• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.9
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• pp.1334-1340
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• 2001

In this paper, the experimental modeling of the force between permanent magnet and iron-core solenoid is suggested for more accurate control of 3 D.O.F. motor using the electromagnetic force. In the case of iron-core solenoid, the general equation of solenoid cant be used simply because of its nonlinearity. Therefore, the magnetic flux density is estimated through the concept of equivalent permanent magnet. The force distribution between permanent magnet and iron-core solenoid is more dependent on the magnetization of iron core caused by the permanent magnet than any other parameters. Therefore, the equation of the force estimation between these magnetic systems can be modeled by the experimental function of the magnetization of iron core. Especially, if the distance between iron-core solenoid and permanent magnet is far enough, the force equation through experiment can be expressed from only the current of coil and the distance between iron-core solenoid and permanent magnet. It means that Coulombs law can be used for magnetic systems and it is validated through the experiment. Therefore, force calibration is performed by the concept of Coulombs law.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.9
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• pp.1341-1349
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• 2001

In this paper, 3 D.O.F. actuator, which has three degrees of freedom in one joint, is proposed. The proposed 3 D.O.F. spherical actuator is composed of the rotor and atator. The upper plate of the stator supports the rotor and five electromagnets are located at the base of the stator. The rotor has two permanent magnets, and each rotational axis of the rotor gimbal system is supported by the bearing. To find out the governing equations for the torque generation, Coulombs law and Lorentz force with respect to magnetism is applied. As the experimental results, if the distance between electromagnet and permanent maget is far enough, the force between these magnets can be expressed from current of coils and z-axial distance. For the purpose of control 3 D.O.F. actuator, PID control law is applied. The experimental results are presented to show the validity of the proposed 3 D.O.F. actuator.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.4
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• pp.226-232
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• 2000

In magnetic systems, distribution of electromagnetic force density causes mechanical deformation, which results in noise and vibration. In this paper, Korteweg-Helmholtzs energy method and equivalent magnetic charge method are employed for comparison of their resulting distributions of force density. The force density from the Korteweg-Helmholtzs method is expresses with two Maxwell stresses on the inside and the outside fo magnetic material respectively. The other is calculated using the magnetic Coulombs law. In the numerical model of an electromagnet, their numerical results are compared. The distributions by the two methods are almost the same. And their total forces are also shown to be the same to the one calculated from the conventional Maxwell stress tensor. But the magnetic charge method is easier and more efficient in numerical calculation.