Non-oriented Silicon Steel Sheets Research Articles

Manufacturing motor core lamination from thin non-oriented silicon steel sheet direct by pulsed laser cutting using multi-quality optimized process parameters

Manufacturing motor core lamination from thin non-oriented silicon steel sheet direct by pulsed laser cutting using multi-quality optimized process parameters

Accurate asymmetrical minor loops modeling with the modified arctangent hysteresis model

In the area of automotive propulsion, electric motors experience core losses due to the presence of higher harmonic frequencies, particularly those arising from pulse width modulation switching. Consequently, it is required to establish a practical model capable of characterizing the hysteresis loops in electrical steel when subjected to harmonic excitations. Nonetheless, existing dynamic models may be inappropriate for real-world applications due to their inherent complexity and their tendency to neglect the influence of minor loops arising from harmonics. In the present work, the minor and major hysteresis curves of non-oriented silicon steel sheets are measured under variable frequency excitation containing harmonic components. To reproduce the asymmetrical minor hysteresis loops, a modified arctangent model is employed. The evaluation of the accuracy of this hysteresis model is conducted by comparing the fitted results of static and dynamic hysteresis loops against experimental data, both with and without harmonic excitation.

Analysis of Permanent Magnet Linear Synchronous Motor Made by Oriented Silicon Steel Sheet

A novel structure of the permanent magnet linear synchronous motors (PMLSMs) is proposed in this paper, in which oriented silicon steel sheet (OSSS) instead of traditional non-oriented silicon steel sheet (NOSSS) is used as the mover core material. Based on the characteristics of longer tooth magnetic circuit of the PMLSMs with similar number of poles and slots structure, the rolling direction of the OSSS is set to be consistent with the magnetic circuit direction of the teeth, so that the motor can improve the magnetic permeability and anti-saturation ability. The operating condition of OSSS in PMLSMs is derived through thrust formulae and magnetic circuit calculations. The thrust performance and saturation of two PMLSMs with different silicon steel sheets are compared and analyzed by finite element simulation, and related prototypes are produced. The simulation and experimental results show that the use of OSSS as the mover core material can increase the electromagnetic thrust and overload capacity.

Anisotropic Vector Play Model and its Application in Magnetization Analysis

An anisotropic vector play model was developed by the superposition of scalar play models. An analytical identification method was derived for a uniaxially anisotropic term. Computed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BH</i> loops accurately reconstructed the measured anisotropic hysteretic characteristics of non-oriented silicon steel sheet. Its application to magnetization analysis by a physical magnetization model using multi-domain particles enhanced the prediction accuracy of the stress-dependent loss property.

Measurement of alternating and rotational magnetostrictions of Non-oriented silicon steel sheets

Extensive numerical analyses and experimental tests have shown that while major regions of magnetic cores in electromagnetic devices, such as transformers and rotating electric machines, are dominated by the alternating magnetic fields, the rotating magnetic fields exist in the corner joints of multi-phase transformers and the yoke area behind the teeth of rotating electric machines. These magnetic fields cause core losses due to hysteresis and eddy currents, mechanical vibration and acoustic noises due to magnetostriction. Many studies have been reported in the literature on alternating and rotational core losses and alternating magnetostriction, but not so much on rotational magnetostriction, especially in non-oriented (NO) silicon steel sheets. The vibration and noise caused by rotational magnetostriction are much higher than those caused by alternating magnetostriction. This paper reports the development of a magnetostriction measurement system consisting of a 2D symmetrical single sheet tester (SST) and resistance strain gauges. The selection considerations of resistance strain gauges are summarized. The alternating and rotational magnetostriction characteristics of a NO silicon steel, B35A300 (0.35 mm), are measured. Because the rotating magnetic field in the stator is not always ideally circular but more often elliptical, the magnetostriction under elliptical magnetizations with different axis ratios is also measured. The magnetostriction anisotropy of the NO steel sheet is observed and analyzed. The elongation and contraction under alternating, circular and elliptical rotating magnetizations with different axis ratios are discussed. The results can provide data support for calculating and designing multi-phase transformers and rotating electric machines under different types of magnetizations. The research can provide theoretical and practical guidance for mitigating mechanical vibration and acoustic noise caused by magnetostriction.

Parameter identification method of J–A hysteresis model based on improved sparrow search algorithm

Aiming at the weak capacity of the parameter identification methods of Jiles–Atherton (J–A) hysteresis model, such as slow convergence speed and low convergence accuracy, an improved sparrow search algorithm (IM-SSA) is proposed based on mutation crossover operator and T-distribution perturbation strategy in this paper to improve the convergence speed and accuracy of parameter identification method. Firstly, the initial population of the sparrow search algorithm is enriched by Tent chaotic sequence, which expand the search area. Then, the adaptive crossover and mutation operator is introduced into the finders population to enrich the diversity of the finders population and balance the global and local search ability of the algorithm. Secondly, the T-distribution perturbation or differential mutation is used to perturb the population after each iteration according to the individual characteristics, which can avoid the population singularity in the later stage of the algorithm and enhance the ability of jump out of the local optimal value of the algorithm. Finally, the proposed parameter identification method is used to identify the parameters of the J–A hysteresis model, which are used to simulate the magnetic properties of Non-oriented silicon steel sheets with different magnetic induction intensity. The calculation result is compared with the experiment ones. The results proved that the proposed method has faster convergence speed and higher convergence accuracy.

Study on the influence of ultra-thin non-oriented silicon steel sheet on the performance of ultra-high-speed permanent magnet motor

The ultra-high-speed permanent magnet motor has the characteristics of high-power density, small size, and high speed, but there are problems with it, such as generation of local excessive heat and obvious vibration and noise. In order to reduce the loss and improve the efficiency of the motor, in this study, ultra-thin silicon steel sheets are used as the material of the iron core of the motor, and two non-oriented silicon steel sheets with different thicknesses—0.05 and 0.15 mm—were selected. First, we use the Epstein square ring electrical steel sheet magnetic properties test to determine the magnetic properties and the loss properties of the two ultra-thin non-oriented silicon steel sheets under working conditions. Then, we use electromagnetic simulation software to calculate the magnetic performance and the temperature rise performance of two kinds of motors with different materials. Finally, through the test of the prototype, we know the difference in the influence of the two kinds of silicon steel sheets on the performance of air compressors. We hope the outcome of the study will provide technical support for optimizing the design of ultra-high-speed permanent magnet motors for air compressors.

Fabrication of high-performance low silicon non-oriented electrical steels by a new method: Low-finishing-temperature hot rolling combined with batch annealing

The grain size prior to cold rolling plays an important role in the microstructural, textural evolution and magnetic properties of non-oriented silicon steel sheets. In this work, we proposed a new way to obtain large grain size before cold rolling and applied it to a 1.0 wt% Si-0.2 wt% Al non-oriented silicon steel, i.e., appropriate low-finishing-temperature hot rolling combined with batch annealing. The grain growth process during batch annealing was investigated using a quasi in-situ electron backscattered diffraction (EBSD) technique. It was demonstrated that significant grain growth took place through a strain-induced boundary migration mechanism. Then a large number of in-grain shear bands were formed in the cold rolled microstructure and could provide nucleation sites for Goss ({110} 〈001〉 ) and λ-fiber (〈001〉//ND) recrystallized grains, thus resulting in a coarse-grained and homogeneous recrystallization microstructure with weakened γ-fiber (〈111〉//ND) texture, strengthened Goss and λ-fiber texture. Consequently, superior magnetic properties (B50 = 1.763 T, P1.5/50 = 4.30 W/kg) were obtained. For comparison, the conventional processing route without batch annealing was also investigated. A small-grained and inhomogeneous recrystallization microstructure with pronounced γ-fiber texture was produced in the finally annealed sheet, which could significantly deteriorate both the magnetic induction and iron loss. This work provided a new way to enlarge the grains in hot rolled sheets by low temperature batch annealing instead of the conventional high temperature normalization. Thus a new processing route to fabricate low silicon non-oriented electrical steels with high permeability and low iron loss was established.

Alternating and rotational loss prediction accuracy of vector Jiles-Atherton model

In this paper, the vector extension of the Jiles-Atherton hysteresis model is modified to predict both alternating and rotational field strength variations observed in a nonoriented silicon steel sheet. The model parameters are changed to be functions of the magnitude and direction of flux density, and the anhysteretic magnetic characteristics are identified from several unidirectional alternating B(H)measurements. We demonstrate that the modified vector Jiles-Atherton model can predict both alternating and rotational field strength variations with better accuracy than the “basic” approach.

Iron loss evaluation of magnetic materials excited by a SiC inverter with a Schottky barrier diode wall-integrated trench MOSFET

This study examines the impact of the different diode characteristics on the magnetic hysteretic and iron loss properties of a conventional non-oriented (NO) silicon steel sheet core under silicon carbide (SiC) inverter excitation. We compared the magnetic properties of the magnetic core excited by the inverter using the developed Schottky barrier diode (SBD) wall-integrated trench MOSFET (SWITCH–MOS), which has a low on-voltage Von diode, with those excited by the inverter using a conventional U-shaped trench gate MOSFET (UMOS), which has a body PiN diode with high Von. This study shows for the first time that the shape of the minor loop and iron loss properties depends strongly on only the diode characteristics in the inverter. The iron loss of magnetic materials excited by the SWITCH–MOS inverter with the low-Von diode (i.e., the built-in SBD) was less than that in the case of using the conventional UMOS with a high-Von diode (i.e., the body PiN diode). That is, the SWITCH–MOS with built-in SBD can reduce not only the switching loss, but also the iron loss in magnetic materials such as motor cores.

A constraint-based optimization technique for estimating physical parameters of Jiles – Atherton hysteresis model

PurposeImproperly fitted parameters for the Jiles–Atherton (JA) hysteresis model can lead to non-physical hysteresis loops when ferromagnetic materials are simulated. This can be remedied by including a proper physical constraint in the parameter-fitting optimization algorithm. This paper aims to implement the constraint in the meta-heuristic simulated annealing (SA) optimization and Nelder–Mead simplex (NMS) algorithms to find JA model parameters that yield a physical hysteresis loop. The quasi-static B(H)-characteristics of a non-oriented (NO) silicon steel sheet are simulated, using existing measurements from a single sheet tester. Hysteresis loops received from the JA model under modified logistic function and piecewise cubic spline fitted to the average M(H) curve are compared against the measured minor and major hysteresis loops.Design/methodology/approachA physical constraint takes into account the anhysteretic susceptibility at the origin. This helps in the optimization decision-making, whether to accept or reject randomly generated parameters at a given iteration step. A combination of global and local heuristic optimization methods is used to determine the parameters of the JA hysteresis model. First, the SA method is applied and after that the NMS method is used in the process.FindingsThe implementation of a physical constraint improves the robustness of the parameter fitting and leads to more physical hysteresis loops. Modeling the anhysteretic magnetization by a spline fitted to the average of a measured major hysteresis loop provides a significantly better fit with the data than using analytical functions for the purpose. The results show that a modified logistic function can be considered a suitable anhysteretic (analytical) function for the NO silicon steel used in this paper. At high magnitude excitations, the average M(H) curve yields the proper fitting with the measured hysteresis loop. However, the parameters valid for the major hysteresis loop do not produce proper fitting for minor hysteresis loops.Originality/valueThe physical constraint is added in the SA and NMS optimization algorithms. The optimization algorithms are taken from the GNU Scientific Library, which is available from the GNU project. The methods described in this paper can be applied to estimate the physical parameters of the JA hysteresis model, particularly for the unidirectional alternating B(H) characteristics of NO silicon steel.

Representation of anisotropic magnetic characteristic observed in a non-oriented silicon steel sheet

This article presents a modified Jiles–Atherton hysteresis model for a weakly anisotropic non-oriented silicon steel sheet. In a toroidal inductor, the magnetic flux density can point toward any direction compared to the sheet orientation, and the hysteresis model should take this into account. We identify the model parameters independently for unidirectional alternating B(H)-characteristics in seven different directions. Then, we construct an anisotropic hysteresis model, where the model parameters can depend on the magnitude and direction of the applied magnetic flux density. We demonstrate that the parameters identified in the rolling and transverse directions of the silicon steel sheet (M400-50A) are sufficient to describe the hysteresis losses in other directions.

Thrust analysis of permanent magnet linear synchronous motor with oriented silicon steel

Thrust performance is one of the important indexes of permanent magnet linear synchronous motors. The traditional non-oriented silicon steel sheet is used as the core material of the permanent magnet linear synchronous motor, which limits the performance of the permanent magnet linear synchronous motors. For the oriented silicon steel sheet has a higher magnetic permeability in the rolling direction, a permanent magnet linear synchronous motor with similar number of poles and slots made of oriented silicon steel is proposed in this paper. By measuring the B-H curves of the rolling direction and the cutting direction, the thrust properties of the two motors made of traditional silicon steel sheets and oriented silicon steel sheets are analyzed and compared by the finite element method (FEM) under rated load and overload conditions respectively. The thrusts under different tooth-yoke ratios are discussed in the end.

Effect of hot band annealing on inclusions, texture, and magnetic properties of 2.97%Si-0.59% Al non-oriented silicon steel

ABSTRACTEffects of hot band annealing on inclusions, texture and magnetic properties of the 2.97%Si-0.59%Al non-oriented silicon steel sheet with 0.3 mm in thickness were investigated by scanning electron microscope and Electron Backscattered Diffraction (EBSD). With the increase of hot band annealing temperature, the inclusions of 0.1–1 μm in hot band obviously reduced, the area fraction of {100}<110> texture prominently increased during recrystallization of hot band. However, the area fraction of {100}<110> dramatically dropped, and α-fibre texture, {111}<112> significantly developed during grain growth of hot band. The texture of the final sheets was dominated by α*-fibre texture, {001}<130> and γ-fibre texture. Furthermore, increasing of hot band annealing temperature increased the grain size, strengthen θ-fibre texture and weaken γ-fibre texture of the final sheets, resulting in the improvement of the magnetic induction and iron loss.

Research on Stress Characteristics of Shunt Reactor Considering Magnetization and Magnetostrictive Anisotropy

In order to reduce the vibration of shunt reactors with gapped iron-core structure, accurate stress computation should be carried out. The magnetization and magnetostrictive anisotropy should be considered in the calculation. In this paper, the magnetization and magnetostrictive properties of non-oriented silicon steel sheets along the rolling direction and the transverse direction are first measured by a magnetization and magnetostriction tester. Based on the measurement results, an electromagneto–mechanical coupled numerical model for shunt reactors, considering magnetization and magnetostrictive anisotropy, has been developed. Then, the stress distribution of the reactor core is calculated and that between isotropy and anisotropy numerical model is compared. From the computation results, it can be seen that magnetization and magnetostrictive anisotropy greatly influences the stress distribution of the reactor core.

Experimental investigation into the coupling effects of magnetic field, temperature and pressure on electrical resistivity of non-oriented silicon steel sheet

In order to analyze the performance of magnetic device which operate at high temperature and high pressure, such as submersible motor, oil well transformer, the electrical resistivity of non-oriented silicon steel sheets is necessary for precise analysis. But the reports of the examination of the measuring method suitable for high temperature up to 180 °C and high pressure up to 140 MPa are few. In this paper, a measurement system based on four-probe method and Archimedes spiral shape measurement specimens is proposed. The measurement system is suitable for measuring the electrical resistivity of unconventional specimens under high temperature and high pressure and can simultaneously consider the influence of the magnetic field on the electrical resistivity. It can be seen that the electrical resistivity of the non-oriented silicon steel sheets will fluctuate instantaneously when the magnetic field perpendicular to the conductive path of the specimens is loaded or removed. The amplitude and direction of the fluctuation are not constant. Without considering the effects of fluctuations, the electrical resistivity of the non-oriented silicon steel sheets is the same when the magnetic field is loaded or removed. And the influence of temperature on the electrical resistivity of the non-oriented silicon steel sheet is still the greatest even though the temperature and the pressure are coupled together. The measurement results also show that the electrical resistivity varies linearly with temperature, so the temperature coefficient of resistivity is given in the paper.

Effect of non-metallic precipitates and grain size on core loss of non-oriented electrical silicon steels

In the current study, the number density and size of non-metallic precipitates and the size of grains on the core loss of the 50W800 non-oriented electrical silicon steel sheets were investigated. The number density and size of precipitates and grains were statistically analyzed using an automatic scanning electron microscope (ASPEX) and an optical microscope. Hypothesis models were established to reveal the physical feature for the function of grain size and precipitates on the core loss of the steel. Most precipitates in the steel were AlN particles smaller than 1 μm so that were detrimental to the core loss of the steel. These finer AlN particles distributed on the surface of the steel sheet. The relationship between the number density of precipitates (x in number/mm2 steel area) and the core loss (P1.5/50 in W/kg) was regressed as P1.5/50 = 4.150 + 0.002 x. The average grain size was approximately 25–35 μm. The relationship between the core loss and grain size (d in μm) was P1.5/50 = 3.851 + 20.001 d−1 + 60.000 d−2.

Simulation of the stress dependence of hysteresis loss using an energy-based domain model

The assembled domain structure model (ADSM) is a multiscale magnetization model that can be used to simulate the magnetic properties of a core material. This paper reveals the mechanism of the hysteresis loss increase due to compressive stress applied to a silicon steel sheet by conducting a simulation using the ADSM. A simple method of adjusting the simulated hysteresis loss to the measured loss is also proposed. By adjusting the hysteresis loss under a stress-free condition, the stress dependence of the hysteresis loss of a non-oriented silicon steel sheet is quantitatively reconstructed using the ADSM, where the stress-induced anisotropy strengthens the pinning effect along the stress direction.

Modeling of surface layer and strain gradient hardening effects on micro-bending of non-oriented silicon steel sheet

Non-oriented silicon steel, as the key magnetic material of motors, has a general tendency toward thinner and coarser-grained. The characteristic of countable grain number in thickness leads to the so- called size effect. In the 4 point micro-bending experiments, it is observed that the deformation behaviors of non-oriented silicon steel sheet are size-dependent on both feature size (grain size, thickness) and strain gradient. The results show that the decrease of grain number in thickness direction would decrease the flow stress of overall material, but also expand the effect of strain gradient hardening. To address this issue, a hybrid model involving surface layer model with conventional strain gradient plasticity theory is proposed. The relationship between shear stress and dislocation density bridges the plastic strain and plastic strain gradient hardening. The proposed hybrid model is adopted to calculate the analytical solution of normalized bending moment, which agrees well with the experimental data. Moreover, the integrated size effect is further illustrated based on the proposed model. It is conclude that which kind of size effect is dominant would depend on the materials microstructure, geometrical and processing parameters. A three-dimensional (3D) region to determine the necessity of considering strain gradient hardening effect in manufacturing is proposed. This research thus advances the understanding of the size effect from material intrinsic characteristics and processing conditions.

Anisotropic Magnetostriction of Nonoriented Silicon Steel Sheet and Its Frequency Dependence

Non-oriented (NO) silicon steel sheet is widely used as industrial materials in electrical machine, and its magnetostriction is a key factor of causing vibration and noise of a large-scale synchronous machine [1, 2]. There have been some foregoing researches to develop magnetostriction of silicon steel sheet under alternating and rotational magnetic flux density based on a two-dimensional (2-D) magnetic measurement system [3-5], in which the sample was 60mm square, and the three-axis strain gauge was employed to measure the in-plane magnetostriction at arbitrary direction. In this paper, an improved one-dimensional (1-D) magnetostriction tester was built to measure the principal strain along different magnetization directions, and the anisotropic magnetostriction was discussed. The model describing the vector relation between the principal strain and magnetic flux density (B) was established and applied to the finite element (FE) analysis of magnetostriction in stator core of a synchronous machine. The validation of proposed method is verified.