Proximity Effect Further Increases Winding Losses
- (a) 6 > d (b) 8 < d
Proximity effect - losses due to eddy current generated by the magnetic field experienced by a particular conductor section but generated by the current flowing in the rest of the winding.
Design methods for minimizing proximity effect losses discussed later.
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Minimum Winding Loss | |
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• Pw = Pdc + Pec ; Pec = eddy current loss. |
Optimum conductor size |
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^ Resistance J • Pw = { Rdc + Rec} [Irms] = Rac [Irms] | |
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• Rac = FR Rdc = [1 + Rec/Rdc] Rdc |
\ / Rec |
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• Minimum winding loss at optimum conductor size. | |
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• Pw = 15 Pdc | |
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• Pec = 05 Pdc |
dopt» d d = conductor diameter or thickness |
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• High frequencies require small conductor sizes minimize loss. | |
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• Pdc kept small by putting may small-size conductors in parallel using Litz wire or thin but wide foil conductors. | |
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Magnetics - 19 WPR - 1/'02 | |
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