High Induction Loss Research Articles

Energy Losses in Composite Materials Based on Two Ferromagnets

We focused on the low and high induction loss separation in soft magnetic composites (SMC), which determine the regions of different predominant magnetization processes. These are the low induction losses which are related to domain wall displacements and the high induction losses related to magnetization vector rotation, domain wall annihilation, and nucleation. The composite samples prepared by replacing of Somaloy 700 (polycrystalline iron powder covered by insulating layer) with Vitrovac 6155 (amorphous co-based alloy) have been investigated. We found out that the porosity remained constant up to 5 wt.% of Vitrovac fraction, which led to slight improvement of magnetic properties of the resulting SMC-the maximum permeability increased and the magnetization process was confirmed to be realized to a greater extent by the processes of domain wall displacement, up to a higher magnetic induction. The higher inner demagnetizing fields caused by higher porosity in sample with 20 wt.% of Vitrovac resulted in lower mobility of domain walls, exhibiting by higher energy losses and lower maximum permeability.

Detection of the Magnetic Easy Direction in Steels Using Induced Magnetic Fields

Conventional manufacturing processes cause plastic deformation that leads to magnetic anisotropy in processed materials. A deeper understanding of materials characterization under rotational magnetization enables engineers to optimize the overall volume, mass, and performance of devices such as electrical machines in industry. Therefore, it is important to find the magnetic easy direction of the magnetic domains in a simple and straightforward manner. The Magnetic easy direction can be obtained through destructive tests such as the Epstein frame method and the Single Sheet Tester by taking measurements in regions of irreversible magnetization usually called domains. In the present work, samples of rolled SAE 1045 steel (formed by perlite and ferrite microstructures) were submitted to induced magnetic fields in the reversibility region of magnetic domains to detect the magnetic easy direction. The magnetic fields were applied to circular samples with different thicknesses and angles varying from 0° to 360° with steps of 45°. A square sample with a fixed thickness was also tested. The results showed that the proposed non-destructive approach is promising to evaluate the magnetic anisotropy in steels independently of the geometry of the sample. The region studied presented low induction losses and was affected by magnetic anisotropy, which did not occur in other works that only took into account regions of high induction losses.

Utilization of lightflecks by seedlings of five dominant tree species of different subtropical forest successional stages under low-light growth conditions

We selected five typical tree species, including one early-successional species (ES) Pinus massoniana Lamb., two mid-successional species (MS) Schima superba Gardn. et Champ. and Castanopsis fissa (Champ. ex Benth.) Rehd. et Wils. and two late-successional species (LS) Cryptocarya concinna Hance. and Acmena acuminatissima (BI.) Merr et Perry., which represent the plants at three successional periods in Dinghushan subtropical forest succession of southern China. Potted seedlings of the five species were grown under 12% of full sunlight for 36 months. The ES and MS showed the slowest and fastest responses to lightflecks, respectively, which correlated with the rate of stomatal opening. In contrast to P. massoniana and C. concinna, the other three species exhibited a high induction loss. Early-successional species showed the lowest specific leaf area and chlorophyll content, the highest photosynthetic capacity (A(max)) and respiratory carbon losses (R(d)). Compared with ES and MS, LS showed lower A(max) and R(d). The five tree species showed a similar chlorophyll a/b ratio after long-term low-light adaptations. On the other hand, LS had a relatively higher de-epoxidation state to protect themselves from excess light during lightflecks. Our results indicated that (i) slower responses to lightflecks could partially explain why ES species could not achieve seedling regeneration in low-light conditions; (ii) fast responses to lightflecks could partially explain why MS species could achieve seedling regeneration in low-light conditions; and (iii) smaller respiratory carbon losses might confer on the LS species a competitive advantage in low-light conditions.

Effect of laser treatment on high and low induction loss components of grain oriented iron-silicon sheets

Power losses of laser scribed GO electrical sheets were measured in the frequency range from 0.05 to 500 Hz and subdivided both into static and eddy current losses, and into low and high induction losses. High induction losses of sheets are increased by laser treatment while low induction losses are increased by a treatment only with very high laser intensity but they are reduced if low laser intensities are used. Low induction losses rise with frequency and high induction losses are nearly constant. Similarly static hysteresis losses are increased by laser scribing while eddy current losses show a similar behavior as low induction losses. It can be concluded that power losses are mainly determined by static losses that increase with defects produced by laser scribing, and the mobility and movement of rigid domain walls while rotation of magnetic moments as well as domain wall annihilation and recreation are having only minor influence.

Hysteresis loss subdivision

Assuming that different energy dissipation mechanisms are at work along hysteresis, a hysteresis loss subdivision procedure has been proposed, using the induction at maximum permeability (around 0.8 T, in electrical steels) as the boundary between the “low-induction” and the “high-induction” regions. This paper reviews the most important results obtained in 10 years of investigation of the effect of microstructure on these components of the hysteresis loss. As maximum induction increases, the “low-induction loss” increases linearly up to 1.2 T, while the “high-induction loss” is zero up to 0.7 T and then increases as a power law with n=5. Low-induction loss behavior is linearly related to H c between 0.4 and 1.2 T. Grain size has a larger influence on low-induction losses than on high-induction losses. Texture has a much stronger influence on high loss than on low-induction loss, and it is related to the average magnetocrystalline energy. 6.5%Si steel shows smaller hysteresis loss at 1.5 T than 3.5%Si steel only because of its smaler high-induction component. The abrupt increase in hysteresis loss due to very small plastic deformation is strongly related to the high-induction loss component. These results are discussed in terms of energy dissipation mechanisms such as domain wall movement, irreversible rotation and domain wall energy dissipation at domain nucleation and annihilation.

Magnetostriction, Barkhausen noise and magnetization processes in E110 grade non-oriented electrical steels

Magnetostriction and Barkhausen noise are investigated in non-oriented electrical steels, with composition FeSi 3.2%, corresponding to the E110 grade produced by ACESITA (Brazil), as a function of both, the magnetic induction level and the angle between the applied magnetic field and the rolling direction. The aim of this study is to understand the magnetization and hysteresis loss processes for this steel, identifying the magnetization mechanism taking place when magnetic field is applied in directions not aligned with the rolling direction, mainly at high magnetic induction levels (above 0.8 T). It is shown that the Barkhausen noise is always present at these high induction levels which can be associated to domain wall motion and to the nucleation and annihilation of 180° and 90° domains as well as to their evolution with the applied field. Thus, it is shown that the origin of the high induction loss in these samples is the motion of domain walls, irrespective to the angle with respect to the rolling direction.

Barkhausen noise and high induction losses in non-oriented electrical steel

Abstract In this work Barkhausen noise of non-oriented electrical steel is investigated. The Barkhausen noise measurements and RMS value were obtained as function of the induction. The results shows that the Barkhausen noise is present in almost all parts of hysteresis loop, including the high induction level. The results obtained are related with the magnetization process and magnetic losses.

Effect of anneal coatings and surface condition on magnetic properties of grain oriented 3% Si - Fe

Reductions in high induction losses were obtained by annealing cold rolled, decarburized 3% Si-Fe samples with an Al 2 O 3 separator coating rather than MgO to obtain the final texture and properties. Reduced coercive force values were associated with the lower losses, and MgO coated samples exhibited subsurface oxide particles, while samples annealed with Al 2 O 3 had smooth surfaces. Similar low losses could be obtained in fully processed grain oriented samples by removing the mill coating by pickling and annealing at 1050°C with an Al 2 O 3 coating. Minimum losses were obtained in high permeability grain oriented samples by applying tension after a high temperature anneal with Al 2 O 3 coating.