D02.8 - Impact of Asymmetrical Leakage Inductance on a 380 V-12 V LLC Converter with Synchronous Rectifier for DCX Application

Thursday, March 20, 2025

11:30 AM – 1:30 PM ET

Location: Level One, Hall A3

Technical Dialogue Presenter(s)

Jinshu Lin

University of Electronic Science and Technology of China

Presentation Paper

Co-Author(s)

SY

Shan Yin

University of Electronic Science and Technology of China
HL

Hui Li

University of Electronic Science and Technology of China
CS

Chen Song

University of Electronic Science and Technology of China
HZ

Honglang Zhang

University of Electronic Science and Technology of China
MD

Minhai Dong

University of Electronic Science and Technology of China
LX

Limei Xu

University of Electronic Science and Technology of China

The 380V-12V DC-DC converter utilizing an LLC resonant topology is a promising option for future data center architecture. To achieve high power density, the planar transformer is widely used with the leakage inductance as the resonance. Additionally, the magnetizing inductance is adjusted by introducing an air gap. However, this approach may disrupt the balance of leakage inductance distribution in the center-tapped (CT) transformer, leading to an asymmetrical operation of the synchronous rectifier (SR) at light load. This study investigates the impact of asymmetrical leakage inductance in a CT transformer for a 380V-12V LLC resonant converter with SR. A prototype of a 600-kHz, 250-W 380V-12V LLC converter has been implemented. Two planar transformers are designed with both EI and EE cores, and the assembling position of the PCB winding is also considered. It is concluded that the EE core with a symmetrical winding position is the optimal design. Two additional solutions with external or integrated resonant inductors are also suggested, providing valuable insights for future converter designs.