Maximum Core Loss Research Articles

Effect of iron particle size and volume fraction on the magnetic properties of Fe/silicate glass soft magnetic composites

Abstract Fe/silicate glass soft magnetic composites (SMC) were fabricated by powder metallurgy with 1000 MPa pressure at room temperature, and then annealed at 700 °C for 90 min. The iron particles distributed uniformly in the composites, and have been separated from each other by a continuous silicate glass insulating layer. Fe/glass interface was well bonded and a quasi-continuous layer Fe3O4 and FeO exited. Very fine crystalline phases Na12Ca3Fe2(Si6O18)2 were formed in silicate glass. Composite containing 57 vol% 75 μm iron particles demonstrated highest resistivity of 7.8×10−3 Ω m. The μm, Bs and Bt increased while Hc of Fe/silicate glass composites decreased with the increase of average size of iron particles. The composite with highest amount (82 vol%) and largest average size (140 μm) of iron particles demonstrated best μm, Bs and Bt and Hc, which were 622, 1.57 T, 1.43 T, 278 A/m, respectively. The composite containing 57 vol% 75 μm iron particles demonstrated minimum core loss of 3.5 W/kg at 50 Hz and 28.1 W/kg at 400 Hz, while the composite containing 82 vol% 140 μm iron particles exhibited maximum core loss of 5.2 W/kg at 50 Hz and 67.7 W/kg at 400 Hz.

Rotational Magnetization in Transformer Cores—A Review

Usually, rotational magnetization (RM) is associated with rotating machine cores. However, in more restricted ways, it also arises in three-phase transformer cores. Modern designs of T-joint yield detours of flux, as a source of RM in the T-joint, the middle limb ends, as well as in the yokes. Simulation of RM is possible by means of so-called rotational single sheet testers which should consider the large grains of highly grain oriented materials. Their high effective anisotropy yields induction patterns of rhombic or lancet-like type with maximum values of axis ratio a up to 0.5, and very high angular velocity round the materials hard directions. Compared to elliptic RM-as arising in non-oriented materials-the corresponding losses are lower due to restricted induction in the hard direction. But they show strong increase with (i) rising a and (ii) rising angular velocity of the induction vector. The magnetostrictive strain shows a pronounced (negative) maximum in the rolling direction with values up to 10 ppm, the transverse direction and normal direction exhibiting positive maxima of lower extent. With respect to industrial relevance, significant RM effects are restricted to the vicinities of T-joints. They represent the location of maximum core loss and also of maximum magnetostrictive strain as a source of audible core noise.

Estimation of Core Losses on Electrical Steel Laminations in Wind Generators Using Epstein Frame and Expanded GSE Method

The paper intends to study the core losses of non-oriented electrical steel laminations under high frequency voltage excitations. The measurement of core losses of the electrical steel laminations in Epstein Frame is implemented step by step from 50 Hz to 5000Hz. The accuracy of results evaluated from Expanded GSE method is compared with those tested by Epstein Frame. The core loss database for three different kinds of medium, medium-high and high quality electrical steel laminations (50CS350, 50CS470, 50CS600) is completed in the paper. Also, 85 test points of core loss data are established in the flux density ranging from 0.3T to 1.8T and in the power supply frequency ranging from 50Hz to 5000Hz. Maximum core loss value is close to 443W/kg. The tested core loss data and the Expanded GSE models are useful and may cover for the applications of large-scale wind-driven generators and general motors. They also enough provide designers with the accurate information to minimize the core losses of wind turbine generators.

Low core loss non-oriented silicon steels

Low core loss non-oriented silicon steels are produced with high (Si+Al) content to reduce eddy current losses. However, high alloy content has detrimental effect on mechanical properties, saturation polarization and thermal conductivity. A new generation of medium and, particularly, low core loss non-oriented silicon steels was developed, with lower alloy content than the conventional grades, based on improved purity and texture. The development allowed the production of new low loss grades, with maximum core loss ( W 1.5/50) of 2.30 W/kg at 0.50 mm and 1.95 W/kg at 0.35 mm, with high permeability ( J 50 of 1.7 and 1.72 T, respectively). Texture improvement was based on hot band structure control and higher boundary mobility. Large hot band grain size and low [1 1 0]∥RD fiber fraction in the hot band texture contribute to reduce the intensity of [1 1 1]∥ND and slightly increase the intensity of [0 0 1]∥RD in the final product. Higher grain boundary mobility and/or a two-stage cold rolling process, with an intermediate annealing, increase the fraction of [0 0 1]∥RD and reduce the fraction of [1 1 1]∥ND on recrystallization and lead to favorable texture evolution on grain growth.

Diode laser scribing of non-oriented 3 wt% Si-steel for core loss reduction

The electrical power industries are experiencing a considerable energy loss in transformers and motors because of inefficiencies caused by core loss. The objective of our research is to investigate any effect of laser scribing on the reduction of the core loss in the low cost, non-oriented steels used in numerous utility applications. A 15 W diode laser transmitted through fiber optics was used to scribe 0.35 mm thick, non-oriented 3 wt% Si steel. The magnetic properties including the core loss and permeability were evaluated both before and after laser scribing. A maximum core loss reduction of 0.08 W kg−1 at a magnetic induction of 1 T and a 21% increase in relative permeability were obtained at the optimum laser parameters. These results are comparable to those of laser scribed, expensive grain-oriented steels. The core losses were further reduced using a treatment procedure consisting of laser scribing, chemical etching, and stress relief annealing performed in sequence. The laser scribing method is simpler, energy efficient, and can be implemented in the production line.

Effect of beam dwell time on surface changes during laser scribing

Laser scribing can be used to reduce the ferromagnetic domain size, and thus core loss, in grain-oriented electrical steels. The localized stress required for domain-size control can be produced either by shock deformation, optimally associated with beam dwell times (pulse lengths) less than 2×10−8 sec, or by thermal stressing occurring with dwell times optimally longer than 1×10−4 sec. In this paper we show that comparable core loss improvements can be obtained at greatly different dwell times, but that the associated changes in the surface condition of coated silicon steel laser scribed for maximum core loss reduction vary dramatically as dwell time varies. At the very short times characterizing shock deformation, achieved using a Q-switched solid-state laser, the coating is almost completely removed, but there is little effect on the steel itself, and recoating has been used to restore coating integrity. Under optimum dwell times for thermal expansion effects, achieved using continuous-wave radiation, there is no significant effect on the coating, and no postscribing treatment is required. At intermediate dwell times, however, significant core loss reduction is associated with extensive disruption of the coating and with melting of the steel. At dwell times of approximately 1×10−6 sec using CO2 laser radiation, there is an unstable transition between the shock (vaporization) and heating modes, with intermittent melting.

LOCORE M45

Abstract LOCORE M45 is a cold-rolled, non-oriented electrical steel used primarily for alternating current (AC) and direct current (DC) motors, generators and transformers. It is produced either semiprocessed (the consumer anneals to produce the desired magnetic properties) or fully processed (the steel producer develops the magnetic properties to meet the maximum core loss values). This datasheet provides information on composition, physical properties, microstructure, and elasticity. It also includes information on heat treating and joining. Filing Code: SA-353. Producer or source: Republic Steel Corporation.

LOCORE M43

Abstract LOCORE M43 is a cold-rolled, non-oriented electrical steel used primarily for alternating current (AC) and direct current (DC) motors, generators and transformers. It is produced either semiprocessed (the consumer anneals to produce the desired magnetic properties) or fully processed (the steel producer develops the magnetic properties to meet the maximum core loss values). This datasheet provides information on composition, physical properties, and elasticity. It also includes information on forming, heat treating, machining, and joining. Filing Code: SA-347. Producer or source: Republic Steel Corporation.