Magnetic circuit

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

Analytical Modeling of the Open-Circuit Magnetic Field in Axial Flux Permanent-Magnet Machines With Semi-Closed Slots

Abstract: This paper presents a multi-slice analytical model for prediction of the open-circuit magnetic field in slotted semi-closed permanent-magnet axial flux synchronous machines. The technique is based on 2-D exact solution of the Maxwell's equations using the separation of variables method. The magnetic field expressions are developed in slots regions, slot opening regions, magnetic air gap regions, and permanent magnet regions leading to an exact calculation of the slot effects on the air gap magnetic field. The model is established considering that ferromagnetic parts are infinitely permeable, and end effects at inner and outer radii are neglected. The open circuit machine's global quantities (electromotive force and cogging torque) are then deduced from the local magnetic field expressions. Finally, the accuracy of the presented analytical model is validated by comparing its results to corresponding finite-element analyses for two different axial flux machines.

Passive magnetorheological fluid device with excursion dependent characteristic

Abstract: A magnetorheological fluid device which exhibits excursion (stroke or rotation) dependent resistance (force or torque) which is obtained passively. Linear and rotary embodiments are described. The devices described herein include various ways for passively varying magnetic circuit reluctance to accomplish the stroke or rotation dependent characteristic. The devices include a first component with an internal cavity, a second component received in the cavity and moveable relative to the first component, a working zone created between the first and second component, a magnetorheological fluid contained therein, at least one permanent magnet for producing a magnetic field, a magnetic circuit for directing a magnetic flux created by the permanent magnet toward the magnetorheological fluid in the working zone, and passively varying a magnetic circuit reluctance (such as by changing a thickness of a magnetic return, by changing a gap thickness, by changing the material reluctance, by interacting multiple magnetic fields, or combinations thereof) as a function of excursion. This changes the magnetic field strength acting upon the MR fluid in the working zone and produces a force/torque which varies as a function of excursion (x or θ).

Iron and Magnet Losses and Torque Calculation of Interior Permanent Magnet Synchronous Machines Using Magnetic Equivalent Circuit

Abstract: We present a faster and simpler approach for the calculation of iron and magnet losses and torque of an interior permanent-magnet synchronous machine (IPMSM) than finite-element methods (FEM). It uses a magnetic equivalent circuit (MEC) based on large elements and takes into account magnetic saturation and magnet eddy currents. The machine is represented by nonlinear and constant reluctance elements and flux sources. Solution of the nonlinear magnetic circuit is obtained by an iterative method. The results allow the calculation of losses and torque of the machine. Due to the approximations used in the formulation of the MEC, this method is less accurate but faster than nonlinear transient magnetic FEM, and is more useful for the comparison of different machine designs during design optimization.

A new miniature magnetic field probe for measuring three-dimensional fields in planar high-frequency circuits

Abstract: A new noncontacting miniature magnetic field probe for measuring the surface current distribution on high-frequency planar circuits in x-, y-, z-directions in the 1-20 GHz band has been designed, fabricated and tested. The field probes have very small dimensions and do not need any connection to the operating circuit under test, therefore there is almost no perturbation of the circuit properties. This simple and practical magnetic field probes can be used to assist the design of microwave circuits, antenna diagnostics and to test products in industry. This paper describes the production procedure of the magnetic field probes, a scanning diagnostic system, measurement examples and comparisons between measurements and calculations. The measurement results agree very well with theoretically expected field distributions.

Magnetic film inductors for radio frequency applications

Abstract: Responding to the increasing demand for miniaturization and circuit integration of rf inductors we analyze various aspects of designing planar inductive circuits based on magnetic films as well as demonstrate substantially enhanced inductance characteristics for some prototype structures.