A Novel Structure of LLC Integrated Planar Transformer for E-Bike Charger Application

EasyChair Preprint 11259

Abstract

The LLC resonant converter is one of the most popular isolated DC/DC converters in E-bike charger applications due to its simple control, wide voltage gain regulation capability, soft switching operation, and high power density. The synchronous rectification (SR) technology is applied in the converter, where the secondary side diodes are replaced with SR MOSFETs, considerably reducing the conduction loss of the secondary rectifier, and improving the system efficiency. Additionally, using a planar transformer for the converter helps achieve a low-profile configuration, high power density, and good heat dissipation capability. For 12V power charger applications, using low-voltage SR-MOSFETs offers the advantage of low ON-resistance, reducing terminal losses. However, for power charger applications from 60 - 70V, the current driving ICs are limited and the use of low-voltage SR-MOSFETs is no longer suitable due to the limitation of the breakdown voltage of switches. Therefore, in this paper, a new structure of LLC integrated transformer with planar cores is proposed for E-bike chargers with high output voltage (60 - 70V) that still uses low-voltage integrated SR-MOSFETs and driving integrated circuits (ICs). The proposed transformer has a very compact structure consisting of an integrated resonant inductor, SR MOSFETs, and output capacitors. An 800W LLC resonant converter prototype for E-bike charger applications was designed and tested.

Keyphrases: LLC converter, SR MOSFET, e-bike charger, planar transformer, synchronous rectification

@booklet{EasyChair:11259,
  author    = {Xuan Phuc Luong and Quang Huy Nguyen and Thanh Hai Phan and Duy Dinh Nguyen},
  title     = {A Novel Structure of LLC Integrated Planar Transformer for E-Bike Charger Application},
  howpublished = {EasyChair Preprint 11259},
  year      = {EasyChair, 2023}}