Case Studies

Translational 2D Static Problems

• PDF: C-core Actuator
  A simple C-core actuator -- The objectives are to examine the magnetic field in the various parts of the magnetic circuit, and to determine the force on the square armature plate and the self-inductance of the coil.
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• PDF: E-core Actuator
  E-core actuator or electromagnet -- This case study is similar in principle to the C-core Actuator 2D Case Study, but it is a better magnetic design because the coil is nearer to the airgap and both sides of the coil are active. The objectives are to determine the self-inductance of the coil and the force on the armature, and to explore the magnetic field distribution in the device.
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• PDF: Magnetic Latch with Permanent Magnet
  C-core permanent magnet -- This case study is similar in principle to the C-core Actuator 2D Case Study, except that the excitation for the magnetic circuit is provided by a permanent magnet. The objectives are to examine the magnetic field in the various parts of the magnetic circuit, and to determine the force on the square armature plate and the self-inductance of the coil.
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• PDF: Busbar Forces
  This case study examines two long non-magnetic busbars, where the force due to the opposing currents is to be calculated.
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• PDF: Field in a Cylindrical Conductor
  This case study examines the nature of the magnetic field in a cylindrical hole, bored off-center in a long solid cylindrical conductor, so that its axis is displaced from the axis of the cylinder.
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• PDF: Transformer Equivalent Circuit
  This case study examines a conventional shell-type transformer with the secondary wound over the top of the primary. MagNet calculates flux linkages for each coil, so it is possible to determine the values for the reactance in the equivalent circuit.
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Rotational 2D Static Problems

• PDF: Self-Inductance of a Brooks Coil
  Brooks coils have a simple shape, and are close to the optimum of a coil that has the largest inductance for wire of a given length and cross-sectional area. The inductance can be calculated analytically, making this a useful test problem for checking the accuracy of the results produced by MagNet.
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• PDF: Mutual Inductance of Coaxial Coils
  Cross-section of a pair of Brooks coils with a common axis -- Some of the flux produced by one coil will link the other coil, so the coils are magnetically coupled. MagNet calculates flux linkages for each coil, so it is possible to determine the values for the inductance in the equivalent circuit.
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• PDF: Magnetic Pull-off Force
  This case study examines a steel sphere attracted to a cylindrical bar magnet. The objective is to calculate the force required to pull the sphere away from the magnet, and to estimate the accuracy of the force calculation.
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• PDF: Moving-Coil Transducer
  This case study examines structures that may be found in loudspeakers, headphones, vibration generators, moving-coil actuators, and chemical balances. The device is comprised of a permanent magnet that creates a radial magnetic field in the air gap and a solenoidal coil that is free to move in the axial direction.
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Note  These Case Studies are condensed versions of the ones available in the Static2DCaseStudies.pdf document that is part of the MagNet Trial Edition download's documentation package.