A Design Methodology for a CLLLC Bidirectional Resonant Converter with an Integrated Planar Transformer

Abstract:
The efficiency and power density of a bidirectional CLLLC resonant converter can be improved by integrating its magnetic components into a single transformer (known as integrated transformer). However, integrated transformers, especially integrated planar transformers, usually suffer from high parasitic capacitance. In the conventional design process of the CLLLC converter, the parasitic capacitance of the transformer is neglected while a high parasitic capacitance can affect the performance of the converter noticeably. Therefore, this paper presents a new design methodology for a bidirectional CLLLC resonant converter, which studies the effect of parasitic capacitance and guarantees ZVS conditions for the switches even when integrated planar transformers with high stray capacitance are used. Simulation results are presented to verify the theoretical analysis.