A WBG based three phase 12.5 kW 500 kHz CLLC resonant converter with integrated PCB winding transformer

The three phase resonant converter gains its popularity in high power areas like off-board charger due to its ability to reduce the current stress on devices and achieve higher efficiency. However, very few takes this advantage for the transformer integration to reduce the size of the magnetic components. In addition, by using wide-band-gap devices, the switching frequency of power electronics converters can be pushed to a much higher level, making it possible to implement Printed Circuit Board (PCB) transformer. In this paper, a novel 6-layer only PCB winding transformer is proposed for a three phase CLLC resonant converter. Not only all the resonant inductors are integrated into the transformer, but also the three phase transformers are integrated together so that the size of the magnetic component is significantly reduced. A 12.5 kW 500 kHz hardware prototype with over 97.3% efficiency and 155 W/in3power density is built to verify the feasibility of the proposed structure.