Design of LLC Magnetically Integrated Transformer Based on Nanocrystalline Soft Magnetic Composite Leakage Core

Magnetic integration technology can reduce the printed circuit board (PCB) size of inductor-inductor-capacitor (LLC) converters. However, conventional methods for adjusting leakage inductance by modifying the transformer's air gap exhibit low sensitivity and limited output power capability. This paper proposes a novel magnetically integrated transformer structure that employs nanocrystalline soft magnetic composite (SMC) lamination to separate primary and secondary cores. Using SMC for the leakage core allows for more precise control of the magnetic flux division, enabling accurate leakage inductance tuning. Furthermore, this design achieves a higher magnetizing inductance per turn. Experimental results show that the proposed GU30 magnetically integrated transformer handles a primary input active power of 206.9 W, outperforming conventional designs while maintaining a full-load efficiency above 95%. This technology has the potential to further enhance the power density of power conversion products.