Effects of secondary leakage inductance on the LLC resonant converter - Part II: Frequency control bandwidth with respect to load variation

Mostafa Noah, Tomohide Shirakawa, Kazuhiro Umetani, Jun Imaoka, Masayoshi Yamamoto, Eiji Hiraki

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Abstract

Resonant converters rely on a precise knowledge of leakage inductance of the equipped transformers. Resonant circuit topologies such as LLC usually utilize the transformer leakage as an inductive component in the resonant tank, allowing for a drastic reduction in the converter weight, size and volume. The existence of the secondary leakage inductance affects the whole operation of the LLC resonant converter. This paper reveals that placing the secondary winding near the air gap would increase the resonant tank input impedance, vertically shrink the voltage-gain curve of the converter, and consequently minimize the frequency range (i.e frequency bandwidth with respect to load variation). On contrary, placing the secondary winding in a close contact with the magnetic core would decrease the resonant tank input impedance, vertically stretches the voltage-gain curve of the converter, and widen the frequency variation range. It has been reported that the winding location with respect to the air gap has an impact on the leakage inductance value. In other words, placing the secondary winding in a close contact with the magnetic core (zero mmf position) would maximize the leakage energy storage originated from the secondary winding, and hence maximize the secondary leakage inductance and vice versa. The theoretical discussion is presented which is merely based on Ampere's law and Dowell's model. Furthermore, transformer prototypes had been constructed and tested in a 390V/12V-220W LLC converter prototype to evaluate the proposed analysis.

Original languageEnglish
Title of host publication34th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2019
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages1408-1414
Number of pages7
ISBN (Electronic)9781538683309
DOIs
Publication statusPublished - May 24 2019
Event34th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2019 - Anaheim, United States
Duration: Mar 17 2019Mar 21 2019

Publication series

NameConference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC
Volume2019-March

Conference

Conference34th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2019
CountryUnited States
CityAnaheim
Period3/17/193/21/19

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Keywords

  • Dc/dc converter
  • Leakage inductance
  • LLC resonant converter
  • Magnetic cores
  • Soft switching converters
  • Transformer

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

Cite this

Noah, M., Shirakawa, T., Umetani, K., Imaoka, J., Yamamoto, M., & Hiraki, E. (2019). Effects of secondary leakage inductance on the LLC resonant converter - Part II: Frequency control bandwidth with respect to load variation. In 34th Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2019 (pp. 1408-1414). [8722190] (Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC; Vol. 2019-March). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/APEC.2019.8722190