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The strong correlation between the level of eddy current losses and the winding geometry shows the necessity to pay attention to the manner of disposition of coils in machine slots. The conductor type, whether it is solid or stranded, also has a crucial influence. Since the transposition of winding strands reduces the degree of skin and proximity effects, it is a recommended solution to reduce eddy current losses. This article suggests an electromagnetic analysis of complex stranded conductors such as Litz and twisted wires. Each conductor is decomposed into individual strands that are twisted or woven in the slot throughout the length of the machine. Combined with several electric circuit relationships that interpret the transposition of the strands, a 2D finite element model is developed in this article so that the copper losses in each strand can be calculated individually.
finite element analysis, eddy currents, twisted wire, Litz wire, switched reluctance machine.
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