Magnetostriction Of Electrical Steel Research Articles

Magnetostrictive hysteretic properties estimation of electrical steel sheet under external stress using improved ADSM model

PurposeThe purpose of this paper is to improve the modeling accuracy of the magnetostrictive hysteretic characteristics by introducing hysteresis energy instead of pinning energy in the assembled domain structure model (ADSM).Design/methodology/approachFirst, the magnetostrictive characteristics and the domain movement process in an electrical steel sheet are measured and observed. The reasons for the influence of stress on magnetostriction are discussed on the mesoscopic level. Second, the ADSM model using the hysteresis energy is investigated to estimate the influence of external stress. Finally, the simulation results of the modified ADSM model are compared with the experimental data under the same calculation conditions.FindingsThe results show that the improved model not only explains the cause of hysteresis clearly from the perspective of the magnetic moment but also improves the modeling ability of magnetostrictive hysteretic.Originality/valueThe magnetostriction in electrical steel lags behind the external magnetic field, and it is significant for reducing core vibration to estimate the magnetostrictive hysteretic property accurately. This paper proposes an effective approach to model the hysteretic characterization of magnetostriction.

Modeling the stress effect on the measurement of magnetostriction in electrical sheets under rotational magnetization

The magnetostriction in electrical steel under rotational magnetization is usually measured with cross-shaped samples. However, the inhomogeneity of the magnetization and stress in the sample might hinder the measured results. In this paper, we investigate this phenomenon by using a magneto-mechanically coupled energy-based model to simulate the sample in a single sheet tester measurement setup, and compare the simulations and measurements. The results show that some anomalies in the measured magnetostriction can be explained by the inhomogeneous magnetization in the sample and the form effect, which result in inhomogeneous stresses and thus affect the observed quantities. The validity of the model as well as the presented statements are ascertained through experiments on the single sheet tester. The backgrounds of the used modelization technique are also detailed.

Magnetostriction of Electrical Steel and Its Relation to the No-Load Noise of Power Transformers

This paper analyzes the relationship between the experimentally determined magnetostriction of grain-oriented electrical steel (GOES) coils and the no-load noise of power transformers (PT). The main source of a PT's no-load noise is the magnetostrictive vibration of the magnetic core built with stacked GOES sheets. With an in-house measurement system, in which steel coils with a mass of up to 6000 kg is measured, differences in the GOES materials’ magnetostriction were identified. In this paper, we analyze the flux dependent behavior and harmonic composition of the magnetostrictive properties of different steel coils. Based on the identified differences in the steel coils’ magnetostriction, two experimental studies with PTs are provided showing exemplary results. The first study shows initial findings of the relationship between the magnetostriction of the deployed steel coils and the emitted no-load noise of model transformers. In a second study, the aforementioned investigations were extended with measurements of large power transformers. Both studies cover a correlation and performance analysis including comparisons of the noise-related GOES certificate value B8 (also known as B800 value).

Measurement and analysis of effect of the stress on magnetostriction of electrical steel under harmonic fields

A magnetostriction single-sheet tester with an air compressor was developed and the magnetostriction in an electrical steel sheet was measured by a triaxial strain gauge under applied stresses externally and higher harmonic of field. The magnetostriction property’s sensitivity on the applied stress was described. This investigation also tried to understand the relationship between the presence of higher harmonics in the magnetization waveform and those in the magnetostriction waveform under a certain stress. The study results for the magnetostriction under stresses and harmonics show that the appearance of harmonic of magnetic field cannot be ignored, which aggravates the principal strain harmonics.

Magnetostriction of Silicon Steel Sheets Under Different Magnetization Conditions

The magnetostriction of electrical steel is one of the main sources causing deformation and vibration in rotational machine and transformer cores. The presence of dc bias or higher harmonics of magnetic field in the electrical apparatus cores makes the vibration and noise of cores more serious. Therefore, it is necessary to identify how different magnetization patterns contribute to the magnetostriction noise. This paper performs the measurement of magnetostrictive strain in non-oriented and grain-oriented electrical steel sheets under sinusoidal excitation, one with a dc bias and the other with a third harmonic component, respectively. An investigation of the effect of dc biased magnetic field on the magnetostrictive property is carried out. The influences of a third harmonic of magnetic field with a variety of amplitudes and phase delay on magnetostriction are studied and the acoustic noise level is calculated due to the presence of the second (100 Hz) and fourth (200 Hz) harmonics of magnetostrictive strain. The research results are important for evaluating the noise of electrical machine and transformer core effectively.

Modeling 2-D Magnetostriction in Nonoriented Electrical Steels Using a Simple Magnetic Domain Model

Magnetostriction in electrical steel is a source of acoustic noise and vibration of rotating electrical machine cores. Magnetostriction of nonoriented (NO) steel under 2-D magnetization is much greater than that under unidirectional, alternating magnetization. An analytical interpretation of the relevance of 2-D magnetostriction and magnetostrictive anisotropy of NO steel based on a simple magnetic domain model is presented. The analysis helps explain the effect of anisotropy on 2-D magnetostriction measurements made on commercial NO steels with different anisotropy factors. The magnitude of the 2-D magnetostriction is shown to depend on the magnetostrictive anisotropy and magnetic Poisson's ratio.

Frequency Characteristics of Magnetostriction in Electrical Steel Related to the Structural Vibrations

The ac magnetostriction in electrical steel is commonly characterized in the time domain (e.g., the peak-to-peak, zero-to-peak amplitude) and also in the frequency domain (e.g., a harmonic analysis). However, due to the dynamical coupling of the test sample with the experimental setup, the characterization of the magnetostriction (especially the one in the frequency domain) can give the wrong result. This research focuses on an experimental frequency characterization of magnetostriction and gives the theoretical background of the test sample's dynamical coupling with the experimental setup. The discussed natural dynamics of the test sample from the point of view of the different boundary conditions that can be used at the experiment gives a clear picture of the dynamical coupling. Besides the theoretical background, a detailed experimental approach is presented. This paper theoretically and experimentally shows that the dynamical coupling of the sample can result in incorrect characterization of the magnetostriction. However, with the theoretical guidelines presented, the dynamical coupling can be completely avoided, which results in an accurate characterization of the magnetostriction.

Neural-Network-Based Model for Dynamic Hysteresis in the Magnetostriction of Electrical Steel Under Sinusoidal Induction

A model is presented to calculate the dynamic hysteresis behaviour of the magnetostriction in electrical steel under 1-D sinusoidal magnetisation. The input of the model is one period of the 1-D induction wave. On this induction wave, a fast Fourier transform (FFT) is performed, of which the frequency components are fed to the input of a neural network (NN).This neural network calculates the frequency components (amplitude and phase) of the magnetostriction, on which an inverse fast Fourier transform (IFFT) is performed, thus obtaining the magnetostriction wave complementary to the input induction wave. The filtering technique was used to model the magnetostriction of a grain oriented electrical steel. The amplitude of the induction in the sample ranged between 0.6T and 1.8T and the frequency ranged between quasi-static and 200Hz.

Magnetizing angle dependence of harmonics of magnetic induction and magnetostriction in electrical steel

The harmonics of magnetic induction and magnetostriction during AC magnetization in electrical steel were measured as a function of the magnetizing angle with respect to [0 0 1] axis, ϕ. The relative amplitudes of odd and even harmonics, respectively, for magnetic induction and magnetostriction decrease with the harmonic order, accompanying the contraction of the amplitudes. The decreasing contraction order of magnetostriction harmonics with ϕ is shown to be an even number multiple of that of magnetic induction. This relationship could provide an easy distinction of harmonics characteristics of magnetostriction from that of magnetic induction.