatively analyzed by numerical simulation using ANSYS‐FLUENT. The results of quantitative analysis show when the rotor cage's outer and inner radii are increased, the tangential velocity, radial velocity and upward axial velocity decrease in the annular region and near the entrance of the rotor cage. However, when the rotor cage's outer and inner radii are too large or too small, the tangential velocity and radial velocity will be fluctuated greatly. Moreover, the rotor cage's outer and inner radii directly influence the radial velocity distribution in the rotor cage channel. The rotor cage's outer and inner radii should not be too large or too small. Therefore, in the seven contrast rotor cage models, model 100–70 and 90–60 are selected to carry out the calcium carbonate classification experiments due to their small tangential velocity and radial velocity fluctuations and well‐distribution in the rotor cage channel. The experimental results reflect the characteristics of the numerically simulated flow field in the classifier.

Снижение пусковых токов и моментов асинхронного короткозамкнутого двигателя за счет последовательности фазных напряжений

Снижение пусковых токов и моментов асинхронного короткозамкнутого двигателя за счет последовательности фазных напряжений

Search Coil-Based Detection of Nonadjacent Rotor Bar Damage in Squirrel Cage Induction Motors

Detection of rotor cage faults in induction motors based on motor current signature analysis (MCSA) is being extensively applied in the field for preventing forced outage of the motor and industrial process. Although MCSA is very effective for detecting broken bars that are adjacent to each other, it can fail if the broken bars are nonadjacent, which is common for applications with frequent starts. If multiple broken bars are spread out at locations where the rotor “electrical” asymmetry is canceled, the presence of broken bars is difficult to detect with MCSA. A false indication can lead to a catastrophic-forced outage, but the only known means of detecting this type of fault in the field is through rotor visual inspection. In this article, the feasibility of detecting nonadjacent broken rotor bars from the rotor rotational frequency sideband components in the internal and external search coil measurements during steady state and motor starting is evaluated. Experimental testing on a 7.5-hp induction motor shows that nonadjacent broken bars can be reliably detected from the analysis of flux measurements for cases where MCSA and all other electrical tests fail.

Studying and Simulating the Influence of the Rotor Fault on Stator Current

Abstract This paper presents fault detection techniques, especially the motor current signature analysis (MCSA) which consists of the phase current measurement of the electrical motor’s stator and/or rotor. The motor current signature analysis consists in determining the frequency spectrum (FFT) of the stator current signal and evaluating the relative amplitude of the current harmonics. Sideband frequencies appear in the frequency spectrum of the current, corresponding to each fault. The broken bar is a frequent fault in induction motors with squirrel-cage rotor. It is presented the equivalent circuit for induction motors and the equivalence between the squirrel-cage rotor and the rotor windings. It is also presented an equivalent circuit model for induction motors with squirrel cage rotor, and based on this a Simulink model was developed. It is shown how a broken rotor bar influences the magnetic field around the rotor and through this the stator current. This modification is highlighted through the developed model.

Iron Loss Modeling in Dual Stator Winding Induction Machines With Unequal Pole Pairs and Squirrel Cage Rotor

This article pertains to dual stator winding induction machines (DSWIMs) modeling and proposes an equivalent electrical circuit for DSWIMs that considers the iron loss effect. It is proved that the iron loss in DSWIMs is comprised of two independent parts resulting from their winding sets. Accordingly, the proposed model is comprised of two distinct parts and it is based on the assumption of independent operation of DSWIM winding sets. This model is valid in dynamic and steady-state operation conditions. The dq0 form of the proposed model is derived in an arbitrary reference frame. In addition, based on this model the iron loss estimation in DSWIMs is presented. The proposed model is simulated in MATLAB/Simulink based on the parameters obtained from IEEE standard characterization tests performed on a 3.3-kW DSWIM and also some experimental tests are executed via a digital signal processor (DSP)-based DSWIM drive system. Comparison of the simulation and experimental results confirms the validity of the proposed model both in steady-state and transient conditions. Moreover, this comparison clarifies that the proposed iron loss estimation method can account for the iron loss with high accuracy.

Altered Grey Wolf Optimization and Taguchi Method with FEA for Six-Phase Copper Squirrel Cage Rotor Induction Motor Design

This paper presents an altered grey wolf optimization, the Taguchi method, and finite element analysis (FEA) with two-phase multi-objective optimization for the design of a six-phase copper squirrel cage rotor induction motor (SCSCRIM). The multi-objective optimization design with high-performance property aims to achieve lower starting current, lower losses, lower input power, higher efficiency, higher output torque, and higher power factor. The multi-objective optimization design with high-performance property using the altered grey wolf optimization, the Taguchi method, and FEA in the first-phase program is used for minimizing the starting current, stator iron loss, stator copper loss, and input power. The multi-objective optimization design with high-performance property using the altered grey wolf optimization, the Taguchi method, and FEA in the second-phase program is used for maximizing the efficiency, output torque, and power factor. Finally, the proposed skill with higher performances is evaluated and verified via a two-phase program design and some performance tests.

Complex vector modeling of a doubly fed cascaded cage rotor induction machine

In this work, a cascaded doubly fed induction machine with a cage rotor is studied. To investigate the machine performance, a model is provided. In this model, the spatial harmonics of the rotor magnetomotive force are exactly considered. For this purpose, each rotor loop is selected as an individual circuit. The winding function theory is applied to compute the self- and mutual inductances of the rotor and stator circuits. To reduce the required simulation time, complex vector representation is adopted. Using the obtained voltage equations, the vector form of the machine state-space equations is yielded. Experimental tests are carried out to show the accuracy of the provided model. In addition, the adequacy of the proposed machine is verified by the appropriate tests.