T02.8 - A 3.3kW OBC Design with 8.14kW/L Power Density and 97.97% Peak Efficiency Using an Integrated Transformer with Litz Wire

Tuesday, March 24, 2026

11:20 AM - 11:40 AM CT

Location: 214B

Technical Lecture Presenter(s)

Xuchen Sun

Huazhong University of Science and Technology

Presentation

Co-Author(s)

HC

Hao Chu

Huazhong University of Science and Technology
TL

Tianxi Li

Huazhong University of Science and Technology
EW

Enyou Wu

Huazhong University of Science and Technology
JG

Jiajia Guan

Huazhong University of Science and Technology
CC

Cai Chen

HuaZhong University of Science and Technology
WJ

Wei Jiang

GAC Aion New Energy Automotive Co., Ltd.
PW

Pengyang Wang

GAC Aion New Energy Automotive Co., Ltd.
BL

Bin Lai

GAC Aion New Energy Automotive Co., Ltd.

With the development of electric vehicles (EVs), the demand for high-efficiency, high-power-density on-board chargers (OBCs) is increasing. Traditional OBCs utilize a two-stage structure, which limits their efficiency and power density. Single-stage AC-DC topology has greater development potential due to their high efficiency, high power density, and the absence of large-capacity electrolytic capacitors with short life span. This paper designs a high-efficiency, high-power-density, 3.3kW single-stage OBC using SiC and GaN devices. The advantages and disadvantages of different magnetic integrated transformer using Litz wire windings are analyzed and compared, and a magnetic integrated transformer with high winding area utilization and low proximity effect losses is proposed. To address the large air gap in the resonant inductor which will cause large eddy current losses, a distributed air-gap magnetic circuit is designed to reduce eddy current losses. Finally, an experimental prototype with a peak efficiency of 97.97% and a power density of 8.14kW/L is designed to validate the effectiveness of the proposed magnetic integrated transformer.