Magnetic core

About: Magnetic core is a research topic. Over the lifetime, 30011 publications have been published within this topic receiving 155247 citations.

Thin film magnetic head

Abstract: PURPOSE:To prevent the movement of magnetic domain walls and to obtain a thin film magnetic head, which has a stable output, by obtaining >=one non-magnetic part in an island shape in the middle of a magnetic thin film pattern to constitute a magnetic circuit. CONSTITUTION:A magnetic core 1 is composed of the upper and lower layers of the magnetic thin film patterns to be interposed between a coil 2 and these patterns are connected by a back gap part 3 and further exposed to an external part in a slider floating surface 4. In a gap part 5, the patterns are faced each other with a non- magnetic film to be formed by the alumina film, etc., whose thickness is 0.1-1.0mum around, between. For the magnetic core 1, in order to prevent the lowering of magnetic efficiency in the middle of a way from the gap part 5 toward the back gap part 3, patterning is executed so that the width of the magnetic core can be wide from a place to be separated from the gap part 5 by 10-20mum. Further, in the place where the magnetic core 1 is extended, an island-shaped part 6 of non-magnetism, whose length and width are 2-6mum around, is formed and this island-shaped part 6 is formed simultaneously with the patterning of the magnetic core 1. This non-magnetic island- shaped part 6 prevents the large movement of the magnetic domain walls at the time of head operation and presents the thin film magnetic head to have the stable output.

Three-Level Forward–Flyback Phase-Shift ZVS Converter With Integrated Series-Connected Coupled Inductors

Abstract: In this paper, a novel three-level Forward-Flyback phase-shift converter is proposed for high-input voltage and high-efficiency applications. The primary-side structure of this converter is similar to that of the conventional three-level phase-shift converters, which makes the switch voltage stress only half of the input voltage and the voltage on the capacitor divider autobalanced. There are only two coupled inductors in this converter and each coupled inductors has two windings. The primary windings of the two coupled inductors are in series to achieve buck-type conversion. And their secondary windings operate in the interleaved mode to sustain the large current. The coupled inductors operate in Flyback and Forward modes to enhance the magnetic core utility rate. Furthermore, the two coupled inductors can be integrated into a magnetic core to further improve the power density. In addition, zero-voltage-switching performance of the inner switches at light load condition can be provided because the magnetizing current can be employed to charge and discharge the parallel capacitors. As a result, the switching losses are minimized at a wide load range. A 500 V prototype is tested to verify the advantages of the proposed converter.

Development of micro-fluxgate sensors with electroplated magnetic cores for electronic compass

Abstract: Micromachined electronic compass integrating two-axis micro-fluxgate sensors was investigated. These sensors were perpendicularly aligned to measure the magnitude of X- and Y-axis magnetic fields, respectively and each of them was composed of rectangular-ring shaped magnetic core, solenoid excitation (49 turns), and pick-up (46 turns) coils. Excitation and pick-up coil patterns, which were formed opposite to each other, wound the magnetic core alternately to improve the sensitivity. In order to induce magnetic anisotropy, the magnetic core(Ni0.81Fe0.19 permalloy) was electroplated under the external magnetic field of 2000 G The fabricated core has dc effective permeability of ∼1250 and has the characteristics to be easily saturated due to the low coercive field of ∼0.1 Oe and closed magnetic path for the excitation field. The size of each micro-fluxgate sensor excluding pad region was about 2.6 mm ×1.7 mm. The fabricated two-axis micro-fluxgate sensors have excellent linear response over the range of −100 to +100 μT with 210 V/T sensitivity at the excitation condition of 2.8 VP–P and 1.2 MHz square wave. The power consumption was estimated to be ∼8.5 mW and perming effect was suppressed below 1.7 μT for the magnetic field shock of 60 G.

Steinmetz Equation for Gapped Magnetic Cores

Abstract: This letter presents a derivation of the modified Steinmetz empirical equation for power loss density and power loss in magnetic cores with air gaps. The modified Steinmetz equation relates the core power loss density with the air gap length, magnitude and frequency of the sinusoidal excitation current, and the permeability of the core material. The reluctance model of a representative core structure is used. The expression for the magnetic field density in gapped cores is derived. In addition, the minimum air gap length required to avoid core saturation is determined. The modified Steinmetz equation for power loss is analyzed using the specifications of a practical magnetic core used in high-frequency applications. The effect of the air gap length and the excitation frequency on the core power loss density is discussed.

Soft magnetism material and powder magnetic core

Abstract: A soft magnetic material includes: a plurality of composite magnetic particles formed from a metal magnetic particle and an insulative coating surrounding a surface of the metal magnetic particle and containing metallic salt phosphate and/or oxide; and a lubricant formed as fine particles added at a proportion of at least 0.001 percent by mass and no more than 0.1 percent by mass relative to the plurality of composite magnetic particles. With this structure, superior lubrication is provided during compacting and desired magnetic characteristics can be obtained after compacting.