Magnetic core

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

Development of Measuring Equipment of DC-Biased Magnetic Properties Using of Open Type Single Sheet Tester

Abstract: The use of an iron core under dc-biased magnetization generates distorted asymmetrical hysteresis loop, and the iron loss is increased compared with that under sinusoidal excitation. Although the accurate measurement of magnetic properties under dc-biased magnetization is important for the estimation of iron loss of apparatuses, such as a reactor for an inverter which is operated under dc-biased condition, the reports of measurement of such magnetic properties are few. This is mainly because the measuring method of such magnetic properties and the method for accurate evaluation of dc-biased magnetization are not established yet. In this paper, a measuring system of magnetic properties of electrical steel sheet under dc-biased magnetization using an open-type single-sheet tester (SST) and a Helmholtz coil is developed. The newly developed system has an advantage that the interaction between ac and dc excitations is negligible, then the control is easy compared with the usual technique using a ring core or SST having both ac and dc exciting windings. It is shown that the increase of iron loss of 6.5% Si-Fe sheet due to the dc bias is larger than that of usual nonoriented silicon steel sheet

High speed miniature solenoid

Abstract: A high speed solenoid valve that has a housing with an inlet and outlet that are typically connected to a pneumatic system to control the flow of air across the valve. The solenoid has a first magnetic core coaxial with an armature. Wrapped around the first core is a coil that is connected to a source of power. The coil emits a magnetic flux when current flows through the coil. Adjacent to the coil is a second magnetic core that is attached at one end to the first core and spaced from the opposite end of the first core by a first bushing. Attached to the armature is a magnetic plate that is adjacent to the spaced apart ends of the first and second cores. When the coil is energized, the magnetic flux flows through the magnetic cores and plate, pulling the plate toward the cores and moving the armature from a first to a second position. The solenoid valve has a rod that is adjacent to the armature, such that the rod is moved from a first position to a second position by the armature, when the plate is pulled by the magnetic field of the coil. A spring is attached to the rod to push the rod and armature into the first position when the coil is deenergized. The rod has a first spool at one end which is seated on a second bushing, such that the first spool prevents fluid communication between the housing inlet and outlet when the rod is in the first position. When the coil is energized and the rod is moved into the second position, the first spool is unseated from the second bushing to allow air to flow through the valve.

Twisted inductors for low coupling mixed-signal and RF applications

Abstract: Parasitic magnetic coupling is a major design challenge for integrated circuit designers. Fundamentally, it originates in conventional spiral inductors because the magnetic field is not localized, extending far beyond the perimeter. This paper introduces a twisted winding scheme for inductors that increases the localization of the magnetic field, reducing parasitic magnetic coupling by as much as 3100X and the edge-to-edge spacing of inductors by 10X. These results are validated in a 0.18 mum CMOS process.

Integrated magnetic resonant power converter

Abstract: A resonant power converter is disclosed which is constructed on an integrated magnetic core, with primary, secondary and tertiary windings occupying separate legs of the core. The tertiary winding is connected in a resonant circuit and induces a flux in the primary leg that causes the primary winding current to assume the shape of a series of generally sinusoidal pulses. Primary winding switching can thus occur at zero primary current between pulses, thereby eliminating prior interference problems. Furthermore, the converter can be operated in a pulse width modulated mode to accommodate for varying output load levels without the problems of low frequency operation encountered by prior frequency modulated resonant converters.

Magnetic core shell nanoparticles trapping in a microdevice generating high magnetic gradient

Abstract: Magnetic core shell nanoparticles (MCSNPs) 30 nm diameter with a magnetic weight of 10% are usually much too small to be trapped in microfluidic systems using classical external magnets. Here, a simple microchip for efficient MCSNPs trapping and release is presented. It comprises a bed of micrometric iron beads (6–8 μm diameter) packed in a microchannel against a physical restriction and presenting a low dead volume of 0.8 nL. These beads of high magnetic permeability are used to focus magnetic field lines from an external permanent magnet and generate local high magnetic gradients. The nanoparticles magnetic trap has been characterised both by numerical simulations and fluorescent MCSNPs imaging. Numerical simulations have been performed to map both the magnetic flux density and the magnetic force, and showed that MCSNPs are preferentially trapped at the iron bead magnetic poles where the magnetic force is increased by 3 orders of magnitude. The trapping efficiency was experimentally determined using fluorescent MCSNPs for different flow rates, different iron beads and permanent magnet positions. At a flow rate of 100 μL h−1, the nanoparticles trapping/release can be achieved within 20 s with a preconcentration factor of 4000.