Magnetic core

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

Magnetic Materials Used in Electrical Machines: A Comparison and Selection Guide for Early Machine Design

Abstract: This article presents an up-to-date magnetic material investigation and overview on soft magnetic materials used in rotating electrical machines. The focus is on small-to-medium-sized high-performance and high-efficiency permanent-magnet and induction motors for different application scenarios. The investigated materials include fully processed silicon-iron (SiFe), nickel-iron (NiFe), and cobalt-iron (CoFe) lamination steels as well as soft magnetic composites (SMCs) and amorphous magnetic materials. This article focuses on the magnetic properties and iron losses as well as the manufacturing influence and required thermal treatments during the manufacturing process. A new loss-to-flux-density factor is introduced to compare the magnetization curve and the iron losses of different materials within the same diagram. This article provides a review and comparison of magnetic substances for use in high-performance machines.

Design considerations for high power high frequency transformers

Abstract: Various design considerations for high-power (multikilowatt), high-frequency transformers for DC-DC power converters are investigated Although Ferrite (PC40) is lossier than Permalloy80 (05 mil) at the frequencies of interest (25-50 kHz) the use of the former is justified on the basis of cost, weight, and wide ranges of shapes The influence of the leakage flux distribution in the window region on the copper losses has been demonstrated for various conventional winding arrangements However, it is seen that in conventionally wound transformers a considerable amount of leakage flux enters the core, resulting in localized core saturation and hot-spots This becomes a very critical issue for high-power, high-frequency transformers Coaxially wound transformers are seen to be a viable alternative, in that the leakage flux is contained with the interwinding space, with very little or none of it permeating the core Such transformers can also realize multiple benefits of a low distributed and controllable leakage inductance, robust construction, low electromechanical forces, and low core and copper losses Test results on two coaxially wound transformers with different tube geometries, designed for 50 kW, 50 kHz, primary voltage of 200 V, and secondary voltage of 1000 V (two windings), are presented Finally the concept of coaxial winding technique for three-phase transformers is also presented >

Charger for hand-held rechargeable electric apparatus with switch for reduced magnetic field

Abstract: A system transfers electric power between two devices using a magnetic coupling and no electrical connections. Each device incorporates a magnetic core surrounded by a coil. When properly aligned the cores form a closed magnetic circuit whereby stray magnetic fluxes are substantially reduced. In the preferred embodiment, a base unit incorporates a substantially `C` shaped magnetic core surrounded by its respective coil. A portable detachable device, such as an electric toothbrush, incorporates a substantially linear shaped magnetic core surrounded by its coil. The linear shaped magnetic core and the portable device are configured to fit within a gap formed in the `C` shaped magnetic core forming a substantially closed magnetic circuit thereby. Stray magnetic fluxes are thus significantly reduced. Additionally, an apparatus deactivates the power to the coil in the base unit when the portable device is removed from the base unit or when the battery within the portable device is charged to a predetermined level.

Isolated Winding-Coupled Bidirectional ZVS Converter With PWM Plus Phase-Shift (PPS) Control Strategy

Abstract: A novel winding-coupled bidirectional dc/dc converter with zero-voltage-switching (ZVS) performance is proposed in this paper. In the low-voltage side, the parallel configuration is employed to share the large current and reduce the current ripple. In the high-voltage side, the series structure is adopted to sustain the high bus voltage and achieve large voltage ratio conversion. There are only two coupled inductors in the proposed interleaved bidirectional converter and their secondary windings are in series to serve as winding-coupled inductors. Furthermore, the two winding-coupled inductors can be integrated into a magnetic core to reduce the passive component numbers and improve the power density. Moreover, ZVS soft-switching operation is implemented for all the power switches to minimize the switching losses by introducing the active clamp scheme. In addition, the pulsewidth modulation plus phase-shift control strategy is employed to reduce the power MOSFET peak current and diminish the circulating losses. The duty cycle is applied to balance the voltages of both sides. The phase-shift angle is introduced to realize the power flow regulation. This decoupling control strategy is advantageous for bidirectional dc/dc conversion to realize high efficiency. Finally, a 1-kW prototype is built to verify the effectiveness of the proposed circuit.

Multi-layer transformer apparatus and method

Abstract: A multi-layer transformer includes a plurality of tapes having a magnetic core area disposed on at least one of the layers forming a magnetic core of the transformer. A primary winding is disposed on at least one of the layers. A secondary winding is disposed on at least one of the layers. A thin layer made of a lower permeability dielectric material is disposed proximate at least one of the windings. A first plurality of interconnecting vias connect the primary winding between the tapes. A second plurality of interconnecting vias connect the secondary winding between the tapes. Magnetic flux is induced to primarily flow into the core area. Magnetic coupling and dielectric breakdown between the windings are improved. A lower cost and smaller sized transformer can be obtained.