Aluminum Rotor Research Articles

Optoelectronic Strain-Measurement System Demonstrated on Scaled-Down Flywheels.

Monitoring the strain in the rotating flywheel in a kinetic energy storage system is important for safe operation and for the investigation of long-term effects in composite materials like carbon-fiber-reinforced plastics. An optoelectronic strain-measurement system for contactless deformation and position monitoring of a flywheel was investigated. The system consists of multiple optical sensors measuring the local relative in-plane displacement of the flywheel rotor. A special reflective pattern, which is necessary to interact with the sensors, was applied to the surface of the rotor. Combining the measurements from multiple sensors makes it possible to distinguish between the deformation and in-plane displacement of the flywheel. The sensor system was evaluated using a low-speed steel rotor for single-sensor performance investigation as well as a scaled-down high-speed rotor made from PVC plastic. The PVC rotor exhibits more deformation due to centrifugal stresses than a steel or aluminum rotor of the same dimensions, which allows experimental measurements at a smaller flywheel scale as well as a lower rotation speed. Deformation measurements were compared to expected deformation from calculations. The influence of sensor distance was investigated. Deformation and position measurements as well as derived imbalance measurements were demonstrated.

Thermal Analysis and Cooling Strategies of High-Efficiency Three-Phase Squirrel-Cage Induction Motors—A Review

In recent times, there has been an increased demand for electric vehicles. In this context, the energy management of the electric motor, which are an important constituent of electric vehicles, plays a pivotal role. A lot of research has been conducted on the optimization of heat flow through electric motors, thus reducing the wastage of energy via heat. Futuristic power sources may increasingly rely on cutting-edge innovations like energy harvesting and self-powered induction motors. In this context, effective thermal management techniques are discussed in this paper. Importance was given to the potential energy losses, hotspots, the influence of overheating on the motor efficiency, different cooling strategies, certain experimental approaches, and power control techniques. Two types of thermal analysis computation methods, namely the lumped-parameter circuit method (LPCM) and the finite element method (FEM), are discussed. Also, this paper reviews different cooling strategies. The experimental research showed that the efficiency was greater by 11% with the copper rotor compared to the aluminum rotor. Each rotor type was reviewed based on the temperature rise and efficiency at higher temperatures. The water-cooling method reduced the working temperatures by 39.49% at the end windings, 41.67% at the side windings, and by a huge margin of 56.95% at the yoke of the induction motor compared to the air-cooling method; hence, the water-cooling method is better. Lastly, modern cooling strategies are proposed to provide an effective thermal management solution for squirrel-cage induction motors.

Determination of Cl and S in crude oil by ICP-OES after sample digestion by microwave-induced combustion in disposable vessels

A simple, fast and promising sample preparation method based on microwave-induced combustion in disposable vessels (MIC-DV) was developed for Cl and S determination in crude oil by inductively coupled plasma optical emission spectrometry (ICP-OES). The MIC-DV consists of a new approach of conventional microwave-induced combustion (MIC). For the combustion, crude oil was pipetted on a disk of filter paper and placed on a quartz holder, followed by the addition of igniter solution (40 μL of 10 mol L−1 NH4NO3). The quartz holder was inserted into a commercial 50 mL disposable polypropylene vessel containing the absorbing solution, which was then inserted in an aluminium rotor. The combustion occurs under atmospheric pressure in a domestic microwave oven not compromising the operator's safety. The following parameters of combustion were evaluated: type, concentration and volume of absorbing solution, sample mass and the possibility of performing consecutive combustion cycles. Using MIC-DV, up to 10 mg of crude oil were efficiently digested, using 2.5 mL of ultrapure H2O as absorbing solution. Moreover, up to 5 consecutive combustion cycles were possible without analyte losses, reaching a total sample mass of 50 mg. The MIC-DV method was validated according to Eurachem Guide recommendations. Results obtained for Cl and S by MIC-DV were in agreement with those obtained using conventional MIC, as well as those obtained for S in a certified reference material of crude oil (NIST 2721). Analyte spike recovery experiments were performed and recoveries at three concentration levels ranged from 99 to 101% for Cl and from 95 to 97% for S, indicating a good accuracy. The limit of quantification achieved by ICP-OES after MIC-DV were 73 and 50 μg g−1 for Cl and S respectively, applying 5 consecutive combustion cycles.

Induction motors with copper rotor: a new opportunity for increasing motor efficiency

<p>The copper rotor induction motor (CURIM) was recently introduced because it has lower rotor fusion losses than the aluminum rotor (ALRIM). Furthermore, with CURIM, it is easier to reach IE4 and IE5 efficiency levels. The CURIM is advantageous for compact motors, escalators, and electric vehicle applications. However, CURIMs present slip, power factor, temperature increase, and torque decrease problems that must be analyzed. This study compared the economic feasibility of using CURIM with ALRIM by applying discount techniques. A case study was carried out in a sugar company with a cyclical operation, where 5.5 kW motors will be installed in the intermediate conductors of the mill's feeders. The facility works three shifts between 3 and 6 months. The cost increase (DCI) of CURIM over ALRIM was between 1.1 and 1.5 times. With 3,600 h/year and 4,000 h/year of operation, the DCI greater than 10%, it was found that the payback is more than four years, and the net present value (NPV) grows linearly.</p>

Performance Characteristics of the Rotor Conductor of an IE4 Class Induction Motor With Varying Al-Cu Ratio

This study analyzed, the performance characteristics of a rotor conductor with respect to changes in the material composition. Because of the low price and high productivity of aluminum (Al) rotors, they have been used in induction motors for general applications. The Al rotor has a limitation in that the size must be increased to improve efficiency. In the same frame, the copper (Cu) rotor has higher efficiency than the Al rotor. However, the Cu rotor has problems with reduced starting torque, low mass production capability, and high manufacturing costs. Thus, the modeling method of Al-Cu rotor with high starting torque and high efficiency is proposed using multiphysics analysis (MA). The efficiency, power factor, and starting torque parameters of an Al-Cu rotor can be adjusted by changing the ratio of the material composition. The loss separation test was performed with the fabricated Al-Cu rotor, and the results were compared with those of thermal analysis and finite element analysis (FEA).

Identification of Fractional Damping Parameters in Structural Dynamics Using Polynomial Chaos Expansion

In order to analyze the dynamics of a structural problem accurately, a precise model of the structure, including an appropriate material description, is required. An important step within the modeling process is the correct determination of the model input parameters, e.g., loading conditions or material parameters. An accurate description of the damping characteristics is a complicated task, since many different effects have to be considered. An efficient approach to model the material damping is the introduction of fractional derivatives in the constitutive relations of the material, since only a small number of parameters is required to represent the real damping behavior. In this paper, a novel method to determine the damping parameters of viscoelastic materials described by the so-called fractional Zener material model is proposed. The damping parameters are estimated by matching the Frequency Response Functions (FRF) of a virtual model, describing a beam-like structure, with experimental vibration data. Since this process is generally time-consuming, a surrogate modeling technique, named Polynomial Chaos Expansion (PCE), is combined with a semi-analytical computational technique, called the Numerical Assembly Technique (NAT), to reduce the computational cost. The presented approach is applied to an artificial material with well defined parameters to show the accuracy and efficiency of the method. Additionally, vibration measurements are used to estimate the damping parameters of an aluminium rotor with low material damping, which can also be described by the fractional damping model.

Steady and dynamic states analysis of induction motor: FEA approach

This paper deals with the steady and dynamic states analysis of induction motor using finite element analysis (FEA) approach. The motor has aluminum rotor bars and is designed for direct-on-line operation at 50 Hz. A study of the losses occurring in the motor performed at operating frequency of 50Hz showed that stator copper loss and rotor copper loss were higher than the other types of losses like the stray, iron core, frictional and windage losses. The motor efficiency based on material design was also studied at operating temperature. The materials considered in this paper are iron, nickel and cobalt. It was observed that iron at 75°C provided the best efficiency than other materials. The steady and dynamic states characteristics of the motor at rated load and on no-load conditions were observed. The flux levels at these loading conditions were also monitored. http://dx.doi.org/10.4314/njt.v36i4.29

Production of low impurity aluminium rotor for motor efficiency enhancement

Induction motors have been widely used in various electrical applications. However, their efficiency are still limited due to losses occurring during operation, especially for smaller ratings. Higher the electrical conductivity of motor rotor by lower its impurity content is one of practical and simple way to improve motor efficiency. The aim of this work is to reduce the impurity content of aluminium rotor by addition of boron in the form of Al-5wt%B master alloy and Na2B4O7-NaCl-KCl flux, and then sedimention of their precipitated particles. The purer melt was then cast as rotors for single-phase induction motors. With the amount of addition of boron in aluminium melt in this work, boron in Al-5wt%B master alloy was more pronounced in removing impurities in aluminium melt than that in Na2B4O7. It was found that the rotors made of aluminium melt with lower impurity contents and hence higher electrical conductivity resulted in more enhancement of motor efficiency.

Investigating Ageing Process of Die Cast Aluminum in Squirrel Cage Rotors Exposed to Heavy-Duty Load Conditions

Most of the applications used in underground mining industries (explosion-proof environment) are performing in heavy-duty load conditions. As a result, standard designs of explosion-proof, water-cooled squirrel cage induction motors (WC-SCIM) equipped with standard designs of die-cast aluminium rotors (DCAR) are exposed to higher than expected rotor bar current values. Site investigations and dynamometer tests confirmed that severe heavy-duty loading induce high thermo-mechanical stresses (TMS) in DCARs. Frequent occurrences of such TMS (superimposed on the rated condition stresses) may bring conductive material (Aluminum) of the rotor bars to its fatigue conditions initiating rotor degradation process with subsequent influence on motor performances with consequent financial losses. The paper uses multidisciplinary techniques to study the ageing process of Die Cast Aluminum in Squirrel Cage Rotors Exposed to Heavy-Duty Load Conditions of a 50 hp SCIM equipped with DCAR. Based on claims regarding performance degradations, the research started with site measurements confirming the adverse heavy-duty load conditions. Statistic-probabilistic methods are used to determine Reliability indicators by using Fault Tree Method (FTM). The mathematical model confirmed the motor reliability and enable detection of weak points of the motor. Thermodynamic calculations are used to assess motor performances and its reliability by estimating air gap reduction and heat transfer to the bearings as the two major consequential effects of the TMS developed within DCAR. Dynamometer tests have been used to replicate the site conditions enabling creation of a mathematical model of thermal stress inside the rotor bars. After specific dynamometer tests a number of rotors have been cut-open to investigate the intimate rotor bar degradation. While there are various methods of detecting failed rotor bars, a Secondary research performed by authors indicate that to date no other research has been undertaken in studying this phenomenon.

Analysis of End-Winding Thermal Effects in a Totally Enclosed Fan-Cooled Induction Motor With a Die Cast Copper Rotor

Thermal overload protection techniques commonly use a simplified 1st order thermal model, which does not provide accurate stator winding temperature prediction and causes frequent undesirable stoppage of the motor in the processes. This paper proposes a higher order lumped parameter thermal network model to accurately predict stator winding temperature. First, the comparison of the predicted stator winding temperature from a 1st order thermal model with a higher order thermal model is performed. Second, a comparison between the actual and the predicted stator winding temperature rise is verified for a 20 hp totally enclosed fan-cooled copper rotor induction motor that has no rotor fins on its short-circuit ring to enhance heat dissipation compared with an aluminum rotor induction motor.

Development of a Super High Efficiency Motor with Boron Aluminum Alloy Rotor

Ultra-efficient motor is a national energy-saving projects to promote the new products, in accordance with the traditional design ideas, we must increase the consumption of effective materials in exchange for the improvement of motor efficiency. In this paper, starting from the analysis of motor loss, to explore the design and production of ultra-efficient motor method. Based on the idea of reducing the rotor resistance to improve the motor efficiency and improve the motor load performance, a new method of reducing the resistivity of cast aluminum by boron-aluminum alloy is proposed,The test data of ordinary cast aluminum and boron aluminum alloy spline resistance are given,and the comparison of the main technical parameters and the load efficiency curves of the super-efficient motors produced by different rotor casting processes. The results show that the ultra efficient motors by boron-aluminum alloy rotor production, the main technical performance is far better than the common cast aluminum rotor ultra-efficient motors, some better than the cast copper rotor motor. It is an ultra- efficient motor production process with high performance price ratio.

Tribological Behavior of CF/PTFE Composite and Anodized Al-Rotor in Traveling Wave Ultrasonic Motors

The tribological behavior of stator friction material and rotor in the traveling wave ultrasonic motor (TWUSM) shows some particularities because of the applied way and the special contact between stator and rotor. In this investigation, the tribological behavior of carbon fiber-reinforced polytetrafluoroethylene composite, which is used as stator friction material, sliding against an anodized aluminum rotor in a TWUSM is reported. The performances of TWUSM were tested, and the surface topography was examined in different stages. The results shown that the speed of USM remained stable at 120 r/min after 60 h of operating and the holding torque and stall torque tended to stabilize after 100 h. Moreover, the fluctuation of roughness of friction material was small, while the surface roughness of rotor decreased 28.8% after 10 h of operating. Both the roughness of friction material and rotor tended to stabilize after 100 h of operating. The wear mechanisms of stator friction material in steady wear stage were found to be adhesive wear and plastic deformation, which was quite different from that of rotor friction material. The wear rate of friction material decreased with time, and wear 1 μm of height required approximately 68 h. The surface topography of rotor changed little, and the wear height after 200 h of operating was less than 2 μm.

Traveling wave ultrasonic motor using polymer-based vibrator

With the characteristics of low density, low elastic modulus, and low mechanical loss, poly(phenylene sulfide) (PPS) is a promising material for fabricating lightweight ultrasonic motors (USMs). For the first time, we used PPS to fabricate an annular elastomer with teeth and glued a piece of piezoelectric-ceramic annular disk to the bottom of the elastomer to form a vibrator. To explore for a material suitable for the rotor surface coming in contact with the PPS-based vibrator, several disk-shaped rotors made of different materials were fabricated to form traveling wave USMs. The polymer-based USM rotates successfully as the conventional metal-based USMs. The experimental results show that the USM with the aluminum rotor has the largest torque, which indicates that aluminum is the most suitable for the rotor surface among the tested materials.

The nanostructured super-oleophobic liquid-floated rotor gyroscope

Liquid-floated rotor gyroscopes can provide high accuracy at small volume and low cost. In rotor gyroscopes, the rotating speed of rotor can significantly affect the detection accuracy. This work presents a new kind of liquid-floated rotor gyroscope using super-oleophobic surface processing, which can improve the performance of driving system. In this work, an unconventional anodization in oxalic-acid electrolyte under high current was employed to fabricate diverse nanostructured alumina surfaces. The top-view SEM image shows the nanowire pyramid structure on the surface of processed sample. Modification of the rough surfaces was achieved by dipping substrates in 0.5wt% 1H,1H,2H,2H-perfluoro-octadecyltrichlorosilane-in-hexane and then curing then at 120°C for 1h. The maximum contact angle (CA) of the aluminum rotor with nanowire pyramid structure was measured to be 156° in average. The oleophobicity of the rotor surface was used to reduce the resistance in the floating liquid. The test results show that, under the normal working state, the rotating speed of super-oleophobic rotor can be reached up to 3200rpm. While a similar system without the micro-nano composite structure can only reach 2860rpm. Thus, the nanostructured super-oleophobic alumina surface processing can greatly increase the rotating speed, thereby improving the performance of the gyro system.

Effect of Controlling Process Parameters on Shrinkage Porosity in Aluminum Die-Casting Rotor

Aluminum rotor prone to have many casting defects especially large amount of gas and shrinkage porosity, which caused eccentricity, loss and noise during motor operation. Many attempts have been made to develop methods of shrinkage porosity control, but still there are some problems to solve. In this research, the process of vacuum squeeze die casting is proposed for limitation of defects. The 6 pin point gated dies which were in capable of local squeeze at the end ring were used. Influences of filling patterns on HPDC were evaluated and the important process control parameters were high injection speed, squeeze length, venting and process conditions. By using local squeeze and vacuum during filling and solidification, air and shrinkage porosity were significantly reduced and the feeding efficiency at the upper end ring was improved 10%. As a result of controlling the defects, the dynamometer test showed improved motor efficiency by more than 4%.

Magnet Software Based Fault Analysis of Induction Motor Using Finite Element Analysis

Induction motor is one of the most commonly preferred motors used in the industry due to its long life & rugged construction. Faults occurring in an induction motor can significantly affect the performance of the motor and the drive which is running it. This project aims to study & analyze the faults which can occur internally in an induction motor .To implement fault analysis first the machine is modeled using MAGNET software. The motor is studied under healthy conditions. Subsequently faults are introduced & fault analysis is carried out. In the model of induction rotor bars are broken and the study is mostly based on magnetic field analysis of the motor under healthy conditions & under faulty conditions. The variation of starting torque with respect to increasing number of broken rotor bars is studied and a graph was plotted to show the variation. The stator winding currents produce a magnetic field that rotates in a counterclockwise direction. The changing magnetic field of the stator induces electromotive force in the rotor cage winding. The induced emf causes current to flow and magneto motive force in the rotor windings. In turn the rotor mmfs produce a magnetic flux pattern which also rotates in the air gap at the same speed as the stator winding field. Induction motors are the most commonly used prime movers in industrial applications. They are best suited for constant speed applications. Speed control can also be done with the help of power converter circuits. The 3-phase squirrel cage induction motor is the workforce of the industry as it is rugged & reliable. The interaction between the primary field and secondary currents produces torque from zero rotor speed onwards. The rotor speed at which the rotor currents are zero is called ideal no-load or synchronous speed. The rotor windings may be multiphase (wound motors) or made of bars short-circuited by end rings (cage rotors). All primary and secondary windings are placed in the uniform slots stamped into thin silicon steel sheets called laminations. The induction machine has a rather uniform air gap of 0.2 to 3mm.The secondary windings may be short circuited or connected to an external impedance or to a power source of variable voltage and frequency. Induction motors are the most commonly used prime movers in industrial applications. They are best suited for constant speed applications. Speed control can also be done with the help of power converter circuits. The 3-phase squirrel cage induction motor is the workforce of the industry as it is rugged & reliable. Electrical related faults are frequently occurring faults in three-phase induction machine which will produce more heat on both stator and rotor winding. This leads to the reduction the life time of induction machine. Stator winding fault in Induction Motors can be detected using Unknown Input Observer (UIO) & Extended Kalman Filter methods. They are used for speed estimation and fault detection methods respectively(1).Using analysis of permeance and MMF harmonics, frequency of air gap flux density harmonics which occur due to irregularities are calculated. It helps in detecting faulty ball bearing conditions (2). A procedure for electromagnetic design of three phase Induction Motor is discussed. This procedure is based on self-consistent equations. The electrical and magnetic properties are imposed by the user but the geometric dimensions are automatically calculated (3).The choice between Copper rotor bars and fabricated Aluminum rotor bars is discussed and debated. The fundamentals of rotor construction and basic information on how the Induction Motor works are discussed (10). The new IEC standard which defines the stator winding insulation requirement when the Induction Motor operates with Adjustable frequency drives (AFDs) is discussed. The

Application of HTS BSCCO Tapes in an Ironless Axial Flux Superconductor Motor

The development of HTS superconductor motors has been focused on the traditional construction, mainly in the magnetic field in radial flux configuration like the traditional electrical motors, for this reason the design and construction of superconductor machines in axial magnetic flux configuration are a new alternative for the development of the HTS superconductor motors. In this work, calculations for design and optimization of a superconductor biphasic induction motor in axial flux configuration are presented. The motor construction was made with BSCCO-2223 tape, its respected electrical evaluation and results are presented in geometries of 4, 6, and 8 poles in an ironless stator. A wound rotor was made with BSCCO tapes in order to test within the stators superconductor developed. The optimization of rotor tests was carried out at the beginning with aluminum rotors. After that, some wound superconductor rotors were constructed on a flat squirrel cage configuration for evaluation with superconductor stators.

Development of 0.5 HP induction motor with reduced slots in rotor and stator core and its performance evaluation

In this paper, we have developed a new prototype of 0.5 hp induction motor with reduced slots in rotor bar and stator core in comparison to the conventional induction motor. The conventional induction motor usually uses 30 slots of aluminum rotor bar and 36 slots in the stator core. In our developed prototype, we used 10 slots of copper rotor bar and 24 slots in the stator core. In order to evaluate the performance of this new prototype, we measured various losses such as core loss, copper loss, friction and windage losses, rotor loss and stray loss and compared them with the 0.5 hp conventional induction motor. The comparison results revealed that the developed prototype provide with a significant reduction, the motor losses. As a result, the efficiency of the new prototype is greatly improved. Key words: Induction motor, 10 slots copper rotor bar, 24 slots stator core, non-grain materials.

Research on Induction Motor for Mini Electric Vehicles

The motor of a mini electric vehicle uses dozens of storage batteries as power supply, which has low voltage and large current. Therefore, the loss and temperature raise of the motor is high. In this paper, the loss of different induction motors for mini electric vehicles is calculated and the effects of rotor materials and air gap length on the performance of these motors are studied. The analyses show that the efficiency of the motor with a copper mouse cage rotor is considerably higher than that of the motor with a aluminum rotor. The temperature raise of both an air-cooling and a water-cooling induction motor is analyzed, which demonstrates that the temperature raise of the motor windings is higher than that of the other parts, and the temperature raise of the water-cooling motor is lower than that of the air-cooling motor. To verify the results of the theoretical analyses, four prototype induction motors (aluminum rotor, copper mouse cage rotor, air-cooling and spiral groove machine) have been designed and processed. The experiments to measure the efficiency and temperature raise were carried out on these motors. The experimental results prove that the theoretical analyses are correct.

Research on a novel Rotor Structure Switched Reluctance Motor

The paper proposes a novel switched reluctance motor with improved rotor structure, in which the segment core is embedded in aluminum rotor block in order to increase the mechanical strength and easy manufacturing as well as to improve the performance characteristics and reduce the vibration and acoustic noise. The effect of design parameters on the average torque is investigated using the finite element method. Comparison with conventional VR type SRM and segment type SRM without conductive metal construction rotor show the proposed novel SRM has advantages in the torque performances and the vibration and noise characteristics. The performance is also investigated by experiment.