Anomalous Eddy Current Loss Research Articles

Dynamic Hysteresis Calculation of Silicon Steel Considering DC Hysteresis and Anomalous Eddy Current Loss

We had proposed a combined 3D solid core and 1D steel plate modeling method for accurate magnetic field and iron loss calculation of laminated iron cores with low computation cost. The effective permeability including the laminated effect can be obtained and fed back to the 3D model. However, only the initial <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BH</i> curve and classic eddy currents are considered in the 1D model, thus it is improved to consider the DC hysteresis property and anomalous eddy current loss in this paper. The improved 1D model is applied to the dynamic hysteresis loop calculation of non-oriented and grain-oriented silicon steels and confirmed to be effective by comparing with the measurement results.

Evolution of coating layers during high-temperature annealing and their effects on magnetic behavior of Fe(Si) soft magnetic composites

Low-loss Fe(Si) soft magnetic composites (SMCs) with atomic-layer-deposition coated layer were successfully prepared in this work. The continuous, compact and uniform Al2O3 layer is found to form tight bonding with the powder base. Evolution of the coating layers has been investigated under different annealing temperatures and closely linked to the magnetic performance of the composites. Results indicate that 1100 °C was the optimal annealing temperature, at which the Fe(Si) SMCs showed lowest core loss of 1237 mW/cm3 and the highest permeability of 99.7 simultaneously (100 mT/100 kHz). Integrity of the coating layer ensures the maximum grain growth and stress removal of powder particles at the highest possible temperature, so as to reduce the hysteresis loss. Formation of high resistivity oxides and silicates (Al2O3, Fe2SiO4 and 3Al2O3·SiO2) after annealing result in a low inter-particle eddy current loss. Besides, high temperature vacuum annealing is helpful to eliminate impurity atoms and decrease the anomalous eddy current loss. The improvement in effective permeability caused by high-temperature annealing is mainly attributed to the relaxation of residual stresses and the reduction of defects. While excessive temperature leads to the decomposition and destruction of the insulation layer, resulting in a significant increase in hysteresis loss, inter-particle and anomalous eddy current loss.

Core loss reduction through a laser scribe on Fe-based amorphous ribbon surface for transformer cores

Core loss reduction of an Fe-based amorphous ribbon for distribution transformer cores by laser scribe is researched and the efficacy of core loss reduction by laser scribe is compared with that by fish scale-formation during ribbon casting. Core loss reduction by laser scribe is found to be more effective than fish scale and the reduction is prominent in a 53 kg single phase core tested. Core loss reduction is realized through the reduction of anomalous eddy current loss by domain refinement. Although a fish scale ribbon shows refined magnetic domains in static magnetic domain observation, effective magnetic domains are not refined and the reduction of anomalous eddy current loss by fish scale is small. Core building factor, the ratio of core loss of a transformer core to that of a strip ribbon, is found to be increased due to higher anomalous eddy current loss in a 53 kg single phase core tested. Building factor is reduced from about 2 to 1.5 by reducing anomalous eddy current loss by laser scribe.

Modeling of Anomalous Eddy Current Losses Due to Movement of Domain Walls in Particles of a Soft Magnetic Composite

Soft magnetic composites (SMCs) are composed of ferromagnetic particles surrounded by electrical insulation. To establish a homogenization technique for the magnetic field analysis of an electrical machine with an SMC core, we have already proposed a method to evaluate the effective permeability and iron loss of the SMC core using a cell model of one particle taking into account the nonlinear magnetic characteristics and eddy currents. However, the measured eddy current loss cannot be represented by using the proposed method. In this article, a 3-D eddy current analysis method modeling the anomalous eddy current loss due to the movement of domain walls in the cell model is developed based on the Pry and Bean magnetic domain model. The effect of the non-uniformity of the domain structure on the anomalous eddy current loss is investigated. It is shown that the measured eddy current loss can be almost represented by adding the anomalous eddy current loss to the classical one.

A unified explicit analytical expression for considering anomalous eddy-current losses of ME laminate

Based on the equivalent circuit approach, a unified explicit analytical expression for RME field and voltage coefficients, taking into account the anomalous eddy-current losses of domain magnetization rotation (DMR) and domain wall displacements (DWD) in the magnetic phase, is established for ME laminate. For slabs with bar domains, the combination of classical eddy-current model and Polivanov’s eddy-current model in derivation achieved the consideration of microstructure of magnetic domains influencing the anomalous eddy-current losses. The proposed expressions are capable of reduction to some existing models, in which only the classical eddy-current losses or anomalous eddy-current losses of DWD are considered. The results prove that (1) the proposed novel expressions unified the previous analytical models on investigations of the anomalous eddy-current losses of ME laminate. (2) The prediction accuracy of the resonant ME (RME) coefficients corresponding to ME coupling effect has been increased due to considering the anomalous eddy-current losses. (3) The present investigations offer analytical expressions for obtaining the lower and upper boundary values of anomalous eddy-current losses for the specific ME laminate under intermediate values of and appropriate The numerical results provide theoretical guidance in design, manufacturing and application of smart structures with ME laminate.

Simple Numerical Calculation Method of Rotational Iron Loss in Silicon Steel Sheets

To evaluate the iron losses of motors and three-phase transformers, the rotational iron loss should be considered. A simple numerical calculation method of the rotational iron losses under rotational flux with high flux density and different axis ratios is proposed in this paper. First, it is shown that the method of decomposing the rotational flux into the directions of the major and minor axes of the rotational flux is effective in calculating the rotational iron losses of the non-oriented and grain-oriented electrical steel sheets in low magnetization region. Then, the simple iron loss calculation method is improved to consider the decrease of rotational hysteresis and anomalous eddy current losses in high magnetization region under circular rotational flux and verified by comparing with measurement results. Furthermore, it is improved to be applicable to rotational iron loss calculation under rotational flux with different axis ratios and verified by comparing with measurement results.

Fundamental Investigation of a Method for Considering Anomalous Eddy Current Loss in Post-processing for Iron Loss Estimation

Fundamental Investigation of a Method for Considering Anomalous Eddy Current Loss in Post-processing for Iron Loss Estimation

Anomalous eddy-current effect of magnetostrictive-piezoelectric laminated composites in consideration of magnetic domain wall displacements

An analytical model of resonant magnetoelectric (ME) coupling in magnetostrictive (MS)- piezoelectric (PE) laminated composites taking consideration of anomalous eddy current effect resulted from the magnetic domain wall displacements in MS layer is proposed based on the equivalent circuit method. Numerical results show that: (1) the anomalous eddy-current loss deteriorates the ME coupling effect and reduces the optimal thickness ratio of MS phase to 0.3 in ME laminate. (2) the nonlinear effect between the ME coefficients and the thickness of ME laminate becomes stronger when considering the anomalous eddy-current loss. Furthermore, the proposed model can be reduced easily to the existing model considering of the classical eddy-current effect.

Magnetic Circuit Model combined with Play Model Obtained from Landau-Lifshitz-Gilbert Equation

This paper presents a novel magnetic circuit model considering magnetic hysteresis behavior, in which dc hysteresis is expressed by a play model while classical and anomalous eddy current losses are calculated by magnetic circuit elements. We describe an efficient method for obtaining the play model from the minimum measured B-H loops. It is proved that the proposed magnetic circuit model can calculate hysteresis loops under Pulse Width Modulation (PWM) excitation with high accuracy in a short time.

Stress induced anisotropy in Co-rich magnetic nanocomposites for inductive applications

Abstract

Magnetic Circuit Model Considering Magnetic Hysteresis

SUMMARYQuantitative estimation of core loss considering magnetic hysteresis property is strongly required to develop high‐efficient electrical machines. This paper presents a novel magnetic circuit model considering magnetic hysteresis. In the proposed model, dc hysteresis loss is calculated by the Landau–Lifshitz–Gilbert (LLG) equation, while classical and anomalous eddy current losses are calculated in the magnetic circuit. It is demonstrated that the hysteresis loop under PWM wave excitation can be expressed by the proposed model. The validity and effectiveness of the method are proved by comparing with measured values.

Prediction method of basic domain structure in Fe3%Si(110) single crystal with grooved surface

This paper proposes the method to accurately predict the 180° basic domain width (Dw) in demagnetized states of the grooved Fe3%Si(110) single crystal with the tilt angle of [001] out of the sheet surface (β). The evaluation of Dw enables the estimation of the anomalous eddy current losses. In this paper, Dw is optimized to minimize the magnetic Gibbs free energy represented by vector potentials using the finite element method and the conjugate gradient method. The μ*-method is adopted to approximate the magnetization relaxation. The stray field energy generated by the magnetic charges occurring on both grooves cross section and sheet surfaces is considered in our proposed method. The validity of the proposed method was confirmed by comparison with the observed Dw. As a result, we could reveal the β dependence of Dw against the groove depth. Moreover, the theoretical threshold of the domain refinement due to the grooves has been suggested.

Calculation of Basic Domain Width Considering Lancet Domains in (110)[001]Fe3%Si

This paper presents the calculation method of basic domain width in demagnetized states of (110)[001]Fe3%Si under tensile stress in the range of lancet domain occurrence. Accurately calculating the 180 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> basic domain width in demagnetized states is one of the important estimations to evaluate the anomalous eddy-current losses. Previously, stripe domain models, under sufficient strong tensile stress to annihilate lancet domains, were used so that the discrepancy between the calculated and the observed widths under tensile stress in which lancet domains occur became large. Applying the decrease of the surface magnetic charge by lancet domains to calculations of the stray field energy of basic domains enables us to accurately evaluate the 180 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> basic domain width under tensile stress in demagnetized states. Furthermore, the eddy-current losses evaluated using the calculated basic domain width show good agreement with the measured values under the tensile stress in the range of lancet domain occurrence.

Magnetic Circuit Model Considering Magnetic Hysteresis

SUMMARY Quantitative estimation of core loss considering magnetic hysteresis property is strongly required to develop high-efficient electrical machines. This paper presents a novel magnetic circuit model considering magnetic hysteresis. In the proposed model, dc hysteresis loss is calculated by the Landau–Lifshitz–Gilbert (LLG) equation, while classical and anomalous eddy current losses are calculated in the magnetic circuit. It is demonstrated that the hysteresis loop under PWM wave excitation can be expressed by the proposed model. The validity and effectiveness of the method are proved by comparing with measured values.

Magnetic-Circuit-Based Iron Loss Estimation Under Square Wave Excitation With Various Duty Ratios

In recent years, development of high-efficiency electric machines is strongly required from the viewpoint of energy saving and environmental protection. It is essential, therefore, that establishment of a simple and practical method for calculating iron loss with high accuracy. This paper presents a novel magnetic circuit model which is obtained from an empirical expression for the iron loss of soft ferromagnetic materials. The proposed magnetic circuit model consists of three elements as follows: a dependent source which expresses dc hysteresis, an inductance element which denotes eddy current loss, and a dependent source which represents anomalous eddy current loss. These elements can be simply obtained from dc hysteresis loops and core loss curves of core material. The validity and usefulness of the proposed method is proved by comparing with experimental results under square wave excitation.

Core Loss in Fe-Si Powder Cores

The applications of powder cores to very high power conversion equipment have recently been spreading. Fe-Si alloys are effective in downsizing magnetic cores because they have large degrees of magnetization. However, core loss needs to be further reduced. The relationships between core losses for Fe-3mass%Si powder cores made under various conditions were investigated in this study, i.e., hysteresis losses, classical eddy current losses, and anomalous eddy current losses including the sizes of their particles and crystal grains. We found that hysteresis losses decreased as crystal grains increased in size. We confirmed that not only there were classical eddy current losses generated uniformly in particles, but also anomalous eddy current losses occurred. The anomalous eddy current losses suggested that they were due to domain wall movement, and they decreased with decreasing crystal grain sizes. Their exponents of the frequency dependency of anomalous eddy current losses varied between 1.5 and 2.0 depending on test conditions, and they reflected the change in the number of domains with frequency.

磁気回路における異常渦電流損の考慮

磁気回路における異常渦電流損の考慮

Investigation on Simple Numeric Modeling of Anomalous Eddy Current Loss in Steel Plate Using Modified Conductivity

To calculate the iron loss in an electric machine accurately, the anomalous eddy current loss generated by domain wall motion should be considered. A simple numeric modeling of anomalous eddy current loss by modifying the conductivity of steel plates is sometimes used. However, investigation on this method in detail has not been carried out. In this paper, this method is investigated in two iron-loss models neglecting and including the skin effect and then applied to the loss calculation of various kinds of nonoriented and oriented silicon steel plates. Then, the dependence of the modified conductivity on the amplitude and frequency of the induction magnetic field for each material is obtained and the appropriate iron-loss model and method for modifying the conductivity are proposed for the nonoriented and oriented silicon steel plates. The calculated iron losses using the appropriate iron-loss model with modified conductivity are compared with the measured data. It is clarified that for nonoriented materials, the iron-loss model including the skin effect with constant modified conductivity shows good agreement. And for oriented materials, the model neglecting the skin effect with the modified conductivity depending on frequency is better.

Dynamic and Anisotropic Vector Hysteresis Model Based on Isotropic Vector Play Model for Nonoriented Silicon Steel Sheet

A phenomenological vector hysteresis model is developed to represent dynamic and weakly anisotropic vector hysteretic properties of nonoriented silicon steel sheets. The anisotropic vector hysteresis is represented by the multiplication of an anisotropy matrix and an isotropic vector play model. An eddy-current field vector given by classical eddy-current theory and an anomaly factor is added to the vector hysteresis model. The anomaly factor is determined to model the decrease in anomalous eddy-current loss under conditions of large rotational magnetic flux. The alternating and rotational properties simulated by the proposed model reconstruct the measured magnetic properties of nonoriented silicon steel sheets.

Method of Evaluating Anomalous Eddy Current Loss in Electrical Steel Sheets

This paper discusses the anomalous eddy current caused by magnetic domain wall movement. The anomalous eddy current due to the change of flux space harmonics distribution generated by domain wall movement is generally not affected by steel thickness, but by crystalline grain size. Then, if magnetic flux is concentrated at the steel sheet surface, such as the skin effect, the anomalous eddy current loss increases and weakens the skin effect although classical eddy current decreases. Therefore, it is necessary to use the magnetization curves, taking into consideration the anomalous eddy current loss to estimate the actual eddy current loss, because anomalous eddy current loss cannot be calculated with the usual method, where the DC hysteresis loop is used and microscopic flux distribution is not considered in Maxwell's equation.