On the estimate of eddy current losses in current carrying conductors

It is shown that ohmic losses in current carrying conductors at nonzero frequency can be decomposed into two parts. One part is due to a current distribution that would have existed within the conductor at zero frequency (dc current distribution). The other is due to excess current distribution defined to be the difference of the actual current distribution at nonzero frequency and the dc current distribution. An integral equation for the computation of excess current distribution is derived and an easily computable upper bound on the excess losses is found. This upper bound is used to estimate the total eddy current losses and the accuracy of this estimate is tested for long wires of circular cross section. This estimate is shown to be accurate if the wire radius is about the same or smaller than the skin depth. (C) 2000 American Institute of Physics. [S0021- 8979(00)91108-3].