Simple equivalent circuit capacitance model for two-winding transformers

Christian Ostergaard*, Claus Kjeldsen, Morten Nymand

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


This paper highlights how a currently available transformer equivalent circuit model incorrectly represents the transformer performance, in scenarios where both sides of the transformer are fixed to a common reference-point. A new transformer equivalent circuit model is presented which accurately predicts the transformer performance. A thorough analysis of the proposed model and a commonly used model is compared and presented. Three foil-wound and three wire-wound transformers with different turns ratio are constructed, with the purpose of evaluating the accuracy of the transformer models impedance prediction. Both models accurately predict the transformer impedance for a turns-ratio equal to one. With turns-ratios different from one, the commonly used model predicts wrong impedance, whereas the proposed model remains accurate. The error in the predicted equivalent capacitance of the measurements is between 32%-170% when using the commonly used model, while it is only 0.6%-9.8% when using the proposed model. The proposed model is therefore the only model that provides accurate impedance analysis for any turns-ratio in any operation scenario.

Original languageEnglish
Title of host publication2020 IEEE Vehicle Power and Propulsion Conference (VPPC)
Number of pages6
Publication dateNov 2020
ISBN (Electronic)9781728189598
Publication statusPublished - Nov 2020
Event17th IEEE Vehicle Power and Propulsion Conference, VPPC 2020 - Virtual, Gijon, Spain
Duration: 18. Nov 202016. Dec 2020


Conference17th IEEE Vehicle Power and Propulsion Conference, VPPC 2020
CityVirtual, Gijon
SponsorAyuntamiento de Gijon, Catedra Gijon - Smart Cities, et al., Gijon, Gijon Convention Bureau, University of Oviedo
SeriesIEEE Vehicle Power and Propulsion Conference (VPPC)


  • DC-DC power converters
  • Equivalent circuits
  • Impedance measurement
  • Modeling
  • Parasitic capacitance
  • Transformers


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