Hysteresis Loss Coefficient Research Articles

Experimental study on the static rolling friction coefficient of a flat-roller-flat configuration considering surface roughness

The friction-based seismic isolation technology is widely used in structural engineering. Despite the advantages and disadvantages of different types of isolated bearings, the coefficient of friction is a crucial factor that affects the seismic performance and stability of the isolation systems. In this study, a test apparatus with a flat-roller-flat configuration is developed to measure the static rolling friction coefficient (SRFC) of roller shafts. The SRFC under different conditions of normal load, material properties, geometry characteristics, and surface roughness are experimentally studied. The SRFC of the aluminum roller shafts ranges between 0.0020 and 0.0150, while that of the acrylic roller shaft ranges between 0.0028 and 0.0177, under low normal load level. The SRFCs of the roller shafts are positively correlated with the normal load and negatively correlated with their diameters. The surface roughness of the bottom plate significantly affects the SRFC. More precisely, the larger the surface roughness, the larger the SRFC. A theoretical model based on the elastic hysteresis theory is also proposed to predicted the SRFC. It is assumed that the elastic hysteresis loss coefficient (EHLC) is linearly correlated with the surface roughness of the bottom plate. Compared with the experimental results, the values predicted theoretically are within the error of 25 % for 85 % cases.

Performance Study of High-Speed Permanent Magnet Synchronous Motor with Amorphous Alloy Considering Temperature Effect.

Because the magnetic properties of an amorphous alloy (AA) obviously change with the change of temperature, a finite element simulation method for a motor, considering the effect of temperature, is proposed in this paper. In the early design stage of the high-speed permanent magnet synchronous motor (PMSM), the simulation of motor performance is mainly based on the magnetic performance test data at room temperature provided by the material's manufacturer. However, the influence of the temperature rise during the actual operation of the motor will lead to large errors between the simulation results and the measured results. Therefore, it is of great practical significance to measure the magnetic properties of the AA at different temperatures and use them for simulation purposes. In this paper, the magnetization characteristics and iron loss characteristics of the AA and silicon steel (ST100) used for comparison are measured at different temperatures, and the iron loss separation of the two materials at different temperatures is completed, and the hysteresis loss coefficient and eddy current loss coefficient at different temperatures are obtained. On this basis, the performance simulation of a motor model is carried out. The more accurate simulation method proposed in this paper can provide a reference for the design of AA motors in industry.

Methodology for determining the degree of magnetic induction of transformers with a sinusoidal magnetic flux

The research presented in the article is aimed at reducing losses in the magnetic circuits of electrical machines. These losses amount to up to 5 % of the generated electricity, do not depend on the load and can increase over the life of the equipment. To effectively design and construct transformers with low no-load losses, total losses in steel are minimized by optimizing the crystal grain size and thickness of core sheets, improving the steel texture and magnetic circuit design, etc. However, the hysteresis, classical eddy current and anomalous eddy current components of losses in steel react in different directions to these measures, which does not effectively minimize total losses. To determine the three components of losses, a modernized method of three frequencies is proposed, which takes into account the dependence of the hysteresis loss coefficient on frequency. A formula for correcting this coefficient is derived. It is shown that the indicator of the degree of magnetic induction given in most modern scientific sources in the expression for eddy current anomalous losses has become irrelevant. A method for calculating this indicator for the core of a specific transformer is presented, which uses the loss components and total losses in steel found by the method of three frequencies and the total losses in steel at a reduced primary voltage. For the transformer under study, the degree of magnetic induction in anomalous losses was 1.88. The results obtained can be used in the design of dry and oil transformers of different powers operating with a sinusoidal magnetic flux.

High frequency magnetic loss characteristic analysis and calculation of magnetostrictive Tb-Dy-Fe alloys under multivariable comprehensive operation conditions

The accurate calculation of magnetic energy losses for electromagnetic materials directly affects the global optimization design and operating efficiency of electromagnetic devices, especially under high frequency excitation. This study gropes for measurement methods of hysteresis, loss, and temperature rise characteristics for magnetostrictive Tb-Dy-Fe alloys materials under comprehensive operation conditions of high-frequency excitation, compressive stresses, temperature, and DC bias. Based on the measured data, a multiple variables loss matrix that can describe the characteristics of multiple energy fields (electromagnetic-, thermal- and mechanical fields) is established. Using loss matrix transformation method, the variation of hysteresis loss coefficients and generalized eddy current loss coefficients with different energy field characteristic variables are obtained. By establishing a dual statistical framework of sensitivity and deviation degree, the main influence variables which have the greatest impact on loss coefficients are extracted from these variables. Then a loss model for magnetostrictive material considering comprehensive operation conditions is presented which can describe the output characteristics of electromagnetic devices with strong non-linearity and multi-coupling effects among different energy fields. Furthermore, this method allows for the expansion of dimensions of linear or nonlinear variables and considers more energy fields, enabling a comprehensive analysis of interplay between multiple fields and facilitating engineering calculations.

SULFONIC ACID POLYIMIDES AND THEIR SALTS: PROPERTIES OF THEIR PARTICLES IN SOLUTION AND SUSPENSION

A high-temperature one-step synthesis resulted in two new polymers PI-I and PI-II (polyimides), which have functional groups as SO<sub>3</sub>H and SO<sub>3</sub>Na in their chain. Their molecular-mass molecular characterization revealed that PIs are polydisperse systems, and show thermal stability up to 400°C. The dynamic characteristics of polyimide particles in polar and nonpolar media were studied. The particle size of PI-I is significantly affected by the polarity of the medium. Due to intermolecular interactions associated with the free proton, the average particles diameters in dimethylformamide (DMF) was 10 μm, while in polymethylsiloxane (PMS-5) it was 1.4 μm. The size particles of PI-II in different media were 246 and 606 nm. Viscoelastic and mechanical properties of polymer systems were studied using microrheology and classical rheology. Hysteresis loss coefficients (κ) at various temperatures (T) were relatively small and stable for PI-I at T < 60°C with insignificant changes at increasing frequency. PI-II coefficient changes markedly but smoothly as a function of ω (angular frequency) at T < 60°C. With increasing temperature, the values of κ are almost independent of ω, taking quite large values compared to the corresponding values for the PI-I. It was determined that the temperature increases the interaction between the particles of the dispersed phase in the electric field. And the decrease in the viscosity of the suspension is due to a decrease in the viscosity of the medium. The electrorheological effect is most pronounced for the PI-I suspension.

Impact of Ultra-Short Pulsed Laser (USPL) Ablation Process on Separated Loss Coefficients of Grain Oriented Electrical Steels

The purpose of this article is to study the impact of surface laser treatments with ultra-short pulses (USPs) (femtosecond laser) on the magnetic properties of grain-oriented electrical steels (GOESs) using the two-temperature model for the ablation process and the magnetic loss separation model of Bertotti. We demonstrated that the hysteresis and excess loss coefficients behave differently depending on the type of laser treatment and its pulse duration [long pulse (LP), short pulses (SPs), and USP]. We also presented the adjusted models to estimate the impact of the USP on the sheet surface in terms of laser energetic quantities; more precisely, the groove depth, the plasma maximum temperature, and the peak surface wave pressure were estimated, relative to its nominal value. The latter physical impacts of laser pulses were then correlated with Bertotti’s loss coefficients: the static hysteresis loss coefficient and the excess loss coefficient. The laser process is not always able to reduce simultaneously both loss contributions. Thus, a compromise must be found to optimize the process. The variation of the flux density level as a function of the applied magnetic field was measured with a single sheet tester (SST) under a one-directional field parallel to the rolling direction. From these measurements, we deduced the whole power loss contributions. Results showed that an optimization of the laser’s parameters ensured an iron loss reduction at 50 Hz up to −30% for an induction below 0.5 T and a percentage close to −15% for an induction above 1.5 T.

Calculation and Experimental Determination of Damping Properties for Polymer Composite Material

In all real materials, energy is dissipated during deformation. You can think of it as a kind of internal friction. The load curve for the full period does not fit into a straight line. Usually, to describe the damping in the material, a model is used in terms of the hysteresis loss coefficient, since the energy losses per period depend weakly on frequency and amplitude. At the same time, the mathematical description in the loss factor model is based on complex values, that is, it implies only the case of harmonic vibration. Therefore, this damping model can only be used for frequency-domain studies. Rayleigh damping is a simple approach to forming the damping matrix as a linear combination of the mass matrix and the stiffness matrix. This damping model is unrelated to any physical loss mechanisms. In this paper, we consider a model of a mathematical pendulum for the experimental and computational determination of the damping properties of a polymer composite material. For the experimental part, a stand was designed and created that simulates the excitation of a plate made of a polymer material. The computational repetition of the experiment was performed by the finite element method and using the analytical Runge-Kutta method of the 4th and 5th order.

Rolling resistance of mechanism with point and linear contact scheme

Problem statement.In most problems, mechanics rolling coefficient of friction either neglect or set its value without taking into account the contact patterns of the rolling bodies, their materials and sizes. Based on the theory of contact stresses by Hertz, analytical dependences are obtained that allow calculating the rolling friction parameters with the greatest reliability in comparison with the analogues of other authors. But in the Hertz formulas, the parameter hysteresis loss coefficient is introduced, the determination of which requires time and money no less than obtaining the value of the rolling friction coefficient itself. This makes it impossible to use them in engineering practice to determine the magnitude of the friction force, and, accordingly, the coefficient of performance (COP) of a number of mechanisms with rolling. This leads to the fact that the drive power of the mechanisms has to be overestimated due to the uncertainty of its efficiency. The purpose of the article. To determine the efficiency of widely used mechanical devices in which rolling friction is present. In accordance with the stated goal, in the process of studying the operation of devices it is necessary to use only generally accepted mechanical constants and sizes. Conclusions.The efficiency of crab traverse mechanism does not depend on the direction of load application of movement relative to the direction of motion. The efficiency of conical friction gear depends on the coefficient of rolling friction, assumed contact voltage and elastic modulus. The proposed analytical dependences for determination of the coefficient of rolling friction in the ball guide allow us to resolve the total resistance into the rolling and sliding and conduct measures to reduce the more significant component. The main component of the motion resistance in the ball guide is a component of slide friction and it is a minimum at the angle of opening guide 2α = 90°.

Effect of Compaction Parameters on the Magnetic and Corrosive Properties of Soft Magnetic Composites with Parylene Insulation

Iron-based soft magnetic composites insulated with parylene C film were prepared via chemical vapor deposition polymerization, and their morphologies, magnetic properties, and corrosive resistance were investigated. Scanning electron microscopy and Fourier transform infrared spectrum confirmed that the surface of the iron particle was completely uniform insulated with parylene C, resulting in reducing the core loss of the synthetic compacts. The results show that compressed pressure has an important influence on the magnetic properties of the soft magnetic composites, enhance the magnetic induction value from 0.64 to 1.01 T and is obtained with increased the compressed pressure from 300 to 650 MPa. The loss separation results show that the hysteresis loss coefficient of 4 wt% parylene C insulated samples decreased from 1.743 to 1.657 and eddy current loss coefficient decreased from 0.019 to 0.012 as compared with uncoated compacts under the same compress pressure. The acid and salt corrosion resistance of the iron particles is apparently enhanced when the chemically stable parylene C layer was exited in the surface.

Prediction and experiment of DC- bias iron loss in radial magnetic bearing for a small scale turbomolecular pump

Iron loss calculation is a crucial part of turbomolecular pump design, since the molecular pump works in vacuum environment and the iron loss eventually transforms into thermal radiation. In this paper, an iron loss prediction model for a radial magnetic bearing of turbomolecular pump considering temperature influence is proposed. A ring specimen test under different dc-bias current, different frequencies, flux densities and temperatures are used to measure iron loss of steel laminations. Then, an iron loss model with variable hysteresis loss coefficients, eddy-current loss coefficients and dc-bias loss coefficients is used for iron loss calculation of the magnetic bearing. Flux densities of different part of magnetic bearing under different working states are obtained by using FEM. Finally, the measurement and subtraction method of iron loss in radial magnetic bearing is proposed, the accuracy the proposed iron loss model is validated by an iron loss test on a prototype of a 300 L/s 36000 r/min turbomolecular pump supported by magnetic bearing.

Effect of annealing on magnetic properties of Fe/Fe3O4 soft magnetic composites prepared by in-situ oxidation and hydrogen reduction methods

Iron-based soft magnetic composites (SMCs) coated with the ferrimagnetic Fe3O4 layer have been fabricated by in-situ oxidation and hydrogen reduction methods, and then the effects of annealing process on the soft magnetic properties were investigated. It showed that the Fe3O4 insulating layer was coated on the surface of the iron powders, which effectively reduced the magnetic dilution and decreased the core loss of the composites. In addition, the Fe/Fe3O4 core-shell composites exhibited high permeability and frequency stability of permeability after annealing. The real part of permeability of the soft magnetic composites could reach a maximal value of 142.9 and a rather low core loss of 274.9 W/kg (measured at 50 mT and 100 kHz). Based on the magnetic loss separation model, the hysteresis loss and eddy current loss coefficient was obtained. It was indicated that the annealing process enhanced the eddy current loss coefficient while the hysteresis loss coefficient is close to each other for all the samples. Therefore, this work can provide a method to prepare soft magnetic composites with excellent magnetic properties and low core loss.

Magnetic hysteresis loss crossover in Ni0.6Zn0.4Fe1.95Ti0.05O4 ferrite

In the present work, Ni0.6Zn0.4Fe1.95Ti0.05O4 ferrites were prepared by the solid state reaction methodology. XRD, SEM and a BH analyzer were utilized to investigate their structural, morphological and magnetic properties, respectively. The XRD patterns indicated that only the spinel phase was detected in some of the samples. It was observed that there was a magnetic hysteresis loss crossover around Bm = 4 mT. The hysteresis loss coefficient from 1.8 × 10−1 T−1 in Bm < 4 mT jumps down to 1.2 × 10−1 T−1 in Bm > 4 mT in the Ni0.6Zn0.4Fe1.95Ti0.05O4 ferrite, by measuring the field dependence of the relative loss factor. This was verified by measuring the field dependence of the real part of the permeability.

Magnetic hysteresis loss crossover in Ni0.4Zn0.6Fe1.95Ti0.05O4 ferrite

Ni0.4Zn0.6Fe2O4 and Ni0.4Zn0.6Fe1.95Ti0.05O4 ferrites were prepared by solid state reaction method and their magnetic properties were investigated. It was found that there is a magnetic hysteresis loss crossover around Bm = 4 mT, the hysteresis loss coefficient from 5.5 × 10−2 T−1 in Bm < 4 mT jump down to 4.0 × 10−2 T−1 in Bm > 4 mT in Ni0.4Zn0.6Fe1.95Ti0.05O4 sample by measuring field dependence of relative loss factor. This crossover was verified by measuring field dependence of real part permeability and magnetic loops. The possible mechanism of this crossover was discussed, and it was regarded that the crossover was due to magnetic domain wall pinning by Ti cation doped in ferrite.

Iron Loss Estimation Method for a General Hysteresis Loop With Minor Loops

In order to design highly-efficient electrical machines, it is necessary to estimate their iron losses accurately. The conventional iron loss estimation method [1], [2] estimates iron loss based on the assumption that eddy current loss coefficient (k e ) and hysteresis loss coefficient (k h ) under non-sinusoidal excitation are equal to k e and k h under sinusoidal excitation. However, these coefficients are not identical because minor loops are not centered but on ascending and descending major hysteretic curves. In this paper, we verify whether k e under dc-biased excitation is equal to k e under sinusoidal excitation. In addition, the method of analyzing iron loss under non-sinusoidal excitation using dc-biased magnetic properties is proposed.

Effect of texture and grain size on the magnetic flux density and core loss of cold-rolled high silicon steel sheets

The effects of texture and grain size on the magnetic flux density and core loss (50–20kHz) of 0.23mm-thick cold-rolled high silicon steel sheets are investigated by means of electron back-scattered diffraction (EBSD), loss separation, and anisotropy parameter (ε) calculation. A model of the hysteresis loss coefficient kh considering average grain size and ε is established. The magnetic flux density at 800A/m (B8) is closely related to the volume fraction of η-fiber-oriented grains, while the magnetic flux density at 5000A/m (B50) is closely related to the volume fractions of γ- and λ-fiber-oriented grains in high silicon steel. The hysteresis loss of high silicon steel can be greatly reduced by increasing the grain size and optimizing the texture of the sheets. Although increases in frequencies decrease the effect of texture on core loss, the effect cannot be ignored. As annealing temperature and time increase, the relative difference in core loss between the rolling direction (RD) and the transverse direction (TD) is maintained at higher frequencies because of increases in grain size, decreases in γ texture, and maintenance of a strong η texture. Texture and grain size jointly affect the high-frequency core loss of high silicon steel.

Magnetic properties of iron-based soft magnetic composites with SiO2 coating obtained by reverse microemulsion method

Abstract In this work, iron-based soft magnetic composites coated with the amorphous SiO2 layer have been fabricated by utilizing tetraethoxysilane in the reverse microemulsion method, and then the effects of addition amount of SiO2 and annealing temperature on the magnetic properties were investigated. The results show that the surface of iron powders contains a thin amorphous SiO2 insulation layer, which effectively decreases the magnetic loss of synthesized magnets. The magnetic loss of coated samples decreased by 87.8% as compared with that of uncoated samples at 150 kHz. Magnetic measurements show that the sample with 1.25 wt% SiO2 has an acceptable real part and minimum imaginary part of permeability in comparison with other samples. Also, the annealing treatment increased the initial permeability, the maximum permeability and the magnetic induction and decreased the coercivity with increasing temperature in the range 300–600 °C. The results of the loss separation imply that the annealed SMCs have a higher hysteresis loss coefficient (k2) and lower eddy current loss coefficient (k3) as compared with the pure iron compacts after the same heat treatment due to the preservation of the SiO2 layer.

Structural and magnetic properties of Fe–Al2O3 soft magnetic composites prepared using the sol–gel method

Abstract In this work, powder metallurgy was performed for preparation of iron-based soft magnetic composites (SMCs). For this purpose, iron powders were coated with a thin alumina insulating layer using the sol–gel process, and then compacted for characterization. Microstructural analysis confirmed the formation of an alumina insulating layer with high thermal stability and uniform coverage on the powder surfaces. The alumina coating increased the magnetic permeability of the composites at high frequencies as a result of increased electrical resistivity and decreased eddy current loss. In addition, the different components of the total loss factor were calculated by means of a loss separation method. It was found that by addition of 8 wt.% insulation, the hysteresis loss coefficient increased from 2.7 × 10−3 to 4 × 10−3 while the eddy current loss coefficient decreased from 3.00 × 10−6 to 1.53 × 10−6 as compared with pure iron compacts.

Effect of heat treatment on magnetic properties of iron-based soft magnetic composites with Al2O3 insulation coating produced by sol–gel method

In this study, influences of the annealing process on the magnetic properties of new soft magnetic composite (SMC) materials with alumina insulator coating were investigated. Iron powders were coated with alumina by the sol–gel process at room temperature. The results of energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and density measurements showed that the iron powders were uniformly coated by a thin layer of alumina coating with high thermal stability. Magnetic measurements indicated that the annealing treatment increased the permeability of the composites at low and medium frequency ranges. It was shown that the annealed composites exhibited noticeably higher frequency stability of the magnetic permeability compared to the heat treated pure iron compacts at the same annealing temperature. The results of the loss separation implied that the heat treatment suppressed the hysteresis loss coefficient while it increased the eddy current loss coefficient of the SMCs. The annealed SMCs showed a lower eddy current loss and higher hysteresis loss coefficients compared to the relaxed pure iron compacts due to the preservation of the alumina coating after heat treatment.

Structural studies, magnetic properties and loss separation in iron–phenolicsilane soft magnetic composites

In this work, six different series of iron based soft magnetic composites are produced and studied: (1) passive iron powder; (2) passive iron powder-0.7% resin with coupling agent; (3) passive iron powder-0.7% resin without coupling agent; (4) passive iron powder-1.5% resin with coupling agent; (5) passive iron powder-1.5% resin without coupling agent; (6) pure iron-1.5% resin. The specimens were shaped as cylindrical rods and characterized by fourier transform infrared spectrometer (FTIR), energy dispersive analyzer (EDX), X-ray diffraction (XRD) and indutance capacitance resistance (LCR) meter. The results show that the hysteresis loss coefficient is close to each other for all the samples (0.0011 < k 2 < 0.0019), but the eddy current loss coefficient is higher for the passive-0.7% resin sample without coupling agent ( k 3 = 0.005) in comparison with the other samples.

Computation of Core Losses in Electrical Machines Using Improved Models for Laminated Steel

Two new models for specific power losses in cold-rolled motor lamination steel are described together with procedures for coefficient identification from standard multifrequency Epstein or single sheet tests. The eddy-current and hysteresis loss coefficients of the improved models are dependent on induction (flux density) and/or frequency, and the errors are substantially lower than those of conventional models over a very wide range of sinusoidal excitation, from 20 Hz to 2 kHz and from 0.05 up to 2 T. The model that considers the coefficients to be variable, with the exception of the hysteresis loss power coefficient that has a constant value of 2, is superior in terms of applicability and phenomenological support. Also included are a comparative study of the material models on three samples of typical steel, mathematical formulations for the extension from the frequency to the time domain, and examples of validation from electrical machine studies.