Magnetic circuit

About: Magnetic circuit is a research topic. Over the lifetime, 15707 publications have been published within this topic receiving 118099 citations.

Magneto‐Dielectric Properties of Mg–Cu–Co Ferrite Ceramics: II. Electrical, Dielectric, and Magnetic Properties

Abstract: DC resistivity, dielectric, and magnetic properties of Mg-ferrite ceramics (Mg1−xCuxFe1.98O4, with x=0.10–0.30, and Mg0.90−xCoxCu0.10Fe1.98O4, with x=0.05–0.20) were investigated. A primary objective is to develop magneto-dielectric materials with almost equal values of permeability and permittivity, as well as low magnetic and dielectric loss tangent, for miniaturization of antennas. The MgFe1.98O4 ceramic sintered at 1125°C possessed values of permeability and permittivity of ∼6.5, and relatively low magnetic and dielectric loss tangents of <10−2, with a sintered density of only ∼70% of the theoretical density. Incorporation of Cu was found to be able to not only improve the densification and grain growth but also alter the electrical and magnetic properties of MgFe1.98O4. Further modification by Co resulted in promising magneto-dielectric materials, with an almost equal permeability and permittivity of ∼9.5 over 3–30 MHz (HF band). Together with their low magnetic and dielectric loss tangents and good sinterability, this class of magneto-dielectric materials could be potential candidates for the design of small antennas in the HF band (3–30 MHz). The DC resistivities and complex relative permittivities of the ferrite ceramics were discussed with respect to their microstructure, grain size, and the formation of Fe2+ ions. The variation of high-frequency magnetic properties of the ferrite materials with sintering temperature can be quantitatively understood by the magnetic circuit model and the Snoek-like law.

Equivalent Circuit Derivation and Performance Analysis of a Single-Sided Linear Induction Motor Based on the Winding Function Theory

Abstract: A linear metro that is propelled by a single-sided linear induction motor (SLIM) has recently attracted much attention. Compared with the rotating-induction-machine drive system, the SLIM drive has advantages such as direct thrust without needing friction between the wheel and the railway track, small cross-sectional area, lack of gear box, and flexible line choice on account of the greater climbing capability and smaller turning circle. However, due to its cut-open primary magnetic circuit, the SLIM has a longitudinal end effect and half-filled slots on the primary ends, which can reduce the air-gap average flux linkage and thrust. Based on the winding function method, the SLIM is supposed to have the following three groups of windings: 1) primary windings; 2) secondary fundamental windings; and 3) secondary end effect windings. The proposed method considers the actual winding distribution and structure dimensions. It can calculate the mutual, self, and leakage inductance to describe the influence of the longitudinal end effect and half-filled slots. Moreover, a new equivalent model is presented to analyze the different dynamic and steady-state performance. Comprehensive comparisons between simulation and experimental results that were obtained from both one arc induction machine and one linear metro indicate that the proposed model can be applied to predict the SLIM performance and control scheme evaluation.

Computation of 3-D magnetostatic fields using a reduced scalar potential

Abstract: Some improvements to the finite element computation of static magnetic fields in three dimensions using a reduced magnetic scalar potential are presented. Methods are described for obtaining an edge element representation of the rotational part of the magnetic field from a given source current distribution. When the current distribution is not known in advance, a boundary value problem is set up in terms of a current vector potential. An edge element representation of the solution can be directly used in the subsequent magnetostatic calculation. The magnetic field in a DC arc furnace is calculated by first determining the current distribution in terms of a current vector potential. A 3-D problem involving a permanent magnet as well as a coil is solved, and the magnetic field in some points is compared with measurement results. >

A Novel Rotor Configuration and Experimental Verification of Interior PM Synchronous Motor for High-Speed Applications

Abstract: On account of high efficiency and high power density, permanent-magnet synchronous motors (PMSMs) are mainly applied to a high-speed machine. Especially, because of relatively easy magnetic circuit design and control, a surface-mounted PMSM of them is adopted in almost the entire high-speed applications. However, the surface-mounted PMSM has some weak points due to a sleeve, which is nonmagnetic steel used in order to maintain the mechanical integrity of a rotor assembly in high-speed rotation. The sleeve causes additional eddy current loss in the rotor besides permanent magnet and increases not only magnetic air-gap length but manufacturing costs by raw material purchase and shrink fitting. Thus, in this paper, a new rotor shape for a high-speed interior permanent-magnet synchronous motor (IPMSM) is presented in order to resolve the faults of the surface-mounted PMSM. Moreover, the amount of permanent magnet employed in the IPMSM is decreased by approximately 53% than that of the surface-mounted PMSM. Except for the rotor configuration, all design conditions of the IPMSM are identical compared with the surface-mounted PMSM. Finally, the IPMSM is fabricated, and its superiority and reliability in high-speed operation are verified by test.

Analytical calculation of the magnetic field produced by electric power lines

Abstract: The magnetic field produced by electric power lines is usually calculated numerically with the use of a computer However, the analytical calculation of the magnetic field is preferable because it results in a mathematical expression for showing its dependences on the various parameters of the line arrangement A method to derive the analytical formula of the magnetic field vector produced by any power line is developed in this paper The specific formulas for the magnetic field produced by any single circuit line in flat, vertical, or delta arrangement, as well as for hexagonal lines considered as double circuit lines in super bundle or low reactance phase arrangements or as six-phase lines, are given The derived formulas are valid at any point with practical importance, close to or far from the line The development of the method is made possible with the use of new kinds of numbers, named double complex numbers, to represent the magnetic field vector in the vicinity of power lines Double complex numbers remarkably simplify the mathematical expressions for the magnetic field vector Using these numbers, it is observed that the infinite terms of the magnetic field multipole expansion, for flat single circuit lines and for lines exhibiting polygonal symmetry are contracted, resulting in simple formulas for the magnetic field vector, which is used to derive the formulas for the resultant value of the magnetic field The general formula of the magnetic field vector produced by an arbitrary power line is a rational function of the distance from it Through the given expressions for the coefficients of this function numerator and denominator, the formula for the magnetic field vector produced by any power line can be derived