Design and magnetics optimization of LLC resonant converter with GaN

This paper presents the design and magnetics optimization of 1-kW regulated LLC resonant converter with GaN FETs. By adopting the GaN FETs for primary side switches, the gate driver loss and turn-off loss are significantly reduced. A new structure of integrated transformer with stacked planar cores, shaped windings and synchronous rectifier MOSFET proposed to reduce the core loss and winding loss. The proposed integrated transformer has highly compact structure including transformer, resonant inductor, SR MOSFET and output capacitor. A regulated 1-kW LLC resonant converter prototype is designed and tested. The peak efficiency can reach 97.4%.