High-Frequency Three-Phase Interleaved LLC converter with Integrated Planar Magnetics for 400V/48V DC/DC Conversion

摘要

The LLC converter is the most suitabletopology as DC/DC converter in server and telecomapplications. To increase the output power and reduce theinput and output current ripples, three-phase interleavedLLC converter is becoming more and more popular. In thispaper, a high-frequency three-phase LLC converter withGaN devices and integrated magnetics is proposed. Theproposed three-phase LLC converter employsdelta-connected resonant capacitor network in primaryside to achieve automatic current sharing and full-bridgesecondary side due to high-frequency operation. A novelmagnetic structure is proposed to integrate three inductorsand three transformers into one magnetic core. By pushingswitching frequency up to 1MHz, all the magnetics can beimplemented with 4-layer PCB winding. Furthermore,additional 2-layer shielding can be integrated to reduce CMnoise. A 1MHz 3kW 400V/48V three-phase LLC converterwith proposed magnetic structure is designed, and peakefficiency of 98.7% and power density of 600W/inch~3 areachieved.