Digital control strategy for dead‑time and synchronous rectification in GaN‑based LLC resonant converters

Yunsuk Oh; Jaehyeok Jang; Younghoon Cho

Digital control strategy for dead‑time and synchronous rectification in GaN‑based LLC resonant converters

Yunsuk Oh

Jaehyeok Jang

Younghoon Cho

Vol. 25, No. 9, pp. 1721-1732, Sep. 2025

10.1007/s43236-025-01098-y

LLC resonant converter

Abstract

This paper proposes a digital control scheme for dead-time and synchronous rectification (SR) in an LLC resonant converter. The proposed digital control scheme enables optimal zero voltage switching (ZVS), and accurate SR operation over a wide range of loads and operating frequencies. The system operation during dead-time is analyzed, and the turn-on and turn-off timing of the switches for SR are examined using time domain analysis (TDA). Based on these analyses, this study proposes a digital implementation for dead-time and SR control, and defines the control priorities within the overall scheme. To improve the control accuracy, a current transformer (CT) without additional components is incorporated into the resonant circuit to detect the current when the primary switch turns off. This method reduces circuit complexity and improves reliability compared to conventional methods. The proposed digital control scheme improves efficiency by up to 5.48% compared to a diode rectifier. The conduction time of the switches for SR demonstrates a minimum error of 0.05% compared to the experimental results.

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Cite this article

[IEEE Style]

Y. Oh, J. Jang, Y. Cho, "Digital control strategy for dead‑time and synchronous rectification in GaN‑based LLC resonant converters," Journal of Power Electronics, vol. 25, no. 9, pp. 1721-1732, 2025. DOI: 10.1007/s43236-025-01098-y.

[ACM Style]

Yunsuk Oh, Jaehyeok Jang, and Younghoon Cho. 2025. Digital control strategy for dead‑time and synchronous rectification in GaN‑based LLC resonant converters. Journal of Power Electronics, 25, 9, (2025), 1721-1732. DOI: 10.1007/s43236-025-01098-y.