Effective Permeability of Multi Air Gap Ferrite Core 3-Phase Medium Frequency Transformer in Isolated DC-DC Converters

Piotr Dworakowski, Andrzej Wilk, Michal Michna, Bruno Lefebvre, Fabien Sixdenier and Michel Mermet-Guyennet
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Piotr Dworakowski: Power Electronics & Converters, SuperGrid Institute, 69100 Villeurbanne, France
Andrzej Wilk: Faculty of Electrical and Control Engineering, Gdańsk University of Technology, 80-233 Gdansk, Poland
Michal Michna: Faculty of Electrical and Control Engineering, Gdańsk University of Technology, 80-233 Gdansk, Poland
Bruno Lefebvre: Power Electronics & Converters, SuperGrid Institute, 69100 Villeurbanne, France
Fabien Sixdenier: Univ Lyon, Université Claude Bernard Lyon 1, INSA Lyon, ECLyon, CNRS, Ampère, 69100 Villeurbanne, France
Michel Mermet-Guyennet: Power Electronics & Converters, SuperGrid Institute, 69100 Villeurbanne, France

Energies, 2020, vol. 13, issue 6, 1-21

Abstract: The magnetizing inductance of the medium frequency transformer (MFT) impacts the performance of the isolated dc-dc power converters. The ferrite material is considered for high power transformers but it requires an assembly of type “I” cores resulting in a multi air gap structure of the magnetic core. The authors claim that the multiple air gaps are randomly distributed and that the average air gap length is unpredictable at the industrial design stage. As a consequence, the required effective magnetic permeability and the magnetizing inductance are difficult to achieve within reasonable error margins. This article presents the measurements of the equivalent B ( H ) and the equivalent magnetic permeability of two three-phase MFT prototypes. The measured equivalent B ( H ) is used in an FEM simulation and compared against a no load test of a 100 kW isolated dc-dc converter showing a good fit within a 10% error. Further analysis leads to the demonstration that the equivalent magnetic permeability and the average air gap length are nonlinear functions of the number of air gaps. The proposed exponential scaling function enables rapid estimation of the magnetizing inductance based on the ferrite material datasheet only.

Keywords: average air gap length; dc-dc power converters; gapped magnetic core; magnetic permeability; magnetizing inductance; medium frequency transformer (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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