Model Of Ferromagnetic Hysteresis Research Articles

Isotropic micromagnetic field model of ferromagnetic stress effects

We model magnetoelastic transducer processes including virgin field DH∼, virgin prestress DσH∼ and post stress DHσ∼ using the isotropic micromagnetic field model of ferromagnetic hysteresis and magnetostriction up to the coercive field. Magnetostriction of Fe94Ni3Cr2Mo1 steel has been precisely measured for DσH∼ with a thermally isolated yoke in order to compute microscopic Brown and macroscopic Villari stress fields. Magnetization M and field H were quasistatically measured with a Hall probe and differential Faraday induction coil. Prestress DσH reveals Brown field advanced virgin susceptibility and Villari field induced stress asymmetry. Post stress DHσ∼ reveals symmetric Brown field, stress asymmetry due to negative domain walls and cyclic creep due to Villari stress sensitivity dM/dσ, hyperbolic domain coupling and Néel viscosity.

Integration of Energetic Model for Ferromagnetic Hysteresis in Finite Volume Method for Electromagnetic Field Calculation

In this article, a coupled algorithm between the control volume method and the hysteresis dynamic energetic model for ferromagnetic hysteresis is presented. To illustrate the dynamic behavior of ferromagnetic materials, the quasi-static model is extended by adding two components to the applied magnetic field “Hedd”, and “Hexc”. The added fields are related to the excess losses and classical eddy losses. Thus, two new supplementary coefficients are added to the model parameters. The determination of those coefficients is attained by measuring the energy density for two distinct frequencies. This model introducing the magnetic induction as an independent variable is presented in order to be directly used in time-stepping finite volume calculations applied to the magnetic vector potential formulation. The calculated results are validated by experiences performed in an Epstein’s frame. To check the effectiveness of this model combined with the control volume method in the time domain, the obtained results are compared with experiments.

Dynamic exponential model of ferromagnetic hysteresis

We introduce a dynamic exponential model of ferromagnetic hysteresis that unifies the cooperative exponential model with the Néel fluctuating field, Jiles-Atherton approach to the anhysteretic and a Preisach convolution integral over a field distribution function. Dynamic effects such as viscous field advance and eddy current field delay are modeled directly by the model parameters. The dynamic effect of creeping in the direction of the previous maximum susceptibility due to viscosity as predicted by Street is observed and is modeled using the proposed method. Negative tilting of asymmetric minor hysteresis loops (lower susceptibility) with cycling is also observed and is also modeled using the proposed model as increased Néel's “opposition” in our cooperative field, Hcoop. Shearing of hysteresis loops is modeled as an averaging of the exponential model <Xexp> over viscous advance and eddy current delay fields, causing truncation and broadening. Detailed measurement procedures are described for a hollow cylinder and thin and thick rings of Fe94Ni3Cr2Mo1 steel with variable frequency sine, triangle and step field waveforms.

Inclusion of a Direct and Inverse Energy-Consistent Hysteresis Model in Dual Magnetostatic Finite-Element Formulations

This paper deals with the implementation of an energy-consistent ferromagnetic hysteresis model in 2-D finite-element computations. This vector hysteresis model relies on a strong thermodynamic foundation and ensures the closure of minor hysteresis loops. The model accuracy can be increased by controlling the number of intrinsic cell components, while parameters can be easily fitted on common material measurements. Here, the native $h $ -based material model is inverted using the Newton–Raphson method for its inclusion in the magnetic vector potential formulation. Simulations are performed on a 2-D T-shaped magnetic circuit exhibiting rotational flux. By way of validation, the results are compared with those obtained with the dual magnetic scalar potential formulation. A very good agreement for global quantities is observed.

Anhysteretic Functions for the Jiles–Atherton Model

The Jiles–Atherton (JA) model of ferromagnetic hysteresis usually bases on the Langevin function as its anhysteretic part. This leads to a problem, since for some known materials, the anhysteretic curve may not be modeled in view of fact, that the coupling parameter $\alpha $ , as determined from their major hysteresis loop, is too large, i.e., greater than the value permissible for the Langevin function. Therefore, a new function is required in order to omit this mathematical dilemma. Here, we present a set of simple functions, with their knees depending on one parameter only. Also, a more complicated function, with knee location depending on two parameters is analyzed, however, the Brillouin function again does not solve the difficulty with $\alpha $ . Therefore, within the frame of the JA model, a new function is proposed, making possible to have the initial differential susceptibility arbitrarily small. In addition, the strengthening of the effective field is considered and the permissible values of the second coupling parameter $\beta $ , in respect to the Brillouin and Langevin functions, are presented. Finally, our new function is successfully used to model the measured anhysteretic curve.

A dynamical energy‐based hysteresis model for iron loss calculation in laminated cores

SUMMARYThis paper proposes a macroscopic model for ferromagnetic hysteresis that is well‐suited for finite element implementation. The model relies on a consistent thermodynamic formulation. The stored magnetic energy and the dissipated energy are known at all times and not solely after the completion of closed hysteresis loops as is usually the case. Copyright © 2013 John Wiley &amp; Sons, Ltd.

An energy-based variational model of ferromagnetic hysteresis for finite element computations

This paper proposes a macroscopic model for ferromagnetic hysteresis that is well-suited for finite element implementation. The model is readily vectorial and relies on a consistent thermodynamic formulation. In particular, the stored magnetic energy and the dissipated energy are known at all times, and not solely after the completion of closed hysteresis loops as is usually the case. The obtained incremental formulation is variationally consistent, i.e., all internal variables follow from the minimization of a thermodynamic potential.

Absolute stabilization of singular systems with ferromagnetic hysteresis nonlinearity

This paper is concerned with the absolute stabilization problem of a class of singular systems with feedback connected ferromagnetic hysteresis nonlinearities. Firstly, a novel differential-integral loop transformation framework is developed to achieve an augmented singular system model. Secondly, by constructing a new passive output derivative operator of hysteresis nonlinearity and establishing the bound condition of the solution of ferromagnetic hysteresis model, the equivalent absolute stability criterion of singular systems with hysteresis feedback is derived based on KYP method and LMIs technique. Furthermore, the strict LMIs conditions for absolute stabilization are obtained, which can easily be checked by the LMI toolbox in MATLAB. Finally, two examples are given to illustrate the effectiveness of the proposed method.

A novel extended Tsypkin criterion for discrete-time descriptor systems with ferromagnetic hysteresis nonlinear physical phenomenon

This paper concerns the absolute stability problem of discrete-time descriptor systems with feedback connected ferromagnetic hysteresis nonlinearities. The ferromagnetic hysteresis model satisfies the passivity conditions of hysteresis operator, that is the input-output relation of the transformed operator is passive. The bound condition of the solution of the ferromagnetic hysteresis model is given. Through the framework of loop transformation, an augmented discrete-time descriptor system model is established for the stability analysis. A new extended Tsypkin criterion for the absolute stability of discrete-time descriptor systems with hysteresis is presented based on the linear matrix inequalities technique. A numerical example is given to illustrate the effectiveness of the extended criterion.

Energetic model of ferromagnetic hysteresis

PurposeThe purpose of this paper is to present a model to describe the nonlinear and hysteretic properties of ferromagnetic materials.Design/methodology/approachThe energetic model of ferromagnetic hysteresis evolved from some well‐known concepts in ferromagnetism in the last years. The magnetisation process is calculated from energy balance and statistical domain behaviour. Based on vectorial, anisotropic, multi‐domain considerations an isotropic, scalar model is derived, which gives quite simple equations to describe the nonlinear, hysteretic magnetisation process.FindingsThe presented simulations for steel samples and ferrite samples show very nice correspondence with measurements.Originality/valueThe scalar model seems to be especially suited for integration into finite element modelling or into simulations of electro‐magnetic circuits.

A new ferromagnetic hysteresis model for soft magnetic composite materials

A new ferromagnetic hysteresis model for soft magnetic composite materials based on their specific properties is presented. The model relies on definition of new anhysteretic magnetization based on the Cauchy–Lorentz distribution describing the maximum energy state of magnetic moments in material. Specific properties of soft magnetic composite materials (SMC) such as the presence of the bonding material, different sizes and shapes of the Fe particles, level of homogeneity of the Fe particles at the end of the SMC product treatment, and achieved overall material density during compression, are incorporated in both the anhysteretic differential magnetization susceptibility and the irreversible differential magnetization susceptibility. Together they form the total differential magnetization susceptibility that defines the new ferromagnetic hysteresis model. Genetic algorithms are used to determine the optimal values of the proposed model parameters. The simulated results show good agreement with the measured results.

Measurement and Simulation of Vector Hysteresis Characteristics

This paper presents a Preisach model of ferromagnetic hysteresis to simulate the vector hysteresis properties of ferromagnetic materials. Vector behavior has been studied using a single sheet tester with a round shaped specimen at low frequency, and the magnetic flux density vector has been controlled by a digital measurement system. Circular magnetic flux density pattern has been measured. An inverse vector Preisach hysteresis model has been developed and identified by applying the measured data. Finally, the inverse model has been inserted into a finite element procedure through the fixed point technique and the reduced magnetic scalar potential formulation. The applicability of the measurement system as well as the developed model has been proven by comparing measured and simulated results.

Numerical determination of Jiles‐Atherton model parameters

PurposeThe purpose of this paper is to propose a robust method to estimate the parameters of Jiles‐Atherton model of ferromagnetic hysteresis by fitting the model to symmetrical hysteresis loops. The performance of the method is evaluated by both theoretical and experimental data.Design/methodology/approachJiles‐Atherton model with five parameters describes the hysteretic behaviour of ferromagnetic materials. To calculate the model parameters, the most common data displaying the hysteresis features are the hysteresis loops stimulated by symmetrical steady state excitations, e.g. sinusoidal sources. Using the characteristic equations at specific points on these hysteresis loops, the Jiles‐Atherton model parameters can be determined by curve fitting and numerical optimized iteration.FindingsPracticality and robustness were not well considered by the conventional parameter estimation method: the initial curve starting from demagnetization is not always available and a direct iterative algorithm to solve the characteristic equations is sensitive to the initial values of the iteration and the evaluation order of the equations because of two main reasons. The first one is that the basic equation group has non‐unique solutions, which is caused by the nonlinearity of the characteristic equations and the fact that there are more unknown quantities (i.e. five model parameters) than the equations available; the second reason is the multimodal feature of the problem, which means that there are many local minima for the iteration algorithm to be trapped in. So curve fitting around the loop tips is proposed before numerical iteration. The goal is to make the initial values, particularly saturation magnetization Ms, not far away from the desired solution to increase the possibility of converging to a physical result. The optimized iterative method with the enhanced ability to avoid local minima and find global roots is then applied to obtain the model parameters.Originality/valueThe proposed method overcomes the difficulties of the other techniques which assume zero remanence. It is also robust as it is guaranteed to converge to physical solutions. The method can facilitate further development and it formed the preliminary basis of our earlier work, where the variation of the Jiles‐Atherton model parameters with different magnetic field strengths was investigated and applied to the simulation of transformer inrush current.

The Pursuit of Hysteresis in Polycrystalline Ferromagnetic Materials Under Stress

External stresses alter the magnetic properties of ferromagnetic materials such as iron and steel, a fact that has been the basis of substantial study in nondestructive testing. Existing theories and models have so far not proven reliable or accurate enough to develop a practical means of using the developed theory relating stress and magnetization to measure biaxial strains without prior knowledge of the strain or magnetic history of the sample. A deterministic model of ferromagnetic hysteresis and the effects of external stresses in materials such as iron and steel is introduced by this study. Changes in hysteresis loops due to stress are explained via changes in the magnetocrystalline anisotropy at the crystal-unit level, and are extended to the macroscopic effects that are seen in experiments. An original equation is presented which accurately describes experimentally acquired major hysteresis loops and directly relates two parameters to the two perpendicular principal strain axes thereby providing a technique able to determine the absolute stress/strain experienced by the sample. This model will potentially enable quantitative, nondestructive stress measuring devices to be developed.

Identification method of giant magnetostrictive transducer’s dynamic parameters and magnetic parameters

On the basis of ferromagnetic hysteresis model presented by JILES-ATHERTON and magnetomechanical effect presented by JILES,dynamics and magnetic parameters identification method is presented for giant magnetostrictive transducer(GMT)in the view of energy equilibrium equation. Aiming at the shortages of too many parameters needed and hard to measure under the actuator mode in JILES model.The method included reasonable deduction and transformation about the model.The method is based on the experimental data, whose experiment is simple and experimental data are easy to obtain.Parameters can be estimated by least square method (LSM),the estimated results is given.The estimated results can provide the reliable parameters for the GMT optimizing control oft'line and online control.

Timeless Discretization of Magnetization Slope in the Modeling of Ferromagnetic Hysteresis

A new methodology is presented to assure numerically reliable integration of the magnetization slope in the Jiles-Atherton model of ferromagnetic core hysteresis. Two hardware description language (HDL) implementations of the technique are presented: one in SystemC and the other in very-high-speed integrated circuit (VHSIC) HDL (VHDL) analog and mixed signal (AMS). The new model uses timeless discretization of the magnetization slope equation and provides superior accuracy and numerical stability especially at the discontinuity points that occur in hysteresis. Numerical integration of the magnetization slope is carried out by the model itself rather than by the underlying analog solver. The robustness of the model is demonstrated by practical simulations of examples involving both major and minor hysteresis loops

Time-domain simulation of nonlinear transformers displaying hysteresis

This paper introduces a novel technique for modeling, in the time domain, a power transformer with nonlinear and hysteretic behavior. The model is particularly suitable for harmonic or protection studies where the transformer is driven into the nonlinear regime. The technique uses a single-phase two-winding transformer model based on the Jiles-Atherton model of ferromagnetic hysteresis. It includes eddy-current loss by adding an extra single-turn winding so that the transients are modeled as fully as possible.

Experimental validation of a homogenized energy model for magnetic after-effects

In this letter, we experimentally validate the ability of a recently developed ferromagnetic hysteresis model to characterize magnetic after-effects in ferromagnetic materials. The modeling framework, which combines energy analysis at the lattice level with stochastic homogenization techniques to accommodate material, stress, and field nonhomogeneities, quantifies after-effects through a balance of the Gibbs and relative thermal energies. Attributes of the framework are illustrated through fits to experimental steel data.

Magnetic modelling of continuously variable transformers

Continuously variable signal transformers utilise the variation of the incremental permeability of ferromagnetic or ferrimagnetic materials with an applied DC magnetisation. The hysteresis losses play the dominant role determining the losses of the transformer. The losses mainly depend on the amplitude of the AC excitation and DC magnetisation. The energetic model for ferromagnetic hysteresis is used to calculate major and minor hysteresis loops and approximately determine the losses (Rayleigh law).

Relation between physical and phenomenological aspects in the framework of an energetic hysteresis model

In this work, an interpretation of the underlying physical and phenomenological aspects is presented in a way that the magnetization process is considered as a process of order. For this purpose the energetic model of ferromagnetic hysteresis is modified so that the local magnetic energy terms, such as anisotropy or applied field energy, are condensed to the corresponding statistical domain classes via expectation values. Furthermore, the anhysteretic magnetization curve is interpreted as a consequence of internal entropy changes, relative to an a priori defined domain configuration at the demagnetized state. Finally, irreversible energy terms take dissipative losses into account.