Hysteresis Measurements and Numerical Losses Segregation of Additively Manufactured Silicon Steel for 3D Printing Electrical Machines

Samples from FeSi4 powder were fabricated with a low power selective laser melting (SLM) system using a laser re-melting strategy. The sample material was characterized through magnetic measurements. The study showed excellent DC magnetic properties, comparable to commercial and other 3D printed soft ferromagnetic materials from the literature at low (1 T) magnetization. Empirical total core losses were segregated into hysteresis, eddy and excessive losses via the subtraction of finite element method (FEM) simulated eddy current losses and hysteresis losses measured at quasi-static conditions. Hysteresis losses were found to decrease from 3.65 to 0.95 W/kg (1 T, 50 Hz) after the annealing. Both empirical and FEM results confirm considerable eddy currents generated in the printed bulk toroidal sample, which increase dramatically at high material saturation after annealing. These losses could potentially be reduced by using partitioned material internal structure realized by printed airgaps. Similarly, with regard to the samples characterized in this study, the substantially increased core losses induced by material oversaturation due to reduced filling factor may present a challenge in realizing 3D printed electrical machines with comparable performance to established 2D laminated designs.

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Determination of eddy current losses and hysteresis losses in magnetic circuits of electrical machines

Izmeritel`naya Tekhnika ◽

10.32446/0368-1025it.2020-11-54-58 ◽

2020 ◽

pp. 54-58

Author(s):

S. M. Plotnikov

Keyword(s):

Eddy Current ◽

Magnetization Reversal ◽

Eddy Currents ◽

Technical Problem ◽

Electrical Machines ◽

Eddy Current Losses ◽

Hysteresis Losses ◽

Magnetic Circuits ◽

Core Losses ◽

Reversal Frequency

The division of the total core losses in the electrical steel of the magnetic circuit into two components – losses dueto hysteresis and eddy currents – is a serious technical problem, the solution of which will effectively design and construct electrical machines with magnetic circuits having low magnetic losses. In this regard, an important parameter is the exponent α, with which the frequency of magnetization reversal is included in the total losses in steel. Theoretically, this indicator can take values from 1 to 2. Most authors take α equal to 1.3, which corresponds to the special case when the eddy current losses are three times higher than the hysteresis losses. In fact, for modern electrical steels, the opposite is true. To refine the index α, an attempt was made to separate the total core losses on the basis that the hysteresis component is proportional to the first degree of the magnetization reversal frequency, and the eddy current component is proportional to the second degree. In the article, the calculation formulas of these components are obtained, containing the values of the total losses measured in idling experiments at two different frequencies, and the ratio of these frequencies. It is shown that the rational frequency ratio is within 1.2. Presented the graphs and expressions to determine the exponent α depending on the measured no-load losses and the frequency of magnetization reversal.

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Effect of the Temperature on the Magnetic and Energetic Properties of Soft Magnetic Composite Materials

Energies ◽

10.3390/en14154400 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4400

Author(s):

Luca Ferraris ◽

Fausto Franchini ◽

Emir Pošković ◽

Marco Actis Grande ◽

Róbert Bidulský

Keyword(s):

Magnetic Materials ◽

Eddy Currents ◽

Electrical Machines ◽

Soft Magnetic Materials ◽

Magnetic Composite ◽

Soft Magnetic ◽

Soft Magnetic Composite ◽

Magnetic Performance ◽

Magnetic Circuits ◽

Energetic Characterization

In recent years, innovative magnetic materials have been introduced in the field of electrical machines. In the ambit of soft magnetic materials, laminated steels guarantee good robustness and high magnetic performance but, in some high-frequency applications, can be replaced by Soft Magnetic Composite (SMC) materials. SMC materials allow us to reduce the eddy currents and to design innovative 3D magnetic circuits. In general, SMCs are characterized at room temperature, but as electrical machines operate at high temperature (around 100 °C), an investigation analysis of the temperature effect has been carried out on these materials; in particular, three SMC samples with different binder percentages and process parameters have been considered for magnetic and energetic characterization.

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Motion in frequency domain for harmonic balance simulation of electrical machines

COMPEL The International Journal for Computation and Mathematics in Electrical and Electronic Engineering ◽

10.1108/compel-08-2017-0359 ◽

2018 ◽

Vol 37 (4) ◽

pp. 1449-1460

Author(s):

Markus Wick ◽

Sebastian Grabmaier ◽

Matthias Juettner ◽

Wolfgang Rucker

Keyword(s):

Steady State ◽

Frequency Domain ◽

Efficient Method ◽

Harmonic Balance ◽

Eddy Currents ◽

Computational Effort ◽

Electrical Machines ◽

Accurate Approximation ◽

Content Type ◽

Magnetic Devices

Purpose The high computational effort of steady-state simulations limits the optimization of electrical machines. Stationary solvers calculate a fast but less accurate approximation without eddy-currents and hysteresis losses. The harmonic balance approach is known for efficient and accurate simulations of magnetic devices in the frequency domain. But it lacks an efficient method for the motion of the geometry. Design/methodology/approach The high computational effort of steady-state simulations limits the optimization of electrical machines. Stationary solvers calculate a fast but less accurate approximation without eddy-currents and hysteresis losses. The harmonic balance approach is known for efficient and accurate simulations of magnetic devices in the frequency domain. But it lacks an efficient method for the motion of the geometry. Findings The three-phase symmetry reduces the simulated geometry to the sixth part of one pole. The motion transforms to a frequency offset in the angular Fourier series decomposition. The calculation overhead of the Fourier integrals is negligible. The air impedance approximation increases the accuracy and yields a convergence speed of three iterations per decade. Research limitations/implications Only linear materials and two-dimensional geometries are shown for clearness. Researchers are encouraged to adopt recent harmonic balance findings and to evaluate the performance and accuracy of both formulations for larger applications. Practical implications This method offers fast-frequency domain simulations in the optimization process of rotating machines and so an efficient way to treat time-dependent effects such as eddy-currents or voltage-driven coils. Originality/value This paper proposes a new, efficient and accurate method to simulate a rotating machine in the frequency domain.

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Microstructure Characteristics and Strengthening Behavior of Cu-Bearing Non-Oriented Silicon Steel: Conventional Process versus Strip Casting

Metals ◽

10.3390/met11111815 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1815

Author(s):

Feng Fang ◽

Diwen Hou ◽

Zhilei Wang ◽

Shangfeng Che ◽

Yuanxiang Zhang ◽

...

Keyword(s):

Mechanical Properties ◽

Yield Strength ◽

High Speed ◽

Silicon Steel ◽

Strip Casting ◽

Precipitation Strengthening ◽

Conventional Process ◽

Core Losses ◽

The Matrix ◽

Bcc Structure

Based on conventional hot rolling processes and strip casting processes, Cu precipitation strengthening is used to improve the strength of non-oriented silicon steel in order to meet the requirements of high-speed driving motors of electric vehicles. Microstructure evolution was studied, and the effects of Cu precipitates on magnetic and mechanical properties are discussed. Compared with conventional processes, non-oriented silicon steel prepared by strip casting exhibited advantages with regard to microstructure optimization with coarse grain and {100} texture. Two-stage rolling processes were more beneficial for uniform microstructure, coarse grains and improved texture. The high magnetic induction B50 of 1.762 T and low core losses with P1.5/50, P1.0/400 and P1.0/1000 of 1.93, 11.63 and 44.87 W/kg, respectively, were obtained in 0.20 mm sheets in strip casting. Cu precipitates significantly improved yield strength over ~120 MPa without deteriorating magnetic properties both in conventional process and strip casting. In the peak stage aged at 550 °C for 120 min, Cu precipitates retained bcc structure and were coherent with the matrix, and the yield strength of the 0.20 mm sheet was as high as 501 MPa in strip casting. The main mechanism of precipitation strengthening was attributed to coherency strengthening and modulus strengthening. The results indicated that balanced magnetic and mechanical properties can be achieved in thin-gauge non-oriented silicon steel with Cu addition in strip casting.

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Effect of Refined Surface Domains Walls on the Core Losses Components in GO Silicon Steel at Different Frequencies

Acta Physica Polonica A ◽

10.12693/aphyspola.137.896 ◽

2020 ◽

Vol 137 (5) ◽

pp. 896-899

Author(s):

I. Petrshynets ◽

F. Kováč ◽

V. Puchý ◽

J. Füzer ◽

P. Kollár ◽

...

Keyword(s):

Silicon Steel ◽

The Core ◽

Core Losses ◽

Surface Domains

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Consideration of ferromagnetic anisotropy in electrical machines built of segmented silicon steel sheets

IET Science Measurement & Technology ◽

10.1049/iet-smt.2019.0348 ◽

2020 ◽

Vol 14 (3) ◽

pp. 242-249

Author(s):

Fabian Müller ◽

Gregor Bavendiek ◽

Nora Leuning ◽

Benedikt Schauerte ◽

Kay Hameyer

Keyword(s):

Silicon Steel ◽

Electrical Machines ◽

Steel Sheets

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Effect of Annealing on the Magnetic Properties of a Cold Rolled Non-Oriented Grain Electrical Steels

MRS Proceedings ◽

10.1557/proc-1243-9 ◽

2009 ◽

Vol 1243 ◽

Author(s):

N.M. López G. ◽

A. Salinas R.

Keyword(s):

Plastic Deformation ◽

Magnetic Properties ◽

Grain Growth ◽

Annealing Temperature ◽

Cold Work ◽

Rolling Direction ◽

Energy Losses ◽

Hysteresis Losses ◽

Core Losses ◽

Rate Of Recovery

ABSTRACTThe effect of plastic deformation and subsequent annealing on the microstructure and magnetic properties (hysteresis core losses) of non-oriented grain semi-processed Si-Al electrical steel sheet are investigated. Plastic deformation of strip samples is performed by cold-rolling (5–20% reduction in thickness) along the original rolling direction. Annealing is carried out in air during 1 or 60 minutes at temperatures between 650 and 850°C. Measurements of B-H hysteresis curves are performed using a Vibrating Sample Magnetometer and characterization of annealed microstructures is carried out using optical metallography. The results show that hysteresis losses increase by a factor between 1.2 and 2.0 as the magnitude of the applied plastic deformation increases from 5 to 20% reduction in thickness. The rate of recovery of energy losses as a result of annealing depends on annealing time. Short annealing times produce full recovery of the effect of cold work and values of energy losses lower than in undeformed material. The magnitude of the additional recovery increases with strain but does not depend on annealing temperature. Long annealing times, which induce complete recrystallization, and either normal or abnormal grain growth, enhance recovery of hysteresis losses. The rate of recovery increases as both the strain and annealing temperature increase. Recovery of the deformation microstructure and internal stress relief produce only limited recovery of the magnetic properties. However, recrystallization and grain growth brings about a significant decrease in hysteresis losses.

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