PCB-based Magnetic Integration and Design Optimization for Three-Phase LLC

The LLC converter is the most efficient topology in server and telecom applications. Furthermore, three interleaved LLC converters have been shown to yield efficiency advantages at power levels of several kilowatts. The magnetic components of a multiphase LLC, on the other hand, are complex, laborious, and difficult to build cost-effectively. To solve these issues, a high-frequency GaN-based three-phase LLC converter is used in this research. With GaN working at 500 kilohertz, all magnetic components, including six inductors and six transformers, can be housed in a single structure, while all magnetic windings are accommodated in a 4-layer PCB with 3 oz. of copper. Furthermore, EMI can be improved by virtue of three-phase by 20 dB and additional two layers is added to gain additional 20-30 dB reduction from a low frequency up to 30 MHz. The proposed construction is simple and economically mass-producible. A 6kW 400V/48V 3-phase prototype is implemented, with a peak efficiency over 99% and a power density of 1000 W/in3 (61 kW/L).