Design of a Medium Frequency Transformer with High Insulation Level for Dual Active Bridge DC-DC Converter

Tianzhu Tang, J. A. Ferreira, Saijun Mao, Wenbo Wang, M. Ghaffarian Niasar

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

5 Citations (Scopus)

Abstract

This paper presents a medium frequency transformer with high insulation level design which is used for the DAB DC-DC converter. The transformer size is largely reduced when operating at medium frequency compared with conventional power frequency transformer which provides the possibility for higher power density. However, there is a trade-off between the high power density and thermal performance. First of all, the exposed cooling surface is reduced accordingly. And the dissipated heat is proportional to the exposed cooling surface directly. Secondly with higher frequencies, effects such as skin and proximity and hysteresis losses are significantly increased compared to transformer operation at 50/60 Hz. Besides the design process should consider high isolation requirement. And this again defects the transformer thermal performance and this is because firstly insulation material adds extra losses to the system, secondly the construction of the insulation will block some cooling surfaces and thirdly those insulation materials normally have relatively low thermal conductivity. As a consequence, the thermal design should be carefully considered and evaluated. To solve this problem, only the high voltage side winding is impregnated in epoxy resin which reduces the insulation material. The stacked transformer cores are gapped from each other which have helped the transformer heat dissipation. Such that, a design with low thermal resistance and high power density is achieved. FEM models are developed to analyze the transformer electric and thermal performances. Finally prototypes are built and tested to verify our design concept.

Original languageEnglish
Title of host publication2019 10th International Conference on Power Electronics and ECCE Asia (ICPE 2019 - ECCE Asia)
PublisherIEEE
Pages523-530
Number of pages8
ISBN (Electronic)978-89-5708-313-0
ISBN (Print)978-1-7281-1612-9
Publication statusPublished - 2019
Event10th International Conference on Power Electronics - ECCE Asia, ICPE 2019 - ECCE Asia: 10th International Conference on Power Electronics - Busan, Korea, Republic of
Duration: 27 May 201930 May 2019
Conference number: 10th

Conference

Conference10th International Conference on Power Electronics - ECCE Asia, ICPE 2019 - ECCE Asia
Country/TerritoryKorea, Republic of
CityBusan
Period27/05/1930/05/19

Keywords

  • High voltage
  • Isolation design
  • Medium frequency transformer
  • Thermal analysis

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