Common Capacitor Multiphase LLC Converter with Passive Current Sharing Ability

Hongliang Wang, Yang Chen, Yajie Qiu, Peng Fang, Yan Zhang, Laili Wang, Yan Fei Liu, Jahangir Afsharian, Zhihua Alex Yang

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

In high-power applications, parallel operation is required to improve both efficiency and reliability. In an LLC converter, it is difficult to achieve parallel operation due to the gain sensitivity to component tolerance. This paper proposes a new structure of a common resonant capacitor for a multiphase LLC converter, which can achieve very good current-sharing performance with no additional components or control. To evaluate the current-sharing performance, a new first harmonic approximation (FHA) model is built in this paper to analyze the LLC converter with coupled resonant tanks. Both FHA analysis and powersim (PSIM) simulation results demonstrate the load-sharing improvement of the proposed common capacitor LLC resonant converter over the conventional two-phase LLC converter. The current-sharing performance from the FHA analysis and the PSIM simulation are compared, and the error of the FHA analysis is evaluated and explained. A 600 W two-phase LLC converter prototype based on the proposed method is also built to verify the feasibility. Excellent current-sharing performance (6% resonant current sharing error at a wide load range) has been achieved.

Original languageEnglish (US)
Article number7835689
Pages (from-to)370-387
Number of pages18
JournalIEEE Transactions on Power Electronics
Volume33
Issue number1
DOIs
StatePublished - Jan 2018
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017 IEEE.

Keywords

  • Current-sharing error
  • multiphase LLC
  • resonant converter

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