Properties Of Electrical Steel Sheets Research Articles

Vector Magnetic Properties of Non-oriented Electrical Steel Sheet under Principal Stress

Magnetic properties of electrical steel sheet which is used motor cores are influenced due to mechanical stress. Therefore, it is necessary to know the magnetic properties under tensile, compressive and shear stress conditions in order to utilize the electrical steel sheet effectively. This paper presents the influence of the principal stress on vector magnetic properties of a non-oriented electrical steel sheet. The vector magnetic properties of the non-oriented electrical steel sheet are measured by changing the amplitude and angle of the principal stress to evaluate the stress effect of the motor core. From these results, it was clarified that the loci of the magnetic field strength vector and magnetic power loss depend on the amplitude and angle of the principal stress.

Measurement Technique of Magnetic Properties for Evaluation of Power Magnetic Materials

In recent years, the precise magnetic properties of electrical steel sheet are needed to develop high efficiency electromagnetic devices. An IEC standard single sheet tester is often used for the magnetic property measurement, especially for commercial transactions. But it is not accurate, so is not proper for the material evaluation based on its precise properties data. Therefore, we developed the measurement technique for the precise magnetic properties of electrical steel sheet. In this paper, two single sheet testers are shown. One is according to IEC standard (IEC-SST), and the other, the Stress load type-Single Sheet Tester (S-SST) is originally designed with our measurement technique for the precise magnetic properties. The key technology for evaluation of electrical steel sheet is proposed, using the S-SST and the IEC-SST. In particular, magnetic field strength distribution in measurement area inside exciting coil and solution of H coil specification difference are studied. And the magnetic properties of the S-SST and the IEC-SST are compared.

Estimation of the iron loss in deep-sea permanent magnet motors considering seawater compressive stress.

Deep-sea permanent magnet motor equipped with fluid compensated pressure-tolerant system is compressed by the high pressure fluid both outside and inside. The induced stress distribution in stator core is significantly different from that in land type motor. Its effect on the magnetic properties of stator core is important for deep-sea motor designers but seldom reported. In this paper, the stress distribution in stator core, regarding the seawater compressive stress, is calculated by 2D finite element method (FEM). The effect of compressive stress on magnetic properties of electrical steel sheet, that is, permeability, BH curves, and BW curves, is also measured. Then, based on the measured magnetic properties and calculated stress distribution, the stator iron loss is estimated by stress-electromagnetics-coupling FEM. At last the estimation is verified by experiment. Both the calculated and measured results show that stator iron loss increases obviously with the seawater compressive stress.

Vector magnetic property of electrical steel sheet and its influence on distributions of magnetic field and iron loss for electrical machines

Purpose – The purpose of this paper is to present the vector magnetic properties of the electrical steel sheet and investigate its influences on the magnetic field and iron loss distributions for the electrical machines. Design/methodology/approach – The vector magnetic property of the electrical steel sheet is measured by using a two-dimensional single sheet tester and modelled through an E&S vector hysteresis model to be applied to finite element analysis. Findings – The magnetic field and iron loss distributions are calculated by finite element analysis combined with the E&S vector hysteresis model for the three-phase transformer and induction motor models. Originality/value – The influences of the vector magnetic property on the electrical machines are verified by comparing with the numerical results from a scalar magnetic property.

Iron Loss Analysis of a Permanent Magnet Rotating Machine Taking Account of the Vector Hysteretic Properties of Electrical Steel Sheet

This paper presents the iron loss prediction of rotating electric machines taking account of the vector hysteretic properties of electrical steel sheet. The E&S vector hysteresis model is adopted to describe the vector hysteretic properties of a non-oriented electrical steel sheet, and incorporated into finite element analysis (FEA) for magnetic field analysis and iron loss prediction. A permanent magnet synchronous generator is taken as a numerical model, and the analyzed magnetic field distribution and predicted iron loss by using the pro- posed method is compared with those from a conventional method which employs an empiri- cal iron loss formula with FEA based on a non-linear B-H curve. Through the comparison the effectiveness of the presented method for the iron loss prediction of the rotating machine is verified.

Metallurgical, Mechanical and Magnetic Properties of Electrical Steel Sheets in TIG and PLASMA Welding

The influence of Tungsten Insert Gas (TIG) and Plasma welding on the microstructure, mechanical and magnetic properties of non-oriented electrical steels is presented and evaluated. Samples of sizes of 5.5 cm x 5.5cm x 2.0 mm were prepared from stock plate, installed on the welding table and welded at welding speeds and pulsed currents following a predesigned protocol. The samples microstructure was studied using SEM after standard mechanical grinding and polishing procedures. The characterization of the samples is concluded with microhardness tests and magnetic measurement (Barkhausen Noise) on TIG and Plasma welded joints in order to investigate the influence of welding on the magnetizing behavior of a high Si-alloyed grade of non-oriented electrical steel.

Estimation model for magnetic properties of stamped electrical steel sheet

AbstractLess deterioration in the magnetic properties of electrical steel sheets in the process of stamping out the iron core is necessary in order to maintain performance. First, the influence of plastic strain and stress on the magnetic properties is studied using test pieces, in which plastic strain is added uniformly and residual stress is not induced. Because the influence of plastic strain is expressed using the equivalent plastic strain, at each equivalent plastic strain state the influence of the load stress is investigated. Second, the elastic limit is determined to be about 60% of the macroscopic yield point (MYP), and this agrees with the stress limit inducing irreversible deterioration in the magnetic properties. Therefore, simulation models, in which excess elastic limit plastic deformation begins and the magnetic properties deteriorate sharply, are proposed. Additional points taken into consideration in the deformation analysis are the strain rate sensitivity of flow stress, the anisotropy under deformation, and the influence of stress triaxiality on fracture. Finally, the proposed models are shown to be valid because the magnetic properties of rectangular sheets 5 mm wide stamped out from a nonoriented electrical steel sheet (35A250 JIS grade) can be estimated with good accuracy. It is concluded that the elastic limit must be taken into account in both the stamping process simulation and magnetic field calculation. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(2): 1–11, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22269

Development of Single Sheet Tester under Stress towards Reduction of Building Factor

In recent years, the precise magnetic properties of electrical steel sheet are needed to develop high efficiency electromagnetic devices. An IEC standard single sheet tester is often used for magnetic property measurement, especially for commercial transactions. But it is not proper for the material evaluation based on its precise properties data. Therefore, we developed measurement techniques for the precise magnetic properties of electrical steel sheet. In this paper, the key technology for evaluation of electrical steel sheet is proposed. The single sheet tester based on evaluation measurement technique is useful for adequate choice of electrical steel sheet for high efficiency electrical devices and evaluation of high performance power magnetic materials, etc.

AC Magnetic Properties of Electrical Steel Sheet Under Two-Dimensional DC-Biased Magnetization

AC magnetic properties of electrical steel sheets are generally evaluated under symmetrical alternating magnetization in the standard magnetic measurement. However, magnetizing conditions of electrical steel sheets in electromagnetic machines are not always symmetric and alternating magnetization. This paper presents a new measuring system for AC magnetic properties of electrical steel sheets under two-dimensional DC-biased magnetization and discusses the properties under DC-biased magnetization.

Accuracy Improved Dynamic E&S Vector Hysteresis Model and its Application to Analysis of Iron Loss Distribution in a Three-Phase Induction Motor

This paper presents an improved dynamic E&S vector hysteresis model to increase modeling accuracy under non-elliptic B-waveforms and describes its implementation to the finite element method (FEM). Since the dynamic E&S model is expressed via magnetic reluctivity and hysteresis coefficients modeling the vector hysteresis property of electrical steel sheet, its modeling accuracy strongly depends on the method of determination of the coefficients. The proposed model increases the modeling accuracy by improving the coefficient calculation algorithm especially under non-elliptic distorted magnetic flux density conditions. The proposed model is incorporated with FEM and applied to iron loss analysis of a three-phase induction motor.

Phase Correction for High Precision Measurement of Iron Loss using H-coil Method

SUMMARY The accurate magnetic properties of electrical steel sheets are important for the development of high-efficiency electromagnetic devices. In particular, the H-coil method is a useful technique for accurately measuring magnetic field strength in a single sheet tester. Therefore, we developed a tester for magnetic field properties using the H-coil method, referred to as the stress load type single sheet tester (S-SST), and a problem was found in iron loss measurement at a high flux density of 1.6 T or more. In this paper, it is shown that the cause of this problem is the phase difference between the induced voltage in the H-coil and the B-coil. Because the phase difference makes the B–H loop slightly twisted near the tip point, the iron losses are evaluated low. Thus, we propose a method of determining the phase correction values. These values are measured in the absence of a specimen in the S-SST measurement system, and the phase correction method for induced voltage in a coil is investigated. Finally, ideal results for the correction of iron loss in nonoriented electrical steel sheets are shown. The proposed method is effective for the calibration of a single sheet tester using the H-coil method.

Measurement Research on Magnetic Properties of Electrical Steel Sheet under DC Bias Conditions

In order to acquire the magnetic properties parameter of transformer core under DC bias conditions, also to reveal the accurate analysis and judgment on the operating characteristics of transformer under the DC bias, this thesis utilized two Epstein Square devices to proceed the experiment and measurement on magnetization curve of some certain transformer which used the 30ZH120 electrical steel sheet under four different lap ways. This paper provided the measure method of bias magnetic density under laboratory conditions, meanwhile it offered the bias magnetization curve and the loss curve. The measure consequence comparison between the electrical sheet steel and the transformer model showed that direct oblique way lap can be more realistically reflected the magnetization characteristic of transformer which worked in the DC bias conditions. For Large Transformer which was difficult to measure the magnetic properties provided a convenient measurement methods, and offered the experiment facts to the theory study of the DC bias transformers.

Development of the 2-D Single-Sheet Tester Using Diagonal Exciting Coil and the Measurement of Magnetic Properties of Grain-Oriented Electrical Steel Sheet

In order to analyze magnetic characteristics of magnetic devices, it is necessary to accurately measure magnetic properties of an electrical steel sheet in arbitrary directions. In this paper, we developed a 2-D-single-sheet tester (SST) using diagonal exiting coils in order to improve the measurement accuracy under high flux condition. The measurement region of flux density B and magnetic-field strength H is examined for the accurate measurement. The magnetic properties of grain-oriented electrical steel sheet under alternating magnetic flux and rotating magnetic flux are measured using our system. The accuracy of measurement in the case of grain-oriented sheet is examined by comparing the measured results using 2-D-SST with those by using an ordinary SST under alternating flux excitation. The effect of positioning error of orthogonal B and H coils on measurement accuracy is also discussed.

전기강판의 벡터 자기특성 모델링을 위한 개선된 E&S Vector Hysteresis Model

Recently, several vector hysteresis models such as vector Preisach, vector Jiles-Atherton and dynamic E&S model have been proposed to describe vector magnetic properties of electrical steel sheets. However, it is still difficult to find an adequate vector hysteresis model in finite element application for both the Non-oriented and Grain-oriented electrical steel sheets under alternating and rotating field conditions. In this paper, an improved E&S vector hysteresis model is suggested to describe the vector magnetic properties of both Non-oriented and Grain-oriented electrical steel sheets under various magnetic field conditions including alternating and rotating magnetic field conditions. The validity of the proposed model is tested through comparisons with the experimental results under various magnetic field conditions.

Several modeling methods for representation of AC magnetic properties of electrical steel sheets taking account of skin effect

AbstractSeveral homogenized models are compared for accurate representation of the AC magnetic properties of silicon steel sheets. Two of them are the generalized Pry and Bean models, which have a parameter for the frequency dependence of eddy‐current loss. The third model assumes a quadratic distribution of the magnetic flux density along the thickness direction. The other model is an extension of the linear magnetization model. Numerical simulations show that the third model yields inaccurate BH loops whereas the other models accurately represent BH loops. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(3): 9–16, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21180

A Generalized Chua-Type Vector Hysteresis Model for Both the Non-Oriented and Grain-Oriented Electrical Steel Sheets

This paper presents a generalized Chua-type vector hysteresis model to describe both the static and dynamic vector magnetic properties of electrical steel sheets. The proposed model takes into account all significant harmonic components of the measured H -waveforms, thus it provides precise prediction of H-waveforms even under highly saturated magnetic flux densities under alternating, rotating, and distorted magnetic fields conditions. The validity of the proposed vector hysteresis model was investigated by comparison to experimental results under various magnetic field conditions for both the non-oriented and grain-oriented silicon steel sheets.

電磁鋼板の打抜き加工による磁気特性劣化量の推定技術の開発

Less deterioration in the magnetic properties of electrical steel sheets in the process of stamping out the iron core is necessary in order to maintain performance. First, the influence of plastic strain and stress on the magnetic properties is studied using test pieces, in which plastic strain is added uniformly and residual stress is not induced. Because the influence of plastic strain is expressed using the equivalent plastic strain, at each equivalent plastic strain state the influence of the load stress is investigated. Second, the elastic limit is determined to be about 60% of the macroscopic yield point (MYP), and this agrees with the stress limit inducing irreversible deterioration in the magnetic properties. Therefore, simulation models, in which excess elastic limit plastic deformation begins and the magnetic properties deteriorate sharply, are proposed. Additional points taken into consideration in the deformation analysis are the strain rate sensitivity of flow stress, the anisotropy under deformation, and the influence of stress triaxiality on fracture. Finally, the proposed models are shown to be valid because the magnetic properties of rectangular sheets 5 mm wide stamped out from a nonoriented electrical steel sheet (35A250 JIS grade) can be estimated with good accuracy. It is concluded that the elastic limit must be taken into account in both the stamping process simulation and magnetic field calculation. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(2): 1–11, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22269

Measurement of Magnetic Properties of Nonoriented Electrical Steel Sheet at Liquid Nitrogen Temperature Using Single Sheet Tester

For the design of high efficiency and miniature electrical machines, the development of superconducting machines, which can be used at low temperature (less than liquid nitrogen temperature), is considered. In order to examine the design of these machines, magnetic properties of electrical steel sheets, etc. used, such as cores of electrical machines are necessary. It is shown that the permeability and iron loss of nonoriented silicon steel is, in general, increased at low temperature.

二軸引張応力下におけるベクトル磁気特性測定システムの応力印加機構の検討

It is well known that magnetic properties of electrical steel sheet deteriorate due to stress in production process of electrical apparatus. Therefore the magnetic power loss increases in comparison to design-time assumptions. Therefore, it is necessary to clarify the relationship between the stress and the magnetic property. In general, the magnetic properties of the electrical steel sheets become better by applying the tensile stress, and deteriorate by applying the compressive stress. The magnetic property under the stress has been evaluated by a scalar magnetic measurement, which means same direction for the excitation and the stress in the electrical steel sheet. We developed new measurement system, which can evaluate the vector magnetic property under the biaxial stress. In this paper, the mechanism to apply the biaxial tensile stress is examined by measuring the principal stress. In addition, the vector magnetic property under the tensile stress of x and y direction is measured with the developed system. Figure 1 shows the developed vector magnetic measurement system under biaxial tensile stress. The strain of the electrical steel sheet is measured with three-axial strain gauge. The stress components sx, sy and txy are calculated to evaluate the principal stress. The vector magnetic property is measured by using VH analyzer (IWATSU, IE131E). Figure 2 shows the vector magnetic property depending on the tensile stress of x direction. The principle stress of x direction is controlled by adding the biaxial stress in the developed system as shown Fig. 2. The trajectory of the magnetic field strength and the BH loop of x and y components under the tensile stress changed in comparison with that of the non-stress. The area of BH loop of x component becomes smaller, and that of y component becomes larger by increasing the value of the tensile stress. Figure 3 shows the magnetic property depending on the maximum principal stress of the x direction. The relative

Development of Measurement System of Magnetic Properties at High Flux Density Using Novel Single-Sheet Tester

For the design of miniature electrical machines of high power density, it is necessary to measure magnetic properties of electrical steel sheet at high magnetic flux density. The JIS standard single-sheet tester (SST) is insufficient to measure magnetic properties at high magnetic flux density around 2.0 T. In this paper, we have designed and developed an SST, which can excite high magnetic strength field up to about 58 000 A/m. The accuracy of measurement of alternating current (ac) loss at high magnetization (55 000 A/m) is verified by measuring the eddy current loss of a copper plate comparing with the theoretical value. It is shown that the magnetic properties of nonoriented electrical steel sheet can be measured until 2.1 T.