Three-Phase Interleaved LLC Converter with Integrated Magnetics for 48 V Output
The conventional three-phase LLC converter is disadvantageous in terms of numerous bulky magnetics. A novel magnetic structure is proposed which integrates three inductors and three transformers into one magnetic core. 600 V gallium-nitride (GaN) devices from Panasonic, and 80V GaN devices from EPC, Inc. are employed for the primary and secondary sides, respectively. By pushing the switching frequency up to 1 MHz, all the windings for the magnetic structure can be implemented with a four-layer printed circuit board (PCB) winding. An additional two-layer shielding can be integrated in the PCB windings to reduce CM noise. A 1 MHz, 3 kW, 400 V/48 V, three-phase LLC converter with the proposed magnetic structure is designed, as shown in Fig. 2., and high efficiency and a power density of 600W/inch3 are achieved.