International Journal of Applied Electromagnetics and Mechanics - Volume 44, issue 3-4

Authors: Cardelli, Ermanno | Faba, Antonio | Tissi, Francesco

Article Type: Research Article

Abstract: In this work we discuss some procedures to increase the accuracy in the measurement of the magnetic field strength using Round Rotational Single Sheet Tester RRSST frames. The procedures are discussed jointly with the use of different magnetic field probes, such as flat coils and Hall sensors, and with a suitable shielding geometry. Experimental comparison between different methods and a discussion about the results is presented.

Keywords: Magnetic materials, vector hysteresis, magnetic measurements

DOI: 10.3233/JAE-141795

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 331-338, 2014

Authors: Psuj, Grzegorz | Chady, Tomasz | Enokizono, Masato | Todaka, Takashi

Article Type: Research Article

Abstract: In this paper influence of uniaxial stress loading on local changes of magnetic properties in a non-oriented silicon steel was examined. The measurements were carried out for different direction of loading force in respect to the rolling direction of the steel. Impact of the relationship between the rolling and the loading direction on evaluation of magnetic properties changes caused by stress was investigated using samples cut out at three different angles from the steel sheet. During …the experiments two types of transducers with two and three sensitivity axes operating under rotating AC and static DC field were utilized. First, the observation of local changes of parameters related to a vector magnetic flux was carried out. Then algorithms of measured signals parameterization were utilized and evaluation of the stress distribution in tested samples was proceeded. Finally, the statistical analysis of computed signals parameters was applied and the correlation with stress-strain curve was assessed. Show more

Keywords: Non-destructive testing, stress evaluation, rotating flux, vector magnetic flux, non-oriented electrical steel

DOI: 10.3233/JAE-141796

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 339-347, 2014

Authors: Hofbauer, Franz | Pfützner, Helmut | Shilyashki, Georgi | Šabić, Damir | Mulasalihović, Edin | Galabov, Viktor

Article Type: Research Article

Abstract: Loss distributions of transformer cores are affected by z-flux effects if considered for the core surface. Here we propose the application of a thermal sensor which is inserted to the core interior through one of 16 channels of 2 mm width. Measurements were made on a 1-phase core assembled from laser-scribed SiFe. Throughout the core, the local building factor BF proved to increase towards the periphery which can be interpreted by interactions of highest anisotropy and …non-linearity. Additional DC superposition yields non-uniform increases of BF at different core positions. Local losses tend to become more balanced – measurement locations with a priori high BF experience lower percentage increases, being more robust with respect to DC components. Show more

Keywords: Core loss, DC bias, building factor distribution, rise-of-temperature method

DOI: 10.3233/JAE-141797

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 349-354, 2014

Authors: Appino, C. | Ragusa, C. | Fiorillo, F.

Article Type: Research Article

Abstract: We review state-of-the-art modeling of two-dimensional (2D) magnetization process in soft magnets. Emphasis is placed on the phenomenological assessment of the energy losses in steel sheets under rotational field. It is stressed that a general physically based theoretical framework, exploitable for applications in practical materials and machine cores, is not available at present. However, a rational approach to the 2D magnetic losses and their frequency dependence can be pursued. This is based on …the separation between quasi-static (hysteresis) and dynamic magnetization processes and the connection with their unidirectional (scalar) counterpart. A number of vector models of the 2D quasi-static hysteresis behavior, typically residing on assessed scalar models, are discussed. They have prevalent formal-mathematical character, and, while being often helpful in numerical calculations, they leave unanswered the quest for solid physical interpretation. The dynamic magnetization process can, on the other hand, rely on a 2D phenomenological extension of the firmly established physical approach to the unidirectional scalar case provided by the statistical theory of losses. This is especially true for isotropic (i.e. nonoriented) magnetic laminations, where both rotational and elliptical flux loci can be conveniently handled. It permits one to achieve general appraisal of the experiments and flexible formulation, useful for numerical applications in machine cores. Show more

Keywords: Two-dimensional magnetization process, energy losses, vector hysteresis, rotational losses

DOI: 10.3233/JAE-141798

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 355-370, 2014

Authors: Kai, Yuichiro | Enokizono, Masato | Kido, Yukihito

Article Type: Research Article

Abstract: Electrical steel sheet that is used as a core in electrical machines deteriorates due to residual stress and external stress. The magnetic properties and stress need to be clarified in order to effectively utilize electrical steel sheet in electrical machines. We have measured the residual stress distribution in a motor core using an X-ray stress measurement device and clarified not only the tensile and compressive stress distributions, but also the shear stress distribution. In this study, …a new measurement system is developed for determining vector magnetic properties under shear stress. The vector magnetic properties of the non-oriented electrical steel sheets under the alternating magnetic flux and rotating magnetic flux conditions were measured with the developed system. As the result, it was clear that the magnitude of the magnetic field strength vector and the magnetic power loss along the direction of about 135° increased by applying the shear stress. Show more

Keywords: Non-oriented electrical steel sheet, vector magnetic property, shear stress, magnetic anisotropy, stress tensors

DOI: 10.3233/JAE-141799

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 371-378, 2014

Authors: Pluta, Wojciech

Article Type: Research Article

Abstract: The efficiency of electrical machines depends among other things on the specific total loss of electrical steel the core is made of. Hence, a better understanding of the loss mechanism can improve the efficiency of machines. In order to analyze the specific total loss of electrical steel grades, they were separated into three components: the hysteresis loss component and both the classical and additional eddy current loss components. The relationship between loss components and direction of …magnetization was analyzed. The aim of this paper is to provide a contribution to a better understanding of magnetic specific total loss in electrical steel sheets. Show more

Keywords: Specific total loss, hysteresis loss, classical eddy current, additional loss, electrical steel sheets

DOI: 10.3233/JAE-141800

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 379-385, 2014

Authors: Yamagashira, Masayuki | Ueno, Shohei | Wakabayashi, Daisuke | Enokizono, Masato

Article Type: Research Article

Abstract: This paper presents measured vector magnetic properties and two-dimensional magnetostriction of a non-oriented electrical steel sheet (including a 6.5% SiFe sheet), a grain-oriented electrical steel sheet, an Fe-based amorphous sheet, and a permendur sheet. These electrical steel sheets have been widely used as a core material of electrical equipment. Because it is difficult to reduce a building factor of a practical machine made of stress sensitive materials, it is therefore important to understand detailed magnetic …properties and magnetostriction characteristics. In order to grasp the basic magnetic properties, vector magnetic properties and two-dimensional magnetostriction were measured in the alternating magnetic flux conditions in the arbitrary direction. In this paper, the relationship among the magnetic flux density vector, the magnetic field strength vector, and the two-dimensional magnetostriction in the various electrical steel sheets under alternating flux condition is clarified. Show more

Keywords: Vector magnetic property, two-dimensional magnetostriction, iron loss, magnetic anisotropy

DOI: 10.3233/JAE-141801

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 387-400, 2014

Authors: Salas, Rosa Ana | Pleite, Jorge

Article Type: Research Article

Abstract: We propose a model of an equivalent electrical circuit specifically designed for a ferrite inductor excited by a nonsinusoidal waveform valid for use in an electronic circuit simulator. We estimate the model parameters by means of Finite Elements in 2D which leads to significant computational advantages over the 3D model. We carry out the validation of the procedure for an RM14/I core by comparing the experimental and simulated output waveforms obtained at different frequencies and levels …of excitation from the linear to the saturation regions. In addition, we consider the effect of power losses in the core. Show more

Keywords: Nonlinear inductors, Finite Element Analysis, core saturation effect, power losses

DOI: 10.3233/JAE-141802

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 401-407, 2014

Authors: Leiss-Holzinger, Elisabeth

Article Type: Research Article

Abstract: The magnetic field distribution in and around thin ferromagnetic structures has been explored. Extrapolation and mathematical air flux compensation were used to obtain magnetic quantities on the sample surface and inside the sample, minimizing systematic errors for flux-metric and Gauss-metric measurements. A magneto elastic model was applied describing large deformations of thin ferromagnetic structures in a static magnetic field. The model based on global balance equations obeys the conservation of energy and …momentum. Exemplified by the deformation of a soft-magnetic elastic plate in a uniform transverse magnetic field, the numerical evaluation of the model was compared to experimental results. Field distribution and deformation of the plate in a stepwise increased external field showed good agreement from small magnetization up to saturation. Show more

Keywords: Shell, plate, magneto-mechanic, ferromagnetic, deformation

DOI: 10.3233/JAE-141803

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 409-416, 2014

Authors: Galabov, Viktor | Pfützner, Helmut | Shilyashki, Georgi | Yamaguchi, Hiroi | Okazaki, Yasuo | Arai, Satoshi

Article Type: Research Article

Abstract: Domain analyses of modern types of grain-oriented (GO) transformer steel are rare, and they are focussed on single grains under academic magnetization patterns. The present Kerr effect study reveals that grains of industrial, polycrystalline materials react in specific ways according to individual crystallographic orientations. The amount of parameters is very large, especially if additional flux components are given as a further impact. The paper reports a procedure for statistical evaluations of quasi-dynamic Kerr …effect images. The instantaneous area ratios of bar domain portion BD, oblique domain portion OD and saturation S are determined with consideration of peak induction B_{RD} in the rolling direction (RD), axis ratio a of rotational magnetization, the angle ψ between B and RD, additional flux B_x in RD or B_z in normal direction. Focus is put on OD(t) which is assumed to be a key function for λ (t), i.e. the course of time of magnetostriction. As the most distinct tendencies, OD increases strongly with increases of a and ψ. OD(t) shows non-sinusoidal course of time with differences of the two halves of cycle. Rotation out of the RD yields sharp onsets of ODs, especially after half-cycle saturation. Additional off-plane flux enhances ODs in a general way. Show more

Keywords: Magnetic domains, rotational magnetization, Kerr-effect, DC-bias, off-plane flux

DOI: 10.3233/JAE-141804

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 417-428, 2014

Article Type: Other

Abstract: Author Index Volume 44 (2014)

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 429-434, 2014