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symmetry_and_boundary_conditions [2024/02/14 22:41]
stanzurek |
symmetry_and_boundary_conditions [2024/02/14 22:53] (current)
stanzurek |
| ^ Comparison of symmetrical models in FEMM, N = number of turns, N/2 = half of turns ^^ | ^ Comparison of symmetrical models in FEMM, N = number of turns, N/2 = half of turns ^^ |
| | {{sym_no_symmetry_-_boundary.png?500}} | Fig. 1. \\ Full model, no symmetry, \\ calculated L = 0.117278 H, \\ By(0,0) = 7.02993e-5 T | | | {{sym_no_symmetry_-_boundary.png?500}} | Fig. 1. \\ Full model, no symmetry, \\ calculated L = 0.117278 H, \\ By(0,0) = 7.02993e-5 T | |
| | {{sym_horiz_symmetry_-_boundary.png?500}} | Fig. 2. \\ Horizontal symmetry, \\ calculated L = 0.05875 H (so L * 2 = 0.1175 H), \\ By(0,0) = 7.04286e-5 T | | | {{sym_horiz_symmetry_-_boundary.png?500}} | Fig. 2. \\ Horizontal symmetry, \\ calculated L = 0.05875 H (so L * 2 = 0.1175 H), \\ By(0,0) = 7.04286e-5 T \\ \\ Full length of one side of the coil is modelled so full number of turns is used (N). Only "half" of the coil is modelled so some output values (such is inductance or force have to be multiplied by 2). | |
| | {{sym_vert_symmetry_-_boundary.png?500}} | Fig. 3. \\ Vertical symmetry, \\ calculated L = 0.0587631 H (so L * 2 = 0.1175262 H), \\ By(0,0) = 7.04353e-5 T | | | {{sym_vert_symmetry_-_boundary.png?500}} | Fig. 3. \\ Vertical symmetry, \\ calculated L = 0.0587631 H (so L * 2 = 0.1175262 H), \\ By(0,0) = 7.04353e-5 T \\ \\ Only half length of the coil is modelled so number of turns has to be reduced by half (N/2). Only "half" of the whole coil is modelled so some output values (such is inductance or force have to be multiplied by 2). | |
| | {{sym_vert_and_horiz_symmetry_-_boundary.png?500}} | Fig. 4. \\ Horizontal and vertical symmetry, \\ calculated L = 0.0294388 H (so L * 4 = 0.1177552), \\ By(0,0) = 7.05736e-5 T | | | {{sym_vert_and_horiz_symmetry_-_boundary.png?500}} | Fig. 4. \\ Horizontal and vertical symmetry, \\ calculated L = 0.0294388 H (so L * 4 = 0.1177552), \\ By(0,0) = 7.05736e-5 T \\ \\ Only half length of the coil is modelled so number of turns has to be reduced by half (N/2). Only quarter of the whole coil is modelled so some output values have to be multiplied by 4. | |
| | {{sym_symmetry_comparison.png?500}} | Fig. 5. \\ Visual comparison of all 4 cases. It should be noted that the actual flux density distribution is the same - as can be judged by the coloured map. The difference in the flux line appearance is only apparent, because the limits of flux change and FEMM scales the plotting of the flux lines differently. \\ \\ The flux density at the central point By(0,0) is identical in all 4 cases, with the difference not exceeding 0.4% resulting only from the changes of the mesh. | | | {{sym_symmetry_comparison.png?500}} | Fig. 5. \\ Visual comparison of all 4 cases. It should be noted that the actual flux density distribution is the same - as can be judged by the coloured map. The difference in the flux line appearance is only apparent, because the limits of flux change and FEMM scales the plotting of the flux lines differently. \\ \\ The flux density at the central point By(0,0) is identical in all 4 cases, with the difference not exceeding 0.4% resulting only from the changes of the mesh. | |
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| | <WRAP download>hdar</WRAP> | | <WRAP center round download 60%> |
| | Download example file: [[http://www.femm.drsz.pl/lib/exe/fetch.php/femm_symmetry.zip|femm_symmetry.zip]] |
| | </WRAP> |
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