Analytical and FEM Based Calculation of Electromagnetic Forces Exerted on Cylindrical Coils due to their own Current
Keywords:
Analytical method, cylindrical coil, electromagnetic force distribution, FEMAbstract
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 the coil in two axial ends are exposed to the largest axial tension, while radial stresses are largest in the middle parts of the coil. In this paper, the calculations focus on the cylindrical coils; however, the method can be used for the calculation of the magnetic force distribution on different parts of spiral coils, disc coils and any type of air-cored coils with different sizes.
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