A Three Phase CLLC Converter with Improved Planar Integrated Transformer for Fast Charger Applications
Jin Feng, Ahmed Nabih, Qiang Li, Fred C. Lee
Abstract
Increased attention is being paid to the solid-state-transformer (SST) based charging station which favors a high efficiency high density DC/DC stage. A two stage DC/DC converter with planer magnetics which consists of a three phase CLLC converter and four phase interleaving buck converters is proposed to achieve a wide output voltage range from 200 V to 800 V. In this paper, the detailed analysis of integrated transformer of three phase CLLC converter is discussed. A novel core structure is proposed to replace the 6-leg planar transformer core which can reduce core loss by 28%. A 12.5 kW prototype with over 98.59 % peak efficiency and 180 W/in3 power density is built to verify the feasibility of the proposed core structure.