scholarly journals Iron Loss Quantification in the Aim of the Estimation of Eddy Currents in Clamping Devices

2021 ◽  
Vol 23 (6) ◽  
pp. 481-486
Author(s):  
K. Darques ◽  
A. Tounzi ◽  
A. Benabou ◽  
S. Shihab ◽  
J. Korecki ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Eddy Currents ◽  
Electrical Machines ◽  
Power Balance ◽  
Stator Core ◽  
Magnetization Direction ◽  
Iron Losses ◽  
Experimental Parameters ◽  
Clamping Device ◽  
The Impact

In high power electrical machines, the leakage magnetic flux due to end windings induces eddy currents in clamping devices. However, it is quite difficult to quantify these losses. In order to study the effect of different clamping materials and the impact of the magnetization direction, an experimental mock-up composed of a stator and a clamping plate has been developed. An axial coil generates a circumferential magnetic flux in the stator core at different frequencies. Eddy current losses in the clamping plates are deduced from a power balance by subtracting Joule losses and iron losses from the total measured losses. Iron losses are deduced from 3D FE calculations while the impact of the frequency on B(H) curve is taken into account. Losses in the clamping device are then analyzed depending on experimental parameters.

Adaptation and parametrization of an iron loss model for rotating magnetization loci in NO electrical steel

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Benedikt Schauerte ◽  
Martin Marco Nell ◽  
Tim Brimmers ◽  
Nora Leuning ◽  
Kay Hameyer
Keyword(s):  
Magnetic Flux ◽  
Flux Density ◽  
Electrical Steel ◽  
Electrical Machines ◽  
Iron Loss ◽  
Magnetic Flux Density ◽  
Loss Model ◽  
Content Type ◽  
One Dimensional ◽  
Iron Losses

Purpose The magnetic characterization of electrical steel is typically examined by measurements under the condition of unidirectional sinusoidal flux density at different magnetization frequencies. A variety of iron loss models were developed and parametrized for these standardized unidirectional iron loss measurements. In the magnetic cross section of rotating electrical machines, the spatial magnetic flux density loci and with them the resulting iron losses vary significantly from these unidirectional cases. For a better recreation of the measured behavior extended iron loss models that consider the effects of rotational magnetization have to be developed and compared to the measured material behavior. The aim of this study is the adaptation, parametrization and validation of an iron loss model considering the spatial flux density loci is presented and validated with measurements of circular and elliptical magnetizations. Design/methodology/approach The proposed iron loss model allows the calculation and separation of the different iron loss components based on the measured iron loss for different spatial magnetization loci. The separation is performed in analogy to the conventional iron loss calculation approach designed for the recreation of the iron losses measured under unidirectional, one-dimensional measurements. The phenomenological behavior for rotating magnetization loci is considered by the formulation of the different iron loss components as a function of the maximum magnetic flux density Bm, axis ratio fAx, angle to the rolling direction (RD) θ and magnetization frequency f. Findings The proposed formulation for the calculation of rotating iron loss is able to recreate the complicated interdependencies between the different iron loss components and the respective spatial magnetic flux loci. The model can be easily implemented in the finite element analysis of rotating electrical machines, leading to good agreement between the theoretically expected behavior and the actual output of the iron loss calculation at different geometric locations in the magnetic cross section of rotating electrical machines. Originality/value Based on conventional one-dimensional iron loss separation approaches and previously performed extensions for rotational magnetization, the terms for the consideration of vectorial unidirectional, elliptical and circular flux density loci are adjusted and compared to the performed rotational measurement. The presented approach for the mathematical formulation of the iron loss model also allows the parametrization of the different iron loss components by unidirectional measurements performed in different directions to the RD on conventional one-dimensional measurement topologies such as the Epstein frames and single sheet testers.

Determination of eddy current losses and hysteresis losses in magnetic circuits of electrical machines

2020 ◽  
pp. 54-58
Author(s):  
S. M. Plotnikov
Keyword(s):  
Eddy Current ◽  
Magnetization Reversal ◽  
Eddy Currents ◽  
Technical Problem ◽  
Electrical Machines ◽  
Eddy Current Losses ◽  
Hysteresis Losses ◽  
Magnetic Circuits ◽  
Core Losses ◽  
Reversal Frequency

The division of the total core losses in the electrical steel of the magnetic circuit into two components – losses dueto hysteresis and eddy currents – is a serious technical problem, the solution of which will effectively design and construct electrical machines with magnetic circuits having low magnetic losses. In this regard, an important parameter is the exponent α, with which the frequency of magnetization reversal is included in the total losses in steel. Theoretically, this indicator can take values from 1 to 2. Most authors take α equal to 1.3, which corresponds to the special case when the eddy current losses are three times higher than the hysteresis losses. In fact, for modern electrical steels, the opposite is true. To refine the index α, an attempt was made to separate the total core losses on the basis that the hysteresis component is proportional to the first degree of the magnetization reversal frequency, and the eddy current component is proportional to the second degree. In the article, the calculation formulas of these components are obtained, containing the values of the total losses measured in idling experiments at two different frequencies, and the ratio of these frequencies. It is shown that the rational frequency ratio is within 1.2. Presented the graphs and expressions to determine the exponent α depending on the measured no-load losses and the frequency of magnetization reversal.

scholarly journals Effect of the Temperature on the Magnetic and Energetic Properties of Soft Magnetic Composite Materials

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4400
Author(s):  
Luca Ferraris ◽  
Fausto Franchini ◽  
Emir Pošković ◽  
Marco Actis Grande ◽  
Róbert Bidulský
Keyword(s):  
Magnetic Materials ◽  
Eddy Currents ◽  
Electrical Machines ◽  
Soft Magnetic Materials ◽  
Magnetic Composite ◽  
Soft Magnetic ◽  
Soft Magnetic Composite ◽  
Magnetic Performance ◽  
Magnetic Circuits ◽  
Energetic Characterization

In recent years, innovative magnetic materials have been introduced in the field of electrical machines. In the ambit of soft magnetic materials, laminated steels guarantee good robustness and high magnetic performance but, in some high-frequency applications, can be replaced by Soft Magnetic Composite (SMC) materials. SMC materials allow us to reduce the eddy currents and to design innovative 3D magnetic circuits. In general, SMCs are characterized at room temperature, but as electrical machines operate at high temperature (around 100 °C), an investigation analysis of the temperature effect has been carried out on these materials; in particular, three SMC samples with different binder percentages and process parameters have been considered for magnetic and energetic characterization.

scholarly journals A flexible ChIP-sequencing simulation toolkit

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
An Zheng ◽  
Michael Lamkin ◽  
Yutong Qiu ◽  
Kevin Ren ◽  
Alon Goren ◽  
...  
Keyword(s):  
Ground Truth ◽  
Peak Calling ◽  
Simulation Framework ◽  
Experimental Conditions ◽  
Ground Truth Data ◽  
Chip Sequencing ◽  
Genome Wide ◽  
Experimental Parameters ◽  
Differential Binding ◽  
The Impact

Abstract Background A major challenge in evaluating quantitative ChIP-seq analyses, such as peak calling and differential binding, is a lack of reliable ground truth data. Accurate simulation of ChIP-seq data can mitigate this challenge, but existing frameworks are either too cumbersome to apply genome-wide or unable to model a number of important experimental conditions in ChIP-seq. Results We present ChIPs, a toolkit for rapidly simulating ChIP-seq data using statistical models of key experimental steps. We demonstrate how ChIPs can be used for a range of applications, including benchmarking analysis tools and evaluating the impact of various experimental parameters. ChIPs is implemented as a standalone command-line program written in C++ and is available from https://github.com/gymreklab/chips. Conclusions ChIPs is an efficient ChIP-seq simulation framework that generates realistic datasets over a flexible range of experimental conditions. It can serve as an important component in various ChIP-seq analyses where ground truth data are needed.

Motion in frequency domain for harmonic balance simulation of electrical machines

2018 ◽  
Vol 37 (4) ◽  
pp. 1449-1460
Author(s):  
Markus Wick ◽  
Sebastian Grabmaier ◽  
Matthias Juettner ◽  
Wolfgang Rucker
Keyword(s):  
Steady State ◽  
Frequency Domain ◽  
Efficient Method ◽  
Harmonic Balance ◽  
Eddy Currents ◽  
Computational Effort ◽  
Electrical Machines ◽  
Accurate Approximation ◽  
Content Type ◽  
Magnetic Devices

Purpose The high computational effort of steady-state simulations limits the optimization of electrical machines. Stationary solvers calculate a fast but less accurate approximation without eddy-currents and hysteresis losses. The harmonic balance approach is known for efficient and accurate simulations of magnetic devices in the frequency domain. But it lacks an efficient method for the motion of the geometry. Design/methodology/approach The high computational effort of steady-state simulations limits the optimization of electrical machines. Stationary solvers calculate a fast but less accurate approximation without eddy-currents and hysteresis losses. The harmonic balance approach is known for efficient and accurate simulations of magnetic devices in the frequency domain. But it lacks an efficient method for the motion of the geometry. Findings The three-phase symmetry reduces the simulated geometry to the sixth part of one pole. The motion transforms to a frequency offset in the angular Fourier series decomposition. The calculation overhead of the Fourier integrals is negligible. The air impedance approximation increases the accuracy and yields a convergence speed of three iterations per decade. Research limitations/implications Only linear materials and two-dimensional geometries are shown for clearness. Researchers are encouraged to adopt recent harmonic balance findings and to evaluate the performance and accuracy of both formulations for larger applications. Practical implications This method offers fast-frequency domain simulations in the optimization process of rotating machines and so an efficient way to treat time-dependent effects such as eddy-currents or voltage-driven coils. Originality/value This paper proposes a new, efficient and accurate method to simulate a rotating machine in the frequency domain.

scholarly journals Magnetic field transport in compact binaries

2020 ◽  
Vol 641 ◽  
pp. A133
Author(s):  
N. Scepi ◽  
G. Lesur ◽  
G. Dubus ◽  
J. Jacquemin-Ide
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Magnetic Flux ◽  
Large Scale ◽  
Compact Object ◽  
Light Curves ◽  
Momentum Transport ◽  
Local Magnetization ◽  
Angular Momentum Transport ◽  
The Impact

Context. Dwarf novæ (DNe) and low mass X-ray binaries (LMXBs) show eruptions that are thought to be due to a thermal-viscous instability in their accretion disk. These eruptions provide constraints on angular momentum transport mechanisms. Aims. We explore the idea that angular momentum transport could be controlled by the dynamical evolution of the large-scale magnetic field. We study the impact of different prescriptions for the magnetic field evolution on the dynamics of the disk. This is a first step in confronting the theory of magnetic field transport with observations. Methods. We developed a version of the disk instability model that evolves the density, the temperature, and the large-scale vertical magnetic flux simultaneously. We took into account the accretion driven by turbulence or by a magnetized outflow with prescriptions taken, respectively, from shearing box simulations or self-similar solutions of magnetized outflows. To evolve the magnetic flux, we used a toy model with physically motivated prescriptions that depend mainly on the local magnetization β, where β is the ratio of thermal pressure to magnetic pressure. Results. We find that allowing magnetic flux to be advected inwards provides the best agreement with DNe light curves. This leads to a hybrid configuration with an inner magnetized disk, driven by angular momentum losses to an MHD outflow, sharply transiting to an outer weakly-magnetized turbulent disk where the eruptions are triggered. The dynamical impact is equivalent to truncating a viscous disk so that it does not extend down to the compact object, with the truncation radius dependent on the magnetic flux and evolving as Ṁ−2/3. Conclusions. Models of DNe and LMXB light curves typically require the outer, viscous disk to be truncated in order to match the observations. There is no generic explanation for this truncation. We propose that it is a natural outcome of the presence of large-scale magnetic fields in both DNe and LMXBs, with the magnetic flux accumulating towards the center to produce a magnetized disk with a fast accretion timescale.

scholarly journals Impact of nonlinear surface inflows into activity belts on the solar dynamo

2020 ◽  
Vol 10 ◽  
pp. 62
Author(s):  
Melinda Nagy ◽  
Alexandre Lemerle ◽  
Paul Charbonneau
Keyword(s):  
Solar Cycle ◽  
Magnetic Flux ◽  
Activity Cycle ◽  
Surface Flux ◽  
Meridional Flow ◽  
Cycle Model ◽  
Flux Transport ◽  
Bona Fide ◽  
Nonlinear Surface ◽  
The Impact

We examine the impact of surface inflows into activity belts on the operation of solar cycle models based on the Babcock–Leighton mechanism of poloidal field regeneration. Towards this end we introduce in the solar cycle model of Lemerle & Charbonneau (2017. ApJ 834: 133) a magnetic flux-dependent variation of the surface meridional flow based on the axisymmetric inflow parameterization developped by Jiang et al. (2010. ApJ 717: 597). The inflow dependence on emerging magnetic flux thus introduces a bona fide nonlinear backreaction mechanism in the dynamo loop. For solar-like inflow speeds, our simulation results indicate a decrease of 10–20% in the strength of the global dipole building up at the end of an activity cycle, in agreement with earlier simulations based on linear surface flux transport models. Our simulations also indicate a significant stabilizing effect on cycle characteristics, in that individual cycle amplitudes in simulations including inflows show less scatter about their mean than in the absence of inflows. Our simulations also demonstrate an enhancement of cross-hemispheric coupling, leading to a significant decrease in hemispheric cycle amplitude asymmetries and temporal lag in hemispheric cycle onset. Analysis of temporally extended simulations also indicate that the presence of inflows increases the probability of cycle shutdown following an unfavorable sequence of emergence events. This results ultimately from the lower threshold nonlinearity built into our solar cycle model, and presumably operating in the sun as well.

scholarly journals The Air Gap and Angle Optimization in the Axial Flux Permanent Magnet Motor

1970 ◽  
Vol 110 (4) ◽  
pp. 25-29 ◽  
Author(s):  
C. Akuner ◽  
E. Huner
Keyword(s):  
Magnetic Flux ◽  
Permanent Magnet ◽  
Permanent Magnets ◽  
Air Gap ◽  
Magnetic Flux Density ◽  
Permanent Magnet Motor ◽  
Axial Flux ◽  
Flux Change ◽  
Torque Values ◽  
The Impact

In this study, the axial flux permanent magnet motor and the length range of the air gap between rotors was analyzed and the appropriate length obtained. NdFeB permanent magnets were used in this study. Permanent magnets can change the characteristics of the motor's torque. However, the distance between permanent magnets and the air gap will remain constant for each magnet. The impact of different magnet angles for the axial flux permanent magnet motor and other motor parameters was examined. To this aim, the different angles and torque values of the magnetic flux density were calculated using the finite element method of analysis with the help of Maxwell 3D software. Maximum torque was obtained with magnet angles of 21°, 26°, 31.4°, and 34.4°. Additionally, an important parameter for the axial flux permanent magnet motor in terms of the air gap flux was analyzed. Minimum flux change was obtained with a magnet angle of 26°. The magnetic flux of the magnet-to-air-gap is under 0.5 tesla. Given the height of the coil, the magnet-to-air-gap distance most suitable for the axial flux permanent magnet motor was 4 mm. Ill. 11, bibl. 4, tabl. 2 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.280

scholarly journals Uptake of p-Nitrophenol (PNP) from model aqueous solutions using raw and quaternised Afromomum melegueta peels

2020 ◽  
Vol 1 (1) ◽  
pp. 1-8
Author(s):  
J. Ndiritu ◽  
I W. Mwangi ◽  
J. I. Murungi ◽  
R. N. Wanjau
Keyword(s):  
Quaternary Ammonium ◽  
Anthropogenic Activities ◽  
Freundlich Isotherm ◽  
Isotherm Models ◽  
Ammonium Compound ◽  
Cellulose Structure ◽  
Experimental Parameters ◽  
Ftir Technique ◽  
Design Simplicity ◽  
The Impact

 Anthropogenic activities contribute large amounts of pollutants to the environment which threaten animal and human health. There is increased realization of the effect of these toxins on surface and ground water, consequently, their elimination is vital in rendering secure water for drinking as well as culpable release of effluents to our habitats. Phenolic compounds cause serious health effects to both humans and animals; a p-Nitrophenol concentration of 1 ppb changes the taste and odour of water as well as meat and fish quality. In humans, exposure to PNP causes eye and skin burns while its interaction with blood leads to confusion, cyanosis and unconsciousness. It is imperative therefore to find ways for removing PNP from water. Among the available techniques for removing PNP from water, adsorption is more convenient and offers more advantages because of its design, simplicity, and operating flexibility. The present study involved application of peels of raw Afromomum melegueta (RAM) and quaternised Afromomum melegueta (QAM) to remove PNP from water through adsorption. The raw adsorbents were modified with a quaternary ammonium salt to improve their uptake efficiency. The impact of experimental parameters; contact time, pH, sorbent dose, temperature and concentration were investigated. Attenuated FTIR technique was employed to characterize the adsorbent materials. It was established that the quaternary ammonium compound was anchored chemically within the cellulose structure of Afromomum melegueta peels. The behavior of adsorption of PNP was investigated using Langmuir and Freundlich isotherm models. The physical sorption load was 8.70 and 106.38 mg/g for RAM and QAM peels respectively from Langmuir adsorption equation. Uptake of PNP is high at the first 30 mins of contact and at sorbent dosage of 0.01 g and 0.03 g for RAM and QAM respectively. Quantity of PNP removed increases as the initial concentration rises however, adsorption decreases after a concentration exceeding 30 mg/L. The ideal pH and temperature for PNP removal is at pH 3 and 25 ˚C respectively. In conclusion, the findings suggest that Afromomum melegueta peels can be friendly to the environment, cheap biosorbents and efficient which can be applied for the uptake of PNP from drinking water

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