AC Resistance Reduction Using Orthogonal Air Gaps in High Frequency Inductors

Gabsu Seo, Satyaki Mukherjee, Yucheng Gao, Regina Ramos, Vivek Sankaranarayanan, Branko Majmunovic, Rahul Mallik, Soham Dutta, Brian Johnson, Dragan Maksimovic

Research output: Contribution to conferencePaperpeer-review

4 Scopus Citations

Abstract

This paper presents a relatively simple technique to reduce winding losses due to fringing fields in high-frequency inductors. In high-frequency power electronics, ac inductor winding losses are affected by skin and proximity effects, including uneven current distribution due to fringing magnetic fields around airgaps. It is well known how fringing effects can be mitigated using distributed airgaps, at the expense of non-standard core or winding geometry. The orthogonal-Airgap approach proposed in this paper combines airgaps in core segments parallel with the windings with airgaps in segments perpendicular to the windings. The approach is developed using a 1D analytical framework and validated by 2D finite-element simulations. Analytical guidelines are presented to optimize the airgaps to achieve minimum ac resistance. As a case study, a planar inductor is designed for an 8 kW SiC-based buck converter operating at 250 kHz. It is shown how the orthogonal airgaps result in more than 45% reduction in ac resistance and substantially reduced inductor losses compared to the design using standard airgaps. The results are verified by loss measurements on an experimental converter prototype.

Original languageAmerican English
Number of pages6
DOIs
StatePublished - 2019
Event20th IEEE Workshop on Control and Modeling for Power Electronics, COMPEL 2019 - Toronto, Canada
Duration: 17 Jun 201920 Jun 2019

Conference

Conference20th IEEE Workshop on Control and Modeling for Power Electronics, COMPEL 2019
Country/TerritoryCanada
CityToronto
Period17/06/1920/06/19

Bibliographical note

See NREL/CP-5D00-74060 for preprint

NREL Publication Number

  • NREL/CP-5D00-74631

Keywords

  • atmospheric modeling
  • conductors
  • inductors
  • magnetic cores
  • proximity effects
  • resistance
  • windings

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