A Perturbative Method for Calculating the Impedance of Coils on Laminated Ferromagnetic Cores (original) (raw)
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A method is presented to determine the magnetic reluctance of a thin or a thick magnetic layer of permeability underneath a planar coil based on inductance measurements. The procedure is substantiated on the basis of the linear electromagnetic network model. The influence of the involved magnetic reluctances on the inductance is analyzed by a transformation into the electrical domain applying linear network theory. From inductance measurements the individual contributing inductances can be calculated and from the back transformation into the magnetic domain the reluctances and further parameters, such as the magnetic field strength for a given electrical current or the permeability. Analytical results are compared with FEM simulations and with measurements obtained from a magnetostrictive bending sensor.
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2012
─ Different parts of the cylindrical coils are exposed to electromagnetic forces due to electric current flowing through it. These forces can deform the coil in axial and radial directions in abnormal operating conditions. So, in design process of cylindrical coils in many magnetic devices, mechanical stresses exerted on different parts of these kinds of coils should be determined. In this paper, analytical expressions for the forces in axial direction are derived in order to calculate the forces exerted on different parts of the cylindrical coils. In order to evaluate the precision of the method, the finite element method (FEM) is used and the results obtained by FEM are compared with the results of the analytical equations. Results obtained by finite element analysis confirm the analytical method. Due to inherent difficulties in calculation of the forces in radial direction, distribution of the latter on the coil body is calculated by FEM. The results show that the outer turns of ...
Inductance of cylindrical coil
Serbian Journal of Electrical Engineering, 2004
The cylindrical coreless and bar core coils are used in instrument transformers and many other electromagnetic devices. In the paper, using the separation of variables an analytical formula for the leakage inductance of thin cylindrical coil with unsaturated core is deduced, assuming a simplified path for the frontal flux. The results are compared with well-known experimental data and data resulting from FEM models.