Mitigation of Gap Losses in Nanocrystalline Tape-Wound Cores

• Published in: IEEE transactions on power electronics Vol. 34; no. 5; pp. 4656 - 4664
• Main Authors: Calderon-Lopez, Gerardo, Wang, Yiren, Forsyth, Andrew J.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Air gaps; Conductivity; Converters; Core loss; Dependence; Eddy currents; Ferrites; Finite element method; Gap losses; gapped high-frequency inductor; Inductors; Lamination; Magnetic cores; nanocrystalline tape-wound core; Nanocrystals; Tape winding; Weight reduction
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2018.2863665

A split-core technique is proposed to mitigate the gap losses in high-frequency nanocrystalline cores, which enables significant size reductions in thermally limited designs. Finite element analysis is used to examine the gap loss dependence on core width D revealing a nonlinear relationship of the form loss ∝ D α . α is approximately constant for frequencies of 10-200 kHz over the range of core widths typically used in power electronics, but α increases with gap length. Splitting the core into a number of subcores can therefore provide significant reductions in gap loss, especially with larger gap lengths. The results from a 300-A (peak), 200-A (continuous) inductor show that with three subcores and a gap length of 4 mm, the gap losses are reduced by 50%, and the hot-spot temperature is reduced by 24.5 °C. Using the technique it is estimated that the original inductor weight could be reduced by 40% with four split cores, making a significant impact on converter power density.