Magnetic core

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

Experimental Investigation of DC-Bias Related Core Losses in a Boost Inductor

Abstract: Soft magnetic components in electronic systems are often subjected to dc bias-flux conditions. These dc bias conditions result in distorted hysteresis loops, increased core losses, and have been shown to be independent of core material. The physical origin of these increased losses is not well understood and there is no simple model that can predict these losses without extensive measurements. Absence of a widely accepted model coupled with the complete lack of dc loss attributes on core manufacturers' data sheets result in a requirement to empirically determine loss values for specific design applications. These deficiencies have motivated our efforts to investigate dc bias dependent loss phenomenon in a Fe-based Metglas core inductor operating in a dc-dc boost converter. Since dc flux levels in the core are proportional to the controllable converter load currents, this topology is ideal to study dc-related losses. Inductor core B - H hysteresis loop characterization was accomplished as a function of switching frequency, input voltage, and load current operating conditions and parameters. In this paper, the core loss results were presented as a function of the dc bias conditions, and the results showed that the core losses increased with the pre-magnetized (Bde) fields. As a result of our observations, we have proposed a modification to the conventional Steinmetz loss equation to include the effects of dc pre-magnetization flux in the core.

Toroidal electrical transformer and method of producing same

Abstract: A toroidal electrical transformer having a low voltage coil, a high voltage coil and an annular magnetic core is disclosed. The preferred low voltage and high voltage coils are each continuous in substantial part over their length and form an arcuate elongated passage therethrough. The preferred annular magnetic core is wound in place in said arcuate elongated passage substantially from a continuous strip of magnetic material. Various components and sub-assemblies are also disclosed along with various apparatus and methods for producing such toroidal electrical transformer, its components and its sub-assemblies.

Design and Fabrication of a 1-MW High-Temperature Superconductor DC Induction Heater

Abstract: The high-temperature superconductor (HTS) dc induction heater shows great potential in the efficiency increase and heating quality improvement, which has been validated by previous prototypes. Now, Shanghai Jiao Tong University has been developing and fabricating an industrial scale 1-MW HTS dc induction heater in China. The heater is utilized to preheat aluminum billets 446 mm in diameter × 800–1500 mm in length. Two cryocoolers are applied for coil cooling with pluggable sleeve and providing an additional safety margin whose normal operating temperature is 30 K. The magnet consists of a double pancake coils wound by REBa2Cu3O7-δ -coated conductors, which are produced by Shanghai Superconductor Technology Company. More than 12-km HTS tapes are used and the inductance of coil with iron is 98 H. The HTS magnet's critical current is 213 A. The 0.5-T dc magnetic field is set up in the two air gaps of HTS magnet with an iron core. The adjustable iron yoke distribution along the axial direction of billets can meet the 100 °C adjustable temperature gradient design requirement. The results will be helpful to design for the commercialization of the HTS dc induction heater.

Design of High Efficiency Integrated Voltage Regulators with Embedded Magnetic Core Inductors

Abstract: Integrated voltage regulators (IVRs) are one of the main trends in power delivery networks (PDNs) for electronic systems. A major challenge in the IVR design is to achieve sufficient integration / minimization of the required passive components of the IVR while still maintaining high power efficiency. This paper demonstrates that a buck converter type IVR designed with package embedded magnetic core inductors can achieve a very high efficiency with a substantially reduced area requirement compared to "air core" inductors. For the final design, an analytical evaluation shows 91% power efficiency for a 1.7V:1.05V conversion. Moreover, a stacked topology of the power stage allows a direct 5V:1V conversion at 79.4% efficiency eliminating the need for a separate off-package voltage regulator.

On-Load Analysis of Saturated Surface Permanent Magnet Machines Using Conformal Mapping and Magnetic Equivalent Circuits

Abstract: This paper presents an iterative method based on conformal mapping and magnetic equivalent circuits for on-load analysis of saturated surface permanent magnet machines with integer slot and fractional slot windings. Magnetic saturation is taken into account by defining additional point wires in the stator slots and interpolar region between the magnets. The added point wires create magnetomotive force equal to the magnetic voltage drops across iron core flux tubes that are calculated using magnetic equivalent circuit. An improved stator tooth model has been introduced that enables more accurate field calculations for tooth geometries with highly saturated tooth tips. The model also takes into account variation of permanent magnet magnetization due to external magnetic field. The proposed method has been implemented on a saturated 12 slot, 10 pole surface permanent magnet machine with nonoverlapping concentrated winding and shows a very good agreement with finite element calculations in terms of flux density, back electromotive force, and torque waveforms as well as $d$ - and $q$ -axis inductances, cross-saturation inductance, and permanent magnet flux linkage in both axes.