Performance evaluation of direct drive high voltage Gallium-Nitride devices in LLC series resonant converters

This paper focuses on performance evaluation of direct drive high voltage Gallium-Nitride (GaN) devices in a high frequency LLC series resonant converter (LLC-SRC). A comparison between synchronous drive and direct drive high voltage (HV) Cascode GaN device has been made. Zero reverse recovery charge and integrated protections make direct drive HV Cascode GaN device attractive to high frequency LLC-SRCs. Dead-time related design considerations of high frequency LLC-SRCs are also discussed. LLC-SRC prototypes using direct drive HV Cascode GaN device have been built. 97.7% peak efficiency is achieved with direct drive HV Cascode GaN device in a 390V to 12V conversion and over 400kHz switching frequency.