Grain-oriented Silicon Steel Sheets Research Articles

Comprehensive magnetic properties of grain-oriented silicon steel sheet considering anisotropy under mechanical stress

The cores of transformers and reactors are subjected to mechanical stresses during both manufacturing and operation, these stresses exert an influence on the magnetic properties of the cores. Additionally, there exists rotating magnetic flux within the cores during operation. Therefore, it is necessary to further consider the magnetic properties of grain-oriented silicon steel sheet in the direction perpendicular to the rolling direction. To delve deeply into the comprehensive magnetic properties of grain-oriented silicon steel sheet under mechanical stress, with a particular focus on both the rolling direction and the direction perpendicular to it, this paper presents the establishment of a comprehensive magnetic properties measurement platform for grain-oriented silicon steel sheet that possesses stress adjustment capabilities. Through meticulous measurements, the impacts of tensile and compressive stresses on the magnetic hysteresis loops, B-H curves, relative permeability, magnetostriction, and iron loss characteristics of grain-oriented silicon steel sheet in both the rolling direction and the perpendicular direction were obtained and analyzed. The measurement results and subsequent analysis indicate that tensile and compressive stresses exert an influence on the magnetization characteristics of grain-oriented silicon steel sheet. Moreover, the extent of this influence varies between the rolling direction and the direction perpendicular to rolling for both tensile and compressive stresses; In the rolling direction, compressive stress promotes the magnetostriction of the grain-oriented silicon steels, while tensile stress inhibits it. In the direction perpendicular to rolling, both tensile and compressive stresses inhibit the magnetostriction of the grain-oriented silicon steels, with tensile stress exerting a greater inhibitory effect; Tensile stress acts to reduce the iron loss of grain-oriented silicon steels, whereas compressive stress increases it, this pattern is consistently observed in both the rolling direction and the direction perpendicular to rolling.

PMSM Design for Elevators: Determination of the Basic Topology Affecting Performance

In recent years, with the increase in high-rise building construction, there has been a rise in demand for elevators. This demand has spurred mutual growth between the vertical transportation sector and high-rise building construction. Both sectors are improving technology, security, and comfort standards. Traditional elevator traction machines typically employ asynchronous motors coupled with geared reducers, despite their low energy efficiency and requirement for large machine rooms. However, with the proliferation of rare-earth magnet materials and advancements in driver technologies, the use of Permanent Magnet Synchronous Motors (PMSMs) in elevator traction machines has increased. PMSMs operate with direct drive, eliminating the need for reducers. High efficiency and passenger comfort are crucial parameters for elevator traction machines. This study focuses on identifying the fundamental topology that could influence the performance of PMSMs for gearless elevator machines. Factors such as stator materials, rotor structures, permanent magnets, winding configurations, slot/pole combinations, cogging torque and torque ripple have been examined to select suitable design topologies for elevator motors. Important topics such as the magnetic properties of grain-oriented silicon steel sheets used in stator construction, B-H curves, lamination forming and stacking factors have been addressed. Two different rotor topologies and magnet arrangements, namely internal and external, have been investigated in PMSM designs. Additionally, the use of four different magnet materials, namely AlNiCo, Ferrite, NdFeB, and SmCo have been compared for PMSM traction motors in elevators. Single-layer and double-layer winding configurations, distributed and concentrated winding configurations have been compared. Fractional slot/pole combinations, which directly affect the performance and comfort of PMSMs, have also been examined based on information obtained from the literature. Particularly, structures with high winding factors, such as 12/10, 12/14, 18/16, 18/20, 24/22, and 24/26 have been identified. Finally, studies on skewing to reduce cogging torque and torque ripple have been addressed.

A Calculation Method for Static Hysteresis Loop and its Applications

Background: Due to experimental equipment limitations, it is usually difficult to measure the quasi-static hysteresis loop at extremely low frequencies, which inevitably introduces errors in the static hysteresis model. Objective: This study aims to propose a method for calculating the static hysteresis loops of grainoriented silicon steel sheets so as to improve the accuracy of the static and dynamic hysteresis model. Methods: The parameters n0 and V0 in the magnetic field strength expression of the excess loss are determined by the measured losses within the range of 0-100Hz. Subsequently, the dynamic components in the quasi-static hysteresis loops are eliminated. Furthermore, a dynamic hysteresis model is established based on the loss and field separation theory, which incorporates the inverse Preisach model. Results: The dynamic hysteresis loops of the grain-oriented silicon steel sheets are measured in the range of 8-250Hz and compared with the results of both the improved model and the original model. Conclusion: Experimental results demonstrate the effectiveness and accuracy of the improved model. The proposed method for calculating static hysteresis loops has universal applicability and is meaningful for accurate simulation and prediction of magnetic properties in soft magnetic materials.

An Improved Preisach Model for Magnetic Hysteresis of Grain-Oriented Silicon Steel under PWM Excitation

In this paper, the Preisach model for magnetic hysteresis of grain-oriented silicon steel under PWM excitation is improved. First, an improved Preisach model for the magnetic hysteresis of grain-oriented silicon steel under PWM excitation is proposed. Second, the experimental platform for grain-oriented silicon steel sheets under PWM excitation is established. Finally, by comparative analysis, it is concluded that the error of the improved model is far less than that of the classical model (the error here refers to the discrepancy between experimental results and theoretical model predictions). The improved model is 1.4% to 9% more accurate than the classical model. A more accurate model can provide more accurate material parameters for the calculation of the magnetic field in the transformer core, which is of great significance to the production and design of the transformer.

A dynamic hysteresis prediction model of grain-oriented silicon steel sheet under AC-DC hybrid magnetization

Firstly, a new method for parameter identification of inverted Preisach model is proposed to simulate static DC-biasing hysteresis behavior of the grain-oriented (GO) silicon steel sheet by using the measured quasi-static concentric hysteresis loops under DC-biasing magnetization. Then, the dynamic magnetic field intensity related to excess loss is improved by considering the nonlinear relationship between the statistical parameter V0 and the AC peaked magnetic flux density, DC magnetic field intensity as well as frequency. Finally, a dynamic hysteresis model in form of field separation is presented to predict asymmetric hysteresis curves under multi-harmonic and DC-biasing hybrid magnetization. The simulated hysteresis curves as well as losses under different AC-DC hybrid magnetizations are compared with the measured ones, which verifies the accuracy and effectiveness of the proposed method.

Investigation and Application of Magnetic Properties of Ultra-Thin Grain-Oriented Silicon Steel Sheets under Multi-Physical Field Coupling

Nowadays, energy shortages and environmental pollution have received a lot of attention, which makes the electrification of transportation systems an inevitable trend. As the core part of an electrical driving system, the electrical machine faces the extreme challenge of keeping high power density and high efficiency output under complex workin g conditions. The development and research of new soft magnetic materials has an important impact to solve the current bottleneck problems of electrical machines. In this paper, the variation trend of magnetic properties of ultra-thin grain-oriented silicon steel electrical steel (GOES) under thermal-mechanical-electric-magnetic fields is studied, and the possibility of its application in motors is explored. The magnetic properties of grain-oriented silicon steel samples under different conditions were measured by the Epstein frame method and self-built multi-physical field device. It is verified that the magnetic properties of grain-oriented silicon steel selected within 30° magnetization deviation angle are better than non-grain-oriented silicon steel. The magnetic properties of the same ultra-thin grain-oriented silicon steel as ordinary non-oriented silicon steel deteriorate with the increase in frequency. Different from conventional non-grain-oriented silicon steel, its magnetic properties will deteriorate with the increase in temperature. Under the stress of 30 Mpa, the magnetic properties of the grain-oriented silicon steel are the best; under the coupling of multiple physical fields, the change trend of magnetic properties of grain-oriented silicon steel is similar to that of single physical field, but the specific quantitative values are different. Furthermore, the application of grain-oriented silicon steel in interior permanent magnet synchronous motor (IPM) for electric vehicles is explored. Through a precise oriented silicon steel motor model, it is proved that the magnetic flux density of stator teeth increases by 2.2%, the electromagnetic torque of motor increases by 2.18%, and the peak efficiency increases by 1% after using grain-oriented silicon steel. In this paper, through the investigation of the characteristics of grain-oriented silicon steel, it is preliminarily verified that grain-oriented silicon steel has a great application prospect in the drive motor (IPM) of electric vehicles, and it is an effective means to break the bottleneck of current motor design.

A Dynamic Model for Prediction of Hysteresis and Loss Property of Soft Material Under Multiple Harmonic Magnetizations

This article presents an improved algorithm for identification of the excess loss statistical parameter to get more accurate prediction of multiple harmonic magnetic hysteresis and loss properties of grain-oriented silicon steel sheets. Magnetic hysteresis characteristics of a specimen are measured on a magnetic measurement platform. Static hysteresis property can be simulated accurately by the Preisach model. The excess loss field expression under multiple harmonic magnetizations is constructed based on an extraction algorithm for the statistical parameters of excess loss. According to the equivalence of loss separation and field separation, a new dynamic model is established. In the case of different multiple harmonic magnetizations, the magnetic hysteresis characteristics obtained by predictions are compared with the test results. Also, the influences of peaked flux density, harmonic order, and harmonic content upon the total iron loss are investigated.

A Simulation Method for Dynamic Hysteresis and Loss Characteristics of GO Silicon Steel Sheet Under Non-Sinusoidal Excitation

The magnetic property measurementfor grain oriented (GO) silicon steel sheet under non-sinusoidal excitations (DC bias and harmonic) were conducted based on the experimental platform. Based on the Preisach model, the static hysteresis and loss properties were accurately simulated. Furthermore, an improved loss model was proposed by adjusting the statistical parameter of abnormal loss, which depends on the characteristic quantities of DC bias or harmonic excitations. The simulated dynamic hysteresis loops and iron losses under different non-sinusoidal conditions were compared with the measured ones, and thus the accuracy and generality of the improved model proposed in this paper were verified. In addition, the influences of the harmonic and DC-biasing quantities upon the total losses is investigated.

Core loss reduction in grain oriented silicon steel sheets by two-sided laser scribing in the presence of a magnetic field

An approach to decrease the core (iron) loss of grain-oriented silicon steel sheets is to reduce the magnetic domain size by using laser irradiation on the surface of the sheets. In this research, after finding the optimal conditions for traditional laser scribing of HIB (high-permeability)-steel sheets, the effect of the two new parameters "two-sided laser-scribing" and "simultaneous application of magnetic field during laser-radiation" on reducing core losses was investigated. By optimizing the variables in the traditional method (laser scribing on one side without the presence of magnetic fields), core losses at 1.7 T and 50 Hz were reduced by 9.7%. Laser treatment of both sides resulted in a decrease of core loss of 13.7%. Applying a magnetic field during laser scribing could have a positive or negative effect on core losses, depending on the direction of the magnetic field. In the optimum conditions, with double-sided laser scribing of HIB-sheets in the presence of a magnetic field, core losses were reduced by 16.8%. This is a significant result compared to the 9.7% of the traditional method.

Study of Transformer Core Vibration and Noise Generation Mechanism Induced by Magnetostriction of Grain-Oriented Silicon Steel Sheet

The problem of vibration and noise in the iron core of power transformers remains quite topical. Insofar as the state-of-the-art iron core and binding production adopt the lamination method and weft-free adhesive tape, respectively, the transformer core vibration is mainly attributed to the silicon steel sheet (SSS) magnetostriction. In this paper, based on the magnetostriction of grain-oriented SSS, an in-depth analysis of the vibration generation mechanism in the transformer core was performed. The SSS microstructure was observed, its magnetostrictive properties at different magnetic flux densities were tested, and a core-simulating four-corner iron core model was constructed to analyze the vibration characteristics. Modal, vibration, and noise tests were performed on an actual 110 kV transformer core under no-load conditions. The results show that the core vibration is related to SSS’s deformation mechanism. The vibration magnitude in different core parts varies due to the magnetostriction anisotropy. The vibration in vertical to the core plane is the largest, and its magnitude in the core center is lower than those at the seams in the same plane. The core vibration and noise exhibit a significant correlation, while modal characteristics strongly influence the core vibration and noise intensity.

A Dynamic Hysteresis Model for Loss Estimation of GO Silicon Steel Under DC-Biased Magnetization

A new algorithm for numerical identification of the static Preisach hysteresis model is proposed for more accurate estimation of dc-biasing hysteresis curves and hysteresis loss of the grain-oriented silicon steel sheet. Based on the experimental asymmetric major hysteresis loop under dc-biased magnetization, two sets of first-order reversal curves corresponding to ascending and descending branches, respectively, are numerically generated for construction of the Everett function. According to the equivalent field separation technique, a dynamic hysteresis model is established by parameter extraction of excess loss, and then used for simulation of dc-biasing dynamic hysteretic behaviors. The consistency between the simulated results and the measured ones demonstrates the effectiveness of the proposed method. The effect of dc bias on iron loss is analyzed as well.

Comparison of Precipitates and Texture Evolution in Nb-Bearing Grain-Oriented Silicon Steel Produced by Conventional Processing and Novel Twin-Roll Casting

The Nb-bearing grain-oriented silicon steel sheets were produced by conventional route and novel twin-roll casting route, respectively. The microstructure, texture and precipitate evolution were comparatively investigated by using electron backscattered diffraction (EBSD) and transmission electron microscope (TEM). The findings revealed that the precipitation behavior and the texture evolution were totally different between the two processing routes. In the conventional route, a great number of nanoscale niobium nitride particles (NbN), which acted as mainly grain growth inhibitors were precipitated during hot rolling, while in the twin-roll casting route, due to the rapid solidification, the precipitation of NbN were suppressed and a new type Nb-bearing precipitate enriched with sulfur element was observed in the as-cast strip. Besides, the primary recrystallized texture of conventional specimens was characterized by strong γ-fiber with a peak at {111} <110>, together with very few Goss components. While in the case of twin-roll casting specimens, the strongest primary recrystallized texture was {111} <112> texture and the area fraction of Goss component was much higher than that of conventional specimens. After final high temperature annealing, complete secondary recrystallization was obtained in twin-roll casting specimens and the magnetic induction of B8 was 0.1 T higher than that of conventional specimens.

Calculation and validation of stray‐field loss in magnetic and non‐magnetic components under harmonic magnetizations based on TEAM Problem 21

On the basis of the TEAM problem 21 benchmark model, a modelling method to predict stray-field loss under real working conditions is presented and validated to investigate the influence of harmonic excitation on stray-field loss of shielding structural components of converter transformers in high-voltage direct current systematically. An improved method is adapted to determine stray-field loss of magnetic and non-magnetic component based on the experimental measurement and numerical simulation. An experimental platform is established to measure magnetic properties and loss characteristics of the grain-oriented silicon steel sheets, aiming at parameter identification and verification of the loss modelling applicable for laminated sheets under harmonic magnetisation. Meanwhile, the additional iron loss caused by perpendicular flux penetration is obtained by special treatment of material properties and analysed to observe its contribution to the stray-field loss under three-dimensional harmonic magnetisation. Field and loss comparison between measurement and simulation verifies the validation of the proposed modelling method.

Effect of heating rate of final annealing stage on secondary recrystallization in grain-oriented silicon steel

A grain-oriented silicon steel sheet was manufactured by slab reheated at “medium temperature” and two-stage cold rolling method. The function of heating rate on secondary recrystallization in grain-oriented silicon steel was investigated. The results show that: compared with 30 °C/h heating rate, the initial temperature of the secondary recrystallization can increase by 10 °C at the heating rate of 20 °C/h. Furthermore, the temperature region of secondary recrystallization also extended either with the increased heating rate. Even though the inhibitors maintain AlN, complex precipitation of AlN and sulphide in both heating rate, the average diameter and Zener factor of inhibitors are distinct. Inhibitors in the route of 20 °C/h heating rate express stronger inhibition than that of 30 °C/h, and the average diameter and Zener factor are 17.519 nm and 3.925 × 10−4 nm−1, respectively. In addition, more Goss texture component and less γ-fiber texture ({111}//ND) component form at the heating rate of 30 °C/h than 20 °C/h at 1000 °C, but the final Goss texture component of 20 °C/h is greater than 30 °C/h. The average grain size of the final annealing sheets increased with the heating rate decreasing from 30 °C/h to 20 °C/h, and iron loss reduced by 0.05 W/Kg, the magnetic induction intensity increased by 0.025 T.

Experimental and Numerical Study on Stray Loss in Laminated Magnetic Shielding Under 3-D AC-DC Hybrid Excitations for HVDC Transformers

To investigate the stray loss in magnetic shielding components immersed in the 3-D AC-DC hybrid leakage magnetic field, a modified method is presented with the variation of the eddy current loss inside the coil due to the change of the leakage magnetic field taken into account. In addition, a new loss separation model is proposed to estimate the standard iron loss of the grain-oriented (GO) silicon steel sheet under AC-DC hybrid excitations. Furthermore, the material properties were appropriately treated based on the simplified model of laminated magnetic shielding for efficient numerical calculation. The comparison of field distribution and loss results obtained by experiment and calculation respectively was made, which shows good consistency and thus verifies the effectiveness of the proposed method in this paper. Meanwhile, the stray loss and additional loss in magnetic shielding are analyzed in detail to evaluate the potential threat of AC-DC hybrid excitations on the local overheating of the structural parts in HVDC transformers.

Dependence of recrystallization behavior on initial Goss orientation in ultra-thin grain-oriented silicon steels

Based on cold rolling and primary recrystallization method, 0.05–0.15 mm-thick ultra-thin grain-oriented silicon steel sheets were successfully produced by utilizing the high induction (Hi-B) and common grain-oriented (CGO) silicon steels as raw materials, respectively. Thus, the effects of sharpness of initial Goss texture on the evolutions of microstructure, texture and magnetic property were investigated in detail. For Hi-B steel, ‘smooth’ microstructures were formed in the cold-rolled sheets, and the textures evolved along the following path: exact {1 1 0}〈0 0 1〉 → {2 3 0}〈0 0 1〉 → {1 1 1}〈1 1 2〉. By contrast, significant deformation bands or shear bands were observed in the CGO steel, and the textures developed along the following path: deviated {1 1 0}〈0 0 1〉 → {2 1 0}〈0 0 1〉 → {1 1 1}〈1 1 2〉. After annealing, inhomogeneous microstructures containing some clusters with large grains (∼2–4 mm) and fine equiaxed grains appeared in the Hi-B steel and the associated texture evolution with increasing cold rolling reduction followed the path: {1 1 0}〈0 0 1〉 → {2 3 0}〈0 0 1〉 → {2 1 0}〈0 0 1〉. Unlike the Hi-B steel, relatively fine and uniform equiaxed recrystallization grains were produced in the final CGO steel, and the texture evolved along the route: {2 1 0}〈0 0 1〉 → {6 1 0}〈0 0 1〉. Consequently, further research focusing on the recrystallization mechanism was studied. The results showed that {1 1 0}〈0 0 1〉 and {2 1 0}〈0 0 1〉 developed into the predominated components due to oriented growth and oriented nucleation respectively in the 0.05 mm-thick Hi-B sheet, while {1 0 0}〈0 0 1〉 became the main texture with the aid of oriented nucleation advantage in the CGO sheet. In addition, more attention was paid on the magnetic properties of the ultra-thin sheets, and the results showed that heavy cold rolling reduction as well as low annealing temperature contributed to better magnetic induction. Furthermore, the separated iron loss components were obtained to clarify the relationships between the iron loss and grain size, texture and thickness.

Magnetostrictive Properties of the Grain-Oriented Silicon Steel Sheet under DC-Biased and Multisinusoidal Magnetizations

As an intrinsic property, elasticity of soft material is affected significantly by the externally applied alternating magnetic field. Magnetostrictive properties of the grain-oriented (GO) silicon steel under DC-biased and multisinusoidal magnetizations are measured by using a laser-based measuring system. Magnetostriction curves of the GO silicon steel sheet under different magnetizations are obtained and the influence of frequency and DC bias on the magnetostrictive property is observed and analyzed based on the measured data. In addition, the spectrum of magnetostriction under harmonic magnetization is obtained, and the acoustic noise level of the GO silicon steel sheet represented by the A-weighted decibel value caused by magnetostriction is measured under DC-biased and multisinusoidal magnetizations. The measurement results are applied to the simulation of the three-limb laminated core model, and the effects of DC bias and harmonics on magnetic flux density and displacement are analyzed.

Measurement and modeling of hysteresis characteristics in ferromagnetic materials under DC magnetizations

The static hysteresis characteristics of soft magnetic materials were measured by the static performance testing system (SPTS). With a toroidal-shape specimen and Epstein frame, the DC magnetizations of different forms of magnetic steel sheet and grain-oriented (GO) silicon steel sheet can be realized by setting a DC excitation. Besides, the corresponding first-order reversal curves (FORCs), higher-order reversal curves (HORCs) and concentric hysteresis loop are measured. Based on the measured FORCs, the parameter identification was carried out, and the Everett function was established. Thus the inverse Preisach model was obtained. The consistency between the simulated results and the measured ones verifies the validity of the measurement method and the accuracy of the numerical simulation method of magnetic hysteresis characteristics.

Ultra-thin grain-oriented silicon steel sheet fabricated by a novel way: Twin-roll strip casting and two-stage cold rolling

0.05–0.15 mm-thick ultra-thin grain-oriented silicon steel sheets were successfully produced by a novel processing route including strip casting, hot rolling, normalizing, two-stage cold rolling with intermediate annealing, primary recrystallization annealing and secondary recrystallization annealing. The evolutions of microstructure, texture and inhibitor along the processing were briefly investigated. The results showed that the initial Goss orientation originated due to the heterogenous nucleation of δ-ferrite grains during solidification. Because of the lack of shear deformation, only a few Goss grains were observed in the hot rolled sheet. After the first cold rolling and intermediate annealing, Goss texture was enhanced and distributed in the whole thickness. A small number of Goss grains having a high fraction of high energy boundaries exhibited in the primary recrystallization annealed sheet. A large number of fine and dispersed MnS and AlN and a few co-precipitates MnS and AlN with the size range of 10–70 nm were also observed. Interestingly, a well-developed secondary recrystallization microstructure characterized by 10–60 mm grains and a sharp Goss texture were finally produced in the 0.05–0.15 mm-thick ultra-thin sheets. A magnetic induction B8 of 1.72–1.84 T was obtained. Another new finding was that a few {2 3 0}〈0 0 1〉 and {2 1 0}〈1 2 7〉 grains also can grow up abnormally because of the high fraction of high energy boundaries and the size and number advantage, respectively. These non-Goss grains finally deteriorated the magnetic properties of the ultra-thin sheets. In addition, low surface energies of {hk0} planes may also contribute to the abnormal growth of Goss, {2 3 0}〈0 0 1〉 and {2 1 0}〈1 2 7〉 grains.

Characterizing Grain-Oriented Silicon Steel Sheet Using Automated High-Resolution Laue X-ray Diffraction

Controlling texture in grain-oriented (GO) silicon steel sheet is critical for optimization of its magnetization performance. A new automated laboratory system, based on X-ray Laue diffraction, is introduced as a rapid method for large scale grain orientation mapping and texture measurement in these materials. Wide area grain orientation maps are demonstrated for both macroetched and coated GO steel sheets. The large secondary grains contain uniform lattice rotations, the origins of which are discussed.