22 kW bidirectional on-board charger for V2X applications based on LLLC and buck converters

Min-Kyo Jeong; Jin-Su Kim; Bo-Gyeong Lee; Eui-Hoon Chung; Jun-Young Lee

22 kW bidirectional on-board charger for V2X applications based on LLLC and buck converters

Vol. 26, No. 3, pp. 720-733, Mar. 2026

10.1007/s43236-026-01283-7

LLLC converter

Bidirectional OBC

Zero voltage transition

Reverse inductor

Abstract

This paper proposes a bidirectional 22 kW OBC for V2X applications. The proposed OBC employs a three-stage topology consisting of an AC–DC inverter stage and a DC–DC stage including a bidirectional LLLC resonant converter and buck converter. The LLLC converter incorporates a reverse auxiliary inductor on the primary side and exhibits voltage-gain characteristics identical to those of an LLC converter regardless of the power transfer direction. This allows a design used in the easily controllable below-resonance region to be applied in both directions so that it can cope with a wide range of bidirectional loads even under fixed input voltage conditions. A bidirectional buck converter, which regulates the current for both charging and discharging operations, employs a ZVT (zero voltage transition) circuit to achieve soft switching and suppress switching surges. A comparative analysis of hard-switching configurations using SiC-FET and GaN devices is also presented. To verify the proposed circuit, a prototype rated for a three-phase 380 VAC input and a battery voltage range of 180–482 V was designed and tested. The results confirmed the validity of the proposed approach, achieving an efficiency exceeding 95% under bidirectional rated conditions without the need for additional complex algorithms, such as input-voltage variation or variable-structure control.

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Cite this article

[IEEE Style]

M. Jeong, J. Kim, B. Lee, E. Chung, J. Lee, "22 kW bidirectional on-board charger for V2X applications based on LLLC and buck converters," Journal of Power Electronics, vol. 26, no. 3, pp. 720-733, 2026. DOI: 10.1007/s43236-026-01283-7.

[ACM Style]

Min-Kyo Jeong, Jin-Su Kim, Bo-Gyeong Lee, Eui-Hoon Chung, and Jun-Young Lee. 2026. 22 kW bidirectional on-board charger for V2X applications based on LLLC and buck converters. Journal of Power Electronics, 26, 3, (2026), 720-733. DOI: 10.1007/s43236-026-01283-7.